Protective effect of curcumin analogue L6H4 on diaphragm of type 2 diabetic rats

AIM: To investigate the protective effect of curcumin analogue L6H4 on diaphragm of type 2 diabetic rats.METHODS: SPF male Sprague-Dawley rats (n=40) were randomly divided into 5 groups: normal control (NC) group, high fat (HF) group, high fat+L6H4 treatment (FT) group, diabetes mellitus (DM) group and DM+L6H4 treatment (DT) group. The rats in the later 4 groups were fed with high-fat diet. After 4 weeks of high-fat diet fee-ding, the rats in DM and DT groups were intraperitoneally injected with streptozotocin to induce type 2 diabetes melliutus. The rats in FT and DT groups were given L6H4 by gavage for 8 weeks. Blood glucose and blood lipid levels were detected biochemically. Fasting serum insulin (FINS) level was measured by radioimmunoassay and insulin resistance index (HOMA-IR) was calculated. Serum adiponectin (APN) level was measured by ELISA. The morphological changes of the diaphragm were observed under light and transmission electron microscopes. Lipid deposition and the activity of succinate dehydrogenase (SDH) and NADH-tetrazolium reductase (NADH-TR) were observed by enzyme histochemical staining. The content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) in the diaphragm were measured by thiobarbituric acid method and hydroxylamine method, respectively. The protein expression of adiponectin receptor 1 (AdipoR1) in the diaphragm was determined by immunohistochemistry and Western blot. RESULTS: The levels of blood lipids, blood glucose, FINS and HOMA-IR in HF and DM groups were higher than those in NC group, but decreased after L6H4 treatment. The serum APN level in HF and DM groups was lower than that in NC group, but increased after treatment with L6H4. The muscle fibers of the diaphragm were shrunk, fat particles accumulated in the muscle fibers, and the mitochondria were slightly swollen in HF and DM groups. The diaphragmatic fibrosis was obvious in DM group. These lesions were relieved after L6H4 treatment. Compared with NC group, the level of MDA and the activity of SDH and NADH-TR in the diaphragm were increased in HF and DM groups, but decreased after treatment with L6H4. The activity of SOD and the expression of AdipoR1 in the diaphragm were lower than those in NC group, but increased after L6H4 treatment.CONCLUSION: The curcumin analogue L6H4 exerts a protective effect on diaphragm in type 2 diabetic rats. The strengthened protein expression of AdipoR1, the increased serum level of APN, and anti-lipid peroxidation may be involved in the process.     

Effect of Nutrient Restriction and Compensation on Weight,Serum Indexes and Gene Expression of Chest Fat Adipokines in Mongolian Lamb

To study the effect of nutrient restriction and compensation on weight,serum indexes and gene expression of chest fat adipokine in Mongolian lamb,thirty male lambs were randomly divided into control group (20.26 kg± 3.63 kg) and feed restricted group (21.29 kg±3.00 kg).The experiment lasted for 120 days,including 60 days for feed restriction and 60 days for compensatory feed.At the end of each stage,five lambs from each group were slaughtered and chest fat was collected.Serum concentration of triglycerides,non-esterified fatty acids (NEFA),total cholesterol were measured.Quantitative Real-time PCR were used to determine Adiponectin,Visfatin,PPAR-γ and ACC genes expression.The results showed that:①The lamb body weight of restricted group kept maintain level and that of control group showed a increase tendency.During the compensatory period,the average daily gain (ADG) of restricted group was significantly higher than control group (P< 0.05).②During the restriction period,serum triglycerides concentration of lambs in restricted group was significantly decreased at day 30 and 60 (P< 0.05),and NEFA concentration was significantly increased at day 30 (P< 0.05).After 60 days of nutritional compensation,all serum parameters we tested were not significantly different between restrict group and control group (P >0.05).③During the restriction period,PPAR-γ and ACC gene expression in restricted group were significantly lower than that of control group (P< 0.05),while no significant differences were found during the compensation period (P>0.05).Adiponectin and Visfatin genes expression in chest fat was not significantly changed throughout the experiment (P >0.05).We could know that nutritional restriction reduced fatty acid synthesis and adipocyte differentiation ability,adipose tissue was mobilized energy metabolism,and total cholesterol was recoveried growth on the compensation.However,the ACC and PPAR-γ genes in restricted group were significantly decreased with the body weight increased rapidly during the compensatory stage.Adiponectin and Visfatin were not significantly different between restricted and compensatory stages.     

Adiponectin links adipose tissue function and monocyte inflammatory responses during bovine metabolic stress

The periparturient period of dairy cows is characterized by intense lipid mobilization from adipose tissue leading to increased plasma concentrations of nonesterified fatty acids (NEFA). High NEFA are a predisposing factor for inflammatory based diseases. A major component of these diseases is uncontrolled macrophage/monocyte inflammatory responses. Changes in the endocrine activity of adipose tissue during the periparturient period could impact macrophage function by modifying the secretion of adipokines including adiponectin. Currently, the effects of adiponectin on monocyte activation in dairy cattle are unknown. In humans and rodents, this adipokine regulates monocyte phenotype and alterations in its plasma levels are linked with the development of inflammatory diseases. The objectives of this study were to establish associations between plasma adiponectin expression dynamics and different markers of lipid mobilization during the periparturient period of dairy cows and to characterize the effects of adiponectin on the inflammatory response of bovine monocytes. Plasma adiponectin, NEFA, BHB, albumin, and subcutaneous and retroperitoneal fat depots depth were measured during the periparturient period of dairy cows. In vitro, bovine monocytes were cultured with adiponectin to assess changes in pro-inflammatory responses following LPS stimulation. Results from this study demonstrate that alterations in plasma adiponectin levels in periparturient cattle are inversely correlated with the concentrations of plasma NEFA, an important marker of lipid mobilization. Furthermore, adiponectin exposure significantly decreased monocyte expression of TNFα after LPS stimulation thus markedly reducing their inflammatory response. Reduced plasma adiponectin during the periparturient period could predispose dairy cows to the development of uncontrolled monocyte inflammatory responses.     

Protective effect of adiponectin on glucose and lipid metabolism by suppressing MHCⅡ expression

AIM: To investigate whether the protective effect of adiponectin on glucose and lipid metabolism is achieved through down-regulating major histocompatibility complex class Ⅱ (MHCⅡ) in the adipose tissue. METHODS: Adiponectin knockout (KO) mice and C57BL/6(WT) mice were fed with high-fat diet and standard diet for 24 weeks, respectively. The body weight, fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), hepatic histology, and class Ⅱ trans-activator (CⅡTA), histocompatibility 2 class Ⅱ antigen E beta (H2-Eb1) and cluster of differentiation 74(CD74) mRNA and MHC Ⅱ protein levels in adipose tissue were measured at sacrifice. siRNA targeting MHC Ⅱ and overexpression vector was used in 3T3-L1 cells to explore the effect of adiponectin on the protein level of MHCⅡ. RESULTS: The levels of body weight, FBG, FINS, HOMA-IR, TC, TG, LDL-C, hepatic steatosis, CⅡTA, H2-Eb1 and CD74 mRNA expression, and MHCⅡ protein expression in the KO mice were higher than those in the WT mice that fed with high-fat diet or standard diet. In 3T3-L1 cells, inhibition of adiponectin reversed MHC Ⅱ protein level induced by specific siRNA. The expression of MHC Ⅱ in adipocytes decreased after adiponectin was overexpressed. CONCLUSION: Adiponectin improves glucose and lipid metabolism through suppressing the expression of MHCⅡ in the adipose tissue.     

Effect of nitric oxide on adiponectin-induced inhibition of platelet aggregation in hyperlipidemia rats

AIM: To investigate the mechanism that adiponectin inhibits platelet aggregation via nitric oxide (NO) signaling pathway. METHODS: Adult rats were fed with normal or high-fat diet for 14 weeks. Their platelets were immediately isolated and treated with or without recombinant full-length adiponectin (rAPN). The platelet aggregation, NO and superoxide production, endothelial nitric oxide synthase (eNOS)/inducible NOS (iNOS) expression, and antioxidant capacity were determined. RESULTS: Treatment with rAPN inhibited platelet aggregation induced by hyperlipidemia (P<0.05). Interestingly, total NO, a crucial molecule depressing platelet aggregate and thrombus formation, was significantly reduced, rather than increased in rAPN-treated platelets. Treatment with rAPN significantly decreased superoxide production by 62% (P<0.05) and increased antioxidant capacity by 38% (P<0.05) in hyperlipidemic platelets. Importantly, hyperlipidemia-induced reduction of eNOS phosphorylation and increase in iNOS expression were markedly reversed by rAPN treatment (P<0.05 and P<0.01, respectively). CONCLUSION: Adiponectin is an adipokine that inhibits platelet aggregation by enhancing eNOS activation and attenuating oxidative/nitrative stress including blockage of iNOS expression and superoxide production.     

Effects of adiponectin on expression of connexin 43 in rat myocardium during ischemia-reperfusion

AIM: To observe the effects of adiponectin(APN) on the expression of connexin 43 (Cx43) in rat myocardium during ischemia-induced arrhythmias. METHODS: The SD rats were randomly divided into 4 groups (n=12): sham operation group (SM group), ischemia and reperfusion group (I/R group), I/R+adiponectin(APN1) group: pre-ischemia with 3.5 μg/kg of APN; I/R+APN2 group: post-ischemia with 3.5 μg/kg of APN. The incidence of ventricular arrhythmias and ventricular arrhythmia score (VAS) were determined. The expression of Cx43 in the ischemic myocardium was studied by the techniques of immunohistochemistry and RT-PCR. The levels of malondialdehyde(MDA) and superoxide dismutase(SOD) were measured by the methods of xanthine oxidase and thiobarbituric acid. The expression of endothelial nitric oxide synthase (eNOS) at mRNA and protein levels was determined by RT-PCR and Western blotting,respectively.The morphological changes of the myocardial tissues were observed under electronic microscope. RESULTS: The VAS and concentration of MDA increased obviously and the activity of SOD was decreased in I/R group as compared with SM group (P<0.01). The expression of Cx43 was evidently decreased and the distribution of Cx43 in the myocardium was disturbed. The expression of eNOS at mRNA and protein levels was decreased in I/R group (P<0.05). The ultrastructure of ventricular myocardium was abnormal in I/R group. Compared with I/R group, APN obviously decreased the VAS caused by ischemia and reperfusion (P<0.01) no matter the drug was given before or after ischemia. APN increased the activity of SOD, inhibited the MDA content in serum, and resulted in normal distribution of Cx43 and increased the expression of Cx43 and eNOS. Compared with I/R group, the changes of heart ultrastructure attenuated greatly in APN group, but didn't recover to normal state. CONCLUSION: Adiponectin antagonizes the arrhythmias during myocardial ischemia and reperfusion via inhibiting oxidative stress and regulating Cx43.     

Effects of curcumin analogue L6H4 on myocardial tissue of type 2 diabetic rats

AIM: To explore the effects of curcumin analogue L6H4 on the myocardial tissue of type 2 diabetic rats and its mechanism. METHODS: Male Sprague-Dawley rats were randomly divided into normal control (NC) group, high-fat (HF) group, high-fat treatment (FT) group, diabetes mellitus (DM) group and diabetes treatment (DT) group.The rats in the latter 4 groups were fed high-fat diet for 4 weeks, then the rats in DM groups and DT groups were intraperitoneally injected with streptozotocin (STZ) to induce type 2 diabetes, while the rats in FT group and DT group were given L6H4. The blood glucose and lipid levels were detected by biochemical method, and serum adiponectin (APN) levels were detected by ELISA. The serum insulin levels were measured by radioimmunoassay and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. The morphological changes of myocardium were observed by Masson staining and electron microscopy. The protein expression of adiponectin receptor 1 (AdipoR1) and transforming growth factor β1(TGF-β1) in myocardial tissue were determined by immunohistochemistry. The protein expression of adipoR1 was also detected by Western blot for verification. RESULTS: Compared with NC group, the blood glucose, lipids, insulin, HOMA-IR and TGF-β1 were increased in HF and DM group, but they were decreased after treated with L6H4. Compared with NC group, the concentration of serum APN were decreased and the expression of AdipoR1 in the myocardium were weakened in HF group and DM group, and they increased after treated with L6H4. The myocardial fibrosis was obvious in HF group and DM group, the mitochondria in cardiomyocytes expanded, and the cristae disordered, partial disappeared. These lesions were significantly reduced after L6H4 treatment. CONCLUSION: L6H4 exerts a protective effect on the heart in type 2 diabetic rats. The increased concentration of serum APN, the enhanced expression of AdipoR1, and the expression of TGF-β1 inhibited by APN may be involved in the mechanism of protection.     

Transition period-related changes in the abundance of the mRNAs of adiponectin and its receptors,of visfatin,and of fatty acid binding receptors in adipose tissue of high-yielding dairy cows

Adipose tissue expresses adipokines, which are involved in regulation of energy expenditure, lipid metabolism, and insulin sensitivity. To adapt for the transition from pregnancy to lactation, particularly in high-yielding dairy cows, adipokines, their receptors, and particular G-protein coupled receptors (GPRs) are of potential importance. Signaling by GPR 41 stimulates leptin release via activation by short-chain fatty acids; GPR 43/109A inhibits lipolysis, and GPR 109A thereby mediates the lipid-lowering effects of nicotinic acid and β–hydroxybutyrate. The aim of this study was to compare the mRNA expression of adiponectin and visfatin, adiponectin receptors 1 and 2 (AdipoR1/2), leptin receptor (obRb), insulin receptor as of the aforementioned GPRs during the transition period in high-yielding dairy cows. Biopsies from subcutaneous fat and blood samples were obtained from 10 dairy cows 1 week before and 3 weeks after calving. For AdipoR1 and AdipoR2 mRNA abundance as well as for leptin concentrations in plasma, a reduction (P ≤ .05) was observed postpartum; for visfatin and putative GPR 109A mRNA abundance in adipose tissue, there was a trend (P < .1) for analogous changes. In contrast, the mRNA content of obRb and GPR 41 in adipose tissue was higher (P ≤ .05) in samples from early lactation than in those from late gestation. Our results indicate decreasing adiponectin sensitivity in adipose tissue after calving, which might be involved in the reduced insulin sensitivity of adipose tissue during early lactation. In addition, visfatin, GPR 41, and GPR 109A may further modulate insulin sensitivity.     

脂联素基因c.249 C>T突变对京海黄鸡部分主要经济性状的影响

以京海黄鸡为试验材料,采用PCR-SSCP技术,探讨脂联素基因第一外显子和部分第一内含子碱基突变对屠宰和母鸡产蛋性状的遗传效应。结果表明,脂联素基因c.249位C>T突变的3种基因型(AA、AB和BB)对京海黄鸡的活体质量、半净膛率、胸肌质量、腿肌质量、胸肌率和腿肌率差异均不显著(P>0.05)。BB型个体的300日龄产蛋数和66周龄产蛋数显著高于AB型个体(P<0.05)。BB型个体的腹脂质量和腹脂率显著高于AB和AA型个体(P<0.05)。Adipo基因座对京海黄鸡开产日龄,300日龄产蛋数,300日龄蛋质量和66周龄产蛋数的主效应指数(MEI)均小于1.21,而其对公母鸡的腹脂质量主效应指数(MEI)分别为8.68和7.40。说明该基因可能是调控脂肪沉积的主效基因或与主效基因连锁。     

Adiposity and adiponectin in dogs: investigation of causes of discrepant results between two studies

Although one study showed lower adiponectin concentrations in obese dogs, other recent studies indicate that adiponectin might not be decreased in obese dogs, raising the possibility that the physiology of adiponectin is different in dogs than in humans. The aim of this study was to investigate possible causes of the discrepancy between the two largest studies to date that assessed the association between adiposity and adiponectin concentration in dogs, including the validity of the assay, laboratory error, and the effects of breed, sex, and neuter status on the relationship between adiposity and adiponectin concentrations. Adiponectin concentrations measured with a previously validated adiponectin ELISA were compared with those estimated by Western blotting analysis of reduced and denatured plasma samples. The possibility of laboratory error and the effect of EDTA anticoagulant and aprotinin were tested. Adiponectin concentration was measured by ELISA in 20 lean dogs (10 male and 10 female, 5 neutered in each sex). There was close correlation between adiponectin concentrations measured by ELISA and those estimated by Western blotting analysis (r = 0.90; P < 0.001). There was no substantial effect of EDTA, aprotinin, or laboratory error on the results. There was confounding by neuter status of the relationship between adiposity and adiponectin concentrations, but adiponectin concentrations were not significantly lower in male than in female lean dogs (females, 36 mg/L; males, 26 mg/L; P > 0.20) and were not significantly lower in intact than in neutered lean male dogs (intact, 28 mg/L; neutered, 23 mg/L; P = 0.49). We conclude that the adiponectin ELISA previously validated for use in dogs appears to be suitable for determination of canine adiponectin concentrations and that testosterone does not appear to have a strong effect on plasma adiponectin concentrations in dogs. Obesity might decrease adiponectin concentrations in intact but not in neutered dogs.