Development of muscarinic cholinergic receptor binding in the visual system of monocularly deprived and dark reared...

In 25 day old rats monocularly deprived by unilateral eyelid suture on postnatal day 10 (MD), [3H]quinuclidinyl benzylate (3H-QNB) binding was significantly reduced in the visual cortex (VC) of both sides, but elevated in both superior colliculi (SC). Muscarinic receptor binding in the frontal cortex (FC), a non-visual brain area, in the lateral geniculate nucleus (LGN), and in the retina was not affected. In 25 day old rats raised in complete darkness from birth (DR) similar changes in 3H-QNB binding were found in VC and SC. However, binding levels were also decreased in the FC and significantly increased in the retina. In adult (6 month old) MD and DR rats the differences in 3H-QNB binding as compared to age-matched controls had disappeared completely in all visual brain areas studied. Detailed Scatchard analyses indicate that the alterations in the 3H-QNB binding were due to changes in receptor number only.