ABSTRACT
Animals deprived of REM sleep by the water tank technique show an important decrease in frequency of yawning, induced by dopaminergic (apomorphine in low doses) and cholinergic (physostigmine and pilocarpine) agonists, if they are tested immediately after the 96 hr of deprivation. In order to understand the mechanisms underlying the effects of REM sleep deprivation on dopaminergic and cholinergic systems, we decided to test the animals after a recovery period of 24 hr. It was observed that apomorphine-induced yawning was still significantly reduced, whereas pilocarpine-induced yawning had returned to normal. The findings suggest that REM sleep deprivation alters dopaminergic and cholinergic systems in different ways: it seems that the interference on the dopaminergic system is prior and stronger than on the cholinergic system, thus its recovery demands more time.
Subject(s)
Dopamine/physiology , Parasympathetic Nervous System/physiology , Sleep Deprivation/physiology , Yawning/physiology , Animals , Apomorphine/pharmacology , Male , Physostigmine/pharmacology , Pilocarpine/pharmacology , Rats , Rats, Inbred Strains , Sleep, REM/physiologyABSTRACT
Central administration of ACTH in rats induces yawning and stretching. In order to study the effects of REM sleep deprivation on ACTH-induced yawning, the peptide was injected immediately after the REM sleep deprivation period or 24 h later. REM sleep deprivation impaired ACTH-induced yawning, but after a 24-hour recovery period, rats displayed a number of yawns similar to those in control animals. Implications for an involvement of dopaminergic and mainly cholinergic systems are discussed.
Subject(s)
Adrenocorticotropic Hormone/pharmacology , Sleep, REM/physiology , Yawning/drug effects , Adrenocorticotropic Hormone/administration & dosage , Animals , Cosyntropin/pharmacology , Injections, Intraventricular , Male , Rats , Rats, Inbred Strains , Sleep, REM/drug effectsABSTRACT
Yawning behavior was used to evaluate the sensitivity of presynaptic dopamine receptors and postsynaptic acetylcholine receptors of normal and REM sleep-deprived (REMSD) rats. The results show a lowering of the dose-response curve obtained with apomorphine and pilocarpine, as well as a shift to the right in the curve obtained with physostigmine. These results suggest that REMSD induces subsensitization of presynaptic dopamine receptors and/or postsynaptic acetylcholine receptors with different characteristics related to the mechanism of action of the cholinomimetic agent employed.