EFFECTS OF DIET ON SENSITIZATION TO COCAINE-INDUCED STEREOTYPY IN FEMALE RATS

The progressive increase in cocaine-induced stereotyped behavior that accompanies repeated cocaine injections (sensitization) was examined i n rats consuming different diets. Adult female Sprague-Dawley rats wer e fed one of three diets: low protein (6% casein), adequate protein (2 5% casein), or a standard chow diet. Following 1 week of adaptation to the diets, the rats were injected every 3-4 days with either cocaine (30 mg/kg, IF) or saline, and the total amount of stereotypy was measu red over a 90-min interval following each of four injections. Cocaine- induced stereotypy peaked at 40-50 min following each injection, alter which it declined for all diet groups. With repeated injections, the total amount of stereotypy increased in all diet groups, By the fourth injection, the low protein diet group (6% casein) exhibited a slower onset and a possibly prolonged duration of cocaine-induced stereotypy when compared with the two adequate protein diet groups (25% casein an d chow). Interestingly, the rats in the two pu rifled diet groups (6% casein and 25% casein) exhibited significantly more stereotypy across injections than those in the chow diet group. Weight differences did n ot explain the differences in stereotypy present among the diet groups , This study concludes that diet significantly alters the pattern of c ocaine-induced stereotypy in female rats, especially after repeated ex posure. (C) 1997 Elsevier Science Inc.