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Aquaporin-4 (AQP4) is the main water channel in the central nervous system. AQP4 is densely expressed in brain structures suggesting a crucial role in water transport in normal conditions and in disease. The effect of changes in drinking regime (water-deprivation and hyperhydration) and inherited arterial hypertension on the expression of the AQP4 water channel gene in the hypothalamus, the center of regulation of visceral functions, was studied. It was shown that the level of the Aqp4 mRNA in hyperhydrated animals more than 1.5 times lower than in animals with water-deprivation. This decrease in the Aqp4 gene expression in the hypothalamus may be associated with the ability to prevent cytotoxic edema during increased fluid intake. Rats with inherited stress induced arterial hypertension (ISIAH) are characterized by an increased level of Aqp4 mRNA in the hypothalamus, which suggests the involvement of this channel in processes associated with the regulation of brain water balance during arterial hypertension and the prevention of vasogenic cerebral edema. Thus, the presence of the AQP4 water channel in the brain, associated with the protection of brain cells, is functionally determined by the state of the body. This may be evidenced by bidirectional changes in the Aqp4 gene expression during hyperhydration and arterial hypertension.
Evtushenko et al. (Sun,) studied this question.