Jessop D S, Chowdrey H S, Lightman S L
Medical Unit, Westminster Hospital, London, U.K.
Brain Res. 1990 Jul 16;523(1):1-4. doi: 10.1016/0006-8993(90)91628-t.
This study demonstrates that a chronic osmotic stimulus can influence the hypothalamo-pituitary axis by inhibiting the secretion of basal and adrenalectomy-elevated adrenocorticotropin (ACTH) from the anterior pituitary. In rats given 340 mM NaCl instead of tap water to drink for 12 days, plasma concentrations of ACTH decreased to 105 +/- 27 pM (mean +/- S.E.M., n = 6) compared with control animals (182 +/- 13 pM). In adrenalectomised (ADX) rats given 150 mM NaCl to drink for 12 days, plasma ACTH concentrations were greatly increased (783 +/- 141 pM) but in ADX rats treated with 340 mM NaCl for the same period, plasma ACTH was similar to controls (237 +/- 59 pM). The corticotropin-releasing factor (CRF-41) content of the median eminence (ME) was reduced in ADX rats on 150 mM NaCl (854 +/- 78 fmol) and further reduced in ADX rats given 340 mM NaCl (510 +/- 56 fmol) compared with control animals (1239 +/- 114 fmol), suggesting that the decrease in plasma ACTH concentrations in saline-treated animals is secondary to a decrease in the secretion of CRF-41 from the ME. These data are the first evidence for a central mechanism, independent of glucocorticoid feedback, through which a chronic osmotic stimulus can inhibit the activity of CRF-41 neurons.
本研究表明，慢性渗透刺激可通过抑制垂体前叶基础促肾上腺皮质激素（ACTH）分泌以及肾上腺切除术后升高的ACTH分泌，来影响下丘脑 - 垂体轴。给大鼠饮用340 mM NaCl而非自来水12天，与对照动物（182±13 pM）相比，血浆ACTH浓度降至105±27 pM（平均值±标准误，n = 6）。给肾上腺切除（ADX）大鼠饮用150 mM NaCl 12天，血浆ACTH浓度大幅升高（783±141 pM），但同期给予340 mM NaCl处理的ADX大鼠，血浆ACTH与对照相似（237±59 pM）。与对照动物（1239±114 fmol）相比，饮用150 mM NaCl的ADX大鼠正中隆起（ME）的促肾上腺皮质激素释放因子（CRF - 41）含量降低（854±78 fmol），饮用340 mM NaCl的ADX大鼠进一步降低（510±56 fmol），这表明盐水处理动物血浆ACTH浓度降低继发于ME中CRF - 41分泌减少。这些数据首次证明了一种独立于糖皮质激素反馈的中枢机制，通过该机制慢性渗透刺激可抑制CRF - 41神经元的活性。
