Carbohydrate metabolism of female rat adipocytes: effects and mechanisms of action of progesterone

This short review describes the role of progesterone in the insulin-resistance of pregnancy and the present knowledge of the intracellular mechanisms of action of the steroid in carbohydrate metabolism of female rat adipocytes. Observations concerning steroid effects on the binding of insulin to its specific receptors are often contradictory, and depend on cells used to study it. It is now generally accepted that, in isolated adipocytes, the decreased responsiveness to insulin produced by progesterone is due to a post-receptor effect. Furthermore, basal glucose metabolism (in the absence of insulin) is decreased by progesterone treatment and by the acute effect of progesterone when added directly into the incubation medium. Progesterone induces an intrinsic post-receptor effect which is related to decreased phosphorylation of glucose by hexokinase but has no effect on glucose transport. The effect on hexokinase activity is an indirect one taking place either before or after activation of the enzyme. During the last decade, a large body of evidence (Xenopus oocytes and other cells) indicates that steroids interact with the cell surface rather than penetrating the cell and interacting exclusively with a nuclear receptor. The second messengers, such as cyclic AMP and calcium, play a major role in this non-genomic mechanism. The direct and rapid effect (20 min.) of progesterone in adipocytes supports the non-genomic mechanism of action; there is neither any lag period prior to the appearance of the physiological response nor any inhibition of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synergistic effects of ascorbic acid and thiazolidinedione on secretion of high molecular weight adiponectin from human adipocytes

Aim: To test the hypothesis that ascorbic acid (AA) and thiazolidinedione (TZD) would have additive effects on HMW adiponectin secretion by virtue of different modes of action. Methods: We determined the effects of supplementation of AA and/or TZD on expression and secretion of total and HMW adiponectin from human Simpson–Golabi–Behmel syndrome (SGBS) adipocytes in the absence or presence of the proinflammatory cytokine TNFα. Results: AA supplementation significantly increased secretion of HMW adiponectin (1.7‐fold) without altering adiponectin expression or total adiponectin secretion. TZD significantly increased expression (3‐fold) and secretion of total (1.4‐fold) but not HMW adiponectin. Combined supplementation resulted in a significant increase in expression (3‐fold) and secretion of total (1.8‐fold) and HMW (5‐fold) adiponectin. Similar results were seen in cells co‐treated with TNFα. Conclusions: These data show that AA and TZD have synergistic rather than simple additive effects on secretion of HMW adiponectin from human adipocytes and raise the possibility that differences in AA levels may contribute to the variability in adiponectin multimer profiles and efficacy of TZD in humans. Our results also provide a rationale for longitudinal clinical trials investigating the effects of AA supplementation with or without TZD on adiponectin and metabolic profiles.     

Dose-dependent effects of phytoestrogens on bone.

Phytoestrogens have the potential to maintain bone health and delay or prevent osteoporosis. This review focuses on their dose-dependent effects on bone and their possible mechanisms of action. Phytoestrogens exert biphasic dose-dependent effects on osteoblasts and osteoprogenitor cells, stimulating osteogenesis at low concentrations and inhibiting osteogenesis at high concentrations. They inhibit osteoclast formation and activity. Recent data show that the balance between estrogen receptors and peroxisome proliferator-activated receptors, which are dose-dependently activated by phytoestrogens, determines their biological effects on bone. This review provides a new understanding of the mechanism of action of phytoestrogens and could be important for future studies to find precise beneficial doses in vivo and in clinical trials.     

Minireview: neuroprotective effects of estrogen-new insights into mechanisms of action

An accumulating body of evidence clearly establishes that estradiol is a potent neuroprotective and neurotrophic factor in the adult: it influences memory and cognition, decreases the risk and delays the onset of neurological diseases such as Alzheimer's disease, and attenuates the extent of cell death that results from brain injuries such as cerebrovascular stroke and neurotrauma. Thus, estradiol appears to act at two levels: 1) it decreases the risk of disease or injury; and/or 2) it decreases the extent of injury incurred by suppressing the neurotoxic stimulus itself or increasing the resilience of the brain to a given injury. During the past century, the average life span of women has increased dramatically, whereas the time of the menopause has remained essentially constant. Thus, more women will live a larger fraction of their lives in a postmenopausal, hypoestrogenic state than ever before. Clearly, it is critical for us understand the circumstances under which estradiol exerts protective actions and the cellular and molecular mechanisms that underlie these novel, nonreproductive actions.     

Dose-dependent effects of a glucocorticoid on prolactin production

Glucocorticoids are known to stimulate growth hormone (GH) production but to suppress prolactin (PRL) production. However, previous data were obtained with rather high doses of corticosterone. In this study we examined the effects of various doses (10 (-12) -10 (-7) M) of corticosterone on GH and PRL production in a rat pituitary somatomammotropic cell line, MtT/SM cells, and found that GH mRNA expression was facilitated by high doses (10 (-7) and 10 (-8) M). In contrast, a biphasic effect of corticosterone on PRL mRNA expression and secretion was observed, i.e., high doses (10 (-7) and 10 (-8) M) suppressed and low doses (10 (-12) -10 (-10) M) facilitated them. In an immunofluorescent staining study, the number of PRL immunopositive cells increased with low doses of corticosterone while it decreased with high doses of it, which corresponded to PRL mRNA expression and hormone secretion, respectively. These effects of corticosterone on PRL production were abolished by a glucocorticoid receptor (GR) antagonist, mifepristone. In addition, co-treatment with low doses of corticosterone (10 (-12) -10 (-10) M) and 17beta-estradiol (E(2), 10 nM) additively increased the number of PRL immunopositive cells. Moreover, a 24 h BrdU incorporation experiment suggested that the increase in the number of PRL immunopositive cells treated with low dose corticosterone was caused by novel synthesis of PRL while, on the other hand, that of those treated with E(2) resulted from PRL cell proliferation. Thus, we concluded that corticosterone biphasically regulates PRL production and the sensitivity of E(2) to different degrees.     

Antiproliferation effects of oridonin on HPB-ALL cells and its mechanisms of action

Oridonin, an ent-kaurane diterpenoid derived from the herbal Rabdosia rubescens, has been recently reported to have antitumor effects on a large variety of cancer cells. The present study was undertaken to investigate the in vitro antiproliferation and apoptosis inducing effects of oridonin on HPB-ALL cell lines and its mechanisms of action. HPB-ALL cells in culture medium in vitro were treated with different concentrations of oridonin (16-56 micromol/L). MTT assay was used to detect the cell growth inhibitory rate, and the cell viability was assessed by the trypan blue dye-exclusion method. Cell apoptosis and the mitochondrial membrane potential (delta psi m) were investigated by flow cytometry (FCM), Hoechst 33258 staining, and DNA fragmentation analysis. The expression of caspase-3 and different apoptosis modulators, including Fas and Bcl-2 family members, was analyzed by Western blotting. The results revealed that oridonin could significantly inhibit the growth of HPB-ALL cells and cause apoptosis, and the suppression was both time- and dose-dependent. After treatment with oridonin for 48 hr, the percentage of disruption of delta psi m gradually increased in a dose-dependent manner along with marked changes of cell apoptosis, and necrotic cells increased remarkably after the cells were treated with oridonin for 72 hr; Western blotting showed cleavage of the caspase-3 zymogen protein (32 kDa) with the appearance of its 20-kDa subunit when apoptosis occurred; expression of Bcl-2 and Bcl-XL was downregulated remarkably while expression of Bax and Bid was upregulated concurrently after the cells were treated with oridonin for 24 hr. Of note, the expressions of Fas and other Bcl-2 family members including Bak and Bad remained constant before and after apoptosis occurred. We therefore conclude that oridonin has significant antiproliferation effects on HPB-ALL cells by induction of apoptosis as well as directly causing cell necrosis and that oridonin-induced apoptosis on HPB-ALL cells is mainly related to the disruption of delta psi m and activation of caspase-3 as well as downregulation of anti-apoptotic protein Bcl-2, Bcl-XL, and upregulation of pro-apoptotic proteins Bax and Bid. The results indicate that oridonin may serve as a potential antileukemia reagent.     

Study of the effects and mechanisms of berberine on slow-response action potentials

The effects of berberine on slow-response action potentials (SAP) of guinea pig papillary muscles were studied. SAP was elicited by histamine in a high concentration of potassium solution (27 mmol). The results showed that berberine (24.5 mumol) was able to increase action potential amplitude, maximum rate of depolarization, action potential duration 50, action potential duration 100 (n = 16, p less than 0.01) and effective refractory period (n = 10, p less than 0.01) of SAP by 6.2%, 21.1%, 50.1%, 47.2% and 92.2%, respectively, but did not affect the resting membrane potential (RMP). To the above parameters, except APD 100, berberine was no longer to induce any significant change by pretreating with propranolol. The results suggested that the effects of berberine on slow-response action potentials were mainly related to the facilitating of slow calcium inward current, which might result from stimulating the beta-adrenoceptor.     

罗格列酮对肥胖患者脂肪细胞中脂联素表达的影响

目的:探讨噻唑烷二酮类药物（thiazolidinediones,TZDs）罗格列酮（rosiglitazone,RSG）对肥胖患者脂肪细胞中脂联素表达的影响。方法: 依据检查者的体质量指数(BMI)分为正常体重者和肥胖者,各3例。脂肪组织采用整形外科吸脂手术（供者知情并同意）获得。分离培养6例检查者的前脂肪细胞,用胰岛素、地塞米松、三碘甲状腺原氨酸（T3）及3-异丁基-1-甲基黄嘌呤（IBMX）诱导其分化为成熟的脂肪细胞。实验分为对照组和RSG处理组,前者培养的脂肪细胞不进行处理;后者的脂肪细胞用10 mol/L的RSG分别处理12 h、24 h、48 h和72 h。收集细胞的培养上清液,用ELISA法检测脂联素蛋白分泌的水平。提取细胞的总RNA,用RT-PCR法检测脂联素mRNA表达的水平。结果: 肥胖患者成熟脂肪细胞脂联素mRNA及其蛋白表达的水平较正常体重者明显降低（P<0.05）。与对照组相比较,RSG组成熟脂肪细胞脂联素mRNA和其蛋白表达的水平在处理不同时间（12 h、24 h、48 h和72 h）后均明显增高（P<0.05或P<0.01）,且呈时间依赖性;但肥胖患者脂联素mRNA和其蛋白表达水平增高持续的时间较正常体重者短（P<0.05或P<0.01）。结论: RSG在一定程度上能增加肥胖患者成熟脂肪细胞中脂联素表达的水平。     

Dose-dependent effects of fentanyl on indomethacin-induced gastric damage.

Whilst developing a rat model for studies of gastric protection, we noticed that the anaesthetic agent 'Hypnorm', containing the opiate fentanyl 0.315 mg/ml and the butyrophenone fluanisone 10 mg/ml, was itself protective against indomethacin-induced damage: unrestrained animals given indomethacin (20 mg/kg) subcutaneously had an ulcer score of 9 +/- 1 mm2, compared with 1 +/- 1 mm2 in animals pre-treated with Hypnorm (0.8 ml/kg) and then given indomethacin (p less than 0.01). Further investigation showed this effect to be due to fentanyl-inhibiting gastric acid secretion: doses of fentanyl (90 and 180 micrograms/kg) which decreased indomethacin-induced damage also caused a rise in intragastric pH from 2.7 +/- 0.6 in controls to 5.1 +/- 0.8 and 5.0 +/- 0.8, respectively. However, the response of fentanyl varied depending on the dose given: fentanyl, 3.6 micrograms/kg did not affect indomethacin-induced damage, 8 +/- 2 vs. 9 +/- 1 mm2; fentanyl, 18 micrograms/kg potentiated damage, 15 +/- 4 mm2 (p less than 0.05), whereas fentanyl, 90 micrograms/kg and 180 micrograms/kg decreased damage, 2 +/- 1 mm2 and 0.1 +/- 0.1 mm2, respectively (p less than 0.01). Neither the butyrophenone haloperidol (8.3 mg/kg) nor the alpha-adrenergic receptor antagonist phenoxybenzamine (3 mg/kg) protected against indomethacin-induced damage. We conclude that fentanyl affects intragastric pH and can both potentiate and protect against indomethacin-induced damage. Furthermore, the potentiation of gastric damage by fentanyl occurred at doses similar to those used for human anesthesia, so clinical studies are suggested.     

Aging in adipocytes: potential impact of inherent, depot-specific mechanisms

Fat mass and tissue distribution change dramatically throughout life. Fat depot sizes reach a peak by middle or early old age, followed by a substantial decline, together with fat tissue dysfunction and redistribution in advanced old age. These changes are associated with health complications, including type 2 diabetes, atherosclerosis, dyslipidemia, thermal dysregulation, and skin ulcers, particularly in advanced old age. Fat tissue growth occurs through increases in size and number of fat cells. Fat cells turn over throughout the lifespan, with new fat cells developing from preadipocytes, which are of mesenchymal origin. The pool of preadipocytes comprises 15-50% of the cells in fat tissue. Since fat tissue turns over throughout life, characteristics of these cells very likely have a significant impact on fat tissue growth, plasticity, function, and distribution. The aims of this review are to highlight recent findings regarding changes in preadipocyte cell dynamics and function with aging, and to consider how inherent characteristics of these cells potentially contribute to age- and depot-dependent changes in fat tissue development and function.     

Molecular mechanisms of GLUT4 regulation in adipocytes

Insulin resistance is strongly linked to type 2 diabetes and associated with a reduced uptake of glucose by muscle and adipose tissue. The transporter that is responsible for this uptake and whose function is disturbed in insulin resistance and type 2 diabetes is GLUT4. In the non-stimulated state, GLUT4 is efficiently sequestered intracellularly. This retention prevents GLUT4 from reaching the cell surface and transporting glucose into muscle and fat cells when blood glucose levels are low. After a meal when blood glucose levels rise, insulin is secreted by the pancreas, which, upon binding to its receptor, triggers an intracellular signaling cascade, leading to the translocation of GLUT4 from intracellular compartments to the cell surface, resulting in glucose uptake and normalization of the blood glucose levels. Its regulation is dominated by its localization, efficient intracellular retention and sensitivity to insulin and contraction, which makes GLUT4 an interesting and unique molecule. These aspects of the intracellular regulation of GLUT4 are described in this review.     

What are the mechanisms of action of anti-inflammatory agents in adipose tissue?: A protocol for systematic review and meta-analysis

Background:Obesity is a disease characterized by the abnormal accumulation of adipose tissue in the body, triggering a chronic subclinical state of inflammation. Bioactive compounds, given their anti-inflammatory properties, are a safe and promising alternative in controlling the inflammatory condition of obesity. This study describes a systematic review protocol aiming to analyze the anti-inflammatory molecules mechanisms and compounds action on adipocytes.Methods:Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) will outline the protocol and PRISMA to the systematic review. The databases used for research will be PubMed, Science Direct, Scopus, Web of Science, BVS, and EMBASE. Experimental studies performed on rats and mice with a control group that describes treatment with anti-inflammatory agents (drugs, nutraceuticals, bio active compounds, among others) at any frequency, time, and dose will be included. Three independent reviewers will select studies and extract data. The evaluation of the methodological quality of each research will be performed using the SYRCLE tool. If at least 2 studies show clinical and/or methodological and/or statistical homogeneity, a meta-analysis will be performed, using the RevMan Analyzes statistical package in Review Manager v.5.3.Results:In this study, we hope to find a considerable number of articles presenting mechanisms involved in the action of anti-inflammatory molecules and compounds on adipocytes.Conclusion:The systematic review produced from this protocol will present evidence on the mechanisms involved in the action of anti-inflammatory molecules and compounds in adipocytes. It will also contribute to developing new research and new insights about anti-inflammatory therapies with a future application view.Record of systematic review:This review was registered with the International Register of Prospective Systematic Reviews on May 18, 2020 (registration: CRD42020182897). Available at: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020182897.     

调节性T细胞在感染性疾病中的作用及其机制

调节性T细胞具有免疫抑制功能,对于维持机体自身耐受具有重要作用。调节性T细胞表达多种分子如CD25、CTLA-4、GITR、CD103和Foxp3等,其中Foxp3为其特异性标志物。多种病原体可诱导宿主产生调节性T细胞,调节性T细胞可作为窗口有利于病原体逃避宿主免疫攻击。使用单克隆抗体封闭调节性T细胞则有利于宿主清除病原体,同时伴有宿主的病理损伤。     

Inhibitory effects of genistein on metastasis of human hepatocellular carcinoma

AIM: To investigate the inhibitory effects of genistein on metastasis of MHCC97-H hepatocellular carcinoma cells and to explore the underlying mechanism.METHODS: MHCC97-H hepatocellular carcinoma cells were exposed to genistein. A cell attachment assay was carried out in a microculture well pre-coated with fibronectin. The invasive activity of tumor cells was assayed in a transwell cell culture chamber, and cell cycle and apoptosis were evaluated by a functional assay. In addition, the expression and phosphorylation of FAK were detected by Western blotting. In situ xenograft transplantation of hepatocellular carcinoma was performed in 12 nude mice and lung metastasis of hepatocellular carcinoma was observed.RESULTS: Genistein significantly inhibited the growth of MHCC97-H cells in vitro. Adhesion and invasiveness of MHCC97-H cells were inhibited in a concentrationdependent fashion, and the inhibitory effect of genistein was more potent in the 10 μg/mL and 20 μg/ mL genistein-treated groups. Genistein caused G0/G1 cell cycle arrest, an S phase decrease, and increased apoptosis. The expression and phosphorylation of FAK in MHCC-97H cells were significantly decreased. In situ xenograft transplantation of hepatocellular carcinoma was also significantly suppressed by genistein. The number of pulmonary micrometastatic foci in the genistein group was significantly lower compared with the control group (12.3 ± 1.8 vs 16.6 ± 2.6, P < 0.05). CONCLUSION: Genistein appears to be a promising agent in the inhibition of metastasis of hepatocellular carcinoma.