Postnatal Development of a Mammalian Retina: Neurotransmitters as Physiological and Anatomical Probes

Abstract

The emergence and maturation of specific neurotransmitter systems in different neurons is a characteristic feature of neural differentiation. In adult nervous systems, neurons which use γ-aminobutyric acid (GABA) and dopamine as neurotransmitters have been shown to contain high concentrations of these substances and their synthetic enzymes, to possess high-affinity transport mechanisms for the accumulation of these substances and to release them upon appropriate stimulations. In addition, putative glycinergic neurons also possess a specific high-affinity uptake mechanism for glycine and release it in response to depolarizing stimuli. We have recently used some of these transmitter-specific properties as physiological and anatomical probes to follow the emergence and maturation of identified neurons in Xenopus and rabbit retinas. (Hollyfield et al., 1979; Rayborn et al., 1981; Sarthy et al., 1981; Lam et al., 1980, 1981; Kong et al., 1980). This article summarises our studies to-date on the postnatal development of putative GABA-ergic, glycinergic and dopaminergic neurons in the rabbit retina.