Effects of visual deprivation during brain development on expression of AMPA receptor subunits in rat's hippocampus

Environmental signals have an essential role in the maturation of neural circuits during critical period of brain development. It has been shown that, change in visual signals during critical period of brain development changes structure and function of glutamate receptors in the visual cortex. After processing in visual cortex, part of visual signals goes to the hippocampus and makes memories. The aim of this study was evaluating effects of visual deprivation during critical period of brain development on AMPA receptor subunits expression in rats’ hippocampus.

This experimental study was done in Physiology Research Center, Kashan University of Medical Sciences at winter 2014 on male Wistar rats. Animals were divided to 2 groups (n= 36 for each) were kept in standard 12 hours light/12 hours dark condition (light reared, LR) or in complete darkness (dark reared, DR) from birth to the end of the experiments. Using reverse transcription polymerase chain reaction (RT-PCR) and Western blotting techniques respectively, expression of mRNA and protein of GluR1 and GluR2 subunits was evaluated in rats’ hippocampus at ages 2, 4 and 6 weeks in both groups. After quantification of the expressions, the data were compared by two way analysis of variance.

The relative expression of GluR1 subunit decreased about 24% (P=0.004) in the hippocampus of 6 WLR rats in comparison to 2 WLR ones. The relative expression of the other AMPA receptor subunit, GluR2, also increased about 190% in the hippocampus of the 6WLR animals when compared to the 2 WLR rats (P< 0.0001). Dark rearing increased the relative expression of both subunits of AMPA receptors, GluR1 and GluR2, about 20 percent (P= 0.01) in the hippocampus of 6 WDR rats in comparison to 2 WLR animals.

Dark rearing of rats during critical period of brain development changes the relative expression and also arrangement of both AMPA receptor subunits, GluR1 and GluR2 in the hippocampus, age dependently.