PARTIAL COEXISTENCE OF NADPH-DIAPHORASE AND SOMATOSTATIN IN THE RAT HYPOTHALAMIC PARAVENTRICULAR NUCLEUS

Coexistence of NADPH-diaphorase (ND) activity and somatostatin (SRIF) immunoreactivity was studied in the paraventricular nucleus (PVN) of the rat hypothalamus by successive incubations of the same sections. ND was found in all PVN subdivisions, mainly in the magnocellular ones. SRIF was practically restricted to the parvicellular periventricular subdivision. Contrary to other brain regions where a wide SRIF-ND coexistence has been observed, the periventricular parvicellular subdivision was the only place of the PVN where some neurons colocalize both markers. The combination of the immunocytochemical and the histochemical labellings allows a further permanent and easy-to-perform parcellation of periventricular PVN neurons.