Changes Of Ng Expression In Hippocampus Of Pentylenetetrazole-kindled Rats With Learning And Memory Impairment

Objectives: Epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of this condition.In addition to the seizure, there are cognitive impairment such as scattered attention,learning and memory impairment. Among of these, learning and memory impairment is the most common symptoms for epilepsy patients with cognitive impairment. According to the research, about 30 % of epilepsy patients have cognitive impairment ,and 20 %～25 % of them have previous impairment. This effects their learing,work and quality of life.Therefore, the cognitive impairment has been the focus of epilepsy care. To observe the effect of Pentylenetetrazole(PTZ)-kindled epilepsy on rats'learning and memory and the expression of neurogranin(Ng) and to explore the role of Ng play in the impairment of learning and memory of pentylenetetrazole-kindled rats.Methods: Use chronic model of epilepsy induced by PTZ intraperitoneal injection.100 mature male Sprague-Dawley(SD) rats (weight 200±20g) selected by Y maze were separated into two random groups : chronic epileptic group(CEP) and normal control group(NC).CEP rats were injected by PTZ 35mg/kg every morning and this administration lasted 30 days, while the NC rats were injected by normal sodium.. According to Racine criterion, seizure intensity was divided into 6 grades: grade 0: any seizure was not observed; grade I: a little tingling of beards and twitching face; grade II: nodding, chewing accompanying with twitching face or wet dog shakes ; grade III: raising one of a forelimb and clonus; grade IV: standing accompanying with bilateral forelimbs; grade V: standing accompanying with falling down, generalized tonic-clonic seizure. If 3 successive seizures of grade IV or V were observed, the lighting was to be successful.The ability of learning and memory was assessed by the Morris water maze and Y maze on the thirty-first day. the expression of Ng mRNA and Ng protein in hippocampus was determined by using RT-PCR and Western Blot method respectively. The changes of Ng at CA1 and CA3 of hippocampus were observed by immunocytochemistry method.Results:1 results of epilepticus mode: most of CEP group rats began to stare,nod,wash their face and twitching face from the sixth day to eighth day. Among the eighteenth day and the twenty-forth their muscle began to clonus,their forelimbs began to uplift and tonic clonic seizure at last. About 80% of rats comforted to the Racine criterion. The administration was 30 days. The NC group rats did not appear epileptic seizure. 2 Morris water maze and Y maze: The escape latency was prolonged and crossing times in platform area was decrease in Morris water maze tes(tP<0.01), the total error was increase in Y maze test (P<0.05).3 Changes of Ng mRNA and protein in hippocampus: the expression level of Ng mRNA in hippocampus was decreased (P<0.01) and the expression level of Ng protein was also decreased (P<0.05).4 Changes of immunological reaction at CA1 and CA3 of hippocampus: the immunoreactant was brown and most of them were in the endochylema of the neuron. The immunological reaction of Ng for CEP group at CA1 was weak than NC group, but it made no difference at CA3.Conclusion: Learning and memory ability of the PTZ-kindled epilepsy rats were impaired and the expression level of Ng in hippocampus was decreased. Therefore, the impairment of learning and memory ability of the epilepsy rats might be related to the changes of Ng in hippocampal neurons.