Molecular biological and molecular genetic studies in apoptosis of retinal ganglion cells and retinal differentiation.

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The expression of isoforms of nitric oxide sythase (NOS), enzymes responsible for NO production, and the synthesis of nitric oxide (NO) in rat retinal cells (RGCs) during synaptogenesis for variation phases of the pre- and postnatal developmental periods were investigated. The reinas from prenatal, lactaing, young, and adult rats were fixed in paraformaldehyde. The cryosections or paraformaldehyde-fixed ganglion cells purified from rat pupus were immunostained for constitutive isoforms of NOS(n and eNOS) and observed with confocal laser scanning microscope. Synthesis of No in the RGCs was achieved by in vitro stimulation with glutamete. The intracellular NO levels measured I real time using diaminofluorescein-2 diacetate, a, fluorescence indicator of NO. immunohistochemical analysis revaled nNOS and eNOSin vitro. Intracellular NO levels in cultured RGCs showed spontaneous fluctuation during a 20-min observation. The presence of both a non-specific NOS inhibitor, L-NAME, and a specific nNOS inhibitor, 7-NI, significantly inhibited the increase of intracellular NO 6 and 8 min after the introduction of L-arginine and glutamete to the medium. This study revealed that all constitutive NOS isoforms are expressed I RGCs and demonstrated that NO is produced by nNOS mainly through stimulation by glitamete in cultured RGCs. We addressed to examine if senescence may decrease the expression levels of tissue brain-derived neurotrophic factor (BDNF) and its receptor TrkB which are thought to support the survival of RGCs.