Postnatal laminar development of cholinergic receptors, protein kinase C and dihydropyridine-sensitive calcium antagonist binding in rat visual cortex. Effect of visual deprivation

Abstract

The postnatal ontogeny of 3H-pirenzepine and 3H-oxotremorine-M binding to M1- and M2-muscarinic acetylcholine receptors, respectively, as well as 3H-nicotine binding to neuronal nicotinic acetylcholine receptors, 3H-phorbol-12,13-dibutyrate binding to protein kinase C and 3H-PN200-110 binding to dihydropyridine-sensitive calcium channels was studied in individual layers of the visual cortex in both normally raised and monocularly deprived rats (one eyelid sutured at the age of 11 days) using quantitative receptor autoradiography. Postnatal ontogeny of M1-muscarinic receptors is similar in each visual cortical layer reaching the highest receptor density at the age of 15 days, whereas M2-muscarinic binding sites increase gradually from day 7 up to day 34. Highest 3H-nicotine binding is reached in all visual cortical layers at postnatal day 15 followed by a considerable decrease in binding sites until day 25. Phorbol ester binding rises considerably from birth until the age of 15 days reaching nearly the adult value in the upper layers, whereas in layers V and VI a marked decrease in binding levels until adulthood can be observed. The developmental course of 3H-PN200-110 binding sites is similar in all visual cortical layers and exhibits a moderate rise in binding sites between postnatal days 7 and 15. Monocular deprivation results in permanent changes in the developmental profiles of phorbol ester as well as calcium antagonist binding sites, whereas the alterations in muscarinic and nicotinic cholinergic receptors folloing monocular deprivation are only of transient nature. The data presented suggest that acetylcholine plays a modulatory role during a certain period of early postnatal maturation of the visual cortex by affecting both cholinergic receptors and associated second messenger cascades.