Intracerebroventricular LHRH may serve as a discriminative stimulus in male rats

Male Wistar rats (N = 16) were trained to discriminate 5 μg/kg LHRH, injected intraperitoneally, from saline in a two-lever, food-reinforced drug discrimination procedure, with an injection-session interval of 45 min. Reliable discrimination of LHRH was acquired within 60 training sessions. Subsequent generalization tests in brain-cannulated animals showed dose-dependent and time-related partial substitution of intracerebroventricular LHRH for intraperitoneal LHRH (ventricle doses ranged from 25–400 ng, and the injection-session intervals ranged from 10–40min). These results indicate that centrally administered LHRH may serve as a dose- and time-dependent discriminative stimulus in male rats.