DISTRIBUTION OF ANDROGEN RECEPTOR IMMUNOREACTIVITY IN VASOPRESSIN-IMMUNOREACTIVE AND OXYTOCIN-IMMUNOREACTIVE NEURONS IN THE MALE-RAT BRAIN

Arginine vasopressin-immunoreactive (AVP-ir) neurons in the bed nucleu s of stria terminalis (BST) and medial amygdaloid nucleus are very res ponsive to gonadal hormones. After gonadectomy, these neurons lose the ir AVP immunoreactivity and stop expressing AVP mRNA. Testosterone tre atment reverses these changes, acting via androgen as well as estrogen receptor-mediated mechanisms. Although AVP-ir neurons contain estroge n receptor immunoreactivity, it is not known whether they also contain androgen receptor immunoreactivity. To answer this question, brains o f male rats were stained immunocytochemically for AVP as well as for a ndrogen receptors. In the BST and medial amygdaloid nucleus, respectiv ely, 90.5% and 91.2% of the AVP-Ir neurons contained androgen receptor immunoreactivity. In contrast, in the suprachiasmatic nucleus, the su praoptic nucleus, and the magnocellular portion of the paraventricular nucleus (PVN), none of the AVP-ir neurons contained androgen receptor immunoreactivity. In the ventral zone of the medial parvocellular par t of the PVN (mpvPVN), 4.3% of the scattered AVP-ir neurons contained androgen receptor immunoreactivity. One of the control experiments, ie . staining sections for oxytocin (OT) rather than AVP, revealed that a lthough OT-ir neurons in the supraoptic and magnocellular portion of t he PVN did not contain androgen receptor immunoreactivity, 52.5% of th e OT-ir neurons in the mpvPVN did. The results suggest that androgens can bind to androgen receptors in AVP-ir neurons in the BST and medial amygdaloid nucleus, possibly to influence AVP expression. The results also suggest that androgens can bind to androgen receptors in AVP-ir and OT-ir neurons in the mpvPVN. The function of the latter interactio n, however, is unclear.