-実験動物開発室-

C57BL/6N-Aqp4<tm1Tsna> (RBRC10054, flox)
C57BL/6N-Aqp4<tm1.1Tsna> (RBRC10053, KO)

Courtesy of Mika Terumitsu-Tsujita, Ph.D.

Confocal laser scanning microscopy showing a cellular and subcellular distribution of AQP4 in microslicer sections. Specificity and overall distribution of AQP4 was determined by triple immunofluorescence with AQP4 (magenta), astrocyte marker 3PGDH (blue) and with neuron marker Map2 (green) in the hippocampal CA1 (CA1) and Cerebellum (Cb) regions. Characteristic labeling was observed in the wild-type(WT) mouse brain but not in the AQP4-KO mouse brain. AQP4 is in a cell surface of astrocytes, particularly abundant in perivascular and peri-Purkinje cell processes.

The aquaporin(AQP) family is a large collection of integral membrane proteins that enable the movement of water and other small, neutral solutes across biological membranes. Mammalian AQPs consist of 13 homologous members with varying degrees of similarity [1]. AQP4 is the main subset in the brain, particularly in glial astrocytes where it is highly expressed in the perivascular and subpial endfeet [2]. Terumitsu-Tsujita and her colleagues generated AQP4 knockout mice and observed a significant suppression of neural activity-dependent extracellular space volume change which is associated with astrocyte swelling [3]. They also found that water influx into the cerebrospinal fluid is regulated by AQP4 and not by AQP1, strongly supporting the idea that AQP4 regulates water homeostasis in the peri-capillary space [4]. Furthermore, they developed a PET ligand for AQP4 imaging based on TGN-020, a potent AQP4 inhibitor. Utilizing [11C]-TGN-020, PET images were successfully generated in wild type and AQP4 null mice [5].