Rebuffat P, Belloni A S, Musajo F G, Rocco S, Markowska A, Mazzocchi G, Nussdorfer G G
Department of Anatomy, University of Padua, Italy.
J Steroid Biochem Mol Biol. 1994 Mar;48(4):353-60. doi: 10.1016/0960-0760(94)90075-2.
The effect of SRIF and its antagonist cyclo(7-aminoheptanonyl-Phe-D-Trp-Lys-Thr magnitude of Bzl)(SRIF-A) were studied in sham-operated and bilaterally adrenalectomized rats bearing ACTH- and angiotensin II (ANG-II)-responsive adrenocortical autotransplants. SRIF-A (10(-5) M) completely annulled SRIF (10(-6) M)-induced inhibition of ANG-II (10(-8) M)-evoked rise in aldosterone (ALDO) secretion by both dispersed zona glomerulosa (ZG) cells and autotransplant slices. A 7-day intraperitoneal infusion with SRIF (0.3 nmol.kg-1.min-1) significantly lowered plasma ALDO concentration (PAC) in both groups of animals, without affecting plasma renin activity and the plasma levels of ACTH and corticosterone. This treatment caused a marked atrophy of adrenal ZG and its parenchymal cells (without inducing any significant change in the zona fasciculata morphology), as well as of ZG-like cells of autotransplants. Isolated ZG cells and autotransplant slices from SRIF-infused rats evidenced a notable decrease in both their basal and maximally ACTH- or ANG-II-stimulated ALDO production. The simultaneous infusion of rats with SRIF-A (3 nmol.kg-1.min-1) completely reversed all these effects of SRIF. The prolonged infusion with SRIF-A alone caused, in sham-operated rats, a marked increase in PAC and a significant hypertrophy of ZG and ZG cells; basal and maximally-stimulated ALDO secretion of dispersed ZG cells was also notably raised. Conversely, SRIF-A infusion did not evoke any appreciable effect in autotransplanted rats. These findings suggest that endogenous SRIF is specifically involved in the negative control of the secretion and growth of the rat adrenal ZG. Since regenerated adrenocortical autotransplants, which are responsive to SRIF but not to SRIF-A infusion, are completely deprived of chromaffin cells, the hypothesis is advanced that adrenal zona medullaris may be the source of endogenous SRIF regulating ZG function.
在假手术和双侧肾上腺切除且带有促肾上腺皮质激素（ACTH）和血管紧张素 II（ANG-II）反应性肾上腺皮质自体移植的大鼠中，研究了生长抑素（SRIF）及其拮抗剂环（7-氨基庚酰基 - 苯丙氨酸 - D - 色氨酸 - 赖氨酸 - 苏氨酸 - 苄酯）（SRIF-A）的作用。SRIF-A（10⁻⁵ M）完全消除了 SRIF（10⁻⁶ M）诱导的对 ANG-II（10⁻⁸ M）引起的分散的球状带（ZG）细胞和自体移植切片中醛固酮（ALDO）分泌增加的抑制作用。两组动物腹腔内连续 7 天输注 SRIF（0.3 nmol·kg⁻¹·min⁻¹）均显著降低血浆 ALDO 浓度（PAC），但不影响血浆肾素活性以及 ACTH 和皮质酮的血浆水平。这种处理导致肾上腺 ZG 及其实质细胞明显萎缩（束状带形态无明显变化），以及自体移植的 ZG 样细胞萎缩。来自输注 SRIF 的大鼠的分离的 ZG 细胞和自体移植切片显示，其基础和最大 ACTH 或 ANG-II 刺激的 ALDO 产生均显著降低。同时给大鼠输注 SRIF-A（3 nmol·kg⁻¹·min⁻¹）完全逆转了 SRIF 的所有这些作用。单独长期输注 SRIF-A 在假手术大鼠中导致 PAC 显著升高以及 ZG 和 ZG 细胞明显肥大；分散的 ZG 细胞的基础和最大刺激的 ALDO 分泌也显著升高。相反，输注 SRIF-A 在自体移植大鼠中未引起任何明显影响。这些发现表明内源性 SRIF 特异性参与大鼠肾上腺 ZG 分泌和生长的负调控。由于对 SRIF 有反应但对输注 SRIF-A 无反应的再生肾上腺皮质自体移植完全没有嗜铬细胞，因此提出肾上腺髓质可能是调节 ZG 功能的内源性 SRIF 的来源这一假说。
