Effects of the metabotropic glutamate receptor ligands on the induction of brain ischemic tolerance in rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Metabotropic glutamate receptor(mGluR) is G-protein coupled membrane receptors, which participate in various physiology or pathology process in brain, but how it induce brain ischemic tolerance(BIT)is unclear.OBJECTIVE: To study roles of mGluR2/3 and mGluR1/5 in the BIT induction.DESIGN: Randomized controlled study based on experimental animals.SETTING: Neurological department of provincial hospital and pathophysiological department of basic institute in a university.MATERIALS The study was conducted at the Pathophysiological Department, Institute of Basic Medicine, Hebei Medical University from May 2002 to May 2003. Totally 64 healthy male SD rats were selected from the Experimental Animal Center of Hebei Medical University. Glial fibrillary acidic protein (GFAP) antibody, MTPG and(s)-4C3HPG were got from Sigma Company.INTERVENTIONS: 4 vessel occlusion(4VO) brain ischemic models in rats stained with thionine staining and GFAP immunohistochemistry staining. were used. Sixty-four rats, of which bilateral vertebral arteries were occluded permanently by electrocautery, were divided into the following 8groups sham operation group, cerebral ischemic preconditioning(CIP)group, ischemic insult group; BIT group; MTPG + sham operation group;MTPG+BIT group; MTPG+ischemia group and(s) -4C3HPG+BIT coup. All the rats were killed 7 days after the operation or the final ischemic treatment. Cerebral sections were selected and stained with thionine staining and GFAP immunohistochemistry staining.MAIN OUTCOME MEASURE: The changes of the morphologic hippocampal pyramidal cell and GFAP expression of astrocyte.RESULTS: ① The 8 minutes ischemic insult increased the histological grade(HG) in CA1 area, decreased the pyramidal neuronal density(ND)and increased the expression of GFAP significantly( P ＜ 0.05) . ② The above changes were not observed in the BIT group, indicating that the CIP could protect pyramidal neurons against the 8-minute ischemic insult. ③The protective effects of the CIP were blocked by MTPG or(s)-4C3HPG, as manifested by significant increases in HG and decreases in ND in the groups of MTPG + BIT, MTPG + ischemia and(s)-4C3HPG + BIT( P ＜ 0.05).CONCLUSION: MTPG or (s) -4C3HPG could block the induction of BIT induced by CIP, but mGluR2/3 or mGluR1/5 could participate in the induction of BIT by which protect effect of mGluR is further induced.