Sabino-Silva R, Freitas H S, Lamers M L, Okamoto M M, Santos M F, Machado U F
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil.
J Membr Biol. 2009 Mar;228(2):63-9. doi: 10.1007/s00232-009-9159-3. Epub 2009 Feb 24.
Oral health complications in diabetes include decreased salivary secretion. The SLC5A1 gene encodes the Na(+)-glucose cotransporter SGLT1 protein, which not only transports glucose, but also acts as a water channel. Since SLC5A1 expression is altered in kidneys of diabetic subjects, we hypothesize that it could also be altered in salivary glands, contributing to diabetic dysfunction. The present study shows a diabetes-induced decrease (p < 0.001) in salivary secretion, which was accompanied by enhanced (p < 0.05) SGLT1 mRNA expression in parotid (50%) and submandibular (30%) glands. Immunohistochemical analysis of parotid gland of diabetic rats revealed that SGLT1 protein expression increased in the luminal membrane of ductal cells, which can stimulate water reabsorption from primary saliva. Furthermore, SGLT1 protein was reduced in myoepithelial cells of the parotid from diabetic animals, and that, by reducing cellular contractile activity, might also be related to reduced salivary flux. Six-day insulin-treated diabetic rats reversed all alterations. In conclusion, diabetes increases SLC5A1 gene expression in salivary glands, increasing the SGLT1 protein content in the luminal membrane of ductal cells, which, by increasing water reabsorption, might explain the diabetes-induced decrease in salivary secretion.
糖尿病的口腔健康并发症包括唾液分泌减少。SLC5A1基因编码钠-葡萄糖协同转运蛋白SGLT1，该蛋白不仅能转运葡萄糖，还可作为水通道。由于糖尿病患者肾脏中SLC5A1的表达发生改变，我们推测其在唾液腺中也可能发生改变，从而导致糖尿病功能障碍。本研究显示，糖尿病导致唾液分泌减少（p < 0.001），同时腮腺（50%）和颌下腺（30%）中SGLT1 mRNA表达增强（p < 0.05）。对糖尿病大鼠腮腺的免疫组织化学分析表明，导管细胞腔膜中的SGLT1蛋白表达增加，这会刺激从初级唾液中重吸收水分。此外，糖尿病动物腮腺的肌上皮细胞中SGLT1蛋白减少，通过降低细胞收缩活性，这也可能与唾液流量减少有关。接受六天胰岛素治疗的糖尿病大鼠逆转了所有改变。总之，糖尿病会增加唾液腺中SLC5A1基因的表达，增加导管细胞腔膜中SGLT1蛋白的含量，通过增加水的重吸收，这可能解释了糖尿病导致的唾液分泌减少。
