Lesion of forebrain nuclei reveals possible presynaptic cholinergic muscarinic receptors in rat cerebral cortex.

Abstract In rats, three days after unilateral lesion of magnocellular basal forebrain nuclei, binding of l -[ 3 H]-quinuclidinyl benzilate and acetylcholinesterase activity decreased significantly in the ipsilateral and, to a lesser extent, in the contralateral cerebral cortex. This result suggests the existence of presynaptic muscarinic receptors in the cortical projections of these nuclei. After 14 days, the binding increased on both sides while the level of acetylcholinesterase activity remained low. These findings suggest that deafferentation causes ultimately an increase in postsynaptic receptors.