脳傷害時のアストロサイトの機能変化におけるエンドセリンの役割 Roles of Endothelins in astrocytic responses to brain injuries
Endothelins, potent vasoconstricting peptides, have multiple actions on nonmuscle tissues. ETs present in brain and the ET contents increase on brain injuries, suggesting an involvement in path hysiological responses of the injured rain. Astrocytes have receptors for ET. However, significance of astrocytic ET receptors are unknown. On brain damages such as ischemia and head trauma, astroc rtes changes their phenotype to "reactive astrocytes". Reactive astrocytes produce neurotro is factors and support synaptic regeneration after brain damages. In this study, effect of ET on induction of reactive astrocytes were examined by immunohistochemical staining for GFAP, a marker of reactive astrocytes. Injection of ET-3 (40pmole) into rat caudiate utamen increased GFAP positive cells. An ET<SUB>B</SUB> receptor agonist, Ala<SUP>1, .3, 11, 15</SUP>-ET-1 (40pmole), also increased GFAP positive astrocytes, while marked cell dams a was not induced. Applications of vasodilators, hydrarazine (20mg/Kg/day, i.p.) and ifenprodil (4mg/Kg/day, i.p.), did not prevent ET-induced increase in GFAP positive cells. These results suggest that ETs are involved in the generation of reactive astrocyte after brain injuries.
日本薬理学雑誌 106, 167-171, 1995-09-01