Decrease in muscarinic M2 receptors from synaptosomes in the pons and hippocampus after REM sleep deprivation in rats.

The effects of both REM sleep deprivation and its recovery on pontine and hippocampus muscarinic M2 receptors were investigated in synaptosomes using [3H]-AF-DX 384 as a ligand. Animals were divided into three groups: REM sleep deprivation group (small platforms 6.5 cm of diameter); stress group (large platforms 14 cm of diameter) and cage control group. In a second experiment REM sleep-deprived animals were allowed 48 h of recovery. REM sleep-deprived rats showed a reduction in M2 receptors compared with both intact and stress groups. Changes in M2 receptors were also observed after 48 h of recovery from REM sleep deprivation only in hippocampus. The enhancement of acetylcholine release during both REM sleep deprivation and recovery could explain the present findings.