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To investigate the role of c-Jun NH (2)-terminal kinase (JNk) in insulin resistance after burn and its mechanism.Twenty-four Sprague-Dawley rats were randomized to control, burn and burn + anisomycin groups. The rats in control group received sham burn trauma, and burn and burn + anisomycin groups received 30% total body surface area (TBSA) full thickness burn injury. Anisomycin (5 mg/kg) together with 250 microl dimethyl sulfoxide (DMSO) was injected to the rats in anisomycin group intravenously, and only 250 microl DMSO in the other two groups. Euglycemic-hyperinsulinemic glucose clamps was performed 2 hours after the injection. The changes of phospho-serine 307, phospho-tyrosine of insulin receptor substrate (IRS)-1 and phospho-JNK in muscle tissues were determined and compared using immunoprecipitation and Western blot analysis or immunohistochemistry in the three groups.The infusing rates of total 10% glucose (mg x kg(-1) x min(-1)) in control, burn and burn + anisomycin group were 12.3 +/- 0.4, 6.6 +/- 0.3, 6.5 +/- 0.4, respectively. The level of IRS-1 Serine 307 phosphorylation and phospho-JNK in muscle increased significantly, while insulin-induced tyrosine phosphorylation of IRS-1 decreased markedly after burn.The activation of JNK elevates the level of IRS-1 phospho-serine 307 and might play a role in insulin resistance after burn in rats.

To determine whether the activation of p38 mitogen-activated protein kinase (MAPK) is involved in the pathogenesis of stress ulcer.Model of stress ulcer was established with the treatment of rats with water-immersion restraint (WIR) stress. Ulcer index (UI) was macroscopically evaluated as a parameter of gastric mucosal lesions. Expression of phospho- and pan-p38 in gastric mucosa was detected using Western blot analysis. Tumor necrosis factor-alpha (TNF-alpha) and Interleukin 1beta (IL-1beta) gene expressions were analyzed by Northern blot analysis. As indicated in some experiments, rats were pretreated with intravenous injection of the specific p38 MAPK inhibitor CNI-1493 prior to WIR stress and then the changes of UI and TNF-alpha and IL-1beta mRNA expression were examined.The p38 MAPK was persistently activated in the gastric mucosa of rats with WIR stress, with maximal activation after 1 h of stress [(6.8 +/- 3.2) fold of baseline levels, P0.01]. Inhibition of p38 MAPK activation with CNI-1493 led to a marked decrease in UI in WIR stress rats. Similarly, the increased gene expression of proinflammatory cytokines TNF-alpha and IL-1beta in gastric mucosa induced by WIR stress were significantly diminished by p38 MAPK inhibition.p38 MAPK might have an important role in the pathogenesis of stress ulcer.

To investigate the role of p38 mitogen-activated protein kinase (MAPK) signal transduction pathway in the Kupffer cells production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in severely burns rats.Male health adult Sprague-Dawley rats were randomized into four groups: sham burn rats given vehicle, sham burn rats given the p38 MAP kinase inhibitor SB203580, rats given a 30% total body surface area (TBSA) full-thickness burn and fluid resuscitation plus vehicle, and burn rats given injury and fluid resuscitation plus SB203580. Rats from each group were killed at 24 h after burn or sham burn and Kupffer cells (KCs) were isolated. After 18 h incubation, KCs next were stimulated with 50 ng/ml of LPS for 18 h. After stimulation, supernatants were removed for analysis of TNF-alpha and IL-1beta levels by ELISA. The TNF-alpha and IL-1beta mRNA expressions (by quantitative real-time RT-PCR) and the activities of p38 MAPK and JNK (by Western blot analysis) in KCs were examined.Eighteen hours after 50 ng/ml LPS stimulation, KCs from burn rats released significantly higher levels of TNF-alpha and IL-1beta than did shams. The mRNA levels of TNF-alpha and IL-1beta in KCs increased significantly postburn. Western blot analysis suggested that expression of phosphorylated p38 MAPK and JNK were increased in KCs harvested from burn group after stimulation with LPS compared with those from sham group. In vivo administration of SB203580 markedly suppressed both the release of TNF-alpha and IL-1beta and the mRNA expressions of TNF-alpha and IL-1beta in KCs from both sham and burn rats. p38 MAPK activity in KCs was abolished by administration with SB203580, whereas JNK was not.p38 MAPK signal transduction pathway mediates KCs production of proinflammatory cytokines TNF-alpha and IL-1beta in severely burned rats.

To investigate the role of p38 mitogen-activated protein kinase (MAPK) signal transduction pathway in the acute lung injury of severely burned rats.Forty-eight adult healthy rats were randomly divided into three groups: sham group, burn control group, and burn + SB203580 group. A third-degree burns over 30% total body surface area rat model was used and pulmonary capillary permeability, lung water content, pulmonary histology and p38 MAPK activity were measured at 24 hours postburn.Burn trauma resulted in increased pulmonary capillary leakage permeability (42.5 +/- 4.7 vs. 12.1 +/- 1.4, P0.01), elevated lung water content (P0.05), and worsen histologic condition. There was a significant activation of p38 MAPK at 24 hours postburn compared with control. SB203580 inhibited the activation of p38 MAPK, reduced the pulmonary capillary leakage permeability (24.7 +/- 2.9 vs. 42.5 +/- 4.7, P0.01), decreased lung water content, and prevented burn-mediated lung injury.The activation of p38 MAPK is one important aspect of the signaling event that contributes to burn-induced lung injury.