Properties of the GABA receptors located on spinal primary afferent neurones and hypophyseal neuroendocrine cells of the rat.

Electrophysiological techniques have been used to study the pharmacological characteristics of GABA receptors in two in vitro preparations likely to provide the ionic basis for GABAergic inhibition of excitation-secretion coupling. The shortening of Ca2+ spikes duration by GABAB receptors was shown to occur in slow conducting dorsal root ganglion cells, independently of marked depression of inward calcium currents. Ion-selective electrodes (K+ or Ca2+) were used to show the presence of both GABAA and GABAB receptors on the neurosecretory terminals and gland cells from hypophyseal neuro-intermediate lobe (NIL). In this latter preparation, potentiation of hormone release was observed under GABAA receptor activation, whilst inhibition was seen with GABAB agonists.