PHYSIOLOGICAL FUNCTIONS OF GABA-INDUCED DEPOLARIZATIONS IN THE DEVELOPING RAT SPINAL-CORD

Gamma-aminobutyric acid (GABA) is one of the principle inhibitory neur otransmitters in the mature spinal cord. It effectively suppresses syn aptic transmission by mechanisms of postsynaptic and presynaptic inhib ition. The function of GABA is less well understood early in spinal co rd development, when the amino acid is transiently expressed in most n eurons, and it depolarizes instead of hyperpolarizes neurons. This art icle reviews the possible physiological roles of GABA in modulating sy naptic transmission, promoting neuronal development, and regulating ne uronal pH during early stages of spinal cord differentiation. It is pr oposed that despite its depolarizing action, GABA acts as an inhibitor y neurotransmitter that may also function as a neurotrophic agent.