Abstract
Rationale: The neurobiological systems that mediate the discriminative stimulus effects of self-administered drugs are largely unknown. The present study examined the discriminative stimulus effects of self-administered ethanol. Methods: Rats were trained to discriminate ethanol (1 g/kg, IP) from saline on a two-lever drug discrimination task with sucrose (10% w/v) reinforcement. Test sessions were conducted with ethanol (0 or 10% v/v) added to the sucrose reinforcement to determine if self-administered ethanol would interact with the discriminative stimulus effects of investigator-administered ethanol, or with the ethanol-like discriminative stimulus effects of the GABAA-positive modulator pentobarbital or the non-competitive NMDA antagonist MK-801. Results: During a saline test session, ethanol (10% v/v) was added to the sucrose reinforcement. Responding by all animals began accurately on the saline-appropriate lever and then switched to the ethanol-appropriate lever after rats self-administered a mean dose of 1.2±0.14 g/kg ethanol. During cumulative self-administration trials, responding initially occurred on the saline lever and then switched to the ethanol-appropriate lever after ethanol (0.68±0.13 g/kg) was self-administered. Investigator-administered MK-801 (0.01-1.0 mg/kg, cumulative IP) and pentobarbital (0.3-10.0 mg/kg, cumulative IP) dose-dependently substituted for ethanol. When ethanol (10% v/v) was added to the sucrose reinforcer, MK-801 and pentobarbital dose-response curves were shifted significantly to the left. Conclusions: Self-administered ethanol substituted for and potentiated the stimulus effects of investigator-administered ethanol, suggesting that the discriminative stimulus effects of self-administered ethanol are similar to those produced by investigator-administered ethanol. Self-administered ethanol enhanced the ethanol-like discriminative stimulus effects of MK-801 and pentobarbital, which suggests that the discriminative stimulus effects of self-administered ethanol are mediated by NMDA and GABAA receptors.
Original language | English (US) |
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Pages (from-to) | 13-22 |
Number of pages | 10 |
Journal | Psychopharmacology |
Volume | 154 |
Issue number | 1 |
DOIs | |
State | Published - 2001 |
Externally published | Yes |
Keywords
- Drug discrimination
- Ethanol
- GABA
- Investigator-administered
- NMDA
- Rat
- Self-administration
ASJC Scopus subject areas
- Pharmacology