Abstract: To study the effect of thyrotropin releasing hormone analogue, YM14673, on c fos protein expression in rat hippocampus following cerebral ischemia, cerebral ischemia was produced by occlusion of middle cerebral artery(MCA)and bilateral common carotid arteries(CCAs)with small aneurysmal clips for 1 h in wistar rats. Cerebral coronal section(10 μm)was routinely stained with hematoxylin eosin(HE)and immunohistochemical stained with standard streptavidin biotin AP technique . YM14673(1 mg/kg, ip, 30 min prior to occlusion)decreased the degeneration of neurons in the cerebral cortex at 1 h of MCA/CCAs occlusion with 24 h of reperfusion. Most of the pyramidal cells in CA4, and dentate granule cells showed intense c fos protein like immunoreactivity(CFPLI)at 1 h of MCA/CCAs occlusion with 4 h of reperfusion. YM14673 attenuated the c fos protein induction in CA4 regions and dentate gyrus at 1 h of MCA/CCAs occlusion with 4 h of reperfusion. The results show that YM14673 has certain inhibiting function on the expression of c fos in the hippocampal regions post-is-chemia.

Key words: cerebral ischemia, TRH analogue, YM14673, protein expression, c-fos