engleski

Na+-glucose cotransporter SGLT1 in kidney and intestine of male and female rats

SGLT1 (Slc5a1) is a high affinity Na+-glucose cotransporter that mediates a part of renal and a bulk of intestinal glucose and galactose (re)absorption. Previous transport studies in isolated brush-border membranes (BBM) from the mammalian kidney (K) and small intestine (SI), and hybridization studies in the same organs localized this transporter to the proximal tubule straight segments (S3) in the K outer stripe (OS) and medullary rays, and in the SI absorptive cells. However, a convincing immunolocalization of SGLT1 along the nephron and SI has not been reported. In this work we used a novel polyclonal antibody against the rat SGTL1 and performed a detailed Western blotting (WB) and immunocytochemical (IC) study of the transporter expression along the nephron and SI in variously-treated adult and prepubertal male (M) and female (F) rats. WBs were performed with isolated BBM and total cell membranes from various K and SI regions. IC was performed in cryosections of the same tissues. In WB of isolated membranes from both organs, the antibody labeled a single protein band at ~75 kDa. In membranes from the K cortex (C) and OS of intact adult rats, this band: a) exhibited strong zonal (OS>C) and gender differences (F>M), and b) increased by castration and remained unaffected by ovariectomy. By IC in K cryosections, the antibody stained BBM of S2 and S3 (S3>S2) with gender-dependent manner (F>M), as well as the apical domain of the cortical thick ascending limb and macula densa epithelial cells. The staining intensity in the C and OS was upregulated by castration and remained unchanged by ovariectomy. In prepubertal rats, the protein band in isolated K membranes and staining intensity in K tubules were weak and gender-independent. In SI, SGLT1 (the 75 kDa protein and the relevant immunostaining) was expressed in the BBM of absorptive cells along the entire organ, exhibiting regional (jejunum duodenum=ileum) but not gender differences. We conclude that in the rat K, SGLT1 in the BBM of S3 and S2 exhibits gender differences (F>M) due to androgen inhibition after puberty, whereas in the SI, SGLT1 in the absorptive cell BBM exhibits regional but not gender differences.

gender differences; androgen inhibition; proximal tubule

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