A method for immunocytochemical identification of biocytin-labeled neurons following intracellular recording

Because of the large number of cell phenotypes in the nervous system, it has been difficult to characterize each as to specific electrophysiological properties. We have developed a technique that allows the identification of central and peripheral nervous system neurons following intracellular recording. We use electrodes that contain 2% biocytin to do current- and voltage-clamp recordings; the recorded neurons are revealed with streptavidin-fluorescein isothiocyanate labeling and identified through immunohistochemical staining for specific antigens. Presently, we report on the use of this technique to identify four cell types--dopamine, beta-endorphin, vasopressin and oxytocin--in the hypothalamus of the mammal. This technique should have widespread applicability for electrophysiologists.