ABSTRACT
Gender differences in fatigue manifest as females being more prone to feel exhaustion and having lower muscle endurance. However, the mechanisms of these effects remain unclear. We investigated whether orosomucoid, an endogenous anti-fatigue protein that enhances muscle endurance, is involved in this regulation. Female rats exhibited lower muscle endurance, and this gender difference disappeared in orosomucoid-1-deficient mice. Female rats also exhibited weaker orosomucoid induction in serum, liver and muscle in response to fatigue compared with male rats. Ovariectomy elevated orosomucoid levels and increased swimming time, and estrogen replenishment reversed these effects. Exogenous estrogen treatment in male and female mice produced opposite effects. Estrogen decreased orosomucoid expression and its promoter activity in C2C12 muscle and Chang liver cells in vitro, and estrogen receptor or p38 mitogen-activated protein kinase blockade abolished this effect. Therefore, estrogen negatively regulates orosomucoid expression that is responsible for the weaker muscle endurance in females.
ABSTRACT
OBJECTIVE Although it is generally believed that nicotine accounts for the beneficial effect of smoking on ulcerative colitis, the underlying mechanisms remain not well understood. Our previous finding that nicotine inhibits inflammatory responses through inducing miRNA-124 prompted us to ask whether the miRNA is involved in the protective action of nicotine on UC. METHODS MiR-124 expres-sion in colon tissues and cells was determined by q-PCR and in situ hybridization.The effect of miR-124 on protective role of nicotine in ulcerative colitis was evaluated in DSS-treated mice and IL-6-treated Caco-2 colon epithelial cells. Expression of p-STAT3/STAT3 was detected by immunohistochemistry and Western-blot analysis. RESULTS miR-124 expression is upregulated in colon tissues from UC patients and DSS-induced colitis mice. Nicotine treatment further elevated miR-124 level in lympho-cytes isolated from human ulcerative colonic mucosa and ulcerative colon tissues from DSS mice,both in infiltrated lymphocytes and epithelial cells. Administration of nicotine also reduced weight loss, improved DAI and decreased HE score in DSS-induced colitis mice.Moreover,knockdown of miR-124 in vivo significantly diminished the beneficial effect of nicotine on murine colitis, and in vitro on IL-6-treated Caco-2 colon epithelial cells.Further analysis indicated that nicotine inhibited STAT3 activation in vivo and in IL-6-treated Caco-2 colon epithelial cells and Jurkat human T lymphocytes,in which miR-124 knockdown led to increased activation of STAT3. Blocking STAT3 activity alone is beneficial for DSS colitis and also abolished nicotine′s protective effect in this model.CONCLUSION These data indicated that nicotine exerts its protective action in UC through inducing miR-124 and its effect on STAT3, and suggest that the miR-124/STAT3 system is a potential target for the therapeutic intervention of UC.
ABSTRACT
Muscle fatigue is a common complaint in clinical practice. In humans, muscle fatigue can be defined as exercise-induced decrease in the ability to produce force. Here, to provide a general understanding and describe potential therapies for muscle fatigue, we summarize studies on muscle fatigue, including topics such as the sequence of events observed during force production, in vivo fatigue-site evaluation techniques, diagnostic markers and non-specific but effective treatments.
Subject(s)
Humans , Muscle FatigueABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of Ghrelin on the expression of acyl coenzyme A:cholesterol acyltransferases-1 (ACAT-1) in THP-1 derived foam cells.</p><p><b>METHODS</b>The human monocytic leukemia cell line (THP-1) was chosen in our study. The differentiation of THP-1 cells into macrophages was induced by phorbol 12-myristate 13-acetate. Macrophages were then incubated with oxidized LDL (ox-LDL) to generate foam cells. Ghrelin and [D-Lys3]-GHRP-6, the special antagonist of growth hormone secretagogue receptor (GHS-R), were treated during foam cells formation. The ACAT-1 protein and mRNA levels were detected by Western blot and RT-PCR. The effect of variance of cholesterol content was measured by zymochemistry via-fluorospectrophotometer.</p><p><b>RESULTS</b>Ghrelin reduced the content of cholesterol ester in foam cells obviously. ACAT-1 protein and mRNA levels were also decreased. The antagonist of GHS-R inhibited the effects of Ghrelin on ACAT-1 expression in dose-dependent manner. The ACAT-1 mRNA levels of the GHS-R specific antagonist groups (10(-5), 5 x 10(-5), 10(-4) mol/L) were 1.14 +/- 0.04, 1.58 +/- 0.03, 2.40 +/- 0.16, significantly higher than that of the Ghrelin group (0.89 +/- 0.05). And the protein expressions were 1.25 +/- 0.09, 1.77 +/- 0.11, 2.30 +/- 0.09, also higher than that of the Ghrelin group (0.86 +/- 0.08).</p><p><b>CONCLUSIONS</b>Ghrelin might interfere atherosclerosis by down-regulating the expression of ACAT-1 via GHS-R pathway.</p>
Subject(s)
Humans , Acetyl-CoA C-Acetyltransferase , Metabolism , Acyl Coenzyme A , Metabolism , Blotting, Western , Cell Line, Tumor , Cholesterol , Metabolism , Down-Regulation , Foam Cells , Metabolism , Ghrelin , Physiology , RNA, Messenger , Metabolism , Receptors, Ghrelin , Physiology , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , SpectrophotometryABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression changes of acyl-coenzyme A: cholesterol acyltransferase 1 (ACAT1) on Chlamydia pneumoniae (C.pn) induced foam cell formation.</p><p><b>METHODS</b>Human monocytic cell line (THP-1) was induced into macrophages by 160 nmol/L phorbol myristate acetate (PMA) for 48 h, and were randomly allocated into four groups: negative control group (50 microg/ml LDL for 48 h); positive control group (50 microg/ml ox-LDL for 48 h); C.pn infection group (50 microg/ml LDL plus 1 x 10(5), 4 x 10(5), 5 x 10(5) and 1 x 10(6) IFU C.pn for 48 h or 1 x 10(6) IFU C.pn for 0, 24, 48 and 72 h); ACAT inhibitor 58-035 plus C.pn infection group (1, 5, 10 microg/ml ACAT inhibitor 58-035 pretreatment for 1 h, 50 microg/ml LDL and 1 x 10(6) IFU C.pn for 48 h). The mRNA and protein expressions of ACAT1 were determined by RT-PCR and Western blot, respectively. Lipid droplets in cytoplasm were observed by oil red O staining. The contents of intracellular cholesteryl esters were detected by enzyme-fluorescence.</p><p><b>RESULTS</b>The mRNA and protein expressions of ACAT1 were significantly up-regulated in positive control cells compared those in negative control cells and further upregulated by C.pn infection in a time-dependent and concentration-dependent manner (all P < 0.05). There were significantly increases in the accumulation of lipid droplets and the ratio of cholesteryl ester to total cholesterol in positive control cells as compared with negative control cells and these were further aggravated by C.pn (at the concentrations of 5 x 10(5) and 1 x 10(6) IFU for 48 h) and C.pn infection induced increases in the accumulation of lipid droplets and the ratio of cholesteryl ester to total cholesterol could be significantly attenuated by ACAT inhibitor 58-035 (all P < 0.05).</p><p><b>CONCLUSION</b>Chlamydia pneumoniae induces THP-1-derived foam cell formation by up-regulating the expression of ACAT1.</p>