Coexistence of neuropeptides in the hypothalamic paraventricular nucleus of the sheep.

The chemical organization of the hypothalamic paraventricular nucleus (NPV) of the sheep was studied immunocytochemically by using antisera raised against oxytocin (OXY), ovine corticotropin releasing factor (CRF), somatostatin (SRIF), neurotensin (NT) and vasoactive intestinal polypeptide (VIP). Examination of immunocytochemically stained frozen, 30-40 microns thick, and paraffin serial, 6 microns thick, sections has shown that chemically specified subsets of neurons are not strictly demarcated anatomically and that OXY and SRIF or CRF and VIP are jointly expressed by certain subpopulations of neurons which are different from that producing both OXY and CRF.