应激状态下兔甲状腺功能及炎症因子的变化

Change of thyroid function and inflammatory cytokines under stress status in rabbits

目的观察应激状态下甲状腺功能及相关炎症因子的变化规律，分析非甲状腺性的病态综合征（NTIS）时甲状腺功能及炎症因子的变化与疾病转归的关系。方法30只家免随机取24只用55％氢氟酸烧伤5％体表面积。伤前5min，伤后2、8、24、72、168、336h分别采集静脉血3ml，采用化学发光法检测游离三碘甲状腺原氨酸（FT3）、游离四碘甲状腺原氨酸（FT4）和促甲状腺素（TSH），ELISA方法检测血清热休克蛋白（HSP）、TNF—a、IL-6。，结果（1）家兔烧伤应激后于24h内死亡5只，死亡率为20．8％，之后分别于48、72h各死亡2只，总死亡率37．5％。与对照组比较，烧伤应激后的存活组家免的FT。于伤后8h下降显著（P〈0．05），FT4、TSH于伤后24h下降显著（P〈005），FT3、FT4、TSH均于24h达最低点（P〈005），随后血FT3、FT4、TSH浓度水平逐步升高，于伤后168h基本升至伤前水平，与伤前相比无统计学差异（P〉0．05）。（2）与正常对照组比较，烧伤应激后的存活组家兔的HSP、TNF—a均在8～24h升至平台期（P〈005），之后逐渐恢复正常，早于甲状腺功能的变化，fL-6也在8h达高峰，但是峰值变化更大（P〈O．01），持续时间更久。（3）死亡组与存活组比较，甲状腺功能变化有统计学差异（P〈0．05），HSP、TNF—oc、IL-6均明显增高（P〈0．05），其中lL-6变化更大（P〈0．01）。结论家兔皮肤烧伤后甲状腺功能随病程的延长呈现规律变化，24h内甲状腺功能达最低水平，之后逐渐自行恢复，呈“U”型曲线变化，与炎症因子HSP、TNF—a、IL-6变化相关。

Objective To investigate the change of thyroid function and inflammatory cytokines in stress status, to provide pathophysiological foundation of nonthyroidal illness syndrome （NTIS）. Methods The 5% body surface area was burned with 55% hydrofluoric acid in 24 rabbits. The venous blood samples were collected on 5 min before and 2, 8, 24, 72, 168, 336h after the injury. Free triiodothyronine （FT3）, free thyroxine （FT4） and thyrotropin （TSH） were detected by chemiluminescence method, and the heat shock protein （HSP）, tumor necrosis factor （TNF- co）, interleukin 6 （IL-6） were detected by ELISA method. Results Five rabbits died in 24 h, 2 died in 48 h and another 2 died in 72 h with the total mortality rate of 37.5%. The FT3 level of the alive group declined significantly in 8h （P〈0.05）, the FT4, TSH levels reached lowest points in 24h, then the FT3, FT4 and TSH level began to rise gradually and returned to the baseline levels after 168h （P 〉0.05）. HSP, TNF-a and IL-6 changed earlier than the thyroid function. The platform period of HSP, TNF- cc and IL-6 of the alive group appeared in 8-24 h, then returned to the normal level gradually （P〈0.05）. IL-6 reached peak level at 8h, the changed markedly and lasted longer （P〈0.01）. The thyroid function be- tween the fatal group and the alive group had significant differences （P〈0.05）. The changes of HSP, TNF- a and IL-6 in the fatal group were more prominently compared to the alive group （P〈0.05）, especially for IL-6 （P〈O.01）. Conclusion The thyroid function in rabbits under burn stress presents U-shaped changes, which are correlated with the levels of inflammatory cytokines.