Effects of naloxone and buprenorphine on intravenous acetaldehyde self-injection in rats

Rats can be induced to self-inject acetaldehyde under an appropriate operant conditioning schedule. The narcotic antagonist naloxone (30 mg/kg) is shown to produce a decrease in schedule-induced acetaldehyde self-injection, but was without effect on both barpress responding and spontaneous activity in rats tested individually for fine, gross and total activity. On the other hand buprenorphine (0.3 and 3 mg/kg), the mixed agonist-antagonist derived from the opium alkaloid thebaine, also produced a significant decrease in acetaldehyde self-injection. However, a significant effect of buprenorphine on barpressing in otherwise drug naive rats indicated that this finding should not be dissociated from a possible involvement of buprenorphine on motor responding. While the findings are consistent with the hypothesis of opiate involvement in acetaldehyde self-administration, caution must be exercised when drawing conclusions about the participation of endogenous opiates in acetaldehyde-mediated behavior.