(2014) Tail flick modification of orexin-A induced changes of electrophysiological parameters in the rostral ventromedial medulla. Cell Journal. pp. 131-140. ISSN 22285806
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Abstract
Objective: It is well known that intracerebroventricular (ICV) and supraspinal injections of orexin-A elicit analgesia, but the mechanism(s) of action remains unidentified. This study aims to characterize the effect of orexin-A on rostral ventromedial medulla (RVM) neurons which are involved in the descending nociception modulating pathway. Materials and Methods: In this experimental study, we injected orexin-A or vehicle directly into rats' ICV while the tail flick (TF) latencies were measured and the on- and off-cell firing activities were monitored for more than 60 minutes. Results: In response to noxious stimuli on the tail, we observed increased firing rate of on-cells and a decreased association with the firing rate of off-cells and in neutral cells the firing rate was unchanged just prior to tail flicking. ICV injection of orexin-A decreased the spontaneous firing rate of on-cells (the type of RVM neurons believed to have facilitatory action on nociception). Furthermore, orexin-A increased firing rate of off-cells (the type of RVM neurons believed to have an inhibitory action on nociception). Orexin-A reduced the TF-related responses of on-cells and TF-related pause duration of off-cells. Conclusion: These results have shown that the analgesic effect produced by orexin-A may be induced by brainstem neurons. It is suggested that the orexinergic system from the hypothalamus to the RVM may have a potential role in modulation of nociceptive transmission.
Item Type: | Article |
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Keywords: | Orexin A, adult; tail flick ,Pain |
Page Range: | pp. 131-140 |
Journal or Publication Title: | Cell Journal |
Journal Index: | Scopus |
Volume: | 16 |
Number: | 2 |
Publisher: | Royan Institute (ACECR) |
ISSN: | 22285806 |
Depositing User: | دکتر محبوبه عبداللهی |
URI: | http://eprints.thums.ac.ir/id/eprint/190 |
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