We investigated the effects of caloric restriction on pancreatic beta cell function. The mouse strain C57Bl/6J was used for the experiments. Acute tissue sections of pancreas were stimulated with glucose solutions (7 mM, 8 mM, 9 mM, 10 mM, 12 mM, 16 mM, 22 mM) and observed with a confocal microscope to measure the time course of activation and deactivation of beta cell oscillatory calcium activity. Three groups of mice differing in diets (Western diet - group WD /restrictive caloric diet - group RCD /control diet - group CD ) were involved in [Ca2+]i imaging in living cells. The beta cell activation and deactivation times in the healthy control group were glucose dependent. The time delay to activation shortened with increasing glucose concentration, as did the heterogeneity of responses. With increasing glucose concentration, delays to deactivation became longer and heterogeneity increased. The WD shortened activation time in beta cells of male mice. In contrast, the RCD improved the metabolic activity of beta cells of male mice in some cases, as the activation delays were similar to those of the control group. But at a certain glucose concentration, the effects of the WD were still present. In the female mice group, there were no significant effects of the WD on the activation delays, therefore, the effects of the RCD could not be observed. Because of the WD, beta cells, in the male and female WD groups, deactivated later and more heterogeneously than in the control group. At some glucose concentrations, the ends of oscillation in the male and female RCD groups were similar to those in the control group, but in some cases the effects of the WD were still present.
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