Role of Medial Preoptic Area Beta Adrenoceptors in the Regulation of Sleep-Wakefulness

doi:10.1016/S0091-3057(96)00384-X

Pharmacology Biochemistry and Behavior

Volume 57, Issues 1–2, May–June 1997, Pages 1-5

https://doi.org/10.1016/S0091-3057(96)00384-X Get rights and content

Abstract

The role of the medial preoptic area (mPOA) beta adrenergic receptors in the regulation of sleep-wakefulness (S-W) was investigated in this study. S-W was assessed on the basis of polygraphic recording of EEG, EMG and EOG, in free moving rats. Intracerebral microinjection of beta agonist, isoproterenol, into the mPOA produced arousal. The study was also conducted on another set of rats in which noradrenergic (NE) innervation to the mPOA was destroyed by injecting 6-hydroxydopamine into the ventral noradrenergic bundle, in the brain stem. Local application of isoproterenol, into the mPOA, in these animals, did not produce any significant change in S-W. Thus, the increase in awake period obtained on isoproterenol administration was the result of its action on the presynaptic NE terminals. Possible involvement of other responses in the isoproterenol induced increase in wakefulness, is discussed.

Section snippets

Materials and methods

Experiments were conducted on male Wistar rats (200–250g) divided into three groups of five each. The experimental rats were housed in separate cages in an animal house having a controlled temperature (26 ± 2°C) and lighting (05.00– 19.00 h). Food and water were provided ad lib. Rats were anaesthetised with sodium pentabarbitone (40 mg/kg bw) and EEG, EMG and EOG electrodes were chronically implanted for assessment of S-W [7]. Bilateral cannulae were also chronically implanted for injection of

Results

There was no significant variation in S-W in the preinjection records obtained from different animals. The animals showed normal polycyclic pattern of sleep awake cycle during this period. Basal recordings from different groups of rats had mean sleep time varying from 41.4 to 64.6% (Table 1). The sleep record was dominated by SWS, while PS was only occasionally observed.

Discussion

Isoproterenol (2 μg), when administered at the mPOA, induced injection-bound arousal in normal rats. This drug did not produce any such change in S-W in the VNA lesioned rats. Thus, it could be suggested from the present study that isoproterenol produces arousal by acting on the presynaptic receptors, as the response was not obtained after the removal of the NE nerve terminals (with the presynaptic receptors). At the same time, a postsynaptic site of action of this drug could also be suggested

Acknowledgements

This study was supported by the Indian Council of Medical Research.

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ArticlesRole of Medial Preoptic Area Beta Adrenoceptors in the Regulation of Sleep-Wakefulness

Abstract

Section snippets

Materials and methods

Results

Discussion

Acknowledgements

Brain Res.

Exp. Neurol.

Brain Res. Bull.

Brain Res.

Behav. Brain Res.

Jpn. J. Physiol.

Physiol. Behav.

Physiol. Behav.

Ascending monoamine neurons to the telencephalon and diencephalon

Acta Physiol. Scand.

Articles
Role of Medial Preoptic Area Beta Adrenoceptors in the Regulation of Sleep-Wakefulness