Medial preoptic area kindling induces sexual behavior in sexually inactive male rats

In the present experiments, sexually experienced and non-copulating male rats were kindled in the medial preoptic area (MPOA) or the amygdala (AMG) with the purpose to investigate if the widespread modification of brain function produced by kindling induces sexual behavior in non-copulating rats and if kindling facilitates sexual behavior in copulating rats. Since kindling in the MPOA has been little studied, a description of this phenomenon is also presented. The animals were stimulated 4 times daily on odd days and sexual behavior monitored on even days. The results showed that the MPOA required higher stimulus intensity to elicit an afterdischarge (AD) than the AMG. The AD duration was significantly longer in animals kindled in the MPOA than in animals kindled in the AMG. No difference was found in the development of kindling between these brain structures. Kindling had no effect upon sexual behavior in copulating rats. In contrast, MPOA kindling induced copulation in non-copulating male rats. Seven out of 9 animals displayed sexual behavior. No significant facilitation was observed after AMG kindling in non-copulating male rats. Furthermore, the sexual behavior displayed by the previously non-copulating MPOA kindled rats was similar to the sexual behavior displayed by sexually experienced animals. It is proposed that sexual behavior is facilitated in these male rats by local neural changes produced by kindling.