Patch-clamp study of membrane properties and GABA-activated currents of rat magnocellular supraoptic neurons in thin slice preparation.

The magnocellular neurons of the rat supraoptic nucleus were investigated by using (a) the patch-clamp technique on thin brain slice preparations to demonstrate voltage- and GABA-activated ionic currents, and (b) immunohistochemistry to demonstrate the expression of the beta 2 and beta 3 subunits of the GABAA-receptor on their membrane surface and the contents of the neuropeptides vasopressin and oxytocin. During electrophysiological recording in the whole-cell mode neurons were stained with Lucifer Yellow and camera lucida drawings were made. Two types of neurons could be distinguished by their different K(+)-currents, an inactivating and a noninactivating type. All neurons had a fast Na+ inward current. GABAA-activated currents were characterized by investigation of their ionic conductance and by blocking experiments with the GABAA-antagonist bicuculline.