TL neuro

March 19, 2017

Vaccination against methamphetamine works in female rats

Filed under: Methamphetamine, Vaccines, Vape inhalation, Vapor Inhalation — mtaffe @ 9:32 am

We have shown that a vaccine designed to blunt the effects of methamphetamine works in male rats in two prior publications, summarized here and here. We have also had success showing that vaccines directed against the synthetic cathinones MDPV (“bathsalts”) and alpha-PVP (“flakka”) work to reduce the effects of those drugs. A brief video outlining the approach to generating vaccines that might be helpful for drug abused created by NIDA can be found here.

The following has recently been accepted for publication:

Nguyen, J.D., Bremer, P.T., Hwang, C.S., Vandewater, S.A., Collins, K.C., Creehan, K.M., Janda, K.D. and Taffe, M.A. Effective active vaccination against methamphetamine in female rats, Drug Alcohol Depend, 2017, 175:179-186. [Publisher Site] [PubMed]

In this study we show that an increase in the amount that female rats move around their cages after an injection of methamphetamine is reduced in the MH6-KLH vaccinated rats.

As you can see in the explainer video, the main principle of anti-drug vaccination is that antibodies can bind some of the drug molecules (methamphetamine in this case) in the bloodstream, thereby preventing them from getting into the brain. This capacity to retain methamphetamine is relatively fixed at a given point in the vaccine sequence, thus administering a sufficiently high dose can (should) overcome the protection.

In our data, the effects of the vaccine were dose dependent. This is Figure 4 from the paper which depicts locomotor activity rates (counts per minute) in the MH6-KLH and KLH groups in the first and second hours after injection of methamphetamine in three doses [Significant differences from the Vehicle and 0.25 mg/kg within Group and Hour are indicated by §, from Vehicle (only) by # and from the 0.5 mg/kg condition by &. ]. There is a dose-dependent increase in activity rate compared with the vehicle injection condition. With respect to the active vaccination group, complete protection was found at the 0.25 mg/kg dose and partial protection at 0.5 mg/kg compared with the KLH group; the two groups were about the same after 1.0 mg/kg was injected. This further enhances our ability to interpret these data as a specific effect of the vaccination and to determine where the threshold for effective protection may lie.

There was another finding in this study which was slightly disappointing in terms of the vaccine study but greatly enhanced our understanding of another thing that we have been working on, namely vapor inhalation techniques to deliver drugs to rats for various research purposes. Most specifically we showed that e-cigarette type vapor inhalation of methamphetamine (and MDPV and mephedrone) increases the activity of male rats to a similar extent as it does when injected (blogpost overview). We used this model in the present study as well and confirmed that just as with male rats, the female rats activity in the cage was increased after vapor inhalation of methamphetamine to about the same extent as after the injected doses. Therefore up to this point in time we were assuming that the dose delivered to the rat was approximately similar when similar behavioral results were produced.

Unfortunately there was no difference in the effects of inhaled methamphetamine across the vaccinated and control groups of rats. We originally interpreted this as potentially a difference in the rate of drug penetration into the brain which minimized the ability of the vaccine-generated antibodies to prevent locomotor effects.

Upon reviewer request we then examined the blood levels of methamphetamine after injection (0.25, 1.0 mg/kg, i.p.) and the inhalation condition in a different group of unvaccinated female rats. We found that methamphetamine was about ten times higher in the blood after inhalation versus injection in this new study. This of course explains why the vaccinated group was not protected, i.e., the dose under inhalation was far past the ability of the antibodies to sequester in the bloodstream.

The curious thing is still why a similar level of locomotor activity was produced at the 10-fold difference in methamphetamine levels. Very likely this is due to the rate at which drug is delivered to the animal- in our inhalation model this takes place over 30 minutes whereas an injection takes seconds. Obviously one of our next avenues of research is to better determine the way that drug levels increase in the blood during vapor inhalation.

June 3, 2016

Inhalation delivery of psychostimulants to rats using e-vape technology

Filed under: 4-MMC/Mephedrone, Cathinones, E-cigarettes, MDPV, Methamphetamine — mtaffe @ 4:03 pm

Although inhaled exposure of drugs is a prevalent route of administration for human substance abusers, animal models of inhaled exposure to psychomotor stimulants (cocaine, methamphetamine, synthetic cathinones, etc) are not commonly available. Inhaled use of methamphetamine is more common than other routes of administration in habitual and dependent users (Das-Douglas et al. 2008; Heinzerling et al. 2010; Wood et al. 2008) and the SAMHSA/TEDS treatment admission database for 2012 shows 4.7% of treatment seekers in the USA were admitted for smoked cocaine vs 2.2% for other routes of cocaine administration. There is limited evidence that people are using e-cigarettes for inhalation of methamphetamine (Evans 2014; Rass et al. 2015), “bath salts” (Johnson and Johnson 2014; Rass et al. 2015) and “flakka” (presumptively α-pyrrolidinopentiophenone; alpha-PVP) as reported (Anderson 2015).

We have therefore developed a method for the delivery of psychostimulant drugs to rats and evaluated the impact of methamphetamine (MA), 3,4-methylenedioxypyrovalerone (MDPV; “bath salts”) and 4-methylmethcathinone (4-MMC; mephedrone). The following paper describing our initial studies has been recently accepted for publication in Neuropsychopharmacology:

Locomotor stimulant and rewarding effects of inhaling methamphetamine, MDPV and mephedrone via electronic cigarette-type technology. Jacques D. Nguyen1, Shawn M. Aarde1, Maury Cole2, Sophia A. Vandewater1, Yanabel Grant1 and Michael A. Taffe1
1Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute; La Jolla, CA, USA
2La Jolla Alcohol Research, Inc, La Jolla, CA, USA

Schematic of the inhalation chamber

Schematic of the inhalation chamber

Our exposure model for this study involved a standard sized rat housing chamber with a sealed lid- these are commercially available for a variety of purposes. The chamber was plumbed for regulated airflow and incorporated the ability to deliver and exhaust the vapor from an e-cigarette type device. The overall approach for delivery to rodents is under patent to La Jolla Alcohol Research, Inc which has been instrumental in developing the equipment for our studies. This collaboration has resulted in a number of studies so far, this one is the second one to be published. The first paper described the effects of THC inhalation (blogpost). The company has also recently been awarded an SBIR Phase II Grant (R44 DA041967) to further develop and enhance commercialization of the device.

Control of the dose administered to the rat in this system is a key initial topic of investigation. We determined in this paper whether the dose can be altered with the manipulation of a number of variables. The concentration off the drug may be altered in the propylene glycol (PG) vehicle (aka “e-juice”)- our standard condition for this study was 100 mg/mL but effects from 12.5-200 mg/mL were also explored for different drugs. For the most part this study found concentration-dependent effects only across drugs (4-MMC was much less potent than MA or MDPV) when the puffing and inhalation duration was held constant. The puffing regimen and duration of inhalation exposure can be altered as well. In most of our studies we delivered 10-s vapor puffs with 2-s intervals between them every 5 minutes for durations of 10-40 min (approximately 0.125 ml was used in a 40 min exposure session). Varying the total duration from 10 to 30 min resulted in dose dependent effects of inhaling MA (12.5 mg/mL) or MA (12.5 mg/mL).

Vape decreases ICSS thresholds

A decrease in ICSS threshold was produced by inhalation exposure to 4MMC (200 mg/mL), MA (100 mg/mL) and MDPV (100 mg/mL). Similar effects were produced by i.p. administration of 4MMC (1.0mg/kg), MA (0.5 mg/kg) or MDPV (0.5 mg/kg). Significant differences from the respective Vehicle condition are indicated by *.

We present data on the intracranial self-stimulation reward paradigm in this paper. This is a model in which electrodes are implanted into the medial forebrain bundle of the rat and it is trained to respond for small deliveries of electrical current which has a rewarding or reinforcing effect. The procedure used for this study ramps the stimulation up and down during a session until the threshold necessary for the individual to experience a reinforcing effect is determined. Once the animals are trained to generate stable thresholds, they can be tested by administering drugs before the session. If a drug has a rewarding or reinforcing effect, it tends to lower the threshold below the baseline level. Here we show that all three drugs decrease reward thresholds in male rats. The reduction in the reward threshold was of a similar magnitude when drug was administered by injection or by vapor inhalation. This is a key indication that this procedure can generate reinforcing or rewarding levels of drug in the rats.

Activity rates after inhalation of  3,4-methylenedioxypyrovalerone (MDPV; 25,50,100mg/mL) or 4-methylmethcathinone (4MMC/mephedrone; 100, 200mg/mL).

Mean (N=13; + SEM) activity rates after inhalation of 3,4-methylenedioxypyrovalerone (MDPV; 25,50,100mg/mL) or 4-methylmethcathinone (4MMC/mephedrone; 100, 200mg/mL). Gray shaded symbols indicate a significant difference from PG vehicle at the corresponding time point. Base = pre-inhalation baseline.

Locomotor activity was measured after vapor inhalation using a radiotelemetry system that generates activity rates as counts per minute. In this figure we show the activity before and after inhalation of the PG vehicle and then three concentrations of MDPV and two concentrations of 4-methylmethcathinone (4-MMC, mephedrone) for 40 min. Locomotor activity was increased for 2-3 h after the initation of vapor for all three MDPV concentrations and for the 200 mg/mL concentration of 4-MMC. Similar effects were observed for MA and we went on to show that the dopamine D1-like receptor antagonist SCH23390 (10 ug/kg, i.p., prior to inhalation) blocked locomotor increases caused by inhalation of each drug. This is as would be expected, similar to the effect of SCH23390 on locomotor stimulant effects of these drugs when injected in rodents.

Wheel Activity after MDPV or MA

Mean (N=7; ± SEM) wheel activity of male rats after inhalation of methamphetamine (100 mg/mL in PG), MDPV (100 mg/mL in PG) or the PG alone for 40 minutes. Gray shaded symbols indicate a significant difference from PG. A significant difference from the 30 min time point within an inhalation condition is indicated with *, and a difference from MA with #, for corresponding time points.

Another study in the paper investigated effects of vapor inhalation of the MA and MDPV on wheel activity. Under vehicle treatment, rats run more on the wheel in the first 30 minutes and then run significantly less for the subsequent 90 min of a 2 h session. When allowed to use the wheel after vapor exposure to MA or MDPV, activity is initially suppressed and then rebounds as the session continues. Presumably, the initial suppression of wheel activity is related to the increase in chamber locomotor activity found in the radiotelemetry study- if the rats were running around the cage they might be unlikely to enter the wheels. In the study depicted, MDPV caused significantly more activity than vehicle inhalation 60-90 min after finishing the vapor inhalation. MA in this experiment did not increase activity compared with vehicle, however activity was significantly higher in the last thirty minutes than the first 30 min after MA inhalation. Additional data found no significant effects of 40 min of inhalation of either MDPV or MA at a 25 mg/mL concentration and a third study found elevations of wheel activity 90-120 min after a 20 min inhalation of MA (100 mg/mL). In total, the wheel activity data confirm dose-dependent effects on a second measure of locomotion.

Overall, this study is the first to demonstrate behavioral effects of e-cigarette type inhalation delivery of psychostimulants to rats. This further validates our model and encourages additional study of the risks of e-cigarette delivery of psychoactive substances in laboratory animal models.
J. D. Nguyen, S. M. Aarde, M. Cole, S. A. Vandewater, Y. Grant and M. A. Taffe. Locomotor stimulant and rewarding effects of inhaling methamphetamine, MDPV and mephedrone via electronic cigarette-type technology, 2016, accepted article preview 9 June 2016; doi: 10.1038/npp.2016.88 [ PublisherSite ][ PubMed ]

Funding and Disclosures for this paper: This work was funded by support from the United States Public Health Service National Institutes of Health (R01 DA024105, R01 DA024705, R01 DA035281 and R44 DA041967) which had no direct input on the design, conduct, analysis or publication of the findings. Subsets of these data were first presented at the Experimental Biology meeting in 2015 and the Annual Meeting of the Society for Neuroscience 2015. Development of the apparatus was supported by La Jolla Alcohol Research, Inc and MC is inventor on a patent for this device. SAV consults for La Jolla Alcohol Research, Inc.

June 7, 2015

Active vaccination against methamphetamine slows acquisition of self-administration

Filed under: Methamphetamine, Vaccines — mtaffe @ 7:01 pm

The following has been recently accepted for publication:

Miller, M.L., Aarde, S.M., Moreno, A.Y., Creehan, K.M., Janda, K.D. and Taffe, M.A Effects of active anti-methamphetamine vaccination on intravenous self-administration in rats. Drug Alcohol Depend, 2015, 153:29-36 [Publisher Site]

In this new paper we follow up on our first finding that a anti-methamphetamine conjugate vaccine (referred to as the MH6-KLH conjugate) changes locomotor activity and body temperature responses to methamphetamine [Miller et al, 2013; blog post]. The new study uses an intravenous self-administration paradigm in rats to determine if MH6-KLH vaccination is capable of altering voluntary dosing with methamphetamine. The rats are surgically implanted with indwelling venous catheters which may be attached to a micro-pump during testing sessions. Upon making a press on the drug-associated lever a small infusion of drug is delivered. Over successive (daily) testing sessions, if the amount of drug-associated lever pressing increases while responses on the other lever stay at low levels, this can be interpreted as the rats having learned that the drug is pleasurable. They also tend to express their satiety point in terms of relatively stable asymptotic levels of intake after about 10-15 sessions.

Figure1AThe main takeaway message from this study is that we are the first to show an attenuation of voluntary methamphetamine (MA) intake by means of active vaccination. In this figure, we show the percentage of rats in the MH6-KLH and KLH-only (control) groups who self-administered at least 11 infusions (0.1 mg/kg/inf) on two consecutive days. This acquisition criterion is arbitrary but using a cutoff of a few more or slightly fewer infusions makes little difference in the overall picture. In this case a survival analysis identified significantly delayed acquisition in the MH6-KLH vaccinated group. As we write in the paper

The delay in acquisition was substantial, with less than 17% of the vaccinated group reaching acquisition criteria after 7 sessions compared with 75% of controls. Furthermore, only 66% of the MH6-KLH-vaccinated rats compared with 100% of the controls reached acquisition criteria by 13 sessions of training.

Whether these findings reflect a real-world impact and significance, well, that is a matter of debate and additional investigation. Our position is that many people experience various psychoactive drugs and never go on to develop lasting addiction and/or liability for compulsive use. Some of these trajectories include the pattern of trying the drug once or a few times and deciding it doesn’t do much for the individual. The largest difference in the percent of animals opting not to take substantial amounts of MA in a daily session came after 7 chances. In our model, rats continue to be offered MA and indeed are given a priming injection if they haven’t made a response in 30 min. This was done to bias the study for complete population acquisition, at least in the control group. Real world users, of course, often make choices which prevent them from even having the opportunity to try MA again if they find it unpalatable after the first few exposures.

These studies are funded by NIH Grant R01 DA024705

May 6, 2015

Methylone is replacing MDMA in Forensic Laboratory samples

Filed under: alpha-PVP, Cathinones, MDMA, MDPV, Methamphetamine, Methylone — mtaffe @ 10:38 am

The National Forensic Laboratory Information System (NFLIS) is, according to the Introduction to the 2014 Mid-year report [PDF]:

a program of the Drug Enforcement Administration (DEA), Office of Diversion Control NFLIS systematically collects results from drug analyses conducted by State and local forensic laboratories These laboratories analyze controlled and noncontrolled substances secured in law enforcement operations across the country, making NFLIS an important resource for monitoring illicit drug use

I was curious to see what this particular dataset had to say about the emergence of substituted cathinone stimulants such as mephedrone, methylone, MDPV and alpha-PVP. We work on the effects of these drugs and it is of interest to monitor the evolution of their use with various epidemiological measures. This is but one such measure and the relative penetration of a given drug may differ depending on whether the measure is from law enforcement, surveys of adolescents, online surveys, etc.

NFLIS-summaryThe NFLIS appears to have started systematically assessing several cathinone drugs in 2011. Either that or they were too infrequent to make the specific tables presented in the reports. These are relatively low incidence, you will note. For comparison, methamphetamine accounts for about 10% of reports and did not change much across 2010 to 2012 when MDMA reports dropped significantly. I would have predicted, before seeing these data, that the incidence of MDMA was still higher than these newer drugs. This figure shows that methylone is now more frequently reported in NFLIS samples than is MDMA. Methylone is probably the most MDMA-like of the cathinones in terms of structure (it is the direct cathinone cousin, 3,4-methylenedioxymethcathinone), neuropharmacology and subjective effects (to the extent this has been assessed).
The second surprise for me was seeing that MDPV and alpha-PVP are less commonly reported than methylone. I would have expected these drugs to have a higher representation, based on the emerging profile as traditional stimulants that support highly repetitive use.

h/t: Forensic Tox Guy

March 16, 2015

Overnight Wheel Access Decreases Stimulant Self-Administration

Filed under: Cathinones, Exercise, MDMA, Methamphetamine, Methylone — mtaffe @ 10:57 am

env046-325x325The following has recently been accepted for publicationpublished:

Shawn M Aarde, Michelle L Miller, Kevin M Creehan, Sophia A Vandewater, Michael A Taffe. One day access to a running wheel reduces self-administration of d-methamphetamine, MDMA and Methylone, 2015, Drug Alcohol Depend, 151:151-158. [Publisher Site, PubMed]

   The laboratory continues to study the role that exercise can play in altering stimulant drug self-administration using rodent models. Our initial paper found that if rats have concurrent access to intravenous methamphetamine and an activity wheel, the drug intake is suppressed below that of animals who can only access an immobile, locked wheel (Miller et al, 2012; blog). In that study, however, unlocking the wheel had no effect on the methamphetamine  intake for those animals who had self-administered methamphetamine for 7-14 sessions without wheel activity.

   A study by Smith and Witte (2012; PubMed) showed that if rats are provided wheel access in their home cages they will self-administer less cocaine. That study maintained constant conditions for groups of animals, thus it was not determined if home cage wheel access could overturn an established self-administration pattern.

   In this new study we examined the effects of overnight wheel access in the vivarium home cage on the intravenous self-administration of three different stimulant drugs in four different experiments. The key feature for our experiment was that animals were trained to stable levels of self-administration of methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) or methylone in the absence of significant prior wheel experience or any ongoing wheel access.

Aarde15-22hrWheelFig2   This figure (click to enlarge) depicts the mean number of infusions earned by groups of rats trained to self-administer A) methamphetamine (1 hr sessions; 0.05 mg/kg/inf; N=18), B) methamphetamine (2 hr; 0.05 mg/kg/inf; N=13), C) MDMA (2 hr; 0.5 mg/kg/inf; N=11) or D) Methylone (2 hr; 0.5 mg/kg/inf; N=12). Data are presented for each of the first four days (Monday-Thursday) in a week in which animals had no access to the activity wheel in the home cage (No Wheel) or were permitted to use the wheels (Wheel; grey and open bars) following the first (M; Monday) session of the week. Therefore the critical comparisons are Monday sessions (no wheel access prior) with the subsequent three days within the Wheel week and between T, W and Th sessions across Wheel and No-Wheel weeks. In the figure, significant differences from the first session within a week are indicated by * and significant differences between Wheel-access and No-Wheel weeks by #.

   The design was repeated-measures meaning that each rat participated in all the conditions. We used a 2 cohort crossover design for the most part, meaning that each experiment was split into two groups of rats with one receiving the Wheel Access week first and the other cohort receiving the No Wheel week first. This order did not make any difference in the effect of the wheel so the data are presented by Wheel-Access condition without respect to the order in which a given rat received the different conditions.

   The key takeaway message for this study is that wheel access in the ~22 h prior to a behavioral session is capable of significantly reducing the amount of drug rats will self-administer.

   This effect was replicated across four studies which varied in specific design, therefore we can conclude it is robust against methodological variation.

   First, this is a confirmation of something that was made obvious by the Smith and Witte (2012) paper. There have been several papers that purport to show that a 6 week history of wheel access in the home cage prior to the initiation of drug self-administration training reduces drug intake. To the extent such models continue the wheel access during the self-administration training, they are confounded with the effect we have shown here. Consequently, neurobiological studies predicated on brain changes that require extensive exercise histories, such as neurogenesis processes, are likely to come up with negative results.

   Second, this study shows that it is possible for an activity intervention to reduce drug self-administration after a pattern of daily intake has been stabilized. It may not occur in every design but it is possible. This supports the further use of this model to study the ways in which exercise programs for human users might be best designed and applied. It even suggests that exercise programs can reduce drug use even without the subject having any intention to alter their use pattern.

Future Directions:
   There are numerous avenues to pursue in the wake of this study. From the behavioral perspective, we are not certain where, in the course of 22 hr of wheel access, the effect on drug intake lies. It is possible that this effect depends on activity early in the dark cycle (rats are nocturnal so this is their active part of the day), just prior to the self-administration session. It is also possible that wheel activity immediately after the last day’s session while acutely intoxicated on the stimulant is somehow aversive and thereby punishes subsequent drug taking. From a mechanistic perspective, it is pretty clear that the most profitable avenue is to follow up on the acute effects of exercise that emerge within a time frame no longer than about 22 hrs. The endogenous opioid systems are particularly attractive becuase of decades-old understandings that the so-called “runner’s high” may be mediated by such neurochemical systems.

activity wheel picture from Med Associates, Inc

November 13, 2014

SfN 2014 Presentation: Vape drug delivery

We will present a poster describing our efforts to develop technologies for the intrapulmonary (inhaled) delivery of psychoactive drugs at the 2004 meeting of the Society for Neuroscience.

Abstract 810.04 on Board AA05: Development and validation of a device for the intrapulmonary delivery of cannabinoids and stimulants to rats .
Authors: M. A. TAFFE, S. M. AARDE, M. COLE;
Cmte Neurobio. of Addictive Disorders, The Scripps Res. Inst., LA JOLLA, CA;

The presentation time is Wednesday, Nov 19, 2014, 1:00 PM – 5:00 PM.

Abstract Text:

The recent popularization of non-combustible methods for intrapulmonary delivery of psychoactive drugs to humans (Vape, Volcano, e-cigarette, etc) has stimulated interest in the intrapulmonary administration models for rodent studies. We have designed a sealed rodent chamber, with a well regulated air flow, that is suitable for the controlled exposure of rats to psychoactive substances. Use of e-cigarette type delivery systems was found to afford excellent dosing control for this purpose. Studies were conducted in male rats to verify the in vivo efficacy of drug delivery. Implantable radiotelemetry methods were used to demonstrate that a 20 min exposure to [[unable to display character: ∆]]9-tetrahydrocannabinol (THC), or the CB1 receptor full agonist JWH-018, produces a robust hypothermia. The temperature nadir was reached within 40 min of exposure, was of comparable magnitude to that found after 30 mg/kg THC or 1.1 mg/kg JWH-018, i.p. and had resolved within 3 hours compared with a 6 hour time course following injection. Studies also demonstrated that 30 min of intrapulmonary exposure to methamphetamine (MA) significantly increased home cage locomotor behavior for up to 2 hrs. A final study showed that a 30 min intrapulmonary exposure to MA reduced drug intake during the loading phase of intravenous self-administration of MA. Finally, it is shown that rats will nosepoke for the delivery of MA vapor. These studies show that an electronic cigarette type delivery system can be successfully used to model intrapulmonary drug delivery in rats. These techniques will be of increasing utility as recreational users continue to adopt “vaping” for the administration of psychtropic drugs.

SrN2014-teaserFigureDisclosures: M.A. Taffe: None. S.M. Aarde: None. M. Cole: E. Ownership Interest (stock, stock options, royalty, receipt of intellectual property rights/patent holder, excluding diversified mutual funds); La Jolla Alcohol Research, Inc..

This work was supported by NIH grants DA035281 and DA024105.

This figure is small preview of the data that we will be presenting. The figure depicts body temperature responses to 20 minutes of Vape-exposure to THC and the synthetic cannabinoid JWH-018 (upper panel) and locomotor activity responses to 30 minutes of Vape-exposure to methamphetamine (lower panel) in a group (N=7) male rats. In both panels there are comparison data for a session in which animals were just in normal cages with no drug intervention (No Chamber) and another session in the inhalation chamber in which animals were exposed to the Vape delivery vehicle without any drug in it (Vehicle). As you can see, we were successful in delivering active doses of the drugs, each of which had class-specific effects, i.e. cannabinoid hypothermia and stimulant hyperlocomotion.

March 19, 2014

Methamphetamine Relapse Rates

Filed under: Methamphetamine — mtaffe @ 11:53 am

A new paper describes the course of relapse in methamphetamine addicts who are seeking cessation treatment.

Mary-Lynn Brechta, Diane Herbeck. Time to relapse following treatment for methamphetamine use: A long-term perspective on patterns and predictors,

The authors examined methamphetamine (MA) using individuals who were admitted to Los Angeles County Substance Use Disorder treatment systems. This study used a California state database with individuals admitted primarily in 1996. The authors then tried to locate as many as possible for interview, resulting in a sample size of 350 people who were interviewed 3 years after their initial entry in the system. Of these 277 were re-interviewed 2-4 years later.  The first figure is a survival curve calculated from the available data.

Microsoft Word - fig1-1.docxThis analysis makes it clear that over half the sample had relapsed to MA use within a year. Out of the total relapsing population 36% had done so within a month of exiting treatment, 14% from months 2-6 and 11% in the second six month interval post-treatment. A pretty dismal outcome, but probably reflective of a lot of substance discontinuation therapy/attempts. Overall the study reports 77% of users had relapsed within 5 years. Of the individuals who were able to be followed for 5 years post-treatment (N=206), 23% of them had been clean for 5 years. The study is pretty diverse, as might be expected for LA. The sample was 56% male, 17% African American and 30% Hispanic/47% non-Hispanic white. The average age at admission was 29 but 30% of the sample had started using MA before age 16.

The study then examined several user characteristics to determine which might be associated with the odds of relapsing. They found that parental drug use and a history of selling MA were both associated with greater odds of relapsing. Maintaining some sort of self-help or treatment program was associated with a degree of protection against relapse. These analyses show that individuals without parental drug use and a history of selling MA that remained on some sort of self-help or treatment program had about 50% odds of relapse after 5 years whereas only about 10% of those who had either parental drug use or a MA selling history and did not maintain any sort of therapy were able to remain abstinent.

The take away message for this lab is that current treatment approaches for MA addiction are not as effective as we would like. Any additional avenues for reducing relapse after an individual has entered therapy for their MA use would be a significant help.

January 3, 2013

Mephedrone (4-methylmethcathinone) self-administration in rats

Filed under: 4-MMC/Mephedrone, Cathinones, Methamphetamine — mtaffe @ 11:14 am

The following paper, continuing our investigations into the substituted cathinone stimulants, has been accepted for publication published (Sep 2013):

Aarde, S.M., Angrish, D., Barlow, D.J., Wright, Jr., M.J., Vandewater, S.A., Creehan, K.M., Houseknecht, K.L., Dickerson, T.J. and Taffe, M.A. Mephedrone (4-methylmethcathinone) supports intravenous self-administration in Sprague-Dawley and Wistar rats. Addict Biol, 2013, 18(5):786-799. [ PublisherLink ]

The drug mephedrone, sometimes called MMCAT or “plant food”, became highly popular in the UK in 2009-2010 and user reports variously compare it to 3,4-methylenedioxymethamphetamine (MDMA) and cocaine, as well as other psychomotor stimulants. The similarity to MDMA was reinforced by three neurochemical findings showing a very MDMA-like pattern of relatively greater serotonin vs dopamine accumulation in the nucleus accumbens using microdialysis techniques (see here, here for discussion).

The takeaway message from this new paper is that 4-methylmethcathinone (4-MMC; mephedrone) is readily self-administered, intravenously, by rats using conditions that are fairly typical of the usual stimulant self-administration paradigms. Our experiments were conducted in 1 hour sessions under normal laboratory ambient temperature conditions (about 24 °C). The only other data available in the published literature at present (Hadlock et al, 2011; see this post) involved 4 hour sessions conducted at 29 °C, both of which conditions might be predicted to elevate intake in rats.

Aarde13-mephedrone-self-adminIn this portion of a figure from the paper we show that male rats of two different strains (Wistar and Sprague-Dawley) common to self-administration experiments maintain stable reward lever pressing (and therefore intakes of 4-MMC) within about 10 sessions. This was the case for two different amounts of drug delivered in each infusion that the animal obtained by lever pressing. In this experiment animals were previously trained to respond on the lever for food pellets under an FR5 response contingency which was continued in the self-administration phase, thus every 5 responses resulted in a drug infusion.

Aarde13-MAvsVehicleBy way of comparison, additional groups of Sprague-Dawley rats were trained similarly and then permitted to obtain d-methamphetamine (0.05 mg/kg/infusion) or only the saline vehicle. This latter group is necessary to rule out the possibility that the animals are continuing to seek the food pellets used in the pre-training interval. As is readily apparent, 4-MMC and methamphetamine maintain a mean of about 30 responses per session whereas saline substitution results in very low levels of lever pressing.

Under these conditions, methamphetamine and 4-MMC have about equal effect on rat self-administration although the 4-MMC is considerably less potent, requiring about 10 times the per-infusion dose for effect. This is consistent with the emerging in vitro and behavioral pharmacological literature, which shows a similar reduced potency of 4-MMC relative to methamphetamine.

Although we don’t show it directly in this paper, MDMA is at best unevenly self-administered by rats. The literature reflects some successes in establishing self-administration of MDMA but the effects are inconsistent across laboratories, lower fractions of the subjects acquire the behavior, session-to-session intake is less consistent, etc. We found no evidence of this in the present study and conclude that despite a MDMA-like serotonin/dopamine neuropharmacological effect, 4-MMC has a liability for repetitive intake more similar to the classical amphetamine-type stimulants such as methamphetamine.

December 20, 2012

Functional efficacy of an anti-methamphetamine vaccine

Filed under: Methamphetamine, Thermoregulation, Vaccines — mtaffe @ 9:31 am

An early study which attempted to generate active vaccination against methamphetamine (METH) found no significant differences between vaccinated and control rats in a locomotor response to METH (Byrnes-Blake et al. 2001), however the vaccine led to a monoclonal antibody which was effective as a passive vaccine in a range of pharmacological studies including pharmacokinetic, animal models of drug overdose, locomotor activity, self-administration, and drug discrimination (Byrnes-Blake et al. 2003; McMillan et al. 2002). Passive vaccines are considered to be less ideal because they require the infusion of large quantities of drug-specific antibodies which must be manufactured and stored for use. In many cases active vaccine can be manufactured more cheaply and the antibodies are then generated by the immune system. Typically, or perhaps ideally, the duration of protection for passive vaccination is not as long as with active vaccination. Thus there continues to be interest if determining if active vaccination can work.

Another group found that active vaccination with the same hapten published by Byrnes-Blake (2001), coupled to a “molecular adjuvant” with a tetanus toxin T-cell epitope in place of the traditional keyhole limpet hemocyanin (KLH), resulted in an intial increase in methamphetamine self-administration in rats, followed by a decrease to levels indistinguishable from controls over 15 sessions (Duryee et al. 2009). This enhances confidence that it would be possible to develop active vaccines against methamphetamine.

The following paper is now in press at Biological Psychiatry.

Miller ML, Moreno AY, Aarde SM, Creehan KM, Vandewater SA, Vaillancourt BD, Wright MJ Jr, Janda KD, Taffe MA. A Methamphetamine Vaccine Attenuates Methamphetamine-Induced Disruptions in Thermoregulation and Activity in Rats.Biol Psychiatry. 2012 Oct 22. pii: S0006-3223(12)00803-7. doi: 10.1016/j.biopsych.2012.09.010. [Epub ahead of print] [PubMed][DOI]

VaccineTelem-Fig2In this paper we have shown that active vaccination can protect against the effects of METH. This figure is reproduced from the paper and the data show that METH causes an elevation of body temperature and an increase in wheel activity in the control animals vaccinated with the carrier protein (KLH). These effects are blocked in the animals vaccinated with the MH6-KLH conjugate vaccine. These data show the potential for active vaccination to oppose effects of methamphetamine.

Another paper from a competing group (Shen et al, 2012) appeared at nearly the same time as ours, demonstrating efficacy of active vaccination against METH stimulated locomotor activity in mice. It is to be hoped that these three successful demonstrations of efficacy of anti-METH vaccines will overcome the apparent failure of the early Byrnes-Blake et al (2001) finding and stimulate additional research.

This project was supported by NIH/NIDA grant R01 DA024705.

A NIDA generated brief animation video on the basic idea of anti-drug vaccination can be found in this post.
Additional Reading:

Byrnes-Blake KA, Carroll FI, Abraham P, Owens SM. Generation of anti-(+)methamphetamine antibodies is not impeded by (+)methamphetamine administration during active immunization of rats. Int Immunopharmacol. 2001 Feb;1(2):329-38. [PubMed]

Duryee MJ, Bevins RA, Reichel CM, Murray JE, Dong Y, Thiele GM, Sanderson SD. Immune responses to methamphetamine by active immunization with peptide-based, molecular adjuvant-containing vaccines. Vaccine. 2009 May 14;27(22):2981-8. doi: 10.1016/j.vaccine.2009.02.105. Epub 2009 Mar 10. [PubMed]

Shen XY, Kosten TA, Lopez AY, Kinsey BM, Kosten TR, Orson FM. A vaccine against methamphetamine attenuates its behavioral effects in mice. Drug Alcohol Depend. 2012 Sep 27. doi: 10.1016/j.drugalcdep.2012.09.007. [Epub ahead of print] [PubMed]

August 15, 2012

Thermoregulatory and locomotor effects of mephedrone

Filed under: 4-MMC/Mephedrone, Cathinones, Methamphetamine — mtaffe @ 8:11 pm

The following has been published:

Wright, Jr, M.J., Angrish, D., Aarde, S.M., Barlow, D.J., Buczynski, M.W., Creehan, K.M., Vandewater, S.A., Parsons, L.H., Houseknecht, K.L., Dickerson, T.J. and Taffe, M.A. Effect of ambient temperature on the thermoregulatory and locomotor stimulant effects of 4-methylmethcathinone in Wistar and Sprague-Dawley rats, PLoS ONE, 2012, 7(8):e44652 [ OpenAccess ]

This paper describes our initial study on the thermoregulatory and locomotor effects of 4-methylmethcathinone, even though it will appear in publication after a second study focused on ambient temperature extremes. In this current study, two strains of rats were monitored (with radiotelemetry implants) for changes in body temperature and home cage ambulatory activity after the administration of 4-methylmethcathinone (4-MMC or mephedrone). The study was conducted at 23°C and 27°C ambient temperature for reasons described in the prior post.

The main finding was that 4-MMC (1.0-10 mg/kg, s.c.) caused a dose-dependent decrease in body temperature in Wistar rats. This effect was not seen in the Sprague-Dawley rats. Effects in each strain were consistent across the two ambient temperature conditions, which was slightly surprising given prior literature with MDMA. We expected that 4-MMC would increase body temperature at 27°C.

Locomotor activity  was dose-dependently increased by 4-MMC in both strains with slightly greater stimulation in the Sprague-Dawley animals.  A followup experiment showed that the maximum locomotor increase produced by 4-MMC at the highest dose was similar to that produced by 1.0 mg/kg methamphetamine. There was no sign of the locomotor suppression / stereotyped behavior induction observed after 5.6 mg/kg methamphetamine with any of the tested doses of 4-MMC.

A microdialysis study was conducted to evaluate the neurochemical profile of 4-MMC since no data were available when we started the study. We found relatively greater accumulation of serotonin relative to dopamine in the nucleus accumbens after the 10 mg/kg, s.c., dose used in the telemetry studies. These findings are consistent with two recent papers, one from Baumann et al (2012) and one from Kehr et al (2011) although those studies used a more restricted dose range.  This neurochemical profile is much like that produced by MDMA and is different from methamphetamine or amphetamine which have a greater effect on nucleus accumbens dopamine vs serotonin.

The strain difference in thermoregulation was unexpected and set us off on some additional work included in this paper. First, we showed with the serotonin 1A/7 agonist 8-OH-DPAT that the Sprague-Dawley and Wistar rats were equivalently responsive to hyperthermia induced by this compound. Second, we included some pharmacokinetic studies which identified only a small difference between rat strains…unlikely to explain the strain differences in thermoregulation.
As mentioned above, we also did a followup study in a separate group of Sprague-Dawley rats in which the ambient temperature conditions were more extreme, 20°C and 30°C. In that case, hypothermia was produced at the lower ambient temperature and there was no evidence of hyperthermia at the highest ambient temperature.

Between these two papers we now conclude that the thermoregulatory properties of 4-MMC differ from those of MDMA to the extent that warmer ambient temperature does not result in 4-MMC causing hyperthermia. Thus on this particular measure of drug risk, these data support a conclusion that 4-MMC is less likely to cause thermoregulatory distress compared with the risks of MDMA.

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