Potential molecular mechanisms of quercetin-induced heme oxygenase-1 in rat primary hepatocytes / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the possible molecular mechanisms of heme oxygenase-1 (HO-1) induction by quercetin using rat primary hepatocytes.</p><p><b>METHODS</b>Sprague-Dawley rat primary hepatocytes were isolated using a two-step collagenase perfusion technique and treated with quercetin at various doses (25 - 200 mumol/L) and times (2 - 12 h). To investigate the roles of various signaling pathways, the hepatocytes were pre-treated with 50 mumol/L quercetin plus an extracellular signal-regulated kinase (ERK) inhibitor (PD98059 at 10 mumol/L), a p38 inhibitor (SB203580 at 10 mumol/L), a c-Jun N-terminal kinase inhibitor (SP600125 at 10 mumol/L) or a phosphatidylinositol 3-kinase inhibitor (Wortmannin at 1 mumol/L) for 12 h. Changes in the mRNA and protein levels of HO-1 and nuclear factor, E-2 related factor 2 (Nrf2) were detected by RT-PCR and western blotting.</p><p><b>RESULTS</b>After 4 - 12 h of treatment with quercetin at all concentrations, the HO-1 mRNA level in hepatocytes had increased significantly (vs. untreated control cells; all P less than 0.01). The quercetin-induced HO-1 expression and Nrf2 translocation into the nucleolus was inhibited by PD98059.</p><p><b>CONCLUSION</b>Quercetin may induce HO-1 expression via the ERK/Nrf2 signaling transduction pathway.</p>

Soy isoflavones with supplemental calcium provide protection against the loss of bone mass and influence insulin-like growth factor (IGF)-I after ovariectomy in rat / 中华预防医学杂志

<p><b>OBJECTIVE</b>To compare the effects of soy isoflavone with supplemental calcium to soy isoflavone or Ca alone on preservation of bone mineral density (BMD) and the expression of insulin-like growth factor (IGF)-I.</p><p><b>METHODS</b>Sprague-Dawley (SD) female Rats, 6 months old, were ovariectomized and randomized into five groups: sham-operated group (n = 10) or ovx (n = 40) group. Shams were fed a 3.272 g/kg Ca diet. Ovx rats were randomized to a 3.272 g/kg Ca diet alone (OVX) or with soy isoflavone (SI) extract (37.95 mg/kg.bw) or to a supplemental Ca diet (Ca, 4.676 g/kg) alone or a supplemental Ca diet with the isoflavone extract (SI + Ca) for 12 weeks. BMD of femur was measured by scanner of bone mineral density. The level of IGF-1 mRNA expression was measured by reverse transcriptase-polymerase chain reaction (RT-PCR), respectively.</p><p><b>RESULTS</b>There was no significant difference between group Sham (0.267 +/- 0.008) and group SI + Ca (0.263 +/- 0.007) g/cm(2) (P > 0.05) on femur BMD of distal end. Femur BMD of distal end in group Sham and group SI + Ca was greater (P < 0.05) as compared to group OVX (0.245 +/- 0.005) g/cm(2), SI (0.258 +/- 0.011) g/cm(2) or Ca (0.255 +/- 0.004) g/cm(2), P < 0.05. The liver tissue IGF-1 mRNA contents (IGF-1 cDNA/B-actin cDNA) were significantly decreased in group Sham (0.200 +/- 0.023) g/cm(2), SI (0.278 +/- 0.019) g/cm(2), Ca (0.302 +/- 0.026) g/cm(2) or SI + Ca (0.231 +/- 0.025) g/cm(2) as compared to group OVX (0.362 +/- 0.031) g/cm(2), P < 0.05; The liver tissue IGF-1 mRNA contents (IGF-1 cDNA/B-actin cDNA) were significantly decreased in group SI + Ca (0.231 +/- 0.025) g/cm(2) compared to group SI (0.278 +/- 0.019) g/cm(2) and Ca (0.302 +/- 0.026) g/cm(2), P < 0.05.</p><p><b>CONCLUSIONS</b>Soy isoflavones combined with supplemental Ca are more protective against the loss of femur BMD than soy isoflavones or supplemental Ca diet alone. The dose of SI (37.95 mg/kg.bw) might significantly restrain the rising of the liver tissue IGF-1 mRNA contents caused by ovariectomy.</p>

Influence of alcohol on insulin sensitivity and insulin receptor substrate-1 mRNA expression in rat skeletal muscle / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the molecular mechanism of the effect of alcohol on insulin sensitivity.</p><p><b>METHODS</b>Four groups of Wistar rats were used, i.e. control (C) group, and low (L), moderate (M) and high (H) alcohol group. Alcohol doses of each group were 0, 0.6, 1.8 and 3.0 ml.(kg.bw)(-1).day(-1). Each group was comprised of 10 male and 10 female rats. Alcohol was given to rats by gastric intubation. Thirteen weeks later, serum was collected for testing of fasting plasma glucose and insulin. HOMA-IR index of each group were calculated. Total muscle RNA was extracted using Trizol Reagent (Promega). The expression level of IRS-1 mRNA in muscle was detected by RT-PCR.</p><p><b>RESULTS</b>In female rats, the fasting plasma glucose of group (8.36 +/- 0.57) mmol/L was higher and the fasting plasma insulin (15.25 +/- 3.32) was lower than those of group C (7.56 +/- 0.85, 20.80 +/- 3.25). The HOMA-IR of group L (1.775 3 +/- 0.138 1) was lower than that of group C (1.982 6 +/- 0.124 6) (P < 0.05), while IRS-1 mRNA (0.766 1 +/- 0.076 9) was up-regulated (P < 0.05); HOMA-IR of group M (2.202 2 +/- 0.271 0) was higher than that of group C (P < 0.01), while IRS-1 mRNA (0.501 8 +/- 0.049 2) was suppressed (P < 0.01); HOMA-IR of group H (1.850 1 +/- 0.162 8) was not significantly changed as compared with that of group C (1.982 6 +/- 0.124 6) (P > 0.05), while IRS-1 mRNA (0.418 1 +/- 0.049 1) was significantly suppressed (P < 0.01). In male rats, the fasting plasma glucose and insulin had the similar change as those of female rats. The HOMA-IR of group M (1.878 5 +/- 0.250 2) was lower than that of C group (2.147 3 +/- 0.330 8) (P < 0.05), IRS-1 mRNA was up-regulated (0.824 9 +/- 0.064 7) (P < 0.05).</p><p><b>CONCLUSIONS</b>The present study showed that low-to-moderate dose of alcohol could increase insulin sensitivity; while alcohol abuse could decrease insulin sensitivity. Sex difference in this effect was found. Changes of IRS-1 mRNA expression may be involved in the molecular mechanism of the effects of alcohol on insulin sensitivity.</p>

Induction of heme oxygenase-1 in human hepatocytes to protect them from ethanol-induced cytotoxicity / 生物医学与环境科学（英文）

<p><b>UNLABELLED</b>We investigated the relationship between ethanol exposure and heme oxygenase (HO-1) in human hepatocytes in order to ascertain if induction of HO-1 can prevent ethanol induced cellular damage.</p><p><b>METHODS</b>Dose-dependent (25-100 mmol/L) and time-dependent (0-24 h) ethanol exposure were used in the present study. HO-1 mRNA and protein expression were detected by PT-PCR and Western blot respectively. HO-1 activity was indicated by bilirubin and Fe2+ formation. Cytotoxicity was investigated by means of lactate dehydrogenate (LDH) and aspartate transaminase (AST) level in culture supernatants, as well as the intracellular formation of malondialdehyde (MDA), cellular glutathione (GSH) status and CYP 2E1 activity.</p><p><b>RESULTS</b>We first demonstrated a dose-dependent response between ethanol exposure and HO-1 mRNA and protein expression in human hepatocytes. We further observed a time-dependent increase of HO-1 mRNA expression using 100 mmol/L ethanol starting 30 minutes after ethanol exposure, reaching its maximum between 3 h and 9 h. Being similar increased protein expression started to what had been demonstrated with the mRNA level, at 6 h after ethanol exposure, and kept continuous elevated over 18 h. In addition, we found that ethanol exposure to hepatocytes markedly increased HO-1 enzyme activity in a time-dependent manner measured as bilirubin and Fe2+ formation in human hepatocytes. Our results clearly showed that ethanol exposure caused a significant increase of LDH, AST, and MDA levels, while the antioxidant GSH was time-dependently reduced. Furthermore, we demonstrated that pre-administration of cobalt protoporphyrin (CoPP) induced HO-1 in human hepatocytes, and prevented an increase of MDA and a decrease of GSH. These effects could be partially reversed by zinc protoporphyrin (ZnPP), an antagonist of HO-1 induction.</p><p><b>CONCLUSION</b>HO-1 expression in cells or organs could lead to new strategies for better prevention and treatment of ethanol-induced oxidative damage in human liver.</p>