摘要
Objective To study the features of the activity changes of glutamate (GLu ) in the hippocampusand hypothalamus and its effects on the activation of the hypothalamus-pituitary-adrenal axis (HPA ) duringacute cerebral ischemia (ACI ). Methods: The changes of Glu content, corticotrophin releasing hormone(CRH ) mRNA expression level and adrenocorticotropic hormone (ACTH ) concentration were determinedwith high-performance liquid chromatography (HPLC ) and in situ hybridization in different time intervals after middle cerebral artery occlusion (MCAO) in rats. Results: Glu content was increased rapidly in the hippocampus and hypothalamus 15 min after MCAO and reached the peak (the average Glu content in the hippocarnpus and hypothalamus were 21. 50± 2. 88 mg/g wt and 14. 20±2. 58 mg/g wt respectively) in the lsthour after MCAO and it returned rapidly to the base line level after reperfusion. The Gln content in the hippocampus and hypothalamus went up once more in the 24th hour of reperfusion, remained at a relatively highlevel till the 48th hour of reperfusion and then declined gradually. The expression level of CRH mRNA wasmarkedly enhanced in the temporal cortex, hippocampus and hypothalamus in the lst hour after MCAO andthis condition was kept on till the 96th hour of reperfusion. In the same time, the plasma level of ACTH wasrelatively increased. In the peak stage of reperfusion injury,there was a positive correlation of the Glu contentin the hypothalamus with the number of positive cells of CRH mRNA expression and the plasma level of ACTH. Conclusion: The central CRH system is possible to locate mainly in the limbic system and Gln might beone of the factors to induce excessive excitable stress response of the HPA axis.
Objective To study the features of the activity changes of glutamate (GLu ) in the hippocampusand hypothalamus and its effects on the activation of the hypothalamus-pituitary-adrenal axis (HPA ) duringacute cerebral ischemia (ACI ). Methods: The changes of Glu content, corticotrophin releasing hormone(CRH ) mRNA expression level and adrenocorticotropic hormone (ACTH ) concentration were determinedwith high-performance liquid chromatography (HPLC ) and in situ hybridization in different time intervals after middle cerebral artery occlusion (MCAO) in rats. Results: Glu content was increased rapidly in the hippocampus and hypothalamus 15 min after MCAO and reached the peak (the average Glu content in the hippocarnpus and hypothalamus were 21. 50± 2. 88 mg/g wt and 14. 20±2. 58 mg/g wt respectively) in the lsthour after MCAO and it returned rapidly to the base line level after reperfusion. The Gln content in the hippocampus and hypothalamus went up once more in the 24th hour of reperfusion, remained at a relatively highlevel till the 48th hour of reperfusion and then declined gradually. The expression level of CRH mRNA wasmarkedly enhanced in the temporal cortex, hippocampus and hypothalamus in the lst hour after MCAO andthis condition was kept on till the 96th hour of reperfusion. In the same time, the plasma level of ACTH wasrelatively increased. In the peak stage of reperfusion injury,there was a positive correlation of the Glu contentin the hypothalamus with the number of positive cells of CRH mRNA expression and the plasma level of ACTH. Conclusion: The central CRH system is possible to locate mainly in the limbic system and Gln might beone of the factors to induce excessive excitable stress response of the HPA axis.
