| Sepsis is the main cause of death of critical patients, and however, so far, we have not yet entirely clarified the mechanism of sepsis entirely.Studies have shown that the HPA axis is the key pathway of neuroendocrine disorder in sepsis, but HPA axis dysfunction appeared with septic episode, and, the degree of dysfunction was positively related with the occurrence of sepsis. Ulinastatin, a protease inhibitor, can restrain the excessive activation of HPA axis. However, the underlying specific molecular mechanism is not very clear yet. Further study on its mechanism is possible for us to develop a new field for the treatment of sepsis. The emergence of JAK-STAT signal transduction pathways is a major breakthrough in the signal transduction system. It plays a key role in cell proliferation, differentiation, apoptosis, inflammation and immune adjustment process, etc. In addition, it is widely involved in signal transduction of cell factors. Among them, the IL-6/STAT3 is very popular.We known, under the action of cold stimulus, IL-6 and STAT3, which are expressed in the hypothalamus, adjusted the transcription of CRH, and influenced the activity of HPA axis. Whether the HPA axis dysfunction in sepsis is related to IL-6 /STAT3 signaling pathway? Whether Ulinastatin can block the excessive activation of HPA axis via IL-6 / STAT3 signaling pathway? There are no relevant research reports. This study used severe sepsis model caused by CLP for preliminary sdudy.Thirty-two wistar rats were randomly divided into four groups: The control group, the sham group, the saline group(NS group), ulinastatin group(UTI group). The sepsis rat models were established by CLP. NS group: The rats treated with 0.9%Na Cl 10 m L/kg through abdominal injection after CLP, ulinastatin group: The rats treated with ulinastatin of100.000U/kg i.p. after CLP. Blood samples were taken after 6 hours in each rat and the hypothalamus tissue, pituitary tissue, adrenal tissue were isolated. The general situation of rats after CLP includes depression,lethargy, shivering, piloerection, canthus secretions, ascites and bowels.Radioimmunoassay was used to detect the levels of the CORTT and ACTH in the plasma. The m RNA expression of CRH, IL-6, STAT3, SOCS3 in hypothalamus tissues was detected with RT-QPCR. The m RNA expression of POMC, IL-6, STAT3, SOCS3 in pituitary tissue was detected with RT-PCR. The m RNA expression of IL-6, STAT3, SOCS3 in adrenal tissue was detected with RT-PCR as well. The results showed:(1) The rats in the Sham group analepsiaed earlier than that in other groups and acted more actively, no ascites, no abdominal dropsy, no unpleasant smell when their abdomens were opened. The rats in the NS group analepsiaed later than that in the Sham group, and then were depressed with inaction,pilo-erection, shivering, dyspnea, act decrease significantly, canthus secretions increase. When the abdomen was opened, feculent bloody ascites and evil smelling were found and bowels looked edema, the cecum was darkened in some rats. Compared with the NS group, the clinical manifestations in the rats of Ulinastatin group were better.(2) In NS group plasma ACTH and CORT level higher than the Sham group(45.837±7.232 vs.21.935±4.713;25.021±4.088 vs.12.592±4.313,P<0.05). In UTI group plasma ACTH and CORT level lower than the NS group(24.636±5.866 vs.45.837±7.232;19.892±4.770 vs. 25.021±4.088,P<0.05). There was no difference in the Sham group and Control group(21.935±4.713 vs.19.704±3.472;12.592±4.313 vs.12.486±3.523,P>0.05).(3) RT-PCR:Compared NS group with Sham group: The m RNA expression levels of CRH, IL-6,STAT3, SOCS3 were up-regulated significantly in the hypothalamus tissues of NS group(3.22±0.65 vs.0.79±0.13;4.69±2.53 vs.0.55±0.28;1.67±1.11 vs.0.49 ± 0.53;4.33 ± 1.58 vs.0.96 ± 0.36,P<0.01), the m RNA expression levels of POMC, IL-6, STAT3, SOCS3 were up-regulated significantly in the pituitary tissues of NS group(2.73±0.42 vs.0.94±0.19;7.21±5.23 vs.0.15±0.08;14.88±10.81 vs.1.48±0.10;14.55±6.23 vs.0.89 ± 0.27,P<0.01), the m RNA expression levels of IL-6, STAT3,SOCS3 were up-regulated significantly in adrenal gland tissues of NS group(72.44±62.35 vs.1.05±0.56;4.60±0.96 vs.0.17±0.08;8.56±2.83 vs.1.21±0.46,P <0.01). Compare with NS group: in the UTI group, the m RNA expression of CRH decreased significantly in the hypothalamus tissues of UTI group(2.04 ± 0.57 vs.3.22 ± 0.65,P<0.05), the m RNA expression of POMC decreased significantly in the pituitary tissues of UTI group(1.03±0.25 vs.2.73±0.42,P<0.01), there was no significant change in the expression of the other target genes. Compared with Control group,in the sham group the gene expression level of all target genes was no statistical significance in the hypothalamus, pituitary gland tissue and adrenal tissue,(P>0.05).In summary, in the early stage of sepsis, the HPA axis was under a state of dysfunction, and normal rhythm of HPA was inordinate. IL-6/STAT3 signaling pathway has a close contact with HPA axis excessive activation in the early stage of sepsis rats. IL-6 / STAT3 signaling pathway may be regarded as a novel therapeutic target for HPA axis excessive activation of the sepsis. Ulinastatin significantly improved the symptoms and signs of sepsis in rats, restrained HPA axis excessive activation, and protected the body from damage. The molecular mechanism of restraining HPA axis excessive activation still need to be further studied. |
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