Experimental Study On Regulation Of Calpain Inhibitor I On Post-traumatic Stress Disorder

Glucocorticoid (GC) is one of the most important endogenous stress hormones and has been used as immunosuppressive, anti-inflammatory, and cytotoxic drug. Most known effects of glucocorticoid are mediated by the intracellular glucocorticoid receptor (GR). Upon acute stress reaction, the glucocorticoid secretion increases and activates its receptor to restrain the release of chemical mediators and cytokines. So it plays an important role in controlling the inflammatory reactions at the earlier period of stress response. Our previous research showed that there had over excitation of hypothalamic pituitary adrenal (HPA) axis response and significantly increased corticosterone in serum after severe trauma, but the glucocorticoid receptor (GR) expression and function in tissue decreased notably, and the decrease of GR function had a positive correlation with trauma severity. Down-regulation of GR would weaken its anti-inflammatory function and impact the stress state of the whole body. It was suggested that the disorder of stress response play an important role in the ignition and development of systemic damage consequent upon severe trauma, such as systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Therefore there exist contradiction between high concentration of serum inflammatory cytokines and glucocorticoids and low level GR expression and GR dysfunction in tissue, hence it has important clinical significance to up-regulation of GR to ameliorate the disorder of stress and relieve systemic damage consequent upon severe trauma.Recently some reports indicated that glucocorticoid can induce its own receptor down-regulation, and this effect was regulated by the ubiquitin-proteasome degradation pathway. Upon post-traumatic stress reaction, the glucocorticoid secretion increased notably; by the way, high dosage of glucocorticoid may be used in therapeutic process, so there should exist the condition of ligand-dependent down-regulation of the glucocorticoid receptor (GR). Therefore maybe we can use proteasome inhibitor to inhibit GR down-regulation by ubiquitin-proteasome degradative pathway during acute inflammatory trauma.Calpain inhibitor I is one kind of proteasome inhibitors, reports showed that calpain inhibitor I attenuates the degree of zymosan-induced multiple organ failure and renal ischemia/reperfusion injury in the rat. In this research, we studied the effect of Calpain inhibitor I on GR expression and transactivition ability, to explore if inhibition the ubiquitin-proteasome degradative system, can ameliorate GR decreasing and increase its transactivition ability. Because Calpain inhibitor I can inhibit I kappa B degradation,we also observed the influence of Calpain inhibitor I on NF-kappa B activation and pre-inflammatory cytokines secretion,and we explored that if both Calpain inhibitor I and dexamethasone can be used to inhibit GR and I kappa b degradation,prevent NF-kappa B activation and pre-inflammatory cytokines secretion, so as to provide new method for clinical therapy to post-traumatic stress disorder (PTSD), and offer new therapeutic tool to relieve and prevent earlier period inflammatory damage after severe stress, such as SIRS and MODS.c-Jun is an important protein of acute stress response, and play an important role in inducing inflammatory mediators. Our previous research showed that the phosphorylation status of Jun N-terminal kinase (JNK) increased in mice hepatic cells after burn injury, so we also observed the change of liver c-Jun expression of burned rice in our research, and explored the expression and transactivation ability of GR when the c-Jun level increased or decreased using gene transfection and RNA interference technology, so as to figure out the influence of c-Jun on GR function, and pave a new way for ameliorating the inhibition of GR function and acute stress disorder.Main results and conclusions are sumarized as follows:1. The expression of glucocorticoid receptor decreased after RAW-264.7 cells were treated with dexa...