Arousal effect of orexin A on rats of anesthesia with ketamine-midazolam

Objective To determine the arousal effect of orexin-A on the rats of anesthesia with ketamine-midazolam.Methods After intraperitoneal injection of ketamine(75mg/kg) and midazolam(5mg/kg),different doses of orexin-A were administered intracerebroventricularly(icv) to rats.The percent of δ wave in ECoG was used to evaluate the depth of anesthesia,the duration of loss-of-righting reflex(LRR) was used to evaluate the recovery time,the duration of post-LRR ataxia was used to evaluate the motor function.Results Compared with the control group,high dose of orexin-A(4nmol) induced significant decrease in the percent of δ wave in ECoG(P0.01) and the duration of LRR and post-LRR ataxia(P0.01).However,there was no significant change in these parameters in low dose orexin-A(1nmol)group compared with the control group(P0.05).Conclusion The intracerebroventricular(ICV) injection of orexin-A in rats can decrease the depth of anesthesia,shorten the recovery from anesthesia and improve motor function after anesthesia.In other word,orexin-A has a potent arousal effect on anesthetized rats.