DIFFERENTIAL LAMINAR EXPRESSION OF AMPA RECEPTOR GENES IN THE DEVELOPING RAT VISUAL-CORTEX USING IN-SITU HYBRIDIZATION HISTOCHEMISTRY - EFFECT OF VISUAL DEPRIVATION

The postnatal development of laminar pattern of AMPA receptor mRNA sub types GluR-A through to GluR-D (flip variants) in the visual cortex of both normally raised and monocularly deprived rats (one eyelid suture d at the age of 11 days) was studied using in situ hybridization histo chemistry and computer-assisted image analysis. The AMPA receptors Glu R-A through to GluR-D transcripts exhibit a differential laminar expre ssion pattern in the developing rat visual cortex. At birth the levels of GluR-A transcripts are lower by about 50% in each visual cortical layer as compared to the adult values. In contrast, GluR-B to GluR-D m RNAs are expressed in all cases at higher levels at birth than in the adult brain. Unilateral eyelid closure at postnatal day 11 for several periods of time resulted in both transient and permanent changes in t he laminar development of GluR-A through to GluR-C transcripts but har dly affected the GluR-D mRNA subtype. The distinct laminar development al pattern of AMPA receptor mRNAs in rat visual cortex as well as the differential effects of visual deprivation suggest specific roles of A MPA receptor subtypes during the early postnatal maturation of visual function.