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Open Access Research

Cytomorphometric changes in the dorsal raphe neurons after rapid eye movement sleep deprivation are mediated by noradrenalin in rats

Amit Ranjan1, Sudipta Biswas2 and Birendra N Mallick1*

Author Affiliations

1 School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India

2 Current address: Behavioral Neuroscience Division, Dept. of Psychology, Arizona State University, Tempe, AZ 85287-1104, USA

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Behavioral and Brain Functions 2010, 6:62  doi:10.1186/1744-9081-6-62

Published: 21 October 2010

Abstract

Objectives

This study was carried out to investigate the effect of rapid eye movement sleep (REMS) deprivation (REMSD) on the cytomorphology of the dorsal raphe (DR) neurons and to evaluate the possible role of REMSD-induced increased noradrenalin (NA) in mediating such effects.

Methods

Rats were REMS deprived by the flowerpot method; free moving normal home cage rats, large platform and post REMS-deprived recovered rats were used as controls. Further, to evaluate if the effects were induced by NA, separate sets of experimental rats were treated (i.p.) with α1-adrenoceptor antagonist, prazosin (PRZ). Histomorphometric analysis of DR neurons in stained brain sections were performed in experimental and control rats; neurons in inferior colliculus (IC) served as anatomical control.

Results

The mean size of DR neurons was larger in REMSD group compared to controls, whereas, neurons in the recovered group of rats did not significantly differ than those in the control animals. Further, mean cell size in the post-REMSD PRZ-treated animals was comparable to those in the control groups. IC neurons were not affected by REMSD.

Conclusions

REMS loss has been reported to impair several physiological, behavioral and cellular processes. The mean size of the DR neurons was larger in the REMS deprived group of rats than those in the control groups; however, in the REMS deprived and prazosin treated rats the size was comparable to the normal rats. These results showed that REMSD induced increase in DR neuronal size was mediated by NA acting on α1-adrenoceptor. The findings suggest that the sizes of DR neurons are sensitive to REMSD, which if not compensated could lead to neurodegeneration and associated disorders including memory loss and Alzheimer's disease.