Age dependent development of ethanol drinking in rats after inhibition of aldehyde dehydrogenase

The purpose of this experiment was to determine the temporal characteristics associated with the age-related development of volitional consumption of ethanol induced by the pharmacological inhibition of aldehyde dehydrogenase (AlDH). To induce preference for ethanol, the AlDH inhibitor, cyanamide, was administered to male Sprague-Dawley rats which were 30 days of age. Cyanamide (n = 8) was injected subcutaneously twice daily in a dose of 10 mg/kg over a period of 3 days while the control group (n = 6) received the saline vehicle solution according to the same schedule. Then at 50, 70, 90, and 110 days of age, both groups of rats were given a standard 11-day test of preference for water versus ethanol offered in concentrations ranging from 3% through 30%. The results showed that at 70 days of age the preference for ethanol increased above the level of the 50-day test in terms of absolute g/kg intakes and proportion of ethanol to water consumed over the lower range of 3% through 15% concentrations. During the tests at 90 and 110 days of age, the cyanamide-treated rats further increased their preference for ethanol significantly over the levels at the 70-day test in terms of both g/kg and proportional intakes. The pattern of drinking of ethanol offered in the higher concentrations of 25% and 30% was unrelated to the age of the rats and the overall intakes were significantly higher than those of the lower concentrations. These findings demonstrate that the enzymatic inhibition of AlDH systematically acts in a delayed fashion to shift the pattern of preference for ethanol which is contingent on the maturation of the animal. In this instance, the volitional intake of ethanol in the cyanamide-treated rats reached its maximal level by 90-110 days of age. It is proposed that an endocrine mechanism involved in gonadal maturation may function in the intense shift in alcohol drinking.