Estrogens ameliorate remote organ inflammation induced by burn injury in rats.

OBJECTIVE AND DESIGN: The present study was designed to investigate the role of sex steroids in burn-induced remote organ injury. MATERIAL OR SUBJECTS: Male Wistar albino rats were given burn trauma (n=39), and underwent castration or sham operation at 2 h following the burn injury. TREATMENT: Rats were injected sc with either 17beta estradiol benzoate (E2, 10 mg/kg) or an androgen receptor blocker cyproterone acetate (CPA, 25 mg/kg) or vehicle, immediately after burn and at 12 h. METHODS: At 24 h of burn insult, rats were decapitated. Blood samples for RIA of testosterone, estradiol and tumor necrosis factor (TNF)-alpha and the tissue samples for myeloperoxidase activitiy (MPO) were taken. ANOVA student's t test was used for statistical analysis. RESULTS: Castration, antiandrogen and E2 treatments increased plasma estradiol levels and depressed burn-induced elevation in serum TNF-alpha levels. In the liver and lung, burn-induced increase in MPO was reduced by E2 and castration, while CPA was effective in reducing neutrophil infiltration only in the liver. CONCLUSION: We propose that treatment with estrogens or antiandrogens might be applicable in clinical situations to ameliorate systemic inflammation induced by burn.

The effect of hyperthermic preconditioning on the immune system in rat peritonitis.

OBJECTIVE: To assess whether hyperthermic (HT) preconditioning prevents the lethal effects of peritonitis by acting on the immune system. DESIGN: Prospective, controlled, experimental study. SETTING: Laboratory and animal facility of the university. MATERIALS: Adult male Sprague-Dawley rats. INTERVENTIONS: In the HT groups animals were subjected to hyperthermia (42 degrees C, 15 min) and 8 h later peritonitis (P) (n = 14) was induced. In the normothermic (NT) groups, animals were subjected to normothermia (38 degrees C, 15 min) and 8 h later peritonitis (n = 14) was induced. Each group had a corresponding sham laparotomy group (n = 14). Six rats from each group were allowed to live 7 days for survival. In the control group (n = 4), rats were not anesthetized or heat treated. MEASUREMENTS AND RESULTS: Sixteen hours after peritonitis and laparotomy, rats were killed. Blood was taken to measure the percentage of CD(4)(+), CD(8)(+), CD(4)(+)CD(56)(+), CD(8)(+) CD(11 b)(+), NK(+), B cells and the level of tumor necrosis factor. Grading of peritonitis and the measurement of free oxygen radicals in the peritoneal fluid were undertaken. All rats in the HT + P and sham laparotomy groups survived for 7 days, while in the NT + P group two rats died in 7 days. HT decreased the severity of peritonitis and increased the free oxygen radicals in the peritoneal fluid; however, the difference did not reach statistical significance. HT prevented the decrease in CD(4)(+) and B cells and the increase in CD(11 b)(+). CONCLUSIONS: HT may have a protective role in sepsis by reducing the severity of peritonitis. A causal relation between hyperthermia and an improved immune system seems possible.