Alcohol consumption and preference in female rats induced by reward downshift reveals sex generality of the modulatory role of physical activity.

Increased voluntary consumption of alcohol has been demonstrated in male rats exposed to frustrative reward downshift (the emotional self-medication effect). Access to a wheel for voluntary running abolished this effect in male rats, suggesting an attenuating effect of physical exercise on the negative affect induced by reward downshift and its consequences on drug intake. The present study analyzed this effect in female rats. Sixty-four food-deprived female Wistar rats received 32% sucrose [4% (Experiment 1) or 2% (Experiment 2) in controls] during 10, 5-min preshift sessions followed by 4% (Experiment 1) or 2% (Experiment 2) sucrose during 5 postshift sessions. Immediately after each consummatory session, animals were exposed to a 2-h, two-bottle preference test involving 32% alcohol vs. water. Half of the animals also had access to a running wheel during the preference test. The results showed (a) lower sucrose consumption in the downshifted groups (32-4% and 32-2%) compared to the unshifted controls (4-4% and 2-2%, respectively); (b) higher alcohol preference in downshifted groups without access to a wheel compared with downshifted groups with access to the wheel (Experiments 1 and 2); and (c) increased alcohol intake (g/kg) after experiencing reward downshift in animals without access to the wheel (Experiment 1). Voluntary wheel running thus reduced alcohol intake in female rats experiencing reward downshift. These findings are comparable to previous results reported in male rats and support the usefulness of physical exercise to prevent alcohol self-medication induced by frustrative nonreward.