Development of GABAA receptors in the central visual structures of rat brain. Effect of visual pattern deprivation.

The postnatal development of high-affinity 3H-muscimol binding to GABAA receptors was studied in the lateral geniculate nucleus, superior colliculus, frontal and visual cortex of the rat brain. In the lateral geniculate nucleus 3H-muscimol binding rises from day 10 through day 37 reaching the highest value during the entire development followed by a slight decrease until adulthood. In the superior colliculus 3H-muscimol binding increased continuously from day 10 through day 37, and then decreased until day 50 reaching the adult value. In the visual and frontal cortex, binding reached the highest levels on days 14 and 25, respectively, persisted until day 37 followed by a slight decrease until adulthood. The ontogeny of 3H-muscimol binding sites in the visual regions does not essentially differ from that in other brain regions, suggesting that the appearance of 3H-muscimol binding sites in the visual system is not correlated with the functional maturation of the visual system. Unilateral eyelid closure from day 11 until day 25 did not affect the development of GABAA receptors in any of the central visual regions examined, indicating the lack of environmentally controlled mechanism.