CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, David Geffen School of Medicine, UCLA, and VA Greater Los Angeles Healthcare System, CA, USA.
Neuroendocrinology. 2011;93(3):165-73. doi: 10.1159/000322590. Epub 2010 Dec 6.
Corticotropin-releasing hormone (CRH) is expressed in the brain, immune cells and the gut, where gene expression is upregulated by lipopolysaccharide (LPS) 6 h after injection. Whether these changes are reflected by increased circulating levels of CRH and adrenocorticotropic hormone (ACTH) is unknown.
LPS (100 μg/kg) was injected intraperitoneally in conscious rats, and blood processed for CRH using the new RAPID (reduced temperatures, acidification, protease inhibition, isotopic exogenous controls and dilution) method compared with EDTA blood with or without plasma methanol extraction. Hormone levels were measured by commercial radioimmunoassay.
The RAPID method improved blood recovery of ¹²⁵I-CRH in vitro compared to EDTA only added to the blood without or with methanol extraction (90.8 ± 2.0 vs. 66.9 ± 2.6 and 47.5 ± 2.0%, respectively; p < 0.001 vs. RAPID). Basal CRH levels from blood processed by the RAPID method were 28.9 ± 2.8 pg/ml, and by other methods below the radioimmunoassay detection limit (<10 pg/ml). At 6 h after LPS, CRH plasma levels increased significantly by 2.9 times, and in the proximal colon tended to decrease (-27.6 ± 5.7%; p > 0.05), while circulating levels were unchanged at 3 or 4 h. ACTH levels rose compared to control rats (135.3 ± 13.8 vs. 101.4 ± 6.0 pg/ml; p < 0.05) 30 min after the increase in CRH, while at 3 or 6 h after LPS, the levels were not changed.
Intraperitoneal LPS induces a delayed rise in plasma CRH levels associated with an elevation in ACTH plasma levels 30 min later, suggesting that under conditions of immune challenge, CRH of peripheral origin may also contribute to pituitary activation, as detected using the RAPID method of blood processing, which improves CRH recovery.
促肾上腺皮质激素释放激素（CRH）在大脑、免疫细胞和肠道中表达，其基因表达在注射脂多糖（LPS）后 6 小时上调。尚不清楚这些变化是否反映在循环 CRH 和促肾上腺皮质激素（ACTH）水平的增加上。
将 LPS（100μg/kg）腹腔内注射到清醒大鼠中，使用新的 RAPID（降低温度、酸化、蛋白酶抑制、同位素外源性对照和稀释）方法处理血液，以与仅添加 EDTA 血液或添加 EDTA 血液加甲醇萃取进行比较。使用商业放射免疫测定法测量激素水平。
RAPID 法与仅添加 EDTA 血液（分别为 66.9±2.6 和 47.5±2.0%；p<0.001 与 RAPID 相比）或添加 EDTA 血液加甲醇萃取（分别为 66.9±2.6 和 47.5±2.0%；p<0.001 与 RAPID 相比）相比，提高了体外 ¹²⁵I-CRH 的血液回收率。RAPID 法处理的血液中基础 CRH 水平为 28.9±2.8 pg/ml，而其他方法则低于放射免疫测定法的检测下限（<10 pg/ml）。LPS 后 6 小时，CRH 血浆水平显著升高 2.9 倍，而在近端结肠有下降趋势（-27.6±5.7%；p>0.05），而 3 或 4 小时时循环水平无变化。与对照大鼠相比，ACTH 水平在 CRH 升高 30 分钟后升高（135.3±13.8 与 101.4±6.0 pg/ml；p<0.05），而在 LPS 后 3 或 6 小时时无变化。
腹腔内 LPS 诱导血浆 CRH 水平延迟升高，与 30 分钟后 ACTH 血浆水平升高相关，提示在免疫挑战条件下，外周来源的 CRH 也可能有助于垂体激活，如使用 RAPID 血液处理方法检测到的那样，该方法可提高 CRH 回收率。
