Glucagon-Producing Cell Expansion in Wistar Rats. Changes to Islet Architecture After Sleeve Gastrectomy.

Abstract

Many studies about bariatric surgery have analyzed the effect of sleeve gastrectomy (SG) on glucose improvement, beta-cell mass, and islet size modification. The effects of SG on the other endocrine cells of the pancreas, such as the alpha-cell population, and their regulatory mechanisms remain less studied. We focused our work on the changes in the alpha-cell population after SG in a healthy model of Wistar rats. We measured alpha-cell mass, glucose tolerance, and insulin release after oral glucose tolerance tests and plasma glucagon secretion patterns after insulin infusion. Three Wistar rat groups were employed: SG-operated, surgical control (Sham), and fasting control. The results obtained showed significant increases in the alpha-cell population after SG. The result was an increase in beta-cell transdifferentiation; it was shown by some expressed molecules (the loss of expression of Pdx-1 and the increase in Arx and Pax6 cells/mm2 of islet). The serum results were enhanced plasma glucagon secretion pattern after insulin infusion assays and normal glucose tolerance and insulin release after OGTT. We concluded that SG leads to an expansion of the alpha-cell population, at expense of beta-cell; this expansion of alpha-cells is related to transdifferentiation. Plasma glucose level was not affected due to an increased glucagon response.