Affective properties of intra-medial preoptic area injections of testosterone in male rats

On alternating days, adult male Long-Evans rats implanted with unilateral c annulae in the medial preoptic area (MPOA) received intracerebral injection s of testosterone (0.05, 0.1 or 0.2 mu g/0.5 mu l), or saline immediately p rior to confinement for 30 min to one of two compartments of a place prefer ence apparatus. All rats received 8 days of pairings (4 hormone and 4 salin e). On day 9, the rats were given a hormone-free 20-min test session during which they had access to all compartments of the apparatus. Intra-MPOA inj ections of testosterone (0.1 mu g) produced a conditioned place preference, while injections of a higher dose (0.2 mu g) produced a conditioned place aversion. The rewarding effects of intra-MPOA testosterone may in part medi ate the facilatory effects of testosterone on motivational aspects of sexua l behavior. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.