DECREASED MUSCARINIC RECEPTOR-BINDING in RAT-BRAIN AFTER PARADOXICAL SLEEP-DEPRIVATION - AN AUTORADIOGRAPHIC STUDY

Previous work demonstrated that paradoxical sleep deprivation (PSD) leads to a decrease in yawning behavior elicited by cholinergic agonists, suggesting that a downregulation of cholinergic muscarinic receptors may occur after PSD. More recent work using intracerebral injections of muscarinic agonists has suggested a critical role for M2 receptors in paradoxical sleep. in this study [H-3]AF-DX 384 was used to investigate the effects of PSD on M2-type cholinergic receptors throughout the brain using quantitative autoradiography. After 96 h of paradoxical sleep deprivation, [3H]AF-DX 384 binding was generally reduced throughout the brain, and significantly so in the olfactory tubercle (-20%), n. accumbens (-23%), frontal caudate-putamen (-16%), islands of Callejas (-20%), piriform cortex (-24%), lateral (-26%) and medial (-24%) septum, anteromedial (-19%), ventrolateral (-22%), and lateral geniculate (-15%) nuclei of thalamus, deep layers of the superior colliculus (-15%), entorhinal cortex (-12%) and subiculum (-23%). [H-3]AF-DX 384 binding was reduced in pontine structures, but not to a higher degree than in other brain areas. the observed downregulation of M2-type muscarinic receptors after PSD may be causally related to the previously reported decrease in cholinergically induced behaviors after PSD.CLARKE INST PSYCHIAT, NEUROIMAGING RES STN, TORONTO M5T 1R8, ON, CANADAESCOLA PAULISTA MED, DEPT PSICOBIOL, BR-04023 São Paulo, BRAZILESCOLA PAULISTA MED, DEPT PSICOBIOL, BR-04023 São Paulo, BRAZILWeb of Scienc