Department of Physiology, and The Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, People's Republic of China.
Crit Care Med. 2011 Mar;39(3):518-26. doi: 10.1097/CCM.0b013e318206b980.
Reversible adrenal insufficiency frequently has been diagnosed in critically ill patients with sepsis who have either low basal cortisol levels or low cortisol responses to adrenocorticotropic hormone (ACTH) stimulation. It is generally accepted that a phenomenon called "endotoxin tolerance" contributes to immunosuppression during sepsis. The present study was to investigate whether endotoxin tolerance occurs in the adrenal gland, leading to hyporesponsiveness of adrenal gland during sepsis.
Controlled laboratory experiment.
University research laboratory.
Sprague-Dawley male rats 200-250 g and primary isolated adrenal fasciculata-reticularis cells.
Rats received intra-arterial injection of purified lipopolysaccharide (0.5 mg/kg) through indwelling femoral arterial catheters, and 24 hrs later the adrenocortical sensitivity to exogenous ACTH (10 ng/kg) was detected. Primary fasciculata-reticularis cells were pretreated with lipopolysaccharide at 0.1-100 ng/mL or with ACTH at 0.01-10 ng/mL and then challenged, in fresh media, with 1 μg/mL lipopolysaccharide or 10 ng/mL ACTH.
Toll-like receptor 4 was expressed in adrenal gland and primary fasciculata-reticularis cells. Plasma corticosterone response to ACTH was decreased in rats receiving preinjection of lipopolysaccharide. Lipopolysaccharide pretreatment caused a significant decrease in corticosterone production in response to subsequent ACTH and lipopolysaccharide stimulation in primary fasciculata-reticularis cells. Lipopolysaccharide pretreatment inhibited ACTH- and lipopolysaccharide-induced expression of steroid metabolizing enzymes. Lipopolysaccharide significantly decreased Toll-like receptor 4 and ACTH receptor expression.
Pre-exposure to lipopolysaccharide resulted in hyporesponsiveness to ACTH stimulation in rats. In vitro, lipopolysaccharide pretreatment impaired corticosterone production of fasciculata-reticularis cells in response to ACTH and lipopolysaccharide, which was associated with decreased expression of synthetic enzymes required for corticosterone production. Our results indicate that endotoxin tolerance of adrenal gland is one of the mechanisms for adrenocortical insufficiency during sepsis.
在患有败血症的危重病患者中，经常诊断出可逆转的肾上腺功能不全，这些患者要么基础皮质醇水平较低，要么对促肾上腺皮质激素（ACTH）刺激的皮质醇反应较低。人们普遍认为，一种称为“内毒素耐受”的现象导致败血症期间的免疫抑制。本研究旨在探讨内毒素耐受是否发生在肾上腺中，导致败血症期间肾上腺反应低下。
对照实验室实验。
大学研究实验室。
200-250 克雄性 Sprague-Dawley 大鼠和原代分离的肾上腺束状带网状带细胞。
大鼠通过留置股动脉导管经动脉内注射纯化脂多糖（0.5mg/kg），24 小时后检测外源性 ACTH（10ng/kg）对肾上腺皮质的敏感性。原代束状带网状带细胞用脂多糖（0.1-100ng/ml）或 ACTH（0.01-10ng/ml）预处理，然后用 1μg/ml 脂多糖或 10ng/ml ACTH 在新鲜培养基中进行冲击。
Toll 样受体 4 在肾上腺和原代束状带网状带细胞中表达。接受预注射脂多糖的大鼠血浆皮质酮对 ACTH 的反应降低。脂多糖预处理导致随后对 ACTH 和脂多糖刺激的皮质酮产生显著减少。原代束状带网状带细胞中，脂多糖预处理抑制了 ACTH 和脂多糖诱导的类固醇代谢酶的表达。脂多糖显著降低了 Toll 样受体 4 和 ACTH 受体的表达。
预先接触脂多糖可导致大鼠对 ACTH 刺激的反应性降低。在体外，脂多糖预处理损害了束状带网状带细胞对 ACTH 和脂多糖的皮质酮产生，这与皮质酮产生所需的合成酶表达减少有关。我们的结果表明，肾上腺的内毒素耐受是败血症期间肾上腺皮质功能不全的机制之一。
