The effect of heat shock protein 70 on inducible nitric oxide synthase during sepsis in rats

ABSTRACT

INTRODUCTION: Heat shock protein70 (HSP70) is a highly conserved family of proteins produced after a variety of stresses. Many studies reported that the overexpression of HSP70 can improve the prognosis of the patients with sepsis through a reduction of the nitric oxide concentration. However, these results only revealed the effect of HSP70 and nitric oxide. No studies have examined the relationship between HSP70 and nitric oxide. The aim of this study was to evaluate the effect of the overexpression of HSP70 on the expression of inducible nitric oxide synthase and the nitric oxide concentration. In addition, the mechanism of the relationship of HSP70 and inducible nitric oxide synthase (iNOS) in sepsis was examined. MATERIALS AND METHODS: The experiments were performed on male sprague-dawley rats. Sepsis was induced by a cecal ligation and puncture (CLP). Glutamine (GLN) or saline was administered 1 hour after the initiation of sepsis. Serum and lung tissues were acquired from the rats 12 hours or 24 hours after the initiation of sepsis. The nitric oxide concentration, the expression of HSP70 in lung, and the gene expression of iNOS in lung were analyzed. The three groups, sham operation, CLP and CLP+GLN, were compared. RESULTS: Compared to the other groups, in CLP+GLN, GLN administered after the initiation of sepsis enhanced the expression of HSP70 in the lung at 12 hours (47.19+/-10.04 vs. 33.22+/-8.28, P=0.025) and 24 hours (47.06+/-10.60 vs. 31.90+/-4.83, P=0.004). In CLP+GLN, GLN attenuated the expression of iNOS messenger RNA (mRNA) in the lung at 12 hours (5,513.73+/-1,051.60 vs. 4,167.17+/-951.59, P=0.025) and 24 hours (18,740.27 +/-8,241.20 vs. 9,437.65+/-2,521.07, P=0.016), and reduced the concentration of nitric oxide in the serum at 12 hours (0.86+/-0.48 vs. 3.82+/-2.53, P=0.016) and 24 hours (0.39+/-0.25 vs. 1.85+/-1.70, P=0.025). CONCLUSION: The overexpression of HSP70 induced by the administration of GLN in sepsis attenuates the expression of the iNOS gene but reduces the nitric oxide concentration.