Visual deprivation during critical period of brain development inhibits expression of glutamic acid decarboxylase enzyme in rat hippocampus

 Introduction: Visual deprivation during critical period of brain development inhibits the GABAergic system growth and completion in visual cortex. Because parts of visual signals are transferred to hippocampus through the visual cortex, the aim of this experiment was to study the effects of visual deprivation during critical period of brain development on expression of Glutamic Acid Decarboxylase enzyme in rats’ hippocampus. Materials and methods: This study was carried on 2 groups (n=36) of male rats kept in standard 12 hour light/dark cycle (Light reared, LR) or in complete darkness (Dark reared, DR). Each group, in turn, was divided into 3 aged-based subgroups of 2, 4 and 6 weeks old rats. Using RT-PCR and Western Blot techniques, expression of both isoforms of Glutamic Acid Decarboxylase enzyme were investigated in hippocampus.  Results: Relative expression of mRNA and protein of GAD65 and GAD67 enzymes increased in the LR animals, time dependently. However, although the expression of both enzymes increased in the DR animals by aging, but, the expression was much lower in compare to the LR rats.  Conclusion: Visual deprivation during critical period of brain development inhibits the expression of GAD65 and GAD67 enzymes in rat hippocampus and delays GABAergic system development