TESTOSTERONE EFFECTS ON VASOTOCINERGIC INNERVATION OF SEXUALLY DIMORPHIC MEDIAL PREOPTIC NUCLEUS AND LATERAL SEPTUM DURING AGING IN MALE QUAIL

Vasotocin fibers are known to innervate regions important in the regul ation of sexual behavior and neuroendocrine systems in quail. In this experiment, vasotocinergic innervation of the lateral septum and of th e sexually dimorphic medial preoptic nucleus was studied during reprod uctive aging relative to sexual behavior or following testosterone (T) . There were 4 groups of male Japanese quail (Coturnix japonica) studi ed: adult reproductive (6 month, n = 4), photoregressed adult (n = 5), old senescent (36 month, n = 4), and old testosterone-treated (n = 5) . Immunocytochemistry for vasotocin (VT) was performed on serial secti ons and quantification of the density of VT-positive fibers was perfor med by image analysis. Results showed a highly significant decrease in VT-immunocytochemical staining in photoregressed and in old senescent males; whereas T-treatment in old males was associated with recovery of VT-immunocytochemical staining, comparable to the adult reproductiv e male. Previous experiments have shown that T treatment restimulates sexual behavior in senescent males similar to the recovery of sexual b ehavior in T-treated castrates. These results indicate that the VT sys tem may be associated with the behavioral recovery observed in senesce nt T-treated males.