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Effects of melatonin and resveratrol on renal expression of sodium-glucose cotransporters SGLT1 and SGLT2 in rat model of aging

Mechanisms of aging are poorly understood. Aging is associated with loss of renal function and structure. Elevated tissue concentrations of reactive oxidative species, known to be present in old humans and experimental animals, may affect the expression and/or activity of various renal transporters, including those that mediate reabsorption of glucose, such as SGLT1 and SGLT2. SGLT2 in the proximal tubule S1/S2 segments mediates a bulk (65–90%) glucose reabsorption, whereas SGLT1 in the S3 segment mediates reabsorption of the remains. To test hypothesis that the expression of SGLT1 and SGLT2 could be changed in old age, and corrected with antioxidants, we treated male and female Wistar rats with melatonin and resveratrol. Starting from their age of 3 months, for the next 21 months the rats were drinking antioxidants in water (~1 mg/kg b.w./day), whereas the control animals were drinking water with vehicle (0.01% ethanol). The expression of renal SGLT1 and SGLT2 was analysed by Western blotting of isolated total cell membranes and by immunohistochemistry of tissue cryosections using specific antibodies. Melatonin and resveratrol did not notably change the expression of renal SGLT1 in both sexes, but in melatonin-treated males, a slight tendency to SGLT1 upregulation was observed. Also, melatonin treatment did not affect the SGLT2 expression in both sexes. However, resveratrol significantly upregulated the SGLT2 expression in male, but not in female rats. We conclude that in old rats, the melatonin treatment has a negligible effect on renal SGLTs, whereas the resveratrol effect on SGLT2 is sex-related, being restricted to males.

antioxidants, resveratrol, melatonin, sex-related expression

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