Haitian Ma

Dehydroepiandrosterone ameliorates H2O2-induced Leydig cells oxidation damage and apoptosis through inhibition of ROS production and activation of PI3K/Akt pathways

Dehydroepiandrosterone (DHEA) is widely used as a nutritional supplement, and administration of DHEA produces a number of beneficial effects in the elderly. Many researchers have suggested that DHEA exerts it function after conversion into more biologically active hormones in peripheral target cells. The actions of DHEA in Leydig cells, a major target cell of DHEA biotransformation in males, are not clear. The present study found that DHEA increased cell viability and decreased reactive oxygen species (ROS) and malondialdehyde contents in H2O2-induced Leydig cells. DHEA significantly increased the activities of superoxide dismutase, catalase and peroxidase, and decreased the DNA damage in H2O2-induced Leydig cells. Apoptosis was significant decreased in H2O2-induced Leydig cells after DHEA treatment. DHEA inhibited the loss of mitochondrial membrane potential (ΔΨm) and the upregulation of the caspase-3 protein level induced by H2O2 in Leydig cells. DHEA also reversed the decrease in PI3K and p-Akt protein levels induced by H2O2. These data showed that DHEA could ameliorate H2O2-induced oxidative damage by increasing anti-oxidative enzyme activities, which resulted in reduced ROS content, and decreased apoptosis, mainly by preventing the loss of ΔΨm and inhibiting caspase-3 protein levels via activation of PI3K/Akt signaling pathways. These results increase our understanding of the molecular mechanism of the anti-ageing effect of DHEA.

Ample Evidence: Dehydroepiandrosterone (DHEA) Conversion into Activated Steroid Hormones Occurs in Adrenal and Ovary in Female Rat.

Dehydroepiandrosterone (DHEA) is important for human health, especially for women. All estrogens and practically half of androgens are synthesized from DHEA in peripheral tissues. However, the mechanism and exact target tissues of DHEA biotransformation in the female are not fully clear. The present study showed that maximal content of androstenedione (AD) and testosterone (T) were observed at 3h after DHEA administration in female rats, which was 264% and 8000% above the control, respectively. Estradiol (E2) content significantly increased at 6h after DHEA administration, which was 113% higher than that in control group. Gavage with DHEA could significantly reduce 3β-hydroxysteroid dehydrogenase (3β-HSD) mRNA level at 3-12h and 17β-hydroxysteroid dehydrogenase (17β-HSD) mRNA level at 12h in ovary, while increasing aromatase mRNA levels at 6, 24, and 48h. It is interesting that administration of DHEA caused a significant increase of 17β-HSD, 3β-HSD and aromatase mRNA levels in adrenal. The AD and T contents also markedly increased by 537% and 2737% after DHEA administration in ovariectomised rats, in company with a significant increase in 17β-HSD and 3β-HSD mRNA levels and decreased aromatase mRNA level in adrenal. However, DHEA administration did not restore the decreased E2, estrone (E1), and progesterone (P) caused by the removal of the ovaries in females. These results clearly illustrated that exogenous DHEA is preferentially converted into androgens in adrenal, while its conversion to estrogens mainly happens in the ovary through steroidogenic enzyme in female rats.

(−)-Hydroxycitric acid reduced fat deposition via regulating lipid metabolism-related gene expression in broiler chickens

AbstractBackgroundChicken as a delicious food for a long history, and it is well known that excess fat deposition in broiler chickens will not only induced metabolic diseases, but also lead to adverse effect in the consumer’s health. (−)-Hydroxycitric acid (HCA), a major active ingredient of Garcinia Cambogia extracts, had shown to suppress fat accumulation in animals and humans. While, the precise physiological mechanism of HCA has not yet been full clarified, especially its action in broiler chickens. Thus, this study aimed to assess the effect of (−)-HCA on lipid metabolism in broiler chickens.MethodsA total of 120 1-day-old broiler chickens were randomly allocated to four groups, with each group was repeated three times with 10 birds. Birds received a commercial diet supplemented with (−)-HCA at 0, 1000, 2000 or 3000 mg/kg, respectively, for a period of 4 weeks ad libitum.ResultsBody weight (BW) in the 2000 and 3000 mg/kg (−)-HCA groups was significantly decreased (P < 0.05) than that in control group. A significantly decreased of serum triglyceride (TG) and density lipoprotein-cholesterol (LDL-C) content were observed in 3000 mg/kg (−)-HCA group (P < 0.05). Broiler chickens supplmented with 2000 and 3000 mg/kg (−)-HCA had pronouncedly higher hepatic lipase (HL) activity, hepatic glycogen and non-esterified fatty acid (NEFA) contents in liver (P < 0.05). Serum free triiodothyronine (FT3) and thyroxin (T4) contents were significantly higher in 3000 mg/kg (−)-HCA group (P < 0.05) compared with the control group. Supplemental (−)-HCA markedly decreased fatty acid synthase (FAS) and sterol regulatory element binding protein-1c (SREBP-1c) (P < 0.05) mRNA levels, while the mRNA abundance of adenosine 5′-monophosphate-activated protein kinaseβ2 (AMPKβ2) (P < 0.05) was significantly increased. In addition, ATP-citrate lyase (ACLY) mRNA level (P < 0.05) was significantly decreased in broiler chickens supplemented with 3000 mg/kg (−)-HCA. No differences was observed on carnitine palmitoyl transferase-I(CPT-I), while peroxisome proliferators-activated receptor α (PPARα) mRNA level (P < 0.05) was significantly increased in broiler chickens supplemented with 2000 and 3000 mg/kg (−)-HCA.ConclusionsSupplemental (−)-HCA inhibited lipogenesis by inhibiting ACLY, SREBP-1c and FAS expression, and accelerated lipolysis through enhancing HL activity and PPARαxa0expression, which eventually led to the reduced abdominal fat deposition in broiler chickens.n Graphical abstractMechanism of (−)-HCA effect on hepatic lipids metabolism.

Long-Term Administration of Dehydroepiandrosterone Accelerates Glucose Catabolism via Activation of PI3K/Akt-PFK-2 Signaling Pathway in Rats Fed a High-Fat Diet.

Dehydroepiandrosterone (DHEA) has a fat-reducing effect, while little information is available on whether DHEA regulates glucose metabolism, which would in turn affect fat deposition. To investigate the effects of DHEA on glucose metabolism, rats were administered a high-fat diet containing either 0 (HCG), 25 (HLG), 50 (HMG), or 100 (HHG) mg·kg-1 DHEA per day via gavage for 8 weeks. Results showed that long-term administration of DHEA inhibited body weight gain in rats on a high-fat diet. No statistical differences in serum glucose levels were observed, whereas hepatic glycogen content in HMG and HHG groups and muscle glycogen content in HLG and HMG groups were higher than those in HCG group. Glucokinase, malate dehydrogenase and phosphofructokinase-2 activities in HMG and HHG groups, pyruvate kinase and succinate dehydrogenase activities in HMG group, and pyruvate dehydrogenase activity in all DHEA treatment groups were increased compared with those in HCG group. Phosphoenolpyruvate carboxykinase and glycogen phosphorylase mRNA levels were decreased in HMG and HHG groups, whereas glycogen synthase-2 mRNA level was increased in HMG group compared with those in HCG. The abundance of Glut2 mRNA in HMG and HHG groups and Glut4 mRNA in HMG group was higher than that in HCG group. DHEA treatment increased serum leptin content in HMG and HHG groups compared with that in HCG group. Serum insulin content and insulin receptor mRNA level in HMG group and insulin receptor substrate-2 mRNA level in HMG and HHG group were increased compared with those in HCG group. Furthermore, Pi3k mRNA level in HMG and Akt mRNA level in HMG and HHG groups were significantly increased than those in HCG group. These data showed that DHEA treatment could enhance glycogen storage and accelerate glucose catabolism in rats fed a high-fat diet, and this effect may be associated with the activation of PI3K/Akt-PFK-2 signaling pathway.

Proteomics reveals changes in hepatic proteins during chicken embryonic development: an alternative model to study human obesity

BackgroundChicken embryos are widely used as a model for studies of obesity; however, no detailed information is available about the dynamic changes of proteins during the regulation of adipose biology and metabolism. Thus, the present study used an isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic approach to identify the changes in protein abundance at different stages of chicken embryonic development.ResultsIn this study, the abundances of 293 hepatic proteins in 19-day old of chicken embryos compared with 14-day old and 160 hepatic proteins at hatching compared with 19-day old embryos were significantly changed. Pathway analysis showed that fatty acid degradation (upregulated ACAA2, CPT1A, and ACOX1), protein folding (upregulated PDIs, CALR3, LMAN1, and UBQLN1) and gluconeogenesis (upregulated ACSS1, AKR1A1, ALDH3A2, ALDH7A1, and FBP2) were enhanced from embryonic day 14 (E14) to E19 of chicken embryo development. Analysis of the differentially abundant proteins indicated that glycolysis was not the main way to produce energy from E19 to hatching day during chicken embryo development. In addition, purine metabolism was enhanced, as deduced from increased IMPDH2, NT5C, PGM2, and XDH abundances, and the decrease of growth rate could be overcome by increasing the abundance of ribosomal proteins from E19 to the hatching day.ConclusionThe levels of certain proteins were coordinated with each other to regulate the changes in metabolic pathways to satisfy the requirement for growth and development at different stages of chicken embryo development. Importantly, ACAA2, CPT1A, and ACOX1 might be key factors to control fat deposition during chicken embryonic development. These results provided information showing that chicken is a useful model to further investigate the mechanism of obesity and insulin resistance in humans.

Hydroxycitric Acid Nourishes Protein Synthesis via Altering Metabolic Directions of Amino Acids in Male Rats

(‐)‐Hydroxycitric acid (HCA), a major active ingredient of Garcinia Cambogia extracts, had shown to suppress body weight gain and fat accumulation in animals and humans. While, the underlying mechanism of (‐)‐HCA has not fully understood. Thus, this study was aimed to investigate the effects of long‐term supplement with (‐)‐HCA on body weight gain and variances of amino acid content in rats. Results showed that (‐)‐HCA treatment reduced body weight gain and increased feed conversion ratio in rats. The content of hepatic glycogen, muscle glycogen, and serum T4, T3, insulin, and Leptin were increased in (‐)‐HCA treatment groups. Protein content in liver and muscle were significantly increased in (‐)‐HCA treatment groups. Amino acid profile analysis indicated that most of amino acid contents in serum and liver, especially aromatic amino acid and branched amino acid, were higher in (‐)‐HCA treatment groups. However, most of the amino acid contents in muscle, especially aromatic amino acid and branched amino acid, were reduced in (‐)‐HCA treatment groups. These results indicated that (‐)‐HCA treatment could reduce body weight gain through promoting energy expenditure via regulation of thyroid hormone levels. In addition, (‐)‐HCA treatment could promote protein synthesis by altering the metabolic directions of amino acids. Copyright

Dehydroepiandrosterone-Regulated Testosterone Biosynthesis via Activation of the ERK1/2 Signaling Pathway in Primary Rat Leydig Cells

Background: Dehydroepiandrosterone decreases with age and this reduction has been shown to be associated with physical health in human. Some studies have suggested that the effects of DHEA are exerted after it is biotransformed into more biologically-active hormones in peripheral target cells. This study investigated the effects of DHEA on the testosterone biosynthesis and possible signaling pathway mechanism underlying these DHEA effects were also explored in primary rat Leydig cells. Methods: Primary Leydig cells were treated with DHEA and then detected testosterone content by RIA and steroidogenic enzymes, ERK1/2 signal pathway factors protein expression level by Western blot. Results: Incubation of primary Leydig cells with DHEA significantly increased testosterone content and 3β-HSD and 17β-HSD protein expression levels, while aromatase protein expression levels were decreased. Compared with the control group, p-ERK1/2 and p-CREB protein levels were significantly increased in DHEA-treated groups. Testosterone content was significantly decreased in the DHEA-treated group pre-incubated with U0126 (p-ERK1/2 inhibitor). Additionally, the rise in p-ERK1/2, 3β-HSD and 17β-HSD protein levels induced by DHEA was reversed when cells were pre-incubated with U0126. Interestingly, no significant difference was found in aromatase protein expression level in cells pretreated with U0126. Conclusion: These findings demonstrate that (a) exogenous DHEA might preferentially convert to testosterone rather than estradiol due to the up-regulation of 3β-HSD and 17β-HSD protein levels and the down-regulation of aromatase protein level in primary Leydig cells, and (b) the action of DHEA is at least partly associated with the elevation of p-ERK1/2 and p-CREB protein levels.

Dehydroepiandrosterone reduces accumulation of lipid droplets in primary chicken hepatocytes by biotransformation mediated via the cAMP/PKA-ERK1/2 signaling pathway

Dehydroepiandrosterone (DHEA) is commonly used as a nutritional supplement to control fat deposition, but the mechanism of this action is poorly understood. In this study, we demonstrated that DHEA increased phosphorylation of AMP-activated protein kinase (p-AMPK). Elevated p-AMPK levels resulted in reduced expression of sterol regulatory element binding protein-1c, acetyl CoA carboxylase, fatty acid synthase and enhanced expression of peroxisome proliferators-activated receptor α and carnitine palmitoyl transferase-I, ultimately leading to the reduction of lipid droplet accumulation in primary chicken hepatocytes. We found that DHEA activates the cyclic adenosine 3, 5-monophosphate/protein kinase A - extracellular signal-regulated kinase 1/2 (cAMP/PKA-ERK1/2) signaling pathway, which regulates the conversion of DHEA into testosterone and estradiol by increasing the 17β-hydroxysteroid dehydrogenase and aromatase protein expression. Importantly, the fat-reducing effects of DHEA are more closely associated with the conversion of DHEA into estradiol than with the action of DHEA itself as an active biomolecule, or to its alternative metabolite, testosterone. Taken together, our results indicate that DHEA is converted into active hormones through activation of the cAMP/PKA-ERK1/2 signaling pathway; the fat-reducing effects of DHEA are achieved through its conversion into estradiol, not testosterone, and not through direct action of DHEA itself, which led to the activation of the p-AMPK in primary chicken hepatocytes. These data provide novel insight into the mechanisms underlying the action of DHEA in preventing fat deposition, and suggest potential applications for DHEA treatment to control fat deposition or as an agent to treat disorders related to lipid metabolism in animals and humans.

Effects of (−)-hydroxycitric acid on lipid droplet accumulation in chicken embryos

This study was conducted to determine the impact of (-)-hydroxycitric acid ((-)-HCA) on biochemical indices and lipid metabolism parameters in chicken embryos. Two hundred and forty fertilized eggs were divided into six groups and injected with (-)-HCA at concentrations of 0, 0.1, 0.5, 1.0, 10.0 and 50xa0mg/kg (nxa0=xa040). After 19xa0days of incubation, serum and liver were collected for analysis of biochemical indices and lipid metabolism parameters. Results showed no significant differences on serum biochemical indices: 1-50xa0mg/kg (-)-HCA significantly increased serum glucose and hepatic glycogen contents (Pxa0<xa00.05). Oil Red O staining analysis showed total area, counts of lipid droplets and hepatic triglyceride content were significantly decreased (Pxa0<xa00.01), meanwhile hepatic lipase and lipoprotein lipase activity were significantly increased (Pxa0<xa00.05). ACLY, ME1, SREBP-1c messenger RNA (mRNA) levels in 0.5-10xa0mg/kg groups and FAS mRNA level in 1-10xa0mg/kg groups were significantly decreased (Pxa0<xa00.05), while PPARα mRNA level, serum adiponectin content and AdipoR1 mRNA level were significantly increased in 0.5-50xa0mg/kg groups (Pxa0<xa00.05). These results indicated (-)-HCA treatment inhibited triglyceride synthesis via decreasing lipogenesis-related factors, mRNA expression level and accelerated lipolysis by enhancing lipoprotein lipase and hepatic lipase activity, which finally reduced lipid droplet accumulation, and this action may be associated with activating the adiponectin signaling pathway.

Dehydroepiandrosterone rehabilitate BRL-3A cells oxidative stress damage induced by hydrogen peroxide

This study aimed to investigate the molecular mechanism of dehydroepiandrosterone (DHEA) rehabilitated BRL‐3A cells oxidative stress damage induced by hydrogen peroxide (H2O2). Results showed that DHEA reversed the decrease of cell viability and ameliorated nuclear chromatin damage in H2O2‐induced BRL‐3A cells. DHEA increased the activities of superoxide dismutase, catalase, peroxidase, and glutathione peroxidase, and decreased the reactive oxygen species (ROS) production in H2O2‐induced BRL‐3A cells. DHEA attenuated the protein damage and lipid peroxidation, and reduced the apoptosis in H2O2‐induced BRL‐3A cells. The mRNA levels of Bax, Caspase‐9, and Caspase‐3 were decreased, while the Bcl‐2 mRNA level was increased in H2O2‐induced BRL‐3A cells treated with DHEA. Our results showed that DHEA treatment increased the PI3K and p‐Akt protein levels, while decreased the Bax and capase‐3 protein levels in H2O2‐induced BRL‐3A cells. However, the rise in PI3K and p‐Akt protein levels, and the decrease in Bax and capase‐3 protein levels induced by DHEA treatment were reversed when the cells pretreated with LY294002 (PI3K inhibitor). These results indicated that DHEA ameliorated H2O2‐induced oxidative damage by increasing anti‐oxidative enzyme activities and ameliorating the protein damage and lipid peroxidation in BRL‐3A cells. In addition, DHEA decreased the apoptosis by inhibiting caspase‐3 and Bax protein levels and this action mainly achieved via the activation of PI3K/Akt signaling pathways in H2O2‐induced BRL‐3A cells. These results provided substantial information for DHEA as a nutritional supplement to treat oxidative stress and it related diseases in animals and humans.