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 [3H]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%). [3H]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.
Nunes Júnior
G P
GP
Departamento de Psicobiologia, Escola Paulista de Medicina, São Paulo, Brazil.
Tufik
S
S
Nobrega
J N
JN
D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism*; D008297:Male; D010890:Pirenzepine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012892:Sleep Deprivation / Q000502:physiology*; D012895:Sleep, REM
D011976:Receptors, Muscarinic; C065959:AFDX 384; D010890:Pirenzepine