Neurotransmitter properties of the newborn human retina

Human retinal tissue from a newborn was examined autoradiographically for the presence of high-affinity uptake and localization of the following putative neurotransmitters: dopamine, glycine, GABA, aspartate, and glutamate. In addition, the dopamine content of this newborn retina was measured by high pressure liquid chromatography. Our study reveals that specific uptake mechanisms for 3H-glycine, 3H-dopamine, and 3H-GABA are present at birth. However, the number and distribution of cells labeled with each of these 3H-transmitters are not identical to those observed in adult human retinas. Furthermore, the amount of endogenous dopamine in the newborn retina is approximately 1/20 the adult level. Photoreceptor-specific uptake of 3H-glutamate and 3H-aspartate are not observed. These findings indicate that, while some neurotransmitter-specific properties are present at birth, significant maturation of neurotransmitter systems occurs postnatally.