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MDMA produces a conditioned place preference and elicits ejaculation in male rats: a modulatory role for the
E J Bilsky1, C L Hubbell, J D Delconte
1Department of Psychology, Rensselaer Polytechnic Institute, Troy, NY 12180.
Abstract:
Methylenedioxymethamphetamine (MDMA) can produce a conditioned place preference (CPP) among rats. The ability of MDMA to produce a CPP was assessed while some rats were under the influence of naltrexone, 56 mg/kg, given 4 h before conditioning. Naltrexone attenuated MDMA's ability to produce a CPP without completely blocking MDMA's effects. Having noticed previously the production of seminal plugs by rats receiving MDMA, the presence of seminal plugs was recorded across the 8 days of conditioning. Roughly half of the rats receiving 6.3 mg/kg of MDMA left plugs during the conditioning period, while over two-thirds of those receiving a combination of MDMA and naltrexone left plugs. A second study, assessing further doses of MDMA, tabulated the drug's effects on the production of seminal plugs across 3 h. Besides eliciting ejaculation, MDMA also led to increased urination and defecation and a loss of body weight. These results support suggestions that the endogenous opioids modulate the reinforcing properties of stimulant drugs and affect male sexuality.
Insights
Naltrexone partially blocks Methylenedioxymethamphetamine (MDMA) induced place preference in rats, suggesting endogenous opioids modulate stimulant reinforcement. MDMA also impacts male sexual behavior and physiological responses.
Area of Science:
- Neuroscience
- Psychopharmacology
- Behavioral Science
Background:
- Methylenedioxymethamphetamine (MDMA) is known to induce conditioned place preference (CPP) in rats.
- Endogenous opioids are hypothesized to modulate the reinforcing effects of stimulant drugs.
- Previous observations indicated MDMA's influence on male rat sexual behavior, specifically seminal plug formation.
Purpose of the Study:
- To investigate the role of endogenous opioids in mediating MDMA's reinforcing properties.
- To assess the effect of naltrexone, an opioid antagonist, on MDMA-induced CPP.
- To further characterize MDMA's effects on male rat sexual behavior and physiological responses.
Main Methods:
- Rats were conditioned with MDMA, with or without naltrexone pretreatment (56 mg/kg, 4h prior).
- Conditioned place preference (CPP) was measured to assess reinforcing effects.
- Seminal plug presence was recorded daily during conditioning.
- A second study examined MDMA's dose-dependent effects on seminal plugs, urination, defecation, and body weight over 3 hours.
Main Results:
- Naltrexone significantly attenuated MDMA's ability to produce a CPP, but did not completely block it.
- MDMA administration (6.3 mg/kg) resulted in seminal plug formation in approximately half of the rats.
- Rats receiving both MDMA and naltrexone showed a higher incidence of seminal plugs (over two-thirds).
- MDMA also induced increased urination, defecation, and body weight loss.
Conclusions:
- These findings support the hypothesis that endogenous opioids play a role in modulating the reinforcing effects of MDMA.
- Naltrexone's partial blockade suggests a complex interaction between opioid and other neurotransmitter systems in MDMA's action.
- MDMA significantly impacts male sexual physiology and general physiological responses in rats.