Expression of prostaglandin E2 receptor subtypes, EP2 and EP4, in the rat hippocampus after cerebral ischemia and ischemic tolerance.
We investigated the distribution and time course of expression of two subtypes of prostaglandin E(2) (PGE(2)) receptors, EP2 and EP4, in a rat model of cerebral ischemia and ischemic tolerance. Adult male Sprague-Dawley rats were subjected to either lethal global ischemia (10 min) with or without sublethal ischemic preconditioning (3 min), or ischemia only (3 min). A short 3-min cerebral ischemia and a 3-min ischemia followed by a second lethal ischemia enhanced the expression of EP2 and EP4 receptors in CA1 pyramidal neurons of the hippocampus. In tolerance-acquired CA1 neurons, the immunoreactivities of EP2 and EP4 were upregulated after 4 h and 12 h, respectively. The immunoreactivities were most prominent at 3 days and were sustained for at least 14 days, consistent with results of immunoblotting experiments. However, immunoreactivities for these PGE(2) receptors increased in reactive glial cells in the vulnerable CA1 and hilar regions of rats subjected to lethal ischemia without ischemic preconditioning. Most of the EP2 immunoreactivity occurred in microglial cells and some astrocytes, whereas increased immunoreactivity for EP4 was found only in astrocytes. These data suggest that ischemia and the induction of ischemia tolerance have different regulatory effects on the expression of EP2 and EP4 receptors. Moreover, PGE(2) may exert its unique pathophysiological functions in relation to delayed neuronal death and ischemic tolerance induction in the rat hippocampus via specific PGE(2) receptors.
Choi
Jeong-Sun
JS
Department of Anatomy, College of Medicine, The Catholic University of Korea, Socho-gu, Seoul, 137-701, South Korea.
Kim
Ha-Young
HY
Chun
Myung-Hoon
MH
Chung
Jin-Woong
JW
Lee
Mun-Yong
MY
D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology; D006624:Hippocampus / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D019194:Ischemic Preconditioning; D008297:Male; D017966:Pyramidal Cells / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018078:Receptors, Prostaglandin E / Q000378:metabolism*; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype
C545646:Ptger2 protein, rat; C545652:Ptger4 protein, rat; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype