Variation of glycine-activated conductivity of the membranes of spinal cord neurons in the chick embryo in culture

The method of leading off whole-cell currents is used to study the neuron responses elicited by applications of glycine at different stages of culturing of the chick embryo dissociated spinal cord. For two types of cells described earlier [4] differently directed shifts of the concentration dependence curves of the transmitter effect are shown to be characteristic. "Mature" cells, surviving several days in culture and represented by motoneurons, typically show a lowered sensitivity to glycine. The sensitivity of little-differentiated neurons increases more than tenfold by the end of the second week of culturing. The desensitization kinetics of the glycine-activated current also slows down with age. Blocking of the spontaneous electrical activity during development prevented these changes, and the presence of agonist in the culture medium did not affect them. Analogous patterns of formation of transmitter sensitivity are assumed to be exhibited by differentiating neurons of the intact nervous system.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 5, pp. 580–587, September–October, 1991.