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This Article Full Text Full Text (PDF) All Versions of this Article: 569/2/587    most recent jphysiol.2005.097212v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gvilia, I. Articles by Szymusiak, R. Search for Related Content PubMed PubMed Citation Articles by Gvilia, I. Articles by Szymusiak, R. Related Collections Cardiovascular

¹ Research Service, V.A Greater Los Angeles Healthcare System, North Hills, CA, USA
² Departments of Medicine
⁴ Psychology, University of California at Los Angeles, CA, USA
³ I. Beritashvili Institute of Physiology, Tbilisi, Georgia

The median preoptic nucleus (MnPN) of the hypothalamus contains sleep-active neurones, and sleep-related Fos-immunoreactivity (IR) in this nucleus is primarily expressed in GABAergic cells. The MnPN also contains cells responsive to hypertonic saline and to angiotensin-II (Ang-II). To clarify functional relationships between MnPN neurones involved in the regulation of sleep and body fluid homeostasis, we examined c-fos expression in the MnPN after administration of hypertonic saline and Ang-II in both spontaneously sleeping and sleep-deprived rats. Systemic administration of hypertonic saline and intracerebroventricular (I.C.V.) injection of Ang-II increased Fos-IR in both spontaneously sleeping and sleep-deprived rats, compared to control animals. To determine if the population of MnPN neurones activated in response to osmotic and hormonal stimuli is similar to or different from neurones activated during sleep, we quantified Fos-IR in MnPN GABAergic neurones in spontaneously sleeping hypertonic saline- and Ang-II-treated rats versus respective control rats. Fos-IR evoked by these treatments occurred primarily (80–85%) in non-GABAergic neurones. Findings of the present study provide evidence that separate populations of MnPN neurones are involved in the regulation of sleep and body fluid homeostasis.

(Received 30 August 2005; accepted after revision 4 October 2005; first published online 6 October 2005)
Corresponding author R. Szymusiak: Research Service (151A3), VAGLAHS, 16111 Plummer Street, North Hills, CA 91344, USA. Email: rszym{at}ucla.edu

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