engleski

Expression of water channel AQP 1 in rat kidneys is regulated by sex hormones

The physiological function of aquaporin 1 (AQP1) has been thoroughly characterized in the mammalian kidneys, where it is responsible for constitutive water reabsorption. The AQP1 protein is found in the apical and basolateral plasma membranes of the proximal tubules and descending thin limbs. In the membrane, it takes two forms: non-glycosylated (NG, ~28 kDa) and glycosylated (G, 40 kDa to 50 kDa). The factors influencing renal AQP1 expression in (patho)physiological conditions are poorly understood. The aim of our work was to investigate the possible effects of sex hormones on renal AQP1 expression in rats, using immunocytochemistry, Western blotting, and real time RT-PCR. The effects were extensively studied in prepubertal and adult, gonadectomised and sex hormone-treated gonadectomised rats. The AQP1 protein expression in various kidney zones was higher in males than in females and observed sex differences were present in both forms of AQP1 (NG and G) in adult rats. The AQP1 mRNA expression was in concordance with the protein expression. Castration reduced and ovariectomy increased the abundance of AQP1 protein in isolated renal total cell membranes. Furthermore, the treatment of castrated animals with testosterone upregulated, whereas treatment with estradiol and progesterone had no significant effect on AQP1 protein expression. The abundance of AQP1 protein and mRNA in the kidneys of prepubertal rats was similar in both sexes. We conclude that sex differences exist in the expression of AQP1 along the nephron of adult rats ; AQP1 is more abundant in males due to upregulating effect of androgens.

aquaporin 1; sex steroids; castration; ovariectomy; immunocytochemistry; Western blotting; real time RT-PCR

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