Page - (000157) - in Biomedical Chemistry: Current Trends and Developments

MetSyn still needs to be clarified (Park, 2012; Cho, 2011). The increase of fecal excretion of fat and inhibition of intestinal bile salts absorption (with the consequent increase of cholesterol conversion into bile acids in the liver) as well as the stimulation of lipolysis and inhibition of lipogenesis improve plasma lipid profile and decrease adipose tissue mass as a consequence of calcium intake (Abete, 2011; Rice, 2011). Regulation of parathyroid hormone and 1,25- dihydroxycholecalciferol levels by dietary calcium mediates its effects on fat mass and insulin signaling/action (Teegarden, 2006). There is also evidence that adequate calcium intake, by decreasing the concentration of 1,25-dihydroxycholecalciferol, decreased the uptake of calcium by vascular SMC and, so, impaired contraction and reduced peripheral resistance and blood pressure (Rice, 2011). Additionally, lowering of 1,25-dihydroxycholecalciferol associated with a calcium- induced decrease of reactive oxygen species, oxidative stress markers and pro-inflammatory markers (such as TNF-α, IL-6 and PCR) and increase of anti-inflammatory markers (such as adiponectin), in adipose tissue and/or blood in obese humans and/or obese mice (Zemel, 2008). Dietary calcium supplementation (started 120 days after birth and lasting for 2 months) in adult offspring rats programmed during lactation by maternal nicotine exposure restored insulin sensitivity, reversed the concentration of serum leptin as well as the percentage of both total body fat content and visceral fat mass, and decreased the mRNA expression of leptin in visceral adipose tissue versus the nicotine exposed/conditioned rat group. Dietary calcium supplementation of the programmed rats also increased the hepatic expression of sirtuin 1 (Sirt1) versus the control rat group (without nicotine exposure or calcium supplementation) (Nobre, 2011). Regarding Sirt1, growing evidence suggests that its deacetylase activity regulates glucose-lipid metabolism, glucose production, inflammation, oxidative stress, autophagy and mitochondrial function and biogenesis as well as adiponectin and insulin secretion. Positive effects of Sirt1 overexpression and Sirt1 activators have been described (Kitada, 2013a; Kitada, 2013b; Xu, 2013; Li, 2014). With an opposite approach, female Wistar rats subjected to a very- low-calcium diet [(0.008% calcium) versus regular-calcium control diet-