Regional distribution of neurotransmitter receptors in the visual structures of the rat brain

The regional distribution of the binding of 3H-quinuclidinyl benzylate, 3H-dihydroergocryptine, 3H-dihydroalprenolol, 3H-serotonin and 3H-flunitrazepam was investigated in the retina, lateral geniculate nucleus, superior colliculus, visual and frontal cortex of 25-day-old and adult rats. In adult rats the highest binding levels for the muscarinic acetylcholine and benzodiazepine receptor are present in the visual and frontal cortex, whereas alpha- and beta-adrenergic receptor binding was highest in the retina and 3H-serotonin binding in the lateral geniculate nucleus. Binding of 3H-quinuclidinyl benzylate, 3H-flunitrazepam and 3H-serotonin increases in the adult rats, whereas alpha- and beta-adrenergic receptor binding is decreased compared to the binding levels found in 25-day-old animals. The distribution of the neurotransmitter receptors studied within the visual structures cannot be readily correlated with the pattern of some neurochemical presynaptic parameters.