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Na+/glucose cotransporter SGLT1 in the salivary glands of diabetic and hypertensive rats: role of sympathetic outflow and protein kinase A activity.

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Author(s):
Robinson Sabino da Silva
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
Defense date:
Examining board members:
Ubiratan Fabres Machado; Karla Fabiana Santana de Melo Cabral Fagundes; Jose Vanderlei Menani; Flavio Fava de Moraes; Fernando Neves Nogueira
Advisor: Ubiratan Fabres Machado
Abstract

Salivary gland dysfunction is a feature in diabetes and hypertension. In Wistar Kyoto rats (WKY), diabetic WKY (WKY-D), spontaneously hypertensive rats (SHR) and diabetic SHR (SHR-D), salivary glands were harvested for SGLT1 and PKA protein expression analysis. Moreover, sympathetic nerve activity to the salivary glands was measured. Diabetes decreased the nerve activity in WKY and SHR (P<0.05), pointing out that it was higher in SHR, as compared to WKY (P<0.001). The regulation of catalytic subunit of PKA and plasma membrane SGLT1 protein were parallel to the sympathetic nerve activity. In diabetic and/or hypertensive rats, imunohistochemical analysis showed increased SGLT1 protein in luminal membrane of ductal cells, where it may promote water uptake, reducing the salivary flow. Confirming that, nonstimulated salivary secretion was reduced (P<0.001) in WKY-D, SHR and SHR-D rats. The results show in luminal membrane of ductal cells SGLT1 protein increased inversely proportional to the nonstimulated salivary flux in diabetic and hypertensive rats. This indicates the water transporter role of SGLT1 and, by increasing salivary water reabsorption, may explain the hyposalivation complained by diabetic subjects. (AU)