ABSTRACT
The vasopressin analog desglycinamide-(Arg8)-vasopressin (DGAVP) has been reported to reduce the acquisition of heroin and cocaine self-injection behavior in rats. This led to the hypothesis that DGAVP can reduce the self-administration of psycho-active drugs (including ethanol) by attenuating central reinforcement processes. Under forced ingestion conditions, DGAVP has been reported, however, to enhance alcohol drinking in rats. We studied the effect of DGAVP on the acquisition of voluntary, free-choice alcohol drinking in naive rhesus monkeys, that had concurrent access to either 1% and 2% (n = 12) or to 4% and 8% (n = 8) ethanol/water solutions in addition to drinking water. Half of the monkeys were injected twice per day with 50 micrograms.kg-1 of DGAVP for 14 successive days, the other half received placebo. Subsequently, all subjects had access to the same solutions for another 14 days without treatment. DGAVP did not significantly affect concentration preference behavior. With regard to net ethanol ingestion in animals drinking 1% and 2% solutions, DGAVP decreased net ethanol intakes, having a time-dependent and long lasting effect; placebo-treated animals gradually increased net ethanol intakes over time. The placebo-treated animals in the 4% and 8% group, showed a different acquisition pattern; DGAVP reduced net ethanol intake in two animals in a similar way as above. Two animals behaved differently. It is concluded that in a free-choice condition DGAVP did not enhance the acquisition of alcohol drinking in monkeys, but rather inhibited ethanol self-administration in the majority of the subjects.
Subject(s)
Alcohol Drinking/psychology , Arginine Vasopressin/analogs & derivatives , Arousal/drug effects , Brain/drug effects , Motivation , Animals , Arginine Vasopressin/pharmacology , Dose-Response Relationship, Drug , Ethanol/pharmacology , Macaca mulatta , MaleABSTRACT
This analysis aims at determining to what extent spontaneous alcohol drinking in adult male rhesus monkeys (Macaca mulatta) represents ethanol-directed behaviour. It is shown that in a condition of free access to an ethanol/water solution (2 percent v/v) and drinking water, alcohol drinking was initiated in all subjects (n = 4) within a few days, without any specific induction procedure. Relationship between drinking behaviour and ethanol concentrations was studied in 8 subjects by use of a concurrent 3-bottle-design. 2 bottles containing ethanol solution (concentrations 2.4; 4.8; 8.16; 16.32 percent v/v), 1 bottle contained drinking water. When ethanol concentrations in the solutions increased, consumption of ethanol solutions decreased, of drinking water increased, and of total water decreased. Net ethanol intake from a certain solution was influenced by its concentration and the concentration of the concurrently available solution. After an initial increase, total net ethanol intake remained relatively constant. Consumed amounts of ethanol (on the average 2-6 ml.kg-1 per day) could lead to notable blood ethanol levels. Drinking from ethanol solution was not just an alternative for ingesting water. The observed alcohol drinking is interpreted as resulting from a central reinforcement of ethanol intake and avoidance of negative, potentially harmful effects of ethanol.
