Alcohol and food self-administration by female Macaque monkeys as a function of menstrual cycle phase.

Female Macaque monkeys were trained to self-administer food (1 g banana pellet) and alcohol (0.12 g/kg/inj IV) in an operant paradigm. Alcohol and food-maintained responding were controlled by a second order schedule of reinforcement FR 4 (VR 16:S) that required an average of 64 responses for delivery of one food pellet or alcohol injection. Alcohol self-administration at average dose levels of 0-1.5, 1.5-3.0, 3.0-4.0 and 4.0 to 5.5 g/kg/day did not vary systematically as a function of menstrual cycle phase in a sample of 30 menstrual cycles. But alcohol self-administration was significantly lower during menstruation (p less than 0.002) in comparison to mid-cycle or the late luteal phase. Monkeys that self-administered high doses of alcohol (3.0-5.5 g/kg/day) also showed stable patterns of food self-administration across the menstrual cycle. Monkeys that self-administered low to moderate doses of alcohol (0-3.0 g/kg/day) showed a consistent decrease in food self-administration at mid-cycle. The implications of these data for hypotheses concerning estrogen modulation of food intake and the influence of the premenstruum on alcohol self-administration are discussed.