COEXISTENCE OF NADPH-DIAPHORASE WITH VASOPRESSIN AND OXYTOCIN IN THE HYPOTHALAMIC MAGNOCELLULAR NEUROSECRETORY NUCLEI OF THE RAT

Coexistence of NADPH-diaphorase with vasopressin and oxytocin was stud ied in the magnocellular neurosecretory nuclei of the rat hypothalamus by use of sequential histochemical and immunocytochemical techniques in the same sections. Coexistence was found in all the nuclei examined (supraoptic, paraventricular, circular, fornical, and in some isolate d neurons located in the hypothalamic area between the paraventricular and supraoptic nuclei). The ratios of neurons expressing both markers (NADPH-diaphorase and vasopressin, NADPH-diaphorase and oxytocin) in each of the nuclei were very similar. Although further studies must be carried out, the partial coexistence found in all nuclei suggests tha t NADPH-diaphorase is probably not related to general mechanisms invol ving vasopressin and oxytocin, but rather in specific functions shared by certain hypothalamic neuronal cell populations.