The Effect Of Induced Hypotension On Microtubule-associated Protein-2 In The Hippocampus CA1 Of Rat And Its Cognitive Impairment

Objective: To observe the influences of controlled hypotension (CH)induced by sodium nitroprusside(SNP) and esmolol(ESM) on expressionof microtubule-associated protein-2 (MAP2) in the hippocampus of ratand its cognitive impairment.Methods: 56 male SD rats, with normal learning and memoryfiltrated by Morris water maze method were randomly divided into fourgroups(n=14): control group, 70mmHg group, 50mmHg group, 30mmHggroup. Every group was subdivided into 2 series, each live for 1 day and7 day. There were 7 rats each series.. The animal was anesthetized with10ï¼…chloral hydrate (ip), spontaneous breathing, femoral arterial andvenous catheterizations were done. CH was achieved by continuousinfusion of 400ug/ml SNP and 2mg/ml ESM solution to mean arterialpressure (MAP) levels of 70mmHg, 50 mmHg, 30mmHg for 1 hr. TheRR and breath rate were recorded every 15 min during the operation. Atthe end of CH, blood-gas analsys was done. Learning and memoryperformance were examined in rats using maze task before sacrificed.The changes of the expression of MAP-2 in hippocampus CAI regionswere detected by immunohistochemistry (sp methods) and computerimage analysis methods.Results During the CH, 30mmHg group compares with other groups, RR, breath rate, and PaO₂ were increased and PaCO₂ wasdeclined. There is no differences observed among 4 groups of escapelatency of the rats, but the escape latency of 7 days is longer than that of 1day in every group(P＜0.5). There is no differences observed among 4groups of the MAP2 expression in hippocampus CAI regions.Conclusion 1 ) Hypotension induced by SNP and ESM for 1 hourMAP30mmHg has no effect on the MAP2 expression in hippocampus ofrats. 2 ) Hypotension induced by SNP and ESM for 1 hour MAP30mmHgdoesn't have significant effect on the cognitive function of rats.