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- Title
REM sleep changes in rats induced by siRNA-mediated orexin knockdown.
- Authors
Chen, Lichao; Thakkar, Mahesh M.; Winston, Stuart; Bolortuya, Yunren; Basheer, Radhika; McCarley, Robert W.
- Abstract
Short interfering RNAs (siRNA) targeting prepro-orexin mRNA were microinjected into the rat perifornical hypothalamus. Prepro-orexin siRNA-treated rats had a significant (59%) reduction in prepro-orexin mRNA compared to scrambled siRNA-treated rats 2 days postinjection, whereas prodynorphin mRNA was unaffected. The number of orexin-A-positive neurons on the siRNA-treated side decreased significantly (23%) as compared to the contralateral control (scrambled siRNA-treated) side. Neither the colocalized dynorphin nor the neighbouring melanin-concentrating hormone neurons were affected. The number of orexin-A-positive neurons on the siRNA-treated side did not differ from the number on the control side 4 or 6 days postinjection. Behaviourally, there was a persistent (∼ 60%) increase in the amount of time spent in rapid eye movement (REM) sleep during the dark (active) period for 4 nights postinjection, in rats treated with prepro-orexin siRNA bilaterally. This increase occurred mainly because of an increased number of REM episodes and decrease in REM-to-REM interval. Cataplexy-like episodes were also observed in some of these animals. Wakefulness and NREM sleep were unaffected. The siRNA-induced increase in REM sleep during the dark cycle reverted to control values on the 5th day postinjection. In contrast, the scrambled siRNA-treated animals only had a transient increase in REM sleep for the first postinjection night. Our results indicate that siRNA can be usefully employed in behavioural studies to complement other loss-of-function approaches. Moreover, these data suggest that the orexin system plays a role in the diurnal gating of REM sleep.
- Subjects
RAPID eye movement sleep; LABORATORY rats; HYPOTHALAMO-hypophyseal system; HUMAN behavior; NEURAL transmission; NEUROSCIENCES
- Publication
European Journal of Neuroscience, 2006, Vol 24, Issue 7, p2039
- ISSN
0953-816X
- Publication type
Article
- DOI
10.1111/j.1460-9568.2006.05058.x