Intravenous self-administration of mephedrone, methylone and MDMA in female rats
K. Creehan, Sophia A. Vandewater, M. Taffe
Neuropharmacology January 17, 2015 DOI: 10.1016/j.neuropharm.2015.01.003 via Semantic Scholar
Summary
Female rats readily learn to self-administer the stimulants mephedrone, methylone, and MDMA, with mephedrone-trained animals taking significantly more drug infusions than the other groups. When the dose was varied under fixed-ratio or progressive-ratio schedules, all three drugs showed similar potency within each training group. Mephedrone-trained rats continued to take more of any drug during dose substitution, suggesting lasting effects of the initial training drug. Abuse liability of these compounds is predicted to be similar in experienced stimulant users but may differ if one is the first drug used.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Population | Female Wistar rats |
| Keywords | Chemistry Medicine |
| Citations | 98 |
| Key finding | Female rats acquired self-administration of mephedrone, methylone, and MDMA, with mephedrone-trained rats showing significantly higher intake, but all three drugs had similar potency in dose-substitution tests. |
Abstract
Male rats will intravenously self-administer (IVSA) the substituted cathinone stimulants (“bath salts”) mephedrone (4-methylmethcathione) and methylone (3,4-methylenedioxymethcathinone) robustly, whereas the IVSA of 3,4-methylenedioxymethamphetamine (MDMA) is inconsistent in many rat models. There are no data available on the self-administration of these drugs in female rats, thus a study was undertaken to contrast them directly. Groups of female Wistar rats were trained to self-administer mephedrone, methylone or MDMA (0.5 mg/kg/inf) under a Fixed-Ratio (FR) 1 schedule of reinforcement for 14 sessions. Following the acquisition interval, animals were evaluated in FR (0.0, 0.125, 0.25, 0.5, 1.0, 2.5 mg/kg/inf) and PR (0.125, 1.0 mg/kg/inf) dose-substitution procedures. The results show that female rats acquired the self-administration of all three compounds with intakes in mephedrone-trained rats that were significantly higher than that of methylone-trained or MDMA-trained rats. In dose-substitution under either FR or PR contingencies, however, the potencies of all three drugs were similar within the original training groups. The mephedrone-trained animals exhibited higher intakes of all drugs during dose-substitution, indicating lasting consequences of the training drug. Abuse liability of these three compounds is therefore predicted to be similar in established stimulant users but may differ in liability if they are primary drugs of initiation.