| ObjectiveEpilepsy (EP) is chronic diseases of the nervous system induced by a group of brain neurons abnormal discharge,characterized by transient dysfunction of brain . Clinical found epileptic except seizures symptom,often accompanied by different degrees of the function of learning and memory'loss,seriously affect the patient's quality of life . Speculating the reason may due to illness itself or long-term use of antiepileptic drugs,which make the patient's thinking and memory ability declined, cause varying degrees of learning difficulties,however the exact impact mechanism is not clear. Orexin is a excitability neuropeptide produced by lateral hypothalamus area neurons,playing an important role in the regulation.of feeding,energy metabolism,sleep awakening and neuroendocrine . Recent studies show that the orexin and its receptors are involved in the activities of learning and memory. But,Whether orexin can improve learning and memory impairment caused by epileptic not yet seen the related research reports . This study aims to observe the impact of orexin - A on the the function of learning and memory of epileptic rats .Our study used PTZ-kindled chronic epileptic rats,respectively intracerebroventricul ar (i.c.v.) injection Orexin-A or saline (NS),Observing the changes of epileptic rats'cogni- tive function ,and through the Morris water maze experiment , investigating the effect of Orexin - A on the function of learning and memory of PTZ- kindled chronic epileptic ratsMethodsAdult Wastar rats were randomly divided into control group (normal saline,NS) and PTZ group. The PTZ-kindled rats were randomly divided into two groups, orexin-A and NS groups administrated by intracerebroventricular (i.c.v.) injection of 10μl orexin-A(1.4 nmol/μl)or 10μl NS. Using Morris water maze experiment, the ability of learning and memory was measured in all rats . Results(1) Eighty percent of rats in PTZ group were kindled successfully after intraperitoneal injection of 35mg/kg PTZ every day for 30 days. Compared to control group, the escape latency in the PTZ-kindled rats was significantly increased in Place navigation test (PNT)(F=200.956,P<0.01),whereas a remarkable reduction of time spent in the target quadrant and number of pool circlings in 120 seconds was observed during probe trials.The search strategies of epileptic rats become poor: straight and taxis was markedly reduced,but random and marginal significantly increased . Compared with the control group, the function of epileptic rats,learning and memory decline associated. The experimental results suggest that:The Spatial learning and memory in the PTZ-kindled rats was declined.(2) Following i.c.v.injection of orexin-A,the latency of escape platform was significantly declined in both PTZ-kindled and NS rats.In addition,the treatment with orexin-A markedly increased swim velocity and number of pool circlings in both groups(P<0.01),particularly to the PTZ-kindled rats. In the PTZ -kindled epileptic rats,i.c.v injection of orexin-A not only made the number of cross platform quadrant obviously increase,but also increased rats platform quadrants swimming time (P < 0.01),as the same time raised the percentage of platform quadrant swimming time, Compared with the EP groups,EP + Orexin rats'constitute of straight and taxis was obviously higher than search strategies , especially taxis , but random and marginal significantly reduced. The experimental results show that: i.c.v.injection of orexin-A can significantly improve the spatial memory capacity and search strategies learning ability of PTZ-kindled epileptic rats .Conclusion1 . The spatial learning and memory capacity of PTZ-kindled epileptic rats was obviously decreased.2 . I.c.v injection of orexin-A can improved the Spatial learning and memory of PTZ-kindled epileptic rats. |
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