Table 1.

Main studies investigating AQP1 and AQP4 in humans.

AQP	Author (years)	Research object	Result
AQP1	Verkman (2008a)	AQP1 gene knockout animals	20% decrease in CSF fluid production and a 56% decrease in intracranial pressure
	Smith et al. (2007)	Communicating hydrocephalus	Lower expression of AQP1 on the apical membrane of the CPEpiC* of the ill choroid plexus
	Jeon et al. (2017)	Kaolin-injected hydrocephalus mice	AQP 1 protein expression reduced abruptly in the choroid plexus of rats with acute hydrocephalus and increased at later stages
	Wang et al. (2011)	Kaolin-injected hydrocephalus mice	A substantial number of AQP1 immune granules are present in the apical membrane of CPEpiC*
	Castañeyra-Ruiz et al. (2016)	iNPH patient	No significant increase in AQP1 levels in cerebrospinal fluid compared to the control group
AQP4	Ismail et al. (2009)	SAH mouse model
	Papadopoulos and Verkman (2007)	AQP4 gene knockout mice	Increase in intracranial pressure and the moisture content of brain tissue
	Mao et al. (2006)	Kaolin-injected hydrocephalus mice	AQP-4mRNA expression increased significantly in the parietal lobe and hippocampus
	Bloch et al. (2006)	Congenital AQP4 protein deficiency rats	AQP4 protein can exacerbate hydrocephalus in kaolin-induced H-t gene deletion rats
	Tourdias et al. (2009)	Hemolytic lecithin-induced traffic hydrocephalus	AQP4 expression increased significantly in the foot process of astrocytes
	Shen et al. (2006)	Congenital hydrocephalus model in rats	Increased AQP4 expression in the blood-brain barrier, ependyma, and subpial astrocytes
	Eide and Hansson (2020)	iNPH	Decrease in AQP4 expression at the LM and EM levels of perivascular astrocyte terminals, which were inversely proportional
	Hasan-Olive et al. (2019b)	iNPH	Reduced density of AQP4 water channels in astrocytic endfoot membranes along cortical microvessels in patients with iNPH

AQP1, aquaporin 1; AQP4, aquaporin 4; iNPH, idiopathic normal pressure hydrocephalus; CPEpiC, choroid plexus epithelial cell.