Luteinizing hormone releasing hormone-induced conditioned place-preference in male rats

Conditioned place-preference induced by intraperitoneal injections of luteinizing hormone releasing hormone (LHRH) was studied in male rats. In Experiment 1, dose-dependent effects (doses: 0, 0.2, 1 and 5 micrograms/kg) were observed in gonadectomized males provided with a subcutaneous silastic implant containing testosterone. Animals injected with 1 or 5 micrograms LHRH developed reliable preference for the LHRH-associated compartment of a two-compartment preference box. The 0 and 0.2 microgram doses were without effect. Experiment 2 further studied the place-preference effects induced by 5 micrograms LHRH, by varying the sex steroid baseline condition of the animals. A significant effect of LHRH on place-preference was found in gonadectomized males with a testosterone or estradiol implant and in gonadally intact males. Differences between these groups were not found. However, in gonadectomized males without steroid substitution, LHRH did not induce place-preference. These data indicate that rewarding properties related to LHRH treatment can be observed in male rats, provided that the males are additionally exposed to sufficient levels of circulating sex steroids.