P2X7 Receptors in Astrocytes: A Switch for Ischemic Tolerance
Yuri Hirayama,
Naohiko Anzai,
Hiroyuki Kinouchi,
Schuichi Koizumi
Affiliations
Yuri Hirayama
Department of Pharmacology, Chiba University Graduate School of Medicine, 1-8-1, Inohana, Chuo-ku, Chiba-shi 260-8670, Chiba, Japan
Naohiko Anzai
Department of Pharmacology, Chiba University Graduate School of Medicine, 1-8-1, Inohana, Chuo-ku, Chiba-shi 260-8670, Chiba, Japan
Hiroyuki Kinouchi
Department of Neurosurgery, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo 409-3898, Yamanashi, Japan
Schuichi Koizumi
Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo 409-3898, Yamanashi, Japan
A sub-lethal ischemic episode (preconditioning [PC]) protects neurons against a subsequent lethal ischemic injury. This phenomenon is known as ischemic tolerance. PC itself does not cause brain damage, but affects glial responses, especially astrocytes, and transforms them into an ischemia-resistant phenotype. P2X7 receptors (P2X7Rs) in astrocytes play essential roles in PC. Although P2X7Rs trigger inflammatory and toxic responses, PC-induced P2X7Rs in astrocytes function as a switch to protect the brain against ischemia. In this review, we focus on P2X7Rs and summarize recent developments on how astrocytes control P2X7Rs and what molecular mechanisms they use to induce ischemic tolerance.
