Sexual activity and the morphology of steroid-sensitive rat spinal motoneurons

In adult male rats, differential sexual experience has been shown to alter plasma androgen titers. Alterations in androgen levels have also been shown to significantly alter the structure of neurons in the spinal nucleus of the bulbocavernosus (SNB), a spinal motor nucleus that innervates perineal muscles involved in copulatory behavior. To determine if experientially induced alterations in androgen levels might alter SNB structure, male rats were assigned to one of three groups: sexually active, sexually inactive but exposed to inaccessible cycling females, and isolated. After 4 weeks of differential sexual experience, the soma size, total arbor, density, maximal fiber length, and frequency distribution of lengths of dendrites were examined in SNB motoneurons. No differences in motoneuron morphology were observed, suggesting that these motoneurons are not sensitive to socially induced alterations in androgen titers.