Adipogenic and Lipolytic Effects of Ascorbic Acid in Ovariectomized Rats

PURPOSE: Ascorbic acid has been reported to have an adipogenic effect on 3T3-L1 preadipocytes, while evidence also suggests that ascorbic acid reduces body weight in humans. In this study, we tested the effects of ascorbic acid on adipogenesis and the balance of lipid accumulation in ovariectomized rats, in addition to long-term culture of differentiated 3T3-L1 adipocytes. MATERIALS AND METHODS: Murine 3T3-L1 fibroblasts and ovariectomized rats were treated with ascorbic acid at various time points. In vitro adipogenesis was analyzed by Oil Red O staining, and in vivo body fat was measured by a body composition analyzer using nuclear magnetic resonance. RESULTS: When ascorbic acid was applied during an early time point in 3T3-L1 preadipocyte differentiation and after bilateral ovariectomy (OVX) in rats, adipogenesis and fat mass gain significantly increased, respectively. However, lipid accumulation in well-differentiated 3T3-L1 adipocytes showed a significant reduction when ascorbic acid was applied after differentiation (10 days after induction). Also, oral ascorbic acid administration 4 weeks after OVX in rats significantly reduced both body weight and subcutaneous fat layer. In comparison to the results of ascorbic acid, which is a well-known cofactor for an enzyme of collagen synthesis, and the antioxidant ramalin, a potent antioxidant but not a cofactor, showed only a lipolytic effect in well-differentiated 3T3-L1 adipocytes, not an adipogenic effect. CONCLUSION: Taking these results into account, we concluded that ascorbic acid has both an adipogenic effect as a cofactor of an enzymatic process and a lipolytic effect as an antioxidant.

Renin-angiotensin system blockers regulate the metabolism of isolated fat cells in vitro

Due to the presence of the renin-angiotensin system (RAS) in tissues and its specific influence on white adipose tissue, fat cells are possible targets of pharmacological RAS blockers commonly used as anti-hypertensive drugs. In the present study, we investigated the effects of different RAS blockers on fat cell metabolism, more specifically on lipolysis, lipogenesis and oxidation of energy substrates. Isolated primary adipocytes were incubated with different RAS blockers (aliskiren, captopril and losartan) in vitro for 24 h and lipolysis, lipogenesis and glucose oxidation capacities were determined in dose-response assays to a β-adrenergic agonist and to insulin. Although no change was found in lipolytic capacity, the RAS blockers modulated lipogenesis and glucose oxidation in a different way. While captopril decreased insulin-stimulated lipogenesis (−19% of maximal response and −60% of insulin responsiveness) due to reduced glucose derived glycerol synthesis (−19% of maximal response and 64% of insulin responsiveness), aliskiren increased insulin-stimulated glucose oxidation (+49% of maximal response and +292% of insulin responsiveness) in fat cells. Our experiments demonstrate that RAS blockers can differentially induce metabolic alterations in adipocyte metabolism, characterized by a reduction in lipogenic responsiveness or an increase in glucose oxidation. The impact of RAS blockers on adipocyte metabolism may have beneficial implications on metabolic disorders during their therapeutic use in hypertensive patients.

Topical Prostaglandin Analogue Drugs Inhibit Adipocyte Differentiation

PURPOSE: To investigate the effects of topical prostaglandin analogue drugs on the differentiation of adipocytes. METHODS: Differentiation of 3T3-L1 preadipocytes was induced with isobutylmethylxanthine, dexamethasone, and insulin. 3T3-L1 cells were exposed to 0.008, 0.08, 0.2 microM of latanoprost and travoprost. Reverse transcription polymerase chain reaction for mRNA expression of lipoprotein lipase and peroxisome proliferator-activated receptor gamma 2 (PPARgamma2), and glycerol-3-phosphate dehydrogenase (G3PDH) assays were performed to examine the effects on early and late differentiation, respectively. Also, glycerol assays were done to evaluate the effect of prostaglandin analogues on lipolysis after differentiation. RESULTS: Both prostaglandin analogues inhibited differentiation of preadipocytes. Topical prostaglandin analogues significantly decreased G3PDH activity, a marker of late differentiation. However, topical prostaglandin analogues did not change mRNA expressions of lipoprotein lipase and PPARgamma2, markers of early differentiation. The activities of the early markers of differentiation were not changed significantly before and after growth arrest. Compared to latanoprost, travoprost decreased G3PDH activity more significantly (p 0.05). CONCLUSIONS: Prostaglandin analogues display an inhibitory effect on the differentiation of adipocytes when the cells start to differentiate especially in the late stage of differentiation. Thus, commercial topical prostaglandin analogues may decrease the fat contents of eyelids.

Antiobesity activity of a sphingosine 1-phosphate analogue FTY720 observed in adipocytes and obese mouse model

Higher levels of body fat are associated with an increased risk for development numerous adverse health conditions. FTY720 is an immune modulator and a synthetic analogue of sphingosine 1-phosphate (S1P), activated S1P receptors and is effective in experimental models of transplantation and autoimmunity. Whereas immune modulation by FTY720 has been extensively studied, other actions of FTY720 are not well understood. Here we describe a novel role of FTY720 in the prevention of obesity, involving the regulation of adipogenesis and lipolysis in vivo and in vitro. Male C57B/6J mice were fed a standard diet or a high fat diet (HFD) without or with FTY720 (0.04 mg/kg, twice a week) for 6 weeks. The HFD induced an accumulation of large adipocytes, down-regulation of phosphorylated AMP-activated protein kinase alpha (p-AMPKalpha) and Akt (p-Akt); down-regulation of hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL) and perilipin mRNA as well as up-regulation of phosphorylated HSL (p-HSL, Ser563) and glycogen synthase kinase 3 alpha/beta (p-GSK3alpha/beta). All these effects were blunted by FTY720 treatment, which inhibited adipogenesis and promoted lipolysis. Also, FTY720 significantly decreased lipid accumulation in maturing preadipocytes. FTY720 down-regulated the transcriptional levels of the PPARgamma, C/EBPalpha and adiponectin, which are markers of adipogenic differentiation. FTY720 significantly increased the release of glycerol and the expression of the HSL, ATGL and perilipin, which are regulators of lipolysis. These results show that FTY720 prevented obesity by modulating adipogenesis and lipolysis, and suggest that FTY720 is used for the treatment of obesity.

Evaluation of polyvinyl alcohol for fatty acid supplementation in adipose tissue explant culture

Cultures of adipose tissue explants are a valuable tool for studying the intracellular mechanisms involving hormones and nutrients. However, testing how fatty acids affect cells requires a carrier molecule; bovine serum albumin (BSA) has been used for this purpose. However, contaminants can alter the cellular response. Our objectives were to: 1) test BSA as a fatty acid carrier and 2) evaluate polyvinyl alcohol (PVA) as a replacement for BSA. Adipose tissue explants from nine pigs were cultured in medium 199 for 4, 12, 24, and 48 h, with the following treatments: control, PVA (100 mM PVA added) and PVA + pGH (100 mM PVA plus 0.1 mg/mL porcine growth hormone). After each culture period, explants were collected and assayed for lipogenesis. After 48 h in culture, explants were assayed for lipolysis. A preliminary study with different commercial sources and high concentrations showed that BSA affected lipogenic rates. On the other hand, there were no effects of PVA on lipid synthesis, while pGH (positive control) reduced glucose incorporation into lipids (P < 0.01) when compared to both control and PVA (P < 0.05). There was no difference between control and PVA for lipolysis rates. However, pGH increased lipolysis when compared to control (P < 0.01) and PVA (P < 0.05). We demonstrated that BSA can alter lipogenesis, which precludes its use as a carrier molecule. On the other hand, addition of PVA had no effect on lipolysis or lipogenesis. We suggest the use of PVA instead of BSA for adding bioactive fatty acids to cultures of adipose tissue

Influence of Coccinia indica on certain enzymes in glycolytic and lipolytic pathway in human diabetes.

Dried extract of C Indica in doses of 500 mgm/kg body weight were administered orally to 30 diabetic patients for six weeks. Blood samples were collected 15 minutes after administration of 10 IU heparin for estimation of LPL, before and after treatment with C. Indica Non heparinised samples were utilized for estimation for G-6-p (ase), LDH and blood sugar. Severity of disease were assessed by the findings of blood sugar level. Mild diabetes had no effect on LPL, LDH and G-6-P (ase). But, reduced activity of enzyme LPL and raised level of G-6-P (ase) and LDH in plasma of severe diabetics were found to be highly significant (p < 0.001). The alteration in these parameters in untreated diabetics were restored after treatment with C. indica Hence, it can be postulated that the ingredients present in the extract of C. indica, act like insulin, correcting the elevated enzymes G-6-p (ase), LDH in glycolytic pathway and restore the LPL activity in lypolytic pathway with the control of hyperglycemia in diabetes.

Impact of protein deficiency and exposure to hexachlorocyclohexane or malathion on lipid metabolism in pregnant rats.

Dietary intake of three oral doses of hexachlorocyclohexane (HCH) (60 mg/kg body wt) or malathion (500 mg/kg) by normal and protein-deficient diet fed pregnant rats on the 6th, 10th and 14th day of gestation resulted in the impairment of lipid metabolism, viz. hypercholesterolemia and hypertriglyceridemia. The cholesterol, triglyceride and phospholipid contents in serum, brain, liver, kidney and uterus were increased significantly by HCH and malathion exposure, irrespective of the protein content in the diet. The incorporation of [1,2-14C]acetate into the hepatic lipids was stimulated by both HCH and malathion, suggesting a higher rate of lipid synthesis in the liver of normal and protein-deficient diet fed dams. The low protein content in the diet intensified the pesticide-induced changes and more severe alterations were noticed in HCH exposed dams than in malathion exposed dams.

Effect of centbucridine & lignocaine on biochemical changes in isoproterenol induced ischemia in rats.

Effect of lignocaine and centbucridine against isoproterenol-induced biochemical changes was studied in the rat. Isoproterenol (40 mg/kg twice) increased the heart weight, level of manolaldehyde (MDA) and activity of acid phosphatase, but decreased the myocardial phospholipid content at 48 h. In addition, increase in plasma triglyceride, cholesterol, MDA and creatine phosphokinase activity was observed. Pretreatment of the animals with lignocaine (10 mg/kg) or centbucridine (1, 3 and 10 mg/kg) protected the animals against these biochemical changes. However, increase in heart weight consequent to isoproterenol treatment could not be prevented. Total protection against creatine phosphokinase release in the blood was also not observed. The results suggest that the two drugs inhibit lipolysis. They may also inhibit phospholipases leading to protection against ischemia-induced changes in the rat.

Effects of ingestion of thermally oxidized edible oils on plasma lipids, lipoproteins and postheparin lipolytic activity of rats.

Acute (after 4 hr) and short-term (after 7 days) effects of ingesting heated and unheated groundnut, coconut and safflower oils on plasma lipids, lipoproteins and postheparin lipopolytic activity (PHLA) were studied in rats. All heated oils were characterized by increases in carbonyl value, peroxide value and free fatty acid (FFA) content, except heated coconut oil which showed a decrease in FFA content. Heating procedure also did not alter to an appreciable extent their fatty acid compositions. Acute and short-term effects of feeding heated and unheated oils showed no significant differences in rat plasma levels of total cholesterol (TC), total triglycerides, total phospholipids, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol + very-low-density lipoprotein cholesterol, TC/HDL-C ratio and PHLA. Inspite of certain changes in some of the indices of thermal alteration of these heated oils, consumption of such heated oils by rats did not have any significant effect on various plasma parameters in these animals.

Lipoprotein profile during perchlorate toxicity.

Perchlorate administration to rats for 45 days alters the lipoprotein profile in plasma. The levels of cholesterol, phospholipids and triglycerides in HDL, LDL and VLDL fractions are significantly increased in perchlorate-treated rats. Post-heparin lipolytic activity of plasma of sodium perchlorate-treated rats is decreased. The risk factor, i.e. the total cholesterol/HDL cholesterol, increases in the experimental animals, indicating that the treatment of rats with perchlorate may develop the susceptibility of the animals to cardiac heart disease.

Relación entre la respuesta individual a la heparina y la actividad lipolítica / Relationship between individual response to heparin and lipolysis activity

Se estudiaron 55 pacientes ambulatorios, de ambos sexos (28 hombres y 27 mujeres), con una edad promedio de 60,93 años (32-80 años) que presentaban menos del 120% de sobrepeso. Fueron divididos en dos grupos normo o hiporreactor a la heparina de acuerdo con los resultados obtenidos en la prueba de tolerancia a la heparina (PTH). Cada grupo fue comparable en edad, talla y tanto por ciento de sobrepeso. De acuerdo con esta clasificación no hubo diferencias significativas en la actividad del sistema lipolítico al comparar los grupos entre sí. Se identificaron dos grupos de pacientes con sensibilidades diferentes a la heparina mediante un análisis de Clusters. Se encontró un descenso significativo (p<0,05) en las actividades del sistema lipolítico total y de la lipasa lipoproteica, así como un aumento (p<0,05) en los niveles endógenos de heparina en el grupo con tipo II de respuesta, al compararlos con el tipo I. No se encontraron cambios de trascendencia en las actividades de la lipasa basal y hepática al comparar los grupos entre sí

Ativaçäo e bloqueio da lipólise in vitro no tecido adiposo de pombos / Activation and blockade of lipolysis \"in vitro\" on pigeon adipose tissue

Säo estudadas in vitro as açöes de diferentes concentraçöes de adrenalina, noradrenalina ou teofilina sobre a lipólise no tecido adiposo de pombos. Relata-se, ainda, a açäo do propranolol e da fentolamina sobre aquelas respostas lipolíticas. Os resultados mostram que doses elevadas de adrenalina ou noradrenalina ocaciosam declínio da lipólise no tecido adiposo de pombos, e que säo necessárias altas concentraçöes de teofilina para que a resposta lipolítica a esta droga se manifeste. Verificou-se que níveis elevados daqueles bloqueadores adrenérgicos, inibem a resposta lipolítica do tecido adiposo daquela ave, possivelmente também em algum passo posterior à formaçäo do AMP cíclico

Acute toxicity of uranyl nitrate and behaviour of serum lipolytic activity.

The alterations in the serum lipolytic activity of mice were studied under Uranyl nitrate (UN) intoxication. The lipemia produced as a result of UN intoxication was probed studying the alterations in the serum triacyl-glycerol-hydrolase (EC 3.1.1.3) activity. After an intraperitoneal injection of UN (10 mg/kg and 25 mg/kg), triacyl-glycerol-hydrolase (TAGH) activity was considerably enhanced. In the initiation phase the elevation in the activity was observed to be higher than the elevation in the maintenance phase of acute UN toxicity. The possible reasons for the elevation in the TAGH activity and its role under such intoxication is discussed.