Changes in pontine muscarinic receptor binding during sleep-waking states in the rat.

Number and affinity of pontine muscarinic receptors were examined in rats sacrificed during polygraphically defined wakefulness (W), synchronized sleep (S) and desynchronized sleep (D). Saturation binding assays with (-)-[3H]quinuclidinyl benzilate [( 3H]QNB) showed that muscarinic receptor levels were higher in W and D than in S. These findings indicate that brain receptor levels may change in relation to sleep-waking states. The significance of such changes in relation to the time course of sleep-waking states, as well as the possibility that the number of pontine muscarinic receptors plays a role in the triggering of D are discussed.