Expression of mGluR7 and PCNA in the Subventricular Zone in Adult Rats Following Focal Cerebral Ischemia-reperfusion

Objective:To investigate the expression of metabotropic glutamate receptor 7 subtype(mGluR7)and proliferating cell nuclear antigen(PCNA)in the subventricular zone in adult rats following focal cerebral ischemia-reperfusion,and to explore its role in neurogenesis.Methods:Forty-two male Sprague-Dawley rats(weight range:280～300 g) were used in this study,and all animals were randomly devided into control group(sham operated)and middle cerebral artery obstruction(MCAO) groups with reperfusion for 6 h,24 h,72 h,7 d,14 d and 28 d respectively.The model of acute reperfusion injury after cerebral ischemia in rat was made by right middle cerebral artery occlusion.All animals were allowed 2 h ischemia and sacrificed after different durations of reperfusion.The expression of mGluR7 and PCNA was detected with an immunohistochemical approach.Results:Compared with the control group,the number of mGluR7 immunoreactive cells in the subventricular zone at 24 h after reperfusion in the ipsilateral(ischemic) side started to increase significantly(P0.05)and peaked at 72 h.However,at 28 d after reperfusion,the number of mGluR7 labeled cells decreased to basal level.Meanwhile,the number of mGluR7 labeled cells in the contralateral(non-ischemic) side increased significantly at 72 h after reperfusion(P0.05).Additionally,the mGluR7 labeled cells were also detected in dorsal caudate putamen,lateral septal nucleus,endopiriform nucleus and some areas of cerebral cortex.A significant increase in numbers of PCNA immunoreactive cells was found in the ipsilateral subventricular zone at 72 h(P0.05)and with a peak at 7 day(P0.01)after reperfusion,then the number descended but still higher than that of basal level.The number of PCNA labeled cells in the ipsilateral side increased significantly at 72 h and 7 d after reperfusion(P0.05).Conclusion:The study implies cerebral ischemia could upregulate the expression of mGluR7 and promote the proliferation of nervous stem cells in the subventricular zone following ischemia.mGluR7 could be involved in the neurogenesis following transient focal cerebral ischemia.