UCP2-dependent redox sensing in POMC neurons regulates feeding.

Paradoxically, glucose, the primary driver of satiety, activates a small population of anorexigenic pro-opiomelanocortin (POMC) neurons. Here, we show that lactate levels in the circulation and in the cerebrospinal fluid are elevated in the fed state and the addition of lactate to glucose activates the majority of POMC neurons while increasing cytosolic NADH generation, mitochondrial respiration, and extracellular pyruvate levels. Inhibition of lactate dehydrogenases diminishes mitochondrial respiration, NADH production, and POMC neuronal activity. However, inhibition of the mitochondrial pyruvate carrier has no effect. POMC-specific downregulation of Ucp2 (Ucp2PomcKO), a molecule regulated by fatty acid metabolism and shown to play a role as transporter in the malate-aspartate shuttle, abolishes lactate- and glucose-sensing of POMC neurons. Ucp2PomcKO mice have impaired glucose metabolism and are prone to obesity on a high-fat diet. Altogether, our data show that lactate through redox signaling and blocking mitochondrial glucose utilization activates POMC neurons to regulate feeding and glucose metabolism.

Genipin, an Inhibitor of UCP2 as a Promising New Anticancer Agent: A Review of the Literature.

Genipin is a protein cross-linking agent extracted from Gardenia (Gardenia jasminoides Ellis) fruits. This fruit has conventionally been used as a Chinese herbal medicine for the treatment of inflammation and jaundice and as an edible colorant in oriental countries. Uncoupling protein (UCP)-2 is a member of the family of uncoupling proteins, which are anion transporters positioned in the mitochondrial inner membrane. Genipin has been shown to have hepatoprotective activity, acting as an effective antioxidant and inhibitor of mitochondrial UCP2, and is also reported to exert significant anticancer effects. In this review, the author presents the latest progress of genipin as an anticancer agent and concisely describes its various mechanisms of action. In brief, genipin inhibits UCP2 to attenuate generation of reactive oxygen species (ROS), leading to ROS/c-Jun N-terminal kinase-dependent apoptosis of cancer cells. Genipin also increases the tissue inhibitors of matrix metalloproteases (MMP)-2, a kind of tumor promoter in a variety of cancers, as well as induces caspase-dependent apoptosis in in vitro and in vivo models. These findings suggest that genipin can serve as a promising novel antitumor agent that could be applicable for chemotherapy and/or chemoprevention for cancers.

All-trans retinoic acid impairs glucose-stimulated insulin secretion by activating the RXR/SREBP-1c/UCP2 pathway.

Diabetes is often associated with vitamin A disorders. All-trans retinoic acid (ATRA) is the main active constituent of vitamin A. We aimed to investigate whether ATRA influences diabetic progression and its mechanisms using both Goto-Kazizazi (GK) rats and INS-1 cells. Rat experiments demonstrated that ATRA treatment worsened diabetes symptoms, as evidenced by an increase in fasting blood glucose (FBG) levels and impairment of glucose homeostasis. Importantly, ATRA impaired glucose-stimulated insulin secretion (GSIS) and increased the expression of sterol regulatory element-binding protein 1c (SREBP-1c) and uncoupling protein 2 (UCP2) in the rat pancreas. Data from INS-1 cells also showed that ATRA upregulated SREBP-1c and UCP2 expression and impaired GSIS at 23 mM glucose. Srebp-1c or Ucp2 silencing attenuated GSIS impairment by reversing the ATRA-induced increase in UCP2 expression and decrease in ATP content. ATRA and the retinoid X receptor (RXR) agonists 9-cis RA and LG100268 induced the gene expression of Srebp-1c, which was almost completely abolished by the RXR antagonist HX531. RXRα-LBD luciferase reporter plasmid experiments also demonstrated that ATRA concentration-dependently activated RXRα, the EC50 of which was 1.37 µM, which was lower than the ATRA concentration in the pancreas of GK rats treated with a high dose of ATRA (approximately 3 µM), inferring that ATRA can upregulate Srebp-1c expression in the pancreas by activating RXR. In conclusion, ATRA impaired GSIS partly by activating the RXR/SREBP-1c/UCP2 pathway, thus worsening diabetic symptoms. The results highlight the roles of ATRA in diabetic progression and establish new strategies for diabetes treatment.

In vitro blood brain barrier exposure to mycotoxins and carotenoids pumpkin extract alters mitochondrial gene expression and oxidative stress.

Food and feed are daily exposed to mycotoxin contamination which effects may be counteracted by antioxidants like carotenoids. Some mycotoxins as well as carotenoids penetrate the blood brain barrier (BBB) inducing alterations related to redox balance in the mitochondria. Therefore, the in vitro BBB model ECV304 was subcultured for 7 days and exposed to beauvericine, enniatins, ochratoxin A, zearalenone (100 nM each), individually and combined, and pumpkin extract (500 nM). Reactive oxygen species were measured by fluorescence using the dichlorofluorescein diacetate probe at 0 h, 2 h and 4 h. Intracellular ROS generation reported was condition dependent. RNA extraction was performed and gene expression was analyzed by qPCR after 2 h exposure. The selected genes were related to the Electron Transport Chain (ETC) and mitochondrial activity. Gene expression reported upregulation for exposures including mycotoxins plus pumpkin extract versus individual mycotoxins. Beauvericin and Beauvericin-Enniatins exposure significantly downregulated Complex I and pumpkin addition reverted the effect upregulating Complex I. Complex IV was the most downregulated structure of the ETC. Thioredoxin Interacting Protein was the most upregulated gene. These data confirm that mitochondrial processes in the BBB could be compromised by mycotoxin exposure and damage could be modulated by dietary antioxidants like carotenoids.

Fluoxetine administration in juvenile overfed rats improves hypothalamic mitochondrial respiration and REDOX status and induces mitochondrial biogenesis transcriptional expression.

Nutritional imbalance in early life may disrupt the hypothalamic control of energy homeostasis and increase the risk of metabolic disease. The hypothalamic serotonin (5-hydroxytryptamine; 5-HT) system based in the hypothalamus plays an important role in the homeostatic control of energy balance, however the mechanisms underlying the regulation of energy metabolism by 5-HT remain poorly described. Several crucial mitochondrial functions are altered by mitochondrial stress. Adaptations to this stress include changes in mitochondrial multiplication (i.e, mitochondrial biogenesis). Due to the scarcity of evidence regarding the effects of serotonin reuptake inhibitors (SSRI) such as fluoxetine (FLX) on mitochondrial function, we sought to investigate the potential contribution of FLX on changes in mitochondrial function and biogenesis occurring in overfed rats. Using a neonatal overfeeding model, male Wistar rats were divided into 4 groups between 39 and 59 days of age based on nutrition and FLX administration: normofed + vehicle (NV), normofed + FLX (NF), overfed + vehicle (OV) and overfed + FLX (OF). We found that neonatal overfeeding impaired mitochondrial respiration and increased oxidative stress biomarkers in the hypothalamus. FLX administration in overfed rats reestablished mitochondrial oxygen consumption, increased mitochondrial uncoupling protein 2 (Ucp2) expression, reduced total reactive species (RS) production and oxidative stress biomarkers, and up-regulated mitochondrial biogenesis-related genes. Taken together our results suggest that FLX administration in overfed rats improves mitochondrial respiratory chain activity and oxidative balance and increases the transcription of genes employed in mitochondrial biogenesis favoring mitochondrial energy efficiency in response to early nutritional imbalance.

Therapeutic potential of genipin in various acute liver injury, fulminant hepatitis, NAFLD and other non-cancer liver diseases: More friend than foe.

Genipin is an aglycone derived from the geniposide, the most abundant iridoid glucoside constituent of Gardenia jasminoides Ellis. For decades, genipin is the focus of studies as a versatile compound in the treatment of various pathogenic conditions. In particularly, Gardenia jasminoides Ellis has long been used in traditional Chinese medicine for the prevention and treatment of liver disease. Mounting experimental data has proved genipin possesses therapeutic potential for cholestatic, septic, ischemia/reperfusion-triggered acute liver injury, fulminant hepatitis and NAFLD. This critical review is a reflection on the valuable lessons from decades of research regarding pharmacological activities of genipin. Of note, genipin represents choleretic effect by potentiating bilirubin disposal and enhancement of genes in charge of the efflux of a number of organic anions. The anti-inflammatory capability of genipin is mediated by suppression of the production and function of pro-inflammatory cytokines and inflammasome. Moreover, genipin modulates various transcription factor and signal transduction pathway. Genipin appears to trigger the upregulation of several key genes encoding antioxidant and xenobiotic-metabolizing enzymes. Furthermore, the medicinal impact of genipin extends to modulation of regulated cell death, including autophagic cell death, apoptosis, necroptosis and pyroptosis, and modulation of quality of cellular organelle. Another crucial effect of genipin appears to be linked to dual role in targeting uncoupling protein 2 (UCP2). As a typical UCP2-inhibiting compound, genipin could inhibit AMP-activated protein kinase or NF-κB in circumstance. On the contrary, reactive oxygen species production and cellular lipid deposits mediated by genipin through the upregulation of UCP2 is observed in liver steatosis, suggesting the precise role of genipin is disease-specific. Collectively, we comprehensively summarize the mechanisms and pathways associated with the hepatoprotective activity of genipin and discuss potential toxic impact. Notably, our focus is the direct medicinal effect of genipin itself, whereas its utility as a crosslinking agent in tissue engineering is out of scope for the current review. Further studies are therefore required to disentangle these complicated pharmacological properties to confer this natural agent a far greater potency.

Oleoylethanolamide supplementation in obese patients newly diagnosed with non-alcoholic fatty liver disease: Effects on metabolic parameters, anthropometric indices, and expression of PPAR-α, UCP1, and UCP2 genes.

The effects of oleoylethanolamide (OEA) on NAFLD are yet to be examined in human. The objective of the present study was to examine the effects of OEA supplementation along with weight loss intervention on the expression of PPAR-α, uncoupling proteins 1and 2 (UCP1 and UCP2) genes in the peripheral blood mononuclear cells (PBMCs), metabolic parameters, and anthropometric indices among obese patients with NAFLD. In this triple-blind placebo-controlled randomized clinical trial, 76 obese patients newly diagnosed with NAFLD were randomly allocated into either OEA or placebo group along with calorie-restricted diets for 12 weeks. At pre-and post-intervention phase, mRNA expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, serum levels of metabolic parameters as well as diet and appetite sensations were assessed. There was a significant increase in the expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, compared to the placebo at the endpoint. A significant decrease in the anthropometric indices, energy and carbohydrate intakes, glycemic parameters, except for hemoglobin A1c concentration was also observed in the OEA group, compared to the placebo group. OEA treatment significantly resulted in decreased serum levels of triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), ALT/AST, increased serum levels of high-density lipoprotein cholesterol (HDL-C), and improved appetite sensations. Importantly, a significant improvement in TG, ALT, AST, ALT/AST, HDL-C levels as well as appetite sensations by OEA were under the influence of body mass index (BMI). Although liver steatosis severity was significantly reduced in both groups, the between-group differences did not reach statistical significance (P = 0.061). In conclusion, the present study, for the first time, revealed that OEA supplementation significantly improved anthropometric and metabolic risk factors related to NAFLD.

Cerium and Yttrium Oxide Nanoparticles and Nano-selenium Produce Protective Effects Against H2O2-induced Oxidative Stress in Pancreatic Beta Cells by Modulating Mitochondrial Dysfunction.

BACKGROUND: Type 1 diabetes mellitus is characterized by the destruction of insulin- producing Beta cells in the pancreas. Researchers hope that islet transplantation will help to patients with insulin-dependent diabetes mellitus (IDDM). Oxidative stress is the most important challenge that beta cells face to it after isolation, and mitochondrial dysfunction is a crucial mediator in beta cells death. Hence, therapeutic approaches can shift to antioxidants through the application of nanoparticles such as cerium and yttrium oxide nanoparticles (Cer and Ytt Ox NPs) and nano-selenium (Nan Se). OBJECTIVE: This study evaluates the effects of Cer and Ytt Ox NPs and Nan Se on H2O2- induced oxidative stress in pancreatic beta cells with focus on mitochondrial dysfunction pathway. METHODS: CRI-D2 beta-cell line were pretreated with Cer Ox NPs (200 µM) + Ytt Ox NPs (0.5 µg/mL) for 3 days and/or Nan Se (0.01 µM) for 1 day. Then markers of oxidative stress, mitochondrial dysfunction, insulin and glucagon secretion were measured. RESULTS: We reported a decrease in H2O2-induced reactive oxygen species (ROS) level and glucagon secretion, and an increase in H2O2-reduced ATP/ADP ratio, MMP, as well as UCP2 protein expression, and insulin secretion by pretreatment of CRI-D2 cells with Cer and Ytt Ox NPs and/or Nan Se. CONCLUSION: We found maximum protective effect with Cer and Ytt Ox NPs on CRI-D2 beta-cell line exposed by H2O2 for keeping beta cells alive until transplant whereas combination of Cer and Ytt Ox NPs and Nan Se had very little protective effect in this condition.

Microglial UCP2 Mediates Inflammation and Obesity Induced by High-Fat Feeding.

Microglia play a crucial role in immune responses, including inflammation. Diet-induced obesity (DIO) triggers microglia activation and hypothalamic inflammation as early as 3 days after high-fat diet (HFD) exposure, before changes in body weight occur. The intracellular mechanism(s) responsible for HFD-induced microglia activation is ill defined. Here, we show that in vivo, HFD induced a rapid and transient increase in uncoupling protein 2 (Ucp2) mRNA expression together with changes in mitochondrial dynamics. Selective microglial deletion of Ucp2 prevented changes in mitochondrial dynamics and function, microglia activation, and hypothalamic inflammation. In association with these, male and female mice were protected from HFD-induced obesity, showing decreased feeding and increased energy expenditure that were associated with changes in the synaptic input organization and activation of the anorexigenic hypothalamic POMC neurons and astrogliosis. Together, our data point to a fuel-availability-driven mitochondrial mechanism as a major player of microglia activation in the central regulation of DIO.

The Anti-Obesity Effect of Polysaccharide-Rich Red Algae (Gelidium amansii) Hot-Water Extracts in High-Fat Diet-Induced Obese Hamsters.

This study investigated the anti-obesity effect of a polysaccharide-rich red algae Gelidium amansii hot-water extract (GHE) in high-fat (HF) diet-induced obese hamsters. GHE contained 68.54% water-soluble indigestible carbohydrate polymers. Hamsters were fed with a HF diet for 5 weeks to induce obesity, and then randomly divided into: HF group, HF with 3% guar gum diet group, HF with 3% GHE diet group, and HF with orlistat (200 mg/kg diet) group for 9 weeks. The increased weights of body, liver, and adipose in the HF group were significantly reversed by GHE supplementation. Lower plasma leptin, tumor necrosis factor-α, and interleukin-6 levels were observed in the GHE+HF group compared to the HF group. GHE also increased the lipolysis rate and decreased the lipoprotein lipase activity in adipose tissues. GHE induced an increase in the phosphorylation of AMP-activated protein kinase (AMPK) and the protein expressions of peroxisome proliferator-activated receptor alpha (PPARα) and uncoupling protein (UCP)-2 in the livers. The decreased triglyceride and total cholesterol in the plasma and liver were also observed in obese hamsters fed a diet with GHE. These results suggest that GHE exerts a down-regulation effect on hepatic lipid metabolism through AMPK phosphorylation and up-regulation of PPARα and UCP-2 in HF-induced obese hamsters.

Active Vitamin D and Vitamin D Receptor Help Prevent High Glucose Induced Oxidative Stress of Renal Tubular Cells via AKT/UCP2 Signaling Pathway.

BACKGROUND: It has been documented that vitamin D supplementation showed an improvement of symptoms of diabetic nephropathy; however, the underlying mechanisms remain unknown. We here tested the hypothesis that active vitamin D is able to up-regulate AKT/UCP2 signaling to alleviate oxidative stress of renal tubular cell line HK2. METHODS: There are eight groups in the present study: normal glucose, osmotic control (5.5 mmol/L D-glucose+24.5 mmol/L D-mannitol), NAC control (30 mmol/L D-glucose + 1.0 mmol/L N-Methylcysteine), high glucose, high glucose+VD, high glucose (HG)+VD+siVDR, HG+VD+AKT inhibitor (AI), and high glucose+VD+UCP2 inhibitor (Gelipin). Concentration of superoxide dismutase (SOD) and malondialdehyde (MDA) was analyzed by ELISA. Reactive oxygen species (ROS), mitochondrial membrane potential and apoptosis were measured by flow cytometry. JC-1 was evaluated by flow cytometry. The presence of VDR, AKT, and UCP2 in HK cells was assessed using RT-PCR and western blot analyses. RESULTS: VD administration significantly upregulated the SOD activation and downregulated MDA levels compared to HG group. siVDR, AKT inhibitor, and UCP2 inhibitor significantly suppressed the activation of SOD and increased the expression of MDA compared to VD group. ROS generation and apoptosis of HK2 cells in HG+VD group were significantly lower than those in HG, HG+VD+siVDR, HG+VD+AI, and HG+VD+Gelipin group. ΔΨm in HG+VD group was obviously higher than those in HG, HG+VD+siVDR, HG+VD+AI, and HG+VD+Gelipin group. Decreased mRNA and protein levels of VDR, p-AKT, and UCP2 were observed in HG+VD+siVDR, HG+VD+AI, and HG+VD+Gelipin group compared to those in HG+VD group. CONCLUSIONS: siVDR, AKT inhibitor, and UCP2 inhibitor elevated the ROS and apoptosis of HK2 cells while attenuating the mitochondrial membrane potential, suggesting that vitamin D protects renal tubular cell from high glucose by AKT/UCP2 signaling pathway.

Platelet bioenergetics correlate with muscle energetics and are altered in older adults.

BACKGROUND: Physical function decreases with age, and though bioenergetic alterations contribute to this decline, the mechanisms by which mitochondrial function changes with age remains unclear. This is partially because human mitochondrial studies require highly invasive procedures, such as muscle biopsies, to obtain live tissue with functional mitochondria. However, recent studies demonstrate that circulating blood cells are potentially informative in identifying systemic bioenergetic changes. Here, we hypothesize that human platelet bioenergetics reflect bioenergetics measured in muscle biopsies. METHODS & RESULTS: We demonstrate that maximal and ATP-linked respiratory rate measured in isolated platelets from older adults (86-93 years) correlates significantly with maximal respiration (r = 0.595; P = 0.003) measured by muscle biopsy respirometry and maximal ATP production (r = 0.643; P = 0.004) measured by 31P-MRS respectively, in the same individuals. Comparison of platelet bioenergetics in this aged cohort to platelets from younger adults (18-35 years) shows aged adults demonstrate lower basal and ATP-linked respiration. Platelets from older adults also show enhanced proton leak, which is likely due to increased protein levels of uncoupling protein 2, and correlates with increased gate speed in this cohort (r = 0.58; P = 0.0019). While no significant difference in glycolysis was observed in older adults compared to younger adults, platelet glycolytic rate correlated with fatigability (r = 0.44; P = 0.016). CONCLUSIONS: These data advance the mechanistic understanding of age-related changes in mitochondrial function. Further, they suggest that measuring platelet bioenergetics provides a potential supplement or surrogate for muscle biopsy measurement and may be a valuable tool to study mitochondrial involvement in age-related decline of physical function.

Novel findings of 18ß-glycyrrhetinic acid on sRAGE secretion through inhibition of transient receptor potential canonical channels in high-glucose environment.

Enhancing soluble receptor for advanced glycation endproducts (sRAGE) is considered as a potent strategy for diabetes therapy. sRAGE secretion is regulated by calcium and transient receptor potential canonical (TRPC) channels. However, the role of TRPC channels in diabetes remains unknown. 18ß-Glycyrrhetinic acid (18ß-GA), produced from liquorice, has shown antidiabetic properties. This study was aimed to investigate the effect of 18ß-GA on sRAGE secretion via TRPC channels in high glucose (HG)-induced THP-1 cells. HG treatment enhanced TRPC3 and TRPC6 expression and consequently caused reactive oxygen species (ROS) accumulation mediated through p47 nicotinamide-adenine dinucleotide phosphate oxidase and inducible nitric oxide synthase (iNOS) associated with uncoupling protein 2 (UCP2) decline and lower sRAGE secretion. Interestingly, 18ß-GA showed the dramatic effects similar to Pyr3 or 2-aminoethyl diphenyl borinate inhibitors and effectively reversed HG-elicited mechanisms including that blocking TRPC3 and TRPC6 protein expressions, suppressing intracellular [Ca2+] concentration, decreasing expressions of ROS, p47s, and iNOS, but increasing UCP2 level and promoting sRAGE secretion. Therefore, 18ß-GA provides a potential implication to diabetes mellitus and its complications.

A Chinese 4-herb formula, Yiqi-Huoxue granule, alleviates H2O2-induced apoptosis by upregulating uncoupling protein 2 in H9c2 cells.

BACKGROUND: Although the protective effects of Yiqi-Huoxue granule (YQHX), a Chinese 4-herb formula, on patients with ischemic heart diseases are related to the attenuation of oxidative stress injury, the mechanism(s) underlying these actions remains poorly understood. PURPOSE: Our aim was to investigate the potential protective effects of YQHX treatment against oxidative stress induced by hydrogen peroxide (H2O2) in rat H9c2 cells. METHODS: H9c2 cells were treated with YQHX for 16 h before exposed to 200 µM H2O2 for 6 h. The apoptosis induced by H2O2 was measured using hoechst 33,342 staining and Annexin-V FITC/PI assay. The expression of uncoupling protein 2 (UCP2), Bcl-2, Bax, and caspase-3 were observed using western blot. The effects of UCP2 knockdown on cell apoptosis and intracellular ROS production were also investigated. RESULTS: H2O2 exposure led to significant activation of oxidative stress followed by increased apoptosis and ROS production, as well as decreased UCP2 expression in H9c2 cells. YQHX treatment at the concentration of 0.75 and 1.5 mg/ml remarkably reduced the expression of Bax and caspase-3, whereas increased the protein expression of Bcl-2 and UCP2. These changes were attenuated by transgenic knockdown of UCP2 with Lenti-shUCP2 vector. CONCLUSIONS: Taken together, our study demonstrated that YQHX attenuates H2O2-induced apoptosis by upregulating UCP2 expression in H9c2 Cells, suggesting that YQHX is a promising therapeutic approach for the treatment of I/R injury-mediated apoptosis.

Shengmai San Alleviates Diabetic Cardiomyopathy Through Improvement of Mitochondrial Lipid Metabolic Disorder.

BACKGROUND/AIMS: Shengmai San (SMS), prepared from Panax ginseng, Ophiopogon japonicus, and Schisandra chinensisin, has been widely used to treat ischemic disease. In this study, we investigated whether SMS may exert a beneficial effect in diabetic cardiomyopathy through improvement of mitochondrial lipid metabolism. METHODS: A leptin receptor-deficient db/db mouse model was utilized, and lean age-matched C57BLKS mice served as non-diabetic controls. Glucose and lipid profiles, myocardial structure, dimension, and function, and heart weight to tibial length ratio were determined. Myocardial ultrastructural morphology was observed with transmission electron microscopy. Protein expression and activity of oxidative phosphorylation (OXPHOS) complex were assessed using western blotting and microplate assay kits. We also observed cellular viability, mitochondrial membrane potential, OXPHOS complex activity, and cellular ATP level in palmitic acid-stimulated H9C2 cardiomyocytes. Changes in the sirtuin (SIRT1)/AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) pathway and mitochondrial uncoupling signaling were assessed using western blotting and quantitative real-time PCR. RESULTS: Leptin receptor-deficient db/db mice exhibit obesity, hyperglycemia, and hyperlipidemia, accompanied by distinct myocardial hypertrophy and diastolic dysfunction. SMS at a dose of 3 g/kg body weight contributed to a recovery of diabetes-induced myocardial hypertrophy and diastolic dysfunction. SMS administration led to an effective restoration of mitochondrial structure and function both in vivo and in vitro. Furthermore, SMS markedly enhanced SIRT1 and p-AMPKα protein levels and decreased the expression of acetylated-PGC-1α and uncoupling protein 2 protein. SMS also restored the depletion of NRF1 and TFAM levels in diabetic hearts and H9C2 cardiomyocytes. CONCLUSION: The results indicate that SMS may alleviate diabetes-induced myocardial hypertrophy and diastolic dysfunction by improving mitochondrial lipid metabolism.

UCP2 Mitigates the Loss of Human Spermatozoa Motility by Promoting mROS Elimination.

BACKGROUND/AIMS: To demonstrate the function of uncoupling protein 2 (UCP2) in the regulation of human spermatozoa motility. METHODS: Semen samples were collected from donors with either normal spermatozoa motility (normospermia [NS]) or poor spermatozoa motility (asthenospermia [AS]). UCP2 protein in spermatozoawas quantified by Western blotting. The level of mitochondrial reactive oxygen species (mROS) was evaluated by MitoSOX Red. The activity of mitochondrial membrane potential (MMP) in spermatozoa was evaluated by a JC-1 assay and the ATP level was monitored by a luciferin-luciferase assay. RESULTS: UCP2 was expressed in both NS and AS groups, with the former exhibiting a higher level than the latter. Immunofluorescence analysis shows that UCP2 is mainly located at the mid-region of human spermatozoa. The inhibition of UCP2 by a highly selective inhibitor, Genipin, results in not only impaired spermatozoa mobility (P<.05) but also an elevated level of mROS (P<.05), suggesting that UCP2 is involved in the maintenance of the spermatozoa mobility, which probably is achieved by promoting mROS elimination. Furthermore, H2O2 treatment of spermatozoa increases the mROS level coupled with the loss of spermatozoa mobility. Unexpectedly, this treatment also has a positive impact on the expression of UCP2 within a certain range of supplemental H2O2, indicating the moderate mROS level possibly serves as a feedback signal to stimulate the expression of UCP2. Finally, the treatment of spermatozoa by an ROS scavenger, N-acetyl-l-cysteine (NAC),decreases the level of mROS and increases the curvilinear velocity (VCL) of spermatozoa, but the UCP2 level is not affected. CONCLUSION: These results suggest an UCP2-mROS-motility regulatory system exists for maintaining spermatozoa mobility in humans. In such a system, UCP2 fulfills its function by promoting mROS elimination, and slightly over-produced mROS in turn serves as a signal to stimulates the expression of UCP2. This regulatory system represents a new potential target for the discovery of novel pharmaceuticals for the treatment of patients with low spermatozoa motility.

Hexane-Isopropanolic Extract of Tungrymbai, a North-East Indian fermented soybean food prevents hepatic steatosis via regulating AMPK-mediated SREBP/FAS/ACC/HMGCR and PPARα/CPT1A/UCP2 pathways.

This study for the first time examined the prophylactic role of Tungrymbai, a well-known fermented soybean food of North-East India, against hepatic steatosis. Treatment with hexane-isopropanolic (2:1, HIET) but not hydro-alcoholic (70% ethanol, HAET) extract dose-dependently (0.1, 0.2, or 0.3 µg/mL) reduced the intracellular lipid accumulation as shown by lower triglyceride levels and both Oil Red O and Nile Red staining in palmitate (PA, 0.75 mM)-treated hepatocytes. Immunobloting, mRNA expression, and knock-down studies demonstrated the role of AMPK-mediated SREBP/FAS/ACC/HMGCR and PPARα/CPT1A/UCP2 signaling pathways in facilitating the beneficial role of HIET against lipid accumulation in PA-treated hepatocytes. Animal studies further showed a positive effect of HIET (20 µg/kg BW, 8 weeks, daily) in regulating AMPK/SREBP/PPARα signaling pathways and reducing body weight gain, plasma lipid levels, and hepatic steatosis in high fat diet (HFD)-fed mice. Histological analyses also revealed the beneficial effect of HIET in reducing hepatic fat accumulation in HFD mice. Chemical profiling (HRMS, IR, and HPLC) demonstrated the presence of menaquinone-7 (vitamin K2) as one of the bio-active principle(s) in HIET. Combining all, this study demonstrates the positive effect of HIET on reducing hepatic steatosis via regulating AMPK/SREBP/PPARα signaling pathway.

Chicoric Acid Improves Heart and Blood Responses to Hypobaric Hypoxia in Tibetan Yaks.

Yak is a wild bovine species living on the Qinghai Tibet Plateau that demonstrates good adaptability to the hypoxic environment. Chicoric acid, a natural phenolic compound, is known as having anti-oxidant, antiviral, anti-inflammatory and analgesic properties. However, its effect on hypoxia adaptability of yak is still unclear. In this study 40 yaks were selected that were of similar age, parity and weight, and divided into the control group and experimental groups 1, 2, 3, randomly. Results showed that chicoric acid significantly improved RBC, HGB, and WBC. There are significantly beneficial effects to increasing total protein contents ([Formula: see text]): all treatments increased HDL-C contents, and supplementations 100[Formula: see text]mg/h significantly decreased the content of TG on the 60th day ([Formula: see text]). Contents of the serum related enzymes like ALP, GOP and GPT showed varying degrees of change, but no significant differences and the indexes of anti-oxidant capacity (T-AOC and GSH-Px) were significantly improved ([Formula: see text]), but MDA was decreased ([Formula: see text]) under the action of the chicoric acid. Hypoxia-inducible factor in serum such as HIF-2[Formula: see text], EPO, ROS, Fe[Formula: see text] and Tf are all significantly decreased ([Formula: see text]). The myocardial mitochondrial parameters mtDNA, UCP2, PGC1-[Formula: see text], NRF1 and mitochondrial complexes were altered remarkably. Some indicators of glucose metabolism presented variation trends. Taken together, chicoric acid has shown a positive effect on the adaptive ability of yak in high altitude, hypoxic environment in plateau areas. Our findings reported a new potential means to enhance immunity and inflammatory response and improve the anti-oxidant capacity.

Naringin prevents HIV-1 protease inhibitors-induced metabolic complications in vivo.

BACKGROUND: Insulin resistance, glucose intolerance and overt diabetes are known metabolic complications associated with chronic use of HIV-Protease Inhibitors. Naringin is a grapefruit-derived flavonoid with anti-diabetic, anti-dyslipidemia, anti-inflammatory and anti-oxidant activities. OBJECTIVES: The study investigated the protective effects of naringin on glucose intolerance and impaired insulin secretion and signaling in vivo. METHODS: Male Wistar rats were divided into six groups (n = 6) and were daily orally treated with distilled water {3.0 ml/kg body weight (BW)}, atazanavir (133 mg/kg BW), saquinavir (333 mg/kg BW) with or without naringin (50 mg/kg BW), respectively for 56 days. Body weights and water consumption were recorded daily. Glucose tolerance tests were carried out on day 55 of the treatment and thereafter, the rats were sacrificed by halothane overdose. RESULTS: Atazanavir (ATV)- or saquinavir (SQV)-treated rats exhibited significant weight loss, polydipsia, elevated Fasting blood glucose (FBG), reduced Fasting Plasma Insulin (FPI) and expression of phosphorylated, Insulin Receptor Substrate-1 (IRS-1) and Akt proteins, hepatic and pancreatic glucokinase levels, and also increasing pancreatic caspase-3 and -9 as well as UCP2 protein expressions compared to controls, respectively. These effects were completely reversed by naringin treatment. CONCLUSION: Naringin prevents PI-induced glucose intolerance and impairment of insulin signaling and as nutritional supplement it could therefore alleviate metabolic complications associated with antiretroviral therapy.

The effects of intracerebroventricular infusion of irisin on feeding behaviour in rats.

Irisin, a novel exercise-induced myokine, has attracted attention with its effects on energy metabolism. This study was conducted to determine the possible effects of irisin on nutritional behaviour. In this study, 40 male Wistar Albino rats were separated into 4 groups (n=10 for each group). Osmotic mini-pumps were connected to metal cannulas implanted to lateral ventricle; and artificial cerebrospinal fluid (vehicle), and 10 and 100nM of irisin was infused for 7days. The daily food and water consumptions and body weights of rats were followed up. After the infusion, the animals were killed, and the hypothalamus and blood samples were collected. NPY, POMC, and UCP2 mRNA levels in the hypothalamus were examined by RT-PCR. In serum, leptin and ghrelin levels as well as the levels of metabolic parameters were measured by using ELISA. It was determined that irisin administration increased the daily food consumption (p<0.05), without causing significant changes in water consumption and body weight. Irisin also caused increases in ghrelin level in circulation and NPY and UCP2 mRNA levels in the hypothalamus, whereas it decreased the leptin level in circulation and POMC mRNA levels in the hypothalamus (p<0.05). Otherwise, irisin caused decrease in LDL, triglycerides and cholesterol levels, while increasing HDL and glucose levels (p<0.05). Results indicates that long-term irisin treatment increases food intake without increasing body weight associated with increased ghrelin, NPY and UCP2 mRNAs, and decreased leptin and POMC mRNA in the hypothalamus.