Worsening effect of partial sleep deprivation on indomethacin-induced gastric mucosal damage

The present study was to investigate the roles of cyclooxygenase-1 and -2 (COX-1 and COX-2) and prostaglandin (PG) on gastric mucosal integrity of partially sleep deprived (PSD) rats. A slowly moving drum was used to induce PSD. The PG levels in the gastric mucosa of PSD rats, with or without indomethacin or rofecoxib treatment, were determined. Exogenous prostaglandin E (PGE) analog, misoprostol, was administered to PSD rats to investigate the modulating effect of PG in indomethacin-induced gastric damage. It was observed that COX-1 mRNA and protein were up-regulated in the gastric mucosa of PSD rats. Selective COX-2 inhibition by rofecoxib failed to decrease mucosal PGE2 levels nor to affect mucosal integrity in both PSD and sleep undisturbed rats. However, indomethacin, a COX-1 preferential non-selective COX inhibitor, significantly reduced mucosal PGE2 content and produced more severe mucosal damage in PSD rats than in the controls. The deleterious effect of indomethacin on gastric mucosal integrity of PSD rats was significantly attenuated with the administration of misoprostol. These results suggest that PSD enhances COX-1 biosynthesis of gastroprotective PGE2 as an adaptive response of the stomach to stress. The administration of non-selective COX inhibitors to subjects with chronic sleep deprivation may induce more gastric damages.

Partial sleep deprivation compromises gastric mucosal integrity in rats. Life Sci. 2005;77:220-229. [PMID: 15862606 DOI: 10.1016/j.lfs.2004.12.027] [Cited by in Crossref: 20] The gastric mucosa is most susceptible to stress that has been shown to induce mucosal damage in humans and animals. This study aims to explore the underlying mechanisms of partial sleep deprivation, as a source of psychophysiological stress, on gastric functions and its effect on mucosal integrity. Sprague-Dawley rats were partially sleep deprived (PSD) for 7 or 14 days by housing inside slowly rotating drums. Gastric tissues and plasma were sampled at the end of the sleep deprivation periods and mucosal lesion scores were evaluated. Morphological examination was performed after Hematoxylin and Eosin staining. Plasma levels of noradrenaline, adrenaline, gastrin, histamine and somatostatin were determined with enzyme immunoassays. Gastric acidity was measured with acid-base titration in pylorus ligated rats. Gastric mucosal blood flow was evaluated with Laser Doppler Flowmetry. It was found that gastric lesions were induced in about 30%-50% of the PSD rats. Gastric acidity as well as plasma levels of noradrenaline, gastrin and histamine were elevated. Gastric mucosal blood flow and plasma somatostatin level were on the contrary reduced, especially in rats with PSD for 14 days. It is concluded that partial sleep deprivation compromises gastric mucosal integrity by increasing gastric acidity, plasma levels of noradrenaline, gastrin, histamine, and decreasing gastric mucosal blood flow. These results provided experimental evidence on the gastric damaging effects of PSD and it could be one of the risk factors contributing to gastric ulcer formation

The gastric mucosa is most susceptible to stress that has been shown to induce mucosal damage in humans and animals. This study aims to explore the underlying mechanisms of partial sleep deprivation, as a source of psychophysiological stress, on gastric functions and its effect on mucosal integrity. Sprague-Dawley rats were partially sleep deprived (PSD) for 7 or 14 days by housing inside slowly rotating drums. Gastric tissues and plasma were sampled at the end of the sleep deprivation periods and mucosal lesion scores were evaluated. Morphological examination was performed after Hematoxylin and Eosin staining. Plasma levels of noradrenaline, adrenaline, gastrin, histamine and somatostatin were determined with enzyme immunoassays. Gastric acidity was measured with acid-base titration in pylorus ligated rats. Gastric mucosal blood flow was evaluated with Laser Doppler Flowmetry. It was found that gastric lesions were induced in about 30%-50% of the PSD rats. Gastric acidity as well as plasma levels of noradrenaline, gastrin and histamine were elevated. Gastric mucosal blood flow and plasma somatostatin level were on the contrary reduced, especially in rats with PSD for 14 days. It is concluded that partial sleep deprivation compromises gastric mucosal integrity by increasing gastric acidity, plasma levels of noradrenaline, gastrin, histamine, and decreasing gastric mucosal blood flow. These results provided experimental evidence on the gastric damaging effects of PSD and it could be one of the risk factors contributing to gastric ulcer formation.

Over-expression of inducible heat shock protein 70 in the gastric mucosa of partially sleep-deprived rats

BACKGROUND

Previous findings have demonstrated increased expression of inducible heat shock protein 70 (iHSP70) in the gastric mucosa of rats exposed to partial sleep deprived (PSD). The purpose of this study was to investigate the functional role of iHSP70 and its relationship with acid secretion in the stomachs of PSD animals.

METHODS

A slowly rotating drum was used to induce PSD in male Sprague-Dawley rats with or without omeprazole treatment. Gastric mucosal samples were harvested for iHSP70 mRNA and protein analysis with RT-PCR and Western blotting, respectively. Enzyme immunoassay was used to determine plasma gastrin level and gastric acidity was measured by titration. The modulating effect of PSD on 0.6 M hydrochloric acid (HCl)-induced gastric damage was also evaluated.

RESULTS

PSD increased plasma gastrin, gastric acidity and expression of iHSP70, while significantly reducing HCl-induced gastric damage. Omeprazole administration decreased gastric acidity and reversed iHSP70 over-expression in PSD rats.

CONCLUSIONS

PSD increases gastric acidity which enhances expression of mucosal iHSP70. Over-expression of iHSP70 may be a protective homeostatic response of the stomach to stress induced by PSD and acid secretion.

Transcriptional gene expression profiles of HGF/SF-met signaling pathway in colorectal carcinoma

AIM: To explore the transcriptional gene expression profiles of HGF/SF-met signaling pathway in colorectal carcinoma to understand mechanisms of the signaling pathway at so gene level.

METHODS: Total RNA was isolated from human colorectal carcinoma cell line LoVo treated with HGF/SF (80 ng/L) for 48 h. Fluorescent probes were prepared from RNA labeled with cy3-dUTP for the control groups and with cy5-dUTP for the HGF/SF-treated groups through reverse-transcription. The probes were mixed and hybridized on the microarray at 60 °C for 15-20 h, then the microarray was scanned by laser scanner (GenePix 4000B). The intensity of each spot and ratios of Cy5/Cy3 were analyzed and finally the differentially expressed genes were selected by GenePix Pro 3.0 software. 6 differential expression genes (3 up-regulated genes and 3 down-regulated genes) were selected randomly and analyzed by β-actin semi-quantitative RT-PCR.

RESULTS: The fluorescent intensities of built-in negative control spots were less than 200, and the fluorescent intensities of positive control spots were more than 5000. Of the 4004 human genes analyzed by microarray, 129 genes (holding 3.22% of the investigated genes) revealed differential expression in HGF/SF-treated groups compared with the control groups, of which 61 genes were up-regulated (holding 1.52% of the investigated genes) and 68 genes were down-regulated (holding 1.70% of the investigated genes), which supplied abundant information about target genes of HGF/SF-met signaling.

CONCLUSION: HGF/SF-met signaling may up-regulate oncogenes, signal transduction genes, apoptosis-related genes, metastasis related genes, and down-regulate a number of genes. The complexity of HGF/SF-met signaling to control the gene expression is revealed as a whole by the gene chip technology.

Sleep deprivation increase the expression of inducible heat shock protein 70 in rat gastric mucosa

AIM: To investigate if sleep deprivation is able to increase the expression of inducible heat shock protein 70 in gastric mucosa and its possible role in mucosal defense.

METHODS: Rats for sleep disruption were placed inside a computerized rotating drum, gastric mucosa was taken from rats with 1, 3 and 7 d sleep deprivation. RT-PCR, immunohistochemistry and Western blotting were used to determine the expression of heat shock protein 70. Ethanol (500 mL·L^-1, i.g.) was used to induce gastric mucosa damage.

RESULTS: RT-PCR, Western blotting and immunostaining confirmed that the sleep deprivation as a stress resulted in significantly greater expression of inducible heat shock protein 70 in gastric mucosa of rats. After the 500 mL·L^-1 ethanol challenge, the ulcer area found in the rats with 7 d sleep deprivation (19.15 ± 4.2) mm² was significantly lower (P < 0.01) than the corresponding control (53.7 ± 8.1) mm².

CONCLUSION: Sleep deprivation as a stress, in addition to lowering the gastric mucosal barrier, is able to stimulate the expression of inducible heat shock protein 70 in gastric mucosa of rats, the heat shock protein 70 may play an important role in gastric mucosal protection.