Heal the NIH, But Not By Chopping Off Its Arm

ASPET 2012: Affective Disorder

Chuck O’Brien-

-individual differences, power of a SNP
-1983: IND for naltrexone for human, based on suppression of alcohol seeking in rats
-naltrexone did not significantly change abstinence but measures of alcohol quantity reduced
-vivitrol (depot formulation) $800 per injection, monthly schedule…compliance is good though
-naltrexone effect driven by groups w/ high craving, highest family history “dose”…because they respond poorly to regular therapy (placebo groups high drinking compared w/ lower craving, less family history)
-OPRM1: 118 A>;G exon associated w/ increased beta-endorphin affinity
-enriched in Swedish populations Bart et al 2005
-G allele associated w/ increased alcoholism and opiate addiction
-o’Brien showed increased naltrexone response in the G allele subpopulation, Anton replicated in alcoholics (both retrospective analyses of banked blood samples)
-Heilig study- alcohol induced dopamine release (PET) highest in G allele carriers

Mark Geyer
-predicting treatment response in schizophrenia
-NIMH-MATRICS, spurred BigPharma to go after non psychotic, cognitive deficit therapy
MG: rush to clinical trials led to some disappointments, need more work at preclinical level
-overview of pre-pulse inhibition as model of sensory gating
-Braff Geyer and Swerdlow 2001 reviews populations tested for PPI deficits
-not present in ADHD for example
-PPI in rats predicts antipsychotic efficacy in clinical
-NIMH-MAtRICS 2002-2004- pathway for approving cog enhancers
-no treatments found yet…..
-Clozapine seems to have some positive effect on cognition, typical antipsychotics (D2 antagonists) don’t
-low PPI in C57Bl/6j vs 129/SvEv mice
-C57Bl/6j mouse as good model to test antipsychotics or other compounds w/o receptor tautology
-MG rightfully cautions about a popular preclinical approach of examining reversal of an effect caused by another drug. (Think scopolamine model if memory deficits)
-Median split on PPI in humans- clozapine only increases PpI in the low-PPI group, just like mouse strain comparison
-pregabalin study: humans and C57Bl/6j : same median split on baseline PPI, drug works in low but not high PPI subgroups
-low PPI “normal” humans may be a model for testing pro-cognitive drugs?

Kathy Cunningham
-serotonin receptor 2A and 2C homeostasis
-context: treatment for drug relapse
-impulsivity and cue reactivity as mediators of relapse liability
-these two phenotypes are “interlocked”
-KC focus is on cocaine users
-Ersche et al 2910, Moeller at al 2001 for background
-5HT2A antagonists and 5HT2C agonists improve impulsive action and cocaine cue reactivity
-target: “reprogram” the 2A/2C rheostat
-1-choice serial RT task to phenotype rats as high and low quartile for impulsive responding (premature responding, low accuracy)
-cocaine reinstatement uses forced abstinence rather than extinction
-NAcc receptor protein: 2A receptor protein higher in high impulsives, 2C protein levels lower.
-cue reactivity also associated- high reactivity >;;;; high 2A, low 2C in mPF
-Moeller work in cocaine using humans, 5HT2C SNP (loss of function) homozygous have elevated cocaine cue reactivity
-genetic knockdown of 2C in rat- shRNA
-premature responding in 1choice serial RT task higher in knockdown animals
-2A antagonist reversal of this deficit is produced at subthreshold dose for normals.

Rich de la Garza
-individual differences in human stimulant dependence
-he lives in the Phase Ib, Phase II zone
-developing new compounds and repurposing approved meds
-still no approved meds for cocaine or methamphetamine dependence
-large number of cocaine dependent have 20 yr histories, lifetime traumas and/or co-abuse other substances. 50% marijuana, for example
-therefore difficult to find a single medication
-modafinil decreased cocaine use only in non-alcohol comorbid patients
-Dackis et al 2012 showed sex split in efficacy for cocaine dependence
-N-acytl-cisteine for subjective high response to smoked methamphetamine
-NAC reduces high in males but not females
-meth users tend to be white, cocaine users tend to be black
-study (n=8) showed lower desire for methamphetamine primed by IV dose (unpublished)
-HR change is identical, other physiological responses similar
-Race and ethnicity may also contribute to medication response
-disulfiram (Antabuse) also works for cocaine, but effect stronger in high body weight cocaine abusers
-typically don’t do mg/kg dosing in human studies
-Modafinil improves working memory (n-back) in meth-dependent individuals, but only in low-performing part of the sample.
-even after 15-20 yr abuse patterns only some stimulant users exhibit impairment on (a given?) cognitive task
-“craving” is similarly variable, some w/ long history show very little craving
-there will be no magic bullet for addiction
-one size doesn’t fit all

Mike Nader
-leads with Anthony 1994 observation that conditional probability of cocaine dependence only 16%, this would kill any animal model
-advantages of Old World monkeys as the model
-d2-like receptor occupancy correlates with cocaine response rates, declines after a year of cocaine (similar to methylphenidate data shown by Porrino on Sun?)
-12 yr olds w/ in utero cocaine exposure
-similar on D2 measures on PET
-quinpirole-induced yawning higher in the prenatal exposed, correlated with maternal dose
-faster acquisition of cocaine self-admin, but similar intakes during maintenance
-Coc-exposed are more impulsive on delay-discounting
-cocaine-food choice procedure also reveals group differences, perhaps driven by a sub-group within the in utero cocaine exposure group
-reviews their dominant/subordinate story….

Interesting Stuff from SfN Day 1

So, Day 1 of the SfN meeting generated some interesting news from the cannabinoid front. First off:

A. STRAIKER, K. MACKIE, J. WAGER-MILLER, T. JAIN. Both dglα and dglβ regulate the production of 2-arachidonoyl glycerol in autaptic hippocampal neurons. (38.07/D22)

The current theory is that 2-AG (one of the two endogenous cannabinoids) is generated by an enzyme called diacylglycerol lipase alpha (a.k.a., DAGL alpha, DGL-alpha, etc). Alex and his group have found evidence that another enzyme, DAGL beta, also plays an important role in 2-AG production. Unfortunately, there aren’t any currently available drugs that can tease apart the contribution of these 2 enzymes. So? Turns out that DAGL alpha deletion may be a lethal mutation. Yeah, the medicinal chemists need to get busy.

The really interesting part is that (I think) Alex (may) believe that 2-AG is also a ligand for presynaptic receptor other than CB1. Did I weaken that statement too much? Alex very circumspect about these conclusions and he clearly wants to publish their data before he makes any public pronouncements, but the prospect is enough to make a cannabi-nerd drool. The Parsimony Principle would demand that 2 distinct endocannabinoid ligands with 2 distinct synthetic pathways and 2 distinct hydrolytic pathways would only evolve if they subserved 2 distinct functions. So? Stay tuned!

And, then:

F. S. DEN BOON, Q. SCHAAFSMA-ZHAO, T. R. WERKMAN, P. CHAMEAU, C. G. KRUSE, W. VAN AKEN, W. J. WADMAN. A CB2R-mediated Ca2+-activated Cl- current contributes to the stabilization of the membrane potential of layer II/III neurons of the rat prefrontal cortex (38.08/D16)

In the good ole’ days, like before 2006, we all believed that psychoactive properties of cannabinoids were exclusively attributable to activity at CB1 receptors and the immune-modulating functions of cannabinoids were exclusively attributable to activity at CB2 receptors. Alas, the good ole’ days may be gone. There is an emerging body evidence that CB2 receptors are also found on normal (i.e., non-inflamed) neurons in the brain. Sigh.

Femke den Boon presented some data on Saturday that suggests that 1) post-synaptic CB2 receptors can be found on neurons in the medial prefrontal cortex and 2) they’re activated by drugs like JWH-133 and HU-210. Femke also thinks that these compounds may be active at intracellular (nuclear??) sites. Hmmmmmmmmmm.

Mephedrone (4-MMC) at SfN on Sunday (11/13)

Program # 263.02/Poster # DD31

Presentation Title: Mephedrone: Behavioural characterisation reveals amphetamine-like effects in the mouse

Time: Sunday, Nov 13, 2011, 2:00 PM – 3:00 PM

Mephedrone is a substituted cathinone which saw a rapid increase in use as a ‘legal high’ in the UK in 2009-2010 until its regulation under the UK Misuse of Drugs Act. Mephedrone has an amphetamine-like structure, but its mechanism of action remains unclear. There are many anecdotal reports of its effects but few scientific studies. The aim of the present study was to characterise the behavioural effects of mephedrone in mice.
Synthesis of (±)-mephedrone hydrobromide was achieved using the method reported by Sutcliffe et al. (J Pharm Biomed Anal, 2011, in press) in 67% yield.
24 male C57 Black 6/J mice (Harlan, UK) 8-9 weeks, 23.3 ± 0.4g, were allocated to treatment with 1 or 5 mg kg-1 mephedrone or saline vehicle ip, and underwent a series of behavioural tests to study: the effects of mephedrone on locomotor activity (LMA); mephedrone’s dependence liability using a conditioned place preference (CPP) paradigm; and the effects of chronic (21 day) mephedrone treatment on bodyweight and on sensorimotor gating as measured by pre-pulse inhibition (PPI).
2-way ANOVA followed by Bonferroni post-hoc tests revealed a significant increase in LMA induced by 5 mg kg-1 (p<0.01), but not by 1 mg kg-1 mephedrone. There was no effect of treatment on entries into or time spent in the open field centre square, suggesting no anxiety-like effects. In the CPP, pairing with mephedrone did not significantly shift the preference for the drug-paired side (% change in time spent in drug-paired side: veh 6.2 ± 4.9; mephedrone 1 mg kg-1 1.6 ± 4.8; 5 mg kg-1 3.3 ± 5.7). Thus we were unable to condition a place preference for mephedrone using a paradigm and mouse strain in which we have previously shown a place preference for d-amphetamine 1 mg kg-1. PPI was not significantly altered by chronic mephedrone at either dose 48 h or 2 weeks after the last drug treatment. Mice receiving daily 5 mg kg-1 mephedrone, unlike saline-treated animals, failed to gain weight over the first 12 days of chronic treatment (0.1 ± 1.7% increase vs 4.1 ± 0.8%, just missing significance, p= 0.085), with intermediate weight gain in 1 mg kg-1-treated mice. Weight gain was recovered during days 13-15.
These data indicate some amphetamine-like effects of mephedrone – increased locomotor activity and weight loss – but mephedrone appears rather less potent. The data show no detectable rewarding properties at the doses used and no psychosis-like disruption of sensorimotor gating after chronic treatment. Studies are under way in our laboratory to examine the mechanism of action of mephedrone and its derivatives

SfN Poster Priorities (11/12/11)

There are several posters that I don’t want to miss during the first day of SfN 2011. First up, a series of posters on learning and memory, especially associative memory. These are obviously of interest because of our current associative memory projects with the monkeys 

1)

Program#/Poster#:        97.07/WW22

Presentation Title:         Posterior cingulate cortex is critical for associative learning

Presentation Time:       Saturday, Nov 12, 2011,3:00 PM – 4:00 PM

Abstract:                      Anatomical and neurophysiological evidence suggest a role for posterior cingulate cortex (CGp) in learning and memory. CGp is situated at the intersection of brain systems involved in visual orienting, emotional processing, and memory, indicated by its connections to parietal cortex, orbitofrontal and anterior cingulate cortex, and the medial temporal lobe (MTL), respectively. Moreover, CGp hypometabolism is closely linked to early cognitive deficits in Alzheimer’s Disease. Despite this evidence, the precise contributions of CGp to learning and memory remain unclear. Some models posit a role for CGp in associative learning, others proffer a more prominent role in valuation, while still others focus on a role for CGp in long-term memory.
To distinguish amongst these possibilities, we studied the relationship of neuronal activity in CGp to learning and memory in monkeys performing a variant of the location-scene association paradigm. On each trial, monkeys saw a neutral scene photograph, then shifted gaze to one of two targets for liquid reinforcement. The correct target for each scene initially had to be learned by trial and error, and subsequently recovered from long-term memory to sustain performance. We included both highly familiar reference scenes and scenes novel for each session, as well as both high and low value scenes.
After monkeys had learned the basic task, we recorded the activity of single CGp neurons and then, in separate sessions, reversibly inactivated tissue in this region with muscimol. Firing rates of single CGp neurons were modulated during the task in ways relevant to learning. Most CGp neurons showed a prominent error signal following incorrect choices. This error signal was larger for new scenes than for previously learned reference scenes. CGp firing rates over the course of the session tracked global learning rate. Finally, muscimol injections significantly impaired learning, but performance on previously-learned scenes was unaffected. Notably, learning of high-value scenes was also unaffected during muscimol inactivation. These results provide strong evidence that CGp functionally contributes to associative learning but not to the storage or retrieval of information from long-term memory.

2)

Program#/Poster#:        99.15/WW66

Presentation Title:         Mitigated effects of methylphenidate on visual working memory in the macaque monkey

Presentation time:         Saturday, Nov 12, 2011,3:00 PM – 4:00 PM

Abstract:          Catecholamine neurotransmission has been implicated as a critical factor in the operation of numerous cognitive functions, including working memory (WM). The psychostimulant drug methylphenidate (MPH) – commonly used to treat Attention Deficit Hyperactivity Disorder and potentially a drug with cognitive enhancing capabilities – has been shown to produce dose-dependent changes in WM performance in both humans and animals, via combined actions at dopamine D1 and noradrenergic α2 receptors. In general, the dose-dependency of these effects conforms to an “inverted U” function, with optimal doses leading to performance enhancements, and doses above and below this level producing minimal effects or performance decrements. Most studies investigating the effects of MPH on WM in animals have employed delayed-response tasks requiring the retention of a single memorandum. Consequently, little is known of the effects of MPH on WM at higher memory loads. Characterization of the effects of MPH across the range of operation of WM is critical to fully establish the link between catecholamine transmission and changes in WM performance. To address this, we employed a psychophysical approach in which WM performance was evaluated over a range of loads and MPH doses. Female rhesus macaque monkeys performed a sequential comparison task which required them to identify the location of a color change within an array of 2 to 5 colored squares following a retention interval (Heyselaar et al., 2011). We compared the proportion of correct responses and response latencies between sessions in which MPH (0.5 – 9.0 mg/kg) was orally administered, and control sessions in which no drug was given. We predicted that MPH would affect WM performance in a dose-dependent manner, with optimal doses leading to an increased proportion of correct responses and shorter response latencies relative to control sessions, and doses above or below this level producing either no or opposite effects. We further reasoned that such effects would scale with memory load due to the increased demands on WM resources at higher loads. Contrary to these predictions, no effects of MPH on the proportion of correct responses were observed at any WM load at any of the doses tested. MPH produced variable effects on response latencies, with the most consistent observation being a general increase at higher doses. These data suggest that the effects of MPH on WM performance are limited, regardless of memory load.

3)

Program#/Poster#:        100.03/XX6

Presentation Title:         NAcc neurons’ inhibition during reversal learning: A pharmacological and an optogenetic approach.

Presentation time:         Saturday, Nov 12, 2011,3:00 PM – 4:00 PM

Abstract:                      Purpose: The aim of this study was to understand the contribution of NAcc cells in reversal learning performance by using two approaches. First, inhibition of NAcc cells using a Gaba-a agonist (Muscimol). Second, inhibition of NAcc cells using light-sensitive opsins (halorhodopsin). The prediction from this investigation was that neuronal suppression of NAcc neurons would have a greater impact on reversal learning performance in a within-session reversal than in a between session. Methods: Rats (Muscimol group) (n=10) were implanted with bilateral guide cannulae above the NAcc. Another group of rats (n=6) received injections of lentivirus (halorhodopsin) in the NAcc, and were implanted with a fiber guide system that would deliver a yellow light to target neurons via an optical fiber. After surgery, rats were trained to complete an FR1 discrimination, and then tested in a between reversal and a within session reversal task. Results: NAcc implanted rats that received muscimol injections made significantly fewer errors during the between reversal session than the control group (saline, n=5): F (1, 9)=42.885, p<0.001. NAcc rats also took significantly longer than the control group to reach criterion: F(1,9)=4.933, p<0.05. However, NAcc rats made significantly more errors than the control group during the more complex within session reversal F(1,9)=7.031,p<0.05. Conclusion: Our preliminary results suggest that NAcc neurons play an instrumental role in reversal learning performance, especially when task complexity increases. Using optogenetics, we will be able to more precisely define what the function of NAcc neurons during reversal performance is (1:before bar pressing, 2: when an error is made, or 3: between choosing the right lever and collecting reward).

Then, there a few cannabinoid-related posters that I’ve got to see.

1)

Program#/Poster#:        38.08/D21

Presentation Title:         Both dglα and dglβ regulate the production of 2-arachidonoyl glycerol in autaptic hippocampal neurons

Presentation time:         Saturday, Nov 12, 2011,4:00 PM – 5:00 PM

Abstract:                      Cannabinoids are part of an endogenous signaling system consisting of cannabinoid receptors and endogenous cannabinoids (eCBs) as well as the enzymatic machinery to produce and break down these eCBs. Depolarization-induced suppression of excitation (DSE) is a form of cannabinoid CB1 receptor-mediated inhibition of synaptic transmission that involves the production of the eCB 2-arachidonoyl glycerol (2-AG). The role of diacylglycerol lipase (DGL) in the formation of 2-AG during depolarization is controversial: hippocampal DSI is absent in DGLα knockout mice, yet DGL inhibitors do not always block DSI. Furthermore, the two isoforms of DGL, DGLα and DGLβ are impossible to distinguish by available pharmacological tools. Of these DGLα has received considerable attention in 2-AG production. What role, if any, might be played by DGLβ remains largely unexplored. Autaptic hippocampal neurons are well-suited to a comparative study of the roles of these enzymes in mediating the robust endogenous DSE present in these cultured neurons under controlled conditions.
To investigate the importance of DGLα and DGLβ for 2-AG production in DSE we developed siRNA constructs for each enzyme. We found that our constructs reduced expression of these proteins by 70% and 72% in DGLα- and DGLβ-expressing HEK293 cells, respectively. We then used these constructs to knockdown DGL expression in autaptic hippocampal neurons.
We find that knockdown of DGLα results in a substantial reduction of DSE, shifting the ‘depolarization response curve’ from an EC50 value of 1.6 sec to 6.4 sec (non-overlapping 95% confidence intervals). Interestingly, DGLβ diminishes DSE as much or more (EC50 54.8 sec, non-overlapping CI), suggesting that DGLβ is responsible for a portion of 2-AG production in autaptic neurons. In separate experiments we confirmed that siRNA for each DGL did not reduce the expression of the other DGL in HEK293 cells.
We conclude that both DGLα and DGLβ play a role in endogenous cannabinoid modulation of synaptic transmission. Our results identify DGLβ as a new potential target for modulation of the cannabinoid signaling system.

2)

Program#/Poster#:        91.08/VV4

Presentation Title:         Executive function, the endocannabinoid system and the default mode network

Presentation time:         Saturday, Nov 12, 2011,4:00 PM – 5:00 PM

Abstract:                      Introduction. The term executive function describes a set of high level cognitive functions that are essential for goal directed behavior, such as the ability to monitor, change and plan behavior as needed. Behavioral studies suggest involvement of the endocannabinoid (eCB) system in executive function [1]. The eCB system acts as a neuromodulatory system through regulation of both excitatory and inhibitory neurotransmission [2]. We used fMRI to investigate eCB involvement in executive function, by measuring the effect of eCB perturbation on task performance, task activity, including default mode network (DMN) activity.
Methods. A pharmacological MRI study was conducted with a placebo-controlled, cross-over design, investigating the effect of the eCB agonist Δ9-tetrahydrocannabinol (THC) on brain function. 20 healthy volunteers performed a continuous performance task with identical pairs [3]. Brains scans were acquired using a Philips Achieva 3.0 T scanner (TR 22.5 ms; TE 33.2 ms; flip angle = 10°; FOV 224×256×160; matrix 56× 64×40; scan time 0.6075 s; 40 slices (sagittal orientation)). Effects of eCB were measured in a set of activated as well as deactivated regions.
Results. After THC administration subjects showed, among other effects, an increase in VAS score of ‘feeling high’ (F(1,19) = 19.10, p < 0.001), and reduced ‘alertness’ (F(1,19) = 9.24; p = 0.007). Task performance was impaired after THC administration, (t = 2.93; p= 0.008). This was associated with elevated activity in the set of deactivated brain regions (F = 13.20; p < 0.002), including posterior cingulate gyrus and angular gyrus. In addition, activity in this network was negatively correlated with task performance after THC administration (r = -0.43, p = 0.03). Positively activated regions, notably prefrontal and parietal cortex, did not show any effects of THC (F = 0.004; p = 0.95).
Conclusion. THC administration caused impairment in task performance as well as reduced deactivation in a set of brain regions that have been linked to the DMN, while regions that were activated by the task were unaffected. These results suggest involvement of the eCB system in regulation of DMN activity, and indicates that executive function can be negatively impacted by a challenged eCB system, through insufficient deactivation of the DMN. Results point to the possibility of involvement of the eCB system in impaired executive function, as found in psychiatric or neurological disorders.

3)

Program#/Poster#:        102.09/XX52

Presentation Title:         Epigenetic modulation of endocannabinoid-dependent extinction of fear memories

Presentation time:         Saturday, Nov 12, 2011,1:00 PM – 2:00 PM

Abstract:                      Treatment of post-traumatic stress disorder, phobias, and panic disorder often rely upon progressive extinction of fear memories, where the fear-inducing stimulus is presented repeatedly without negative consequence. Previous reports indicate that that the endocannabinoid system is essential for the extinction of learned fear. Global genetic deletion of the cannabinoid 1 receptor (Cb1) in a mouse model system blocks extinction learning. Administration of a Cb1 antagonist in wild-type mice prior to extinction learning similarly blocks extinction learning (Marsicano 2002). Additionally, Barad and colleagues demonstrated that broad, non-specific HDAC inhibition enhances emotional learning and extinction of conditioned fear (Bredy et al., 2007; Bredy and Barad, 2008). We have several goals: 1) if extinction learning can be blocked with administration of a Cb1 antagonist, we predict that we can enhance extinction with a compound that augments endogenous cannabinoid tone, and 2) if extinction learning can be enhanced with a broad, non-specific HDAC inhibitor, we propose that a relatively specific HDAC inhibitor, RGFP963, will also augment extinction of conditioned fear.
To test this hypothesis, fear conditioned mice were systemically infused with URB597, the fatty acid amide hydrolase inhibitor, and/or RGFP963 during fear extinction training. We have found URB597 enhances within-session extinction compared to vehicle (p<.05) and RGFP963 enhances extinction retention. We are additionally examining whether approaches that enhance within-session extinction (URB597) and those that enhance consolidation of extinction (RGFP963) are complementary and thus potentially additive in their overall effects. These data suggest that HDAC inhibitors and compounds modulating the endocannabinoid system effectively enhance the extinction of fearful memories, and may provide further understanding of mechanisms and potential drug targets that may enhance behavioral therapy treatment of fear and anxiety/panic-related disorders.

SfN Posters (updated 11-14-2011)

103.04/XX61: Voluntary wheel running throughout rearing in the rat alters baseline monoamine content and content levels in response to cocaine in brain regions that mediate motivation. Location: Hall A-C; Saturday, Nov 12, 2011, 4:00 PM – 5:00 PM. Authors: *J. C. BASSO, J. W. CALLAHAN, A. M. FARRAR, E. D. ABERCROMBIE, J. I. MORRELL; Rutgers Univ., Newark, NJ

Abstract: Voluntary wheel running (VWR) is a motivated behavior in rodents, suggested by the facts that rats run voluntarily with great vigor, lever press for access to a wheel, and develop a conditioned place preference (CPP) for a place associated with the wheel or the aftereffects of wheel running. VWR decreases anxiety- and depression-like behaviors, improves attention, learning, and memory, and decreases consumption, self-administration, and CPP for drugs of abuse, including cocaine. VWR is reported to alter neurotransmitter content in brain regions that mediate voluntary movement and motivation, but there is limited research on the effects of VWR throughout rearing. We investigated the effects of VWR throughout rearing on monoamine content in regions involved in motivation, voluntary movement, and regulatory functioning. At weaning (p21), one group of female rats was housed with a running wheel, another in standard cages; all groups had food and water ad libitum. At adulthood (p65), rats were injected IP with either saline or 5.0 mg/kg cocaine; 30 minutes later they were decapitated and their brains were removed, frozen, sectioned on a cryostat, and punch dissections were taken from the ventral tegmental area (VTA), nucleus accumbens core (NAc) and shell (NAs), medial prefrontal cortex (mPFC), caudate putamen (CP), and medial preoptic area (mPOA). The tissue samples were processed and analyzed for content of dopamine (DA), serotonin (5HT), norepinephrine (NE), and their metabolites (DOPAC, HVA, 5-HIAA) using high performance liquid chromatography (HPLC). VWR throughout rearing altered monoamine and metabolite content, increasing levels of DA, NE, DOPAC, and HVA in the CP, 5-HIAA in the mPFC, DOPAC in the VTA, and DOPAC in the mPOA while decreasing DA in the mPOA. Cocaine without any wheel running experience had no effect except to decrease DA levels in the mPOA; surprisingly, VWR animals showed a robust cocaine response with decreased levels of NE, DOPAC, and HVA in the VTA and NE, 5HT, and DOPAC in the MPOA, and increased levels of 5HT in the NAs. Since plasma levels of cocaine and its major metabolites at 30 minutes post-injection were similar between rats raised with and without a wheel, differences in peripheral metabolism of cocaine cannot explain any of the differences. Interestingly, these two groups also showed a similar CPP for 5.0 mg/kg cocaine. These data suggest that VWR throughout rearing alters central monoamine content and the central but not peripheral or behavioral response to cocaine at adulthood, which suggests a variety of potential changes, some unexpected, in the neuronal functioning of animals raised with VWR compared to their sedentary counterparts.

Summary: I had the pleasure of meeting Dr. Joan Morrell and she was enthusiastic to hear about our work on exercise and meth SA. She sent me a PDF of the poster, and Julia Colette from her lab will attend Brittani’s poster on Wednesday.  In their study, rats were group housed (3-4 per cage) with toys and an activity wheel available 24-hrs per day from ages 18-21 days. CPP training assessed a range of doses of cocaine from ages 65-85 days. CPP was reduced in wheel-running rats at the 0.5 mg/kg dose, but not at higher doses. They speculate that the early wheel experience plus low initial doses produced reduction in CPP. As dose increased, CPP became more prevalent.

372.19/LL18: Running wheel exercise ameliorates methamphetamine-induced damage to striatal dopamine terminals. Location: Hall A-C. Monday, Nov 14, 2011, 10:00 AM -11:00 AM. Authors: *S. J. O’DELL, A. J. BALL, B. A. GALVEZ, J. F. MARSHALL; Dept Neurobiol & Behav, Univ. of California, Irvine, Irvine, CA.

Abstract:Previous research has shown that exercise can promote recovery of motor function and lessen dopamine terminal injury resulting from 6-hydroxydopamine, MPTP, or methamphetamine (mAMPH) administration. An important unresolved issue in this field is whether exercise protects against the initial neurotoxic insult or accelerates recovery from partial dopaminergic damage.
Repeated mAMPH administration to rodents in a single-day “binge” dosing regimen produces long-lasting damage to forebrain dopaminergic nerve terminals that spontaneously recovers over the course of approximately one year. We previously showed that voluntary aerobic exercise in rats could alter the damaging effects of a neurotoxic mAMPH binge. In our initial experiments, adult male Sprague-Dawley rats were allowed to run in 1-meter circumference wheels or kept in home cages for 3 weeks, then given an acute binge regimen of mAMPH (4 mg/kg, sc, at 2 hr intervals for a total of 4 injections) or SAL (4 x 1 ml;/kg, sc). After these injections, the rats were replaced into their original environments (wheels or no wheels) for an additional 3 weeks, then sacrificed for autoradiographic determination of the levels of dopamine transporters (DAT) in the striatum. The data showed that binge mAMPH treatment produced regionally specific decreases in striatal DAT, with the greatest damage occurring in ventral caudate-putamen (CP) and relative sparing of the nucleus accumbens. Exercise significantly blunted the mAMPH-induced CP DAT losses.
To help resolve the issue of whether exercise protected against the mAMPH-induced injury or accelerated recovery from it, rats were allowed to run in wheels for 3 weeks prior to a neurotoxic mAMPH binge (or SAL), then placed into non-wheel cages for an additional 3 weeks post- mAMPH-administration. The resulting autoradiographic data showed a trend towards amelioration of mAMPH-induced induced DAT loss in the CP, relative to sedentary animals given mAMPH. These data suggest that prior running provides some protection against mAMPH-induced neurotoxicity. Although the mechanism of this neuroprotection is still being investigated, we have found that protection is not due to a decrease in mAMPH-induced hyperthermia during the binge injection regimen. Overall, our data show that exercise is an important variable in determining vulnerability to mAMPH-induced neuronal damage; consequently, voluntary exercise may be useful as therapeutic adjunct in the treatment mAMPH addicts.

Summary: In this study, groups of rats had 3 weeks of wheel access or no wheel access (control) followed by a METH neurotox regimen. Then, all rats had no access to a running wheel, and all brains were analyzed for DAT and CERT depletion. They found that rats with running wheel experience had less DAT and CERT depletion, but the results were not significanly significant because they lost a good number of rats during the neurotox regimen. They measured and found no change in hyperthermia (control vs wheel rats) at 22C. Procedural detail: rats running increased steadily across a 21-day period, up to ~7km/day. Looks like running distance would have continued to increase if rats were given the opportunity.

04.01/VV80: The protective effect of exercise against learned helplessness persists after forced cessation of exercise. Location: Hall A-C. Monday, Nov 14, 2011, 1:00 PM – 2:00 PM. Authors: *A. B. LOUGHRIDGE1, B. N. GREENWOOD2, N. C. SADAOUI2, E. R. WOODRUFF2, M. FLESHNER2; 1Integrative Physiol., BOULDER, CO; 2Integrative Physiol., Univ. of Colorado, Boulder, CO.

Abstract: Exposure of rats to an uncontrollable stressor produces behavioral consequences that resemble symptoms of human anxiety and depression. These behaviors are known as learned helplessness and include exaggerated freezing, deficits in shuttle box escape, and reductions in social exploration. Learned helplessness behaviors are dependent upon hyperactivation and sensitization of serotonin neurons in the dorsal raphe nucleus (DRN). Six weeks of voluntary wheel running constrains activation of serotonin neurons in the DRN and protects against learned helplessness behaviors. It is unknown, however, how long the protective effect persists after cessation of physical activity. Voluntary wheel running produces neural plasticity within the DRN itself, at DRN afferent sites, and at DRN projection sites. Exercise-induced adaptations within these sites may confer ongoing protection against the behavioral consequences of exposure to an uncontrollable stressor, regardless of the exercise status of the rat. The aim of the current study was to determine the duration of the protective effect of exercise against learned helplessness behaviors after forced cessation of voluntary wheel running. Male Fisher 344 rats (n=9-20/grp) remained sedentary or were allowed voluntary access to running wheels for six weeks. At six weeks, wheels remained mobile or were locked. Rats in the locked group had wheels rendered immobile for five, ten, or fifteen days before behavioral testing. Behavioral testing occurred 24 hours after exposure to stress or uncontrollable tail shock. Social exploration of a juvenile, freezing, and shuttle box escape behaviors were measured. Studies are ongoing, but preliminary data indicate that the protective effect of wheel running against learned helplessness behaviors persists for at least five days after forced exercise cessation. A partial protection against learned helplessness behaviors was observed ten days following exercise cessation. These data suggest that six weeks of wheel running produces changes in stress responsive neurocircuitry that persist and endure following forced cessation of exercise.

Summary: missed this one.

#: 412.08/AAA17 Chronic exercise exerts anxiolytic-like effects and promotes active defensive  behaviors despite repeated pharmacological stress. Hall A-C. Monday, Nov 14, 2011, 11:00 AM -12:00 PM  Authors: *N. R. SCIOLINO1,3, R. K. DISHMAN3,2, P. V. HOLMES1,3;1Psychology, Univ. of Georgia, ATHENS, GA; 2Kinesiology, Univ. of Georgia, Athens, GA;   3Neurosci. Program, Biomed. and Hlth. Sci. Inst., Athens, GA.

Abstract: Exercise reduces anxiety in humans. However, it is uncertain whether exercise is anxiolytic in animal models because it also enhances some defensive behaviors. It is also unclear how stress influences the anxiolytic profile of exercise. We tested the hypothesis that exercise would enhance adaptive responding in behavioral tests of acute anxiety and mitigate the effects of chronic pharmacological stress. Rats were housed in the presence or absence of a running wheel for 21 d and concomitantly received either no injections or repeated intraperitoneal injections of vehicle or the benzodiazepine receptor inverse agonist FG7142 (7.5 mg/kg per d on last 10 d of running). Anxiety-like and defensive behaviors were assessed in the defensive withdrawal (DW), shock probe defensive burying (SPDB), and elevated plus maze (EPM) test the day following the last injection. Injections did not alter voluntary wheel running, as all rats similarly increased running distance across the first 7-10 days and ran ~6 km/d thereafter. Consistent with anxiolytic effects of exercise, rats allowed to run spent less time burying in the SPDB and exhibited increased open arm time and entries in the EPM compared to sedentary rats. Similarly, exercise facilitated locomotor habituation in the DW test; exercise rats were not initially (first 5 min of test) different in distance traveled in the DW test, but later (last 10 min of the test) exhibited reduced distance traveled relative to sedentary rats. Consistent with exercise enhancing active defensive responding, rats allowed to run exhibited a faster onset of burying and greater frequency of probe returns and bites in the SPDB. Chronic treatment with FG7142 did not alter behavior in the DW compared to vehicle. However, chronic FG7142 treatment increased open arm time and entries in the EPM and decreased immobility time in the SPDB relative to vehicle. The “stress” of injection did not reliably affect these measures, as rats not receiving injections were similar to those injected with vehicle. The results suggest alterations in emotion rather than locomotion or pain sensitivity, as neither exercise nor FG7142 altered the initial distance traveled in the DW, number of closed arm entries in the EPM, or onset of initial probe contact and shock reactivity in the SPDB. The data caution against interpreting exercise-induced increases in defensive behavior as anxiogenic, and they further support the conclusion that a chronic exercise regimen produces beneficial effects on anxiety.

Summary: Rats were given 24-hr access to running wheel for 21 days (daily running distance increased steadily across this time period up to ~5 km/day) followed by an injection stress paradigm (acute or chronic injections FG7142). They assessed defensive withdrawal & burying, maze behavior, and shock probes. They found that exercise combined with stress produced anxiolytic-like behaviors and increased defensive behaviors. These were male SD rats; 2 months old.

504.02/VV81: The role of exercise controllability in exercise-induced stress resistance Location: Hall A-C. Monday, Nov 14, 2011, 2:00 PM – 3:00 PM. Authors: *K. SPENCE, B. N. GREENWOOD, D. M. CREVLING, J. M. RIGALI, M. FLESHNER; Fleshner Lab., Boulder, CO.

Abstract: Exercise increases stress resistance and reduces the incidence of stress-related mood disorders, such as depression and anxiety. In rats, voluntary access to a running wheel for 6 wk produces similar protection against the behavioral consequences of inescapable stress; which resemble depression and anxiety. Although voluntary, or controllable, exercise clearly increases stress resistance, whether or not forced, or uncontrollable, exercise confers similar stress-buffering effects is unknown. Results of prior rodent studies employing forced treadmill training or swimming suggest that forced exercise does not increase stress resistance, and is itself anxiogenic. These studies, however, are difficult to interpret because these types of forced exercise introduce additional stressors, such as foot shock or water exposure. To determine if the protective effects of exercise against the depression- and anxiety-like behavioral consequences of inescapable stress are dependent upon the controllability of exercise, young adult, male F344 rats were divided into the following groups (n=9/grp): sedentary, treadmill training (TT), controllable wheel running (CW), and uncontrollable wheel running (UW). Rats in the TT group were forced to run on a progressive schedule (up to 1 hr/day) known to produce fitness benefits and were motivated by foot shock. Rats in the CW group were allowed voluntary access to running wheels. Rats in the UW group were placed into motorized wheels that were forced to rotate on a schedule closely matching the pattern (speed, duration, distance, and frequency) of voluntary activity. Rats in the UW group were forced to exercise, but additional stressors were not necessary to motivate the animals to run. All rats exercised 5 days / wk for 6 weeks during the active cycle. Running distance, food intake, and body weight were measured throughout the study. Following 6 wk of these exercise conditions, rats either remained in their home cages or were exposed to inescapable stress. Social exploration, fear conditioning, and shuttle box escape learning were assessed the following day. Although CW prevents stress-induced behaviors, preliminary data indicate that TT does not prevent the behavioral consequences of uncontrollable stress. The effect of UW on behavior is currently being investigated. The results of these studies will provide insight into the mechanism by which the experience of exercise is communicated to the brain, and can inform the design of exercise programs designed to maximize stress resistance.

Summary: In addition to the above, they did another study: they created a simulated “forced” exercise regimen based on naturalistic running patterns of rats given unlimited access to a running wheel, which shows bouts of running interespersed with periods of non-running. The rats were “forced” to run according to this schedule (by locking and unlocking the running wheel): both voluntary and forced regimen blocked behavioral deficits. They also lesioned the mPFC; similar effects in both groups. 

89.10/KK1: 96-hour methamphetamine self-administration in rats: A novel model of human drug addiction. Location: Hall A-C. Tuesday, Nov 15, 2011, 2:00 PM – 3:00 PM. Authors: *E. M. CORNETT, C. D. SCHMOUTZ, G. F. GUERIN, N. E. GOEDERS; Pharmacology, Toxicology, Neurosci., Louisiana State Univ. Hlth. Sci. Ctr., Shreveport, LA.

Abstract: In 2009, the economic cost to society of methamphetamine use was estimated at $16.2-$48.3 billion. Additionally, methamphetamine addiction is associated with crime, violence and deviant and risky sexual behavior. In the laboratory, methamphetamine addiction is typically modeled using non-contingent drug injections and/or 2 hr or 6 hr access self-administration sessions. While these models have increased our understanding of both the molecular and behavioral intricacies of methamphetamine addiction, they can be improved by more closely modeling human drug usage, which was the goal of these experiments. Human methamphetamine users typically follow a binge-pattern of 3-15 days of continual drug use, followed by a 1-3 day “crash” period of continuous sleep, and then they repeat the cycle. Of additional importance are potential gender differences associated with methamphetamine use since there are few reports of the effects of methamphetamine on female rats, especially using a binge paradigm. Male and female adult Wistar rats were implanted with jugular catheters and allowed to recover from surgery. The rats were placed in self-administration chambers and trained to self-administer methamphetamine with free access to water and fed 1x per day for 96 consecutive hours. Blood samples were drawn before, during and after the 96-hour session to monitor corticosterone, ACTH and testosterone. Estrous cycle fluctuations were also monitored in the female rats. Both male and female rats displayed shifts in their circadian rhythms (more drug intake during their normally inactive periods compared to their active periods), and interestingly, significantly decreased corticosterone and ACTH levels during the first 96-hour session relative to baseline that then increased back to baseline during the second 96-hour session. Additionally, female rats displayed estrous cycle disruption by the second 96-hour methamphetamine session, consistent with human female menstrual cycle disruption reported with methamphetamine use. Finally, both male and female rats displayed violent, aggressive and self-harmful behaviors, all consistent with human methamphetamine users. These data suggest that our 96-hour binge model of methamphetamine exposure may be useful as a novel model to more closely mimic human drug-taking behavior and perhaps further contribute to elucidating gender differences in methamphetamine use and addiction.

688.03/JJ3: Sex differences in the effects of exercise on subsequent cocaine craving in rats. Location: Hall A-C. Tuesday, Nov 15, 2011, 3:00 PM – 4:00 PM. Authors: *A. PETERSON, W. LYNCH; Psychiatry and Neurobehavioral Sci., Univ. of Virginia, Charlottesville, VA .

Abstract: Currently there are no approved pharmacotherapies for treating cocaine addiction. Recent studies using animal models of cocaine addiction demonstrate that concurrent access to a running wheel can decrease the reinforcing effects of cocaine during a maintenance phase. Consistent with this idea, our lab has recently shown in males that 2-hrs/day of exercise during abstinence not only prevents an increase in cocaine-seeking that develops over an abstinence period, but also prevents an increase in neuronal signaling in the prefrontal cortex (PFC). Thus, the objective of this study was to extend our previous findings to females and determine whether there are sex differences in the effects of exercise, during an abstinence period, on subsequent cocaine-seeking in an animal model of cocaine relapse. Intact adult male and female rats were trained to self-administer (SA) cocaine (1.5 mg/kg/infusion) under a fixed ratio 1 schedule of reinforcement with a maximum of 20 infusions per session. Once rats acquired cocaine SA, they were given 24/hr extended access to cocaine (1.5 mg/kg/infusion) under a discrete trial procedure (4 infusions/hr) for a total of 10 days. Following extended access rats began a 14 day abstinence period in which they either had 2-hr/day access to a running-wheel (exercise group, n=9 for males and n=9 for females) or 2-hr/day access to a locked running wheel (environmentally enriched sedentary group, n=10 for males and n=10 for females). As an additional control for environmental enrichment, following the same extended access self-administration protocol, an additional group of female rats (n= 3-6) were placed in isolated living conditions (without any running-wheel attachment). Cocaine-seeking, assessed under a cued-induced reinstatement paradigm, were examined after the 14day abstinence period when cocaine seeking is known to be high. Results showed that in males wheel running significantly reduced cocaine-seeking in response to the cues formerly associated with cocaine. In females, both groups that had access to the wheel (locked and unlocked) had similar low levels of reinstatement responding, and these levels were significantly lower than those observed in the isolated group. This finding suggests that exercise and environmental enrichment had equal effects on cocaine-seeking in females. Taken together, these results suggest that exercise blocks incubation of cocaine-seeking in males and has equal effects as environmental enrichment in females.

Coffee Shops

For our colleagues from out of town who might want to grab a coffee a little ways off the beaten Neuroscience geek track, Java Jones is a good option. WiFi is free and functional (last time I was there, anyway) which is key.

Located: 631 9th Avenue which is only a few blocks away from the convention center.

Test of the iPhone app

The new WordPress iPhone app… Loading blogs by user name is a nice feature, saves on URL typing anyway.