1Institute of Neuroscience and Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou 310058, China
2Hangzhou Key Laboratory of Neurobiology and Department of Pharmacology, School of Basic Medicine, Hangzhou Normal University, Hangzhou 310036, China

Abstract 

Objective Aquaporin-4 (AQP4), the main water channel protein in the brain, plays a critical role in water homeostasis and brain edema. Here, we investigated its role in the inflammatory responses after focal cerebral ischemia. Methods In AQP4-knockout (KO) and wild-type mice, focal cerebral ischemia was induced by 30 min of middle cerebral arterial occlusion (MCAO). Ischemic neuronal injury and cellular inflammatory responses, as well as the expression and localization of cysteinyl leukotriene CysLT2 and CysLT1 receptors, were determined at 24 and 72 h after MCAO. Results AQP4-KO mice showed more neuronal loss, more severe microglial activation and neutrophil infiltration, but less astrocyte proliferation in the brain after MCAO than wild-type mice. In addition, the protein levels of both CysLT1 and CysLT2 receptors were up-regulated in the ischemic brain, and the up-regulation was more pronounced in AQP4-KO mice. The CysLT1 and CysLT2 receptors were primarily localized in neurons, microglia and neutrophils; those localized in microglia and neutrophils were enhanced in AQP4-KO mice. Conclusion AQP4 may play an inhibitory role in postischemic inflammation.

Keywords

aquaporin 4; gene deficiency; inflammation; cysteinyl leukotriene receptor; microglia; astrocyte; focal cerebral ischemia

[SpringerLink]