The influence of fasting/refeeding on the lipoprotein lipase activity of adipose tissue and muscle

Lipoprotein lipase activity in adipose tissue and muscle is modulated by changes in the pattern of food intake. We have measured total lipoprotein lipase activity in adipose tissue and muscle of male Wistar rats (N = 6-10), weighing 200-250 g (~12 weeks), during the refeeding/fasting state following 24 h of fasting. Lipoprotein lipase activity in tissue homogenates was evaluated using a [³H]-triolein-containing substrate, and released [³H]-free fatty acids were extracted and quantified by liquid scintillation. Adipose tissue lipoprotein lipase activity did not completely recover within 2 h of refeeding (60% of refed ad libitum values). Cardiac lipoprotein lipase activity remained increased even 2 h after refeeding (100% of refed ad libitum values), whereas no significant changes were observed in the soleus and diaphragm muscles. Adipose tissue lipoprotein lipase activities were consistently higher than the highest skeletal muscle or heart values. It is therefore likely that adipose tissue, rather than muscle makes the major contribution to triacylglycerol clearance. There was concomitant relatively high lipoprotein lipase activity in both adipose tissue and cardiac muscle during the first few hours of refeeding, therefore cardiac muscle may contribute significantly to triacylglycerol clearance during this period. The results suggest that during fasting, increased lipoprotein lipase activity provides a complementary source of free fatty acids from circulating triacylglycerol, allowing the heart to maintain its continuous, high-energy expenditure

Angiotensin-(1-7) Mas-receptor deficiency decreases peroxisome proliferator-activated receptor gamma expression in adipocytes

The renin-angiotensin system is an important link between metabolic syndrome and cardiovascular diseases. Besides angiotensin II, other angiotensin peptides such as angiotensin-(1-7), have important biological activities. It has been demonstrated that angiotensin-(1-7), acting through the G protein-coupled receptor encoded by the Mas protooncogene have important actions on the cardiovascular system. However, the role of angiotensin-(1-7)-Mas axis in lipidic profile is not well established. In the present study, the adipocyte metabolism was investigated in wild type and FVB/N Mas-deficient male mice. The gene expression of peroxisome proliferator-activated receptor gamma, acetyl-CoA carboxylase and the amount of fatty acid synthase protein were reduced in the Mas-knockout mice. Serum nonesterified fatty acids of Mas-knockout showed a 50% increase in relation to wild type group. Basal and isoproterenol-stimulated lipolysis was similar between the groups, however, a significant decrease of the glycerol release (lipolytic index) in response to insulin was observed in wild type animals, while no effect of the insulin action was observed in a Mas-knockout group. The data suggest that the lack of angiotensin-(1-7) action through Mas receptor alters the response of adipocytes to insulin action. These effects might be related to decreased expression of PPARgamma

Performance of Tilapia (Oreochromis niloticus) supplemented with vitamin C.

The objective of this study was to evaluate the supplementation of Vitamin C in the productive performance of reverted tilapias (Oreochromis niloticus). Four hundred tilapias were used. The experiment was mounted according to a completely randomized design with 5 treatments (0, 50, 100, 150 and 200 mg/kg of vitamin C monophosphate of ascorbic acid L) in a ration isoproteinic (36% of PB) and isocaloric (3600 kcal of DE/kg) with 4 repetitions. Significant effect was observed in final weight and weight gain for in treatments of 50, 100 and 200 mg/kg of vitamin C. It was not observed significant difference for the total length. However, for the standard length was observed significant difference in treatments 50, 100 and 200 mg/kg of vitamin C. Significant effect was observed for protein efficiency rate with supplementation of 50, 100, 150 and 200 mg/kg of vitamin C. Vitamin C supply did not influenced MS percentage, crude protein and protein percentage in weight gain. Significant difference was not observed for ether extract and fat percentage in weight gain. Vitamin C supply did not influence significantly the concentration of muscle glycogen. It was not observed significant difference for liver glycogen.Objetivou-se avaliar a suplementação de vitamina C no desempenho produtivo de tilápias revertidas (Oreochromis niloticus). Foram utilizadas 400 pós-larvas revertidas num delineamento inteiramente ao acaso com cinco tratamentos (0, 50, 100, 150 e 200 mg/kg de vitamina C monofosfato de ácido ascórbico L) numa ração isoprotéica de 36% de PB e isocalórica 3600 kcal de ED/kg com 4 repetições. Observou-se efeito significativo no peso médio final e ganho de peso com 50, 100 e 200 mg de vitamina C por kg. Não foi observada diferença significativa para o comprimento total. No entanto, para o comprimento padrão foi observada diferença significativa com os tratamentos 50, 100 e 200 mg/kg. Verificou-se efeito significativo na taxa de eficiência protéica com suplemen-tação de 50, 100, 150 e 200 mg/kg de vitamina C. A suplementação de vitamina C não influenciou a porcentagem de MS, proteína bruta e porcentagem de proteína no ganho de peso. Não foi observada diferença significativa dos tratamentos para extrato etéreo, porcentagem de gordura no ganho de peso. A suplementação de vitamina C não influenciou significativamente a concentração de glicogênio no músculo. Não foi observada diferença significativa para glicogênio do fígado

Mas deficiency in FVB/N mice produces marked changes in lipid and glycemic metabolism

OBJECTIVE: Metabolic syndrome is characterized by the variable coexistence of obesity, hyperinsulinemia, insulin resistance, dyslipidemia, and hypertension. It is well known that angiotensin (Ang) II is importantly involved in the metabolic syndrome. However, the role of the vasodilator Ang-(1-7)/Mas axis is not known. The aim of this study was to evaluate the effect of genetic deletion of the G protein-coupled receptor, Mas, in the lipidic and glycemic metabolism in FVB/N mice. RESEARCH DESIGN AND METHODS: Plasma lipid, insulin, and cytokine concentrations were measured in FVB/N Mas-deficient and wild-type mice. A glucose tolerance test was performed by intraperitoneally injecting d-glucose into overnight-fasted mice. An insulin sensitivity test was performed by intraperitoneal injection of insulin. Uptake of 2-deoxy-[(3)H]glucose by adipocytes was used to determine the rate of glucose transport; adipose tissue GLUT4 was quantified by Western blot. Gene expression of transforming growth factor (TGF)-beta, type 1 Ang II receptor, and angiotensinogen (AGT) were measured by real-time PCR. RESULTS: Despite normal body weight, Mas-knockout (Mas-KO) mice presented dyslipidemia, increased levels of insulin and leptin, and an approximately 50% increase in abdominal fat mass. In addition, Mas gene-deleted mice presented glucose intolerance and reduced insulin sensitivity as well as a decrease in insulin-stimulated glucose uptake by adipocytes and decreased GLUT4 in adipose tissue. Mas(-/-) presented increased muscle triglycerides, while liver triglyceride levels were normal. Expression of TGF-beta and AGT genes was higher in Mas-KO animals in comparison with controls. CONCLUSIONS: These results show that Mas deficiency in FVB/N mice leads to dramatic changes in glucose and lipid metabolisms, inducing a metabolic syndrome-like state

Improved lipid and glucose metabolism in transgenic rats with increased circulating angiotensin-(1-7)

OBJECTIVE: Obesity and diabetes remain among the world's most pervasive health problems. Although the importance of angiotensin II for metabolic regulation is well documented, the role of the angiotensin-(1-7)/Mas axis in this process is poorly understood. The aim of this study was to evaluate the effect of increased angiotensin-(1-7) plasma levels in lipid and glucose metabolism using transgenic rats that express an angiotensin-(1-7)-releasing fusion protein, TGR(A1-7)3292 (TGR). METHODS AND RESULTS: The increased angiotensin-(1-7) levels in TGR induced enhanced glucose tolerance, insulin sensitivity, and insulin-stimulated glucose uptake. In addition, TGR rats presented decreased triglycerides and cholesterol levels, as well as a significant decrease in abdominal fat mass, despite normal food intake. These alterations were accompanied by a marked decrease of angiotensinogen expression and increased Akt in adipose tissue. Furthermore, augmented plasma levels and expression in adipose tissue was observed for adiponectin. Accordingly, angiotensin-(1-7) stimulation increased adiponectin production by primary adipocyte culture, which was blocked by the Mas antagonist A779. Circulating insulin and muscle glycogen content were not altered in TGR. CONCLUSIONS: These results show that increased circulating angiotensin-(1-7) levels lead to prominent changes in glucose and lipid metabolism