Intestinal calcium absorption in a model of experimental diabetes mellitus

RIVOIRA M; RODRÍGUEZ V; PERALTA LÓPEZ M; TOLOSA DE TALAMONI N

Bs As

Congreso; AAOMM; 2013

Type I diabetesmellitus (Dm) could be induced by streptozotocin (STZ) in rats. The aim of this work was to study intestinal Ca2+ absorption and the molecularmechanisms involved in STZ rats as compared to controls. Adult male Wistar rats were injected with a single dose of STZ 60mg/kg b.w. and sacrificed at 5, 30 or 60 days. A group of STZ rats were treated with insulin. Intestinal Ca2+ absorption was measured as well as the expression of proteins and genes involved in the transcellular Ca2+ transport. Glutathione (GSH) and the enzyme activities of the antioxidant system were measured by spectrophotometry. Intestinal Ca2+ absorption decreased in the STZ rats at 5 and 30 days, which was reversed by insulin treatment, while Ca2+ absorption at 60 days was similar to controls.TRPV6 protein expression was always higher in STZ rats. STZ rats showed Ca2+-ATPase and Na+/Ca2+ protein expressions higher than the control rats at 5 and30 days,but at 60 days the expression of both proteins was similar to the controls. Ca2+-ATPase expression in STZ rats at 60 days was lower compared to STZ rats at 5 or 30 days. Ca2+-ATPase and TRPV6 mRNA levels were decreased after 60 dayswith STZ.Na+/Ca2+mRNAlevels were higher in STZ rats at 5 days, similar to the 30 days and lower at 60 days compared to controls at the respective times. STZ rats exhibited lower GSH values in comparison with control rats at all times. CAT activity increased in STZ rats as compared to controls at 5 and 30 days, and normalized at 60 days. In conclusion, Dm induced by STZ inhibits intestinal Ca2+ absorption due to triggering of oxidative stress. The effect is transient, alters the transcellular pathway and triggers a physiological adaptation towards the normalization of the intestinal Ca2+ absorption.