Immunohistochemical identification of Lucifer Yellow-labeled neurons in the rat supraoptic nucleus.

An attempt was made to identify Lucifer Yellow-labeled neurons in the rat supraoptic nucleus as vasopressin-containing neurons, by means of a combination of immunoperoxidase histochemistry and iontophoretic single cell-injection. We came to the conclusion that the fluorescent dye does not diminish the immunoreactivity of vasopressin in the magnocellular neurons. This newly developed method, along with its modifications, should prove to be quite useful for electrophysiological and morphological studies on the neuropeptide-releasing neurons in the mammalian neuroendocrine system.