van Wijk P A, Rijnberk A, Croughs R J, Wolfswinkel J, Selman P J, Mol J A
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
Eur J Endocrinol. 1994 Apr;130(4):410-6. doi: 10.1530/eje.0.1300410.
Corticotropin-releasing hormone (CRH) and vasopressin are the most important hypothalamic factors regulating adrenocorticotropic hormone (ACTH) secretion. In this study we have investigated the responsiveness of the pituitary-adrenocortical axis to intravenous administration of CRH or lysine vasopressin (LVP) in 16 control dogs, 22 dogs with pituitary-dependent hyperadrenocorticism and five dogs with hyperadrenocorticism due to an adrenocortical tumor, using doses of CRH and LVP that caused equivalent ACTH responses in the control dogs. After CRH administration, the increment in plasma ACTH was significantly (p < 0.05) lower in dogs with pituitary-dependent hyperadrenocorticism (221 +/- 53 ng/l) than that in control dogs (279 +/- 41 ng/l). In the dogs with pituitary-dependent hyperadrenocorticism, the relative increases in ACTH after CRH were significantly (p < 0.05) lower than those after LVP. Despite the absence of an increase in ACTH following LVP administration in dogs with hyperadrenocorticism due to an adrenocortical tumor, there was a significant increase in plasma cortisol, the increment (790 +/- 238 nmol/l) being not statistically different from that in the control dogs (412 +/- 37 nmol/l). We conclude that in spite of the changes inherent to pituitary-dependent hyperadrenocorticism, i.e. neoplastic transformation of corticotropic cells and hypercortisolism, there is persistence of responsiveness to hypophysiotropic hormones. The ACTH secretion by corticotropic cells in pituitary-dependent hyperadrenocorticism was relatively less sensitive to stimulation with CRH than with LVP. Adrenocortical tumors develop an aberrant sensitivity to LVP.
促肾上腺皮质激素释放激素（CRH）和血管加压素是调节促肾上腺皮质激素（ACTH）分泌的最重要的下丘脑因子。在本研究中，我们使用能使对照犬产生等效ACTH反应的CRH和赖氨酸血管加压素（LVP）剂量，研究了16只对照犬、22只垂体依赖性肾上腺皮质功能亢进犬和5只肾上腺皮质肿瘤所致肾上腺皮质功能亢进犬的垂体-肾上腺皮质轴对静脉注射CRH或LVP的反应性。注射CRH后，垂体依赖性肾上腺皮质功能亢进犬（221±53 ng/l）血浆ACTH的增量显著低于对照犬（279±41 ng/l）（p<0.05）。在垂体依赖性肾上腺皮质功能亢进犬中，CRH注射后ACTH的相对增加显著低于LVP注射后（p<0.05）。尽管肾上腺皮质肿瘤所致肾上腺皮质功能亢进犬注射LVP后ACTH没有增加，但血浆皮质醇有显著增加，增量（790±238 nmol/l）与对照犬（412±37 nmol/l）无统计学差异。我们得出结论，尽管垂体依赖性肾上腺皮质功能亢进存在固有的变化，即促肾上腺皮质细胞的肿瘤转化和高皮质醇血症，但对促垂体激素仍有反应性。垂体依赖性肾上腺皮质功能亢进中促肾上腺皮质细胞分泌的ACTH对CRH刺激的敏感性相对低于LVP。肾上腺皮质肿瘤对LVP产生异常敏感性。
