Effects of quercetin on hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol through the reactive oxygen species-nitric oxide pathway

AIM： To investigate the effect of quercetin （3,3,4,5, 7-pentahydroxy flavone）, a major flavonoid in human diet, on hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol. METHODS： Forty male Sprague-Dawley rats, weighing 200-250 g, were randomly divided into control group （tap wateradlibitum）, ethanol treatment group （6 mL/L ethanol）, quercetin treatment group （intragastric gavage with 100 mg/kg of quercetin per day）, and ethanol plus quercetin treatment group （quercetin and 6 mL/L ethanol）. Expression levels of proliferating cell nuclear antigen （PCNA）and Cyclin D1 were detected by Western blot to assay gastric mucosal cell proliferation in rats. To demonstrate the influence of quercetin on the production of extra-cellular reactive oxygen species/ nitrogen species （ROS/RNS） in rats, changes in levels of thiobarbituric acid reactive substance （TBARS）, protein carbonyl, nitrite and nitrate （NOx） and nitrotyrosine （NT） were determined. The activity of inducible nitric oxide synthase （NOS） including iNOS and nNOS was also detected by Western blot.RESULTS：Compared to control animals, cell proliferation in the gastric mucosa of animals subjected to ethanol treatment for 7 days was significant increased （increased to 290% for PCNA density P 〈 0.05, increased to 150 for Cyclin D1 density P 〈 0.05 and 21.6 ± 0.8 vs 42.3 ± 0.7 for PCNA positive cells per view field）, accompanied by an increase in ROS generation （1.298 ± 0.135 μmol vs 1.772 ± 0.078 μmol for TBARS P 〈 0.05; 4.36 ± 0.39 μmol vs 7.48 ± 0.40 μmol for carbonyl contents P 〈 0.05） and decrease in NO generation （11.334 ± 0.467 μmol vs 7.978 ± 0.334 μmol P 〈 0.01 for NOx; 8.986 ± 1.351 μmol vs 6.854 ± 0.460 μmol for nitrotyrosine P 〈 0.01） and nNOS activity （decreased to 43% P 〈 0.05）. This function was abolished by the co-administration of quercetin. CONCLUSION： The antioxidant action of quercetin relies, in part, on its ability to stimulate nNOS and enhance production of NO that would interact with endogenously produced reactive oxygen to inhibit hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol.

Mitomycin C induces apoptosis in human epidural scar fibroblasts after surgical decompression for spinal cord injury

Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C （1, 5, 10, 20, 40 μg/mL） for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 （Z-IETD-FMK and Z-LEHD-FMK, respectively） did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein （CHOP） and caspase 4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.

α-fetoprotein involvement during glucocorticoid-induced precocious maturation in rat colon

AIM： TO investigate the role of a-fetoprotein （AFP）, a cancer-associated fetal glycoprotein, in glucocorticoidinduced precocious maturation in rat colon. METHODS： Colons from suckling Sprague-Dawley rats were used in this study. Corticosterone acetate at a dose of 100 μg/g body weight was given to normal pups on days 7, 9 and 11 after birth to induce hypercorticoidism. Control animals were injected with identical volumes of normal saline. Some rats receiving corticosterone 7 d after birth were also treated with mifepristone （RU38486）, a glucocorticoid cytoplasm receptor antagonist to investigate the effects of glucocorticoids （GCs）. The morphological changes of the crypt depth and villous height of the villous zone in colon were observed as indicesof colon maturation. Expression levels of AFP in colons were detected by reverse transcriptase polymerase chain reaction and Western blotting. To identify the cellular lo- calization of AFP in developing rat colons, double-immu- nofluorescent staining was performed using antibodies to specific mesenchymal cell marker and AFP. RESULTS： Corticosterone increased the crypt depth and villous height in the colon of 8- and 10-d-old rats with hypercorticoidism compared with that in the control ani- mals （120% in 8-d-old rats and 118% in 10-d-old rats in villous height, P = 0.021; 145% in 8-d-old rats and 124% in 10-d-old rats in crypt depth, P = 0.017）. These increases were accompanied by an increase of AFP ex- pression in both mRNA and protein （2.5-folds in 8-d- old and 2.5-folds in 10-d-old rats higher than in control animals, P = 0.035; 1.8-folds in 8-d-old and 1.3-folds in 10-d-old rats higher than in control animals, P = 0.023）. Increased crypt depth and villous height and increased expression of AFP in the colon of rats with hypercorti- coidism were blocked by mifepristone. Both had positive staining for AFP or vimentin, and overlapped in mesen- chymal cells at each tested colon. CONCLUSION： GCs promote the development of rat colon. AFP appears to be involved, in part, in mediating the effects of GCs in the developmental colon.