Miki N, Ono M, Shizume K
Department of Medicine, Tokyo Women's Medical College, Japan.
J Endocrinol. 1988 May;117(2):245-52. doi: 10.1677/joe.0.1170245.
Secretion of GH occurs in episodic bursts under the dual control of two hypothalamic peptides, GH-releasing factor (GRF) and GH-inhibiting factor (somatostatin, SRIF). Recent studies in rats suggest that episodic GH secretion is generated by the periodic release of GRF, which is associated with the simultaneous withdrawal of SRIF secretion. To test the possibility that GRF discharge is functionally coupled with the withdrawal of SRIF, we investigated whether acute withdrawal of SRIF can induce GRF release by the rat hypothalamus using highly specific antisera against SRIF and rat GRF. In conscious unrestrained rats, i.v. administration of SRIF antiserum at the period of the GH trough induced a rapid onset of the GH secretory surge with a peak value of 309 +/- 67 micrograms/l (mean +/- S.E.M.) 30 min after injection. Pretreatment with antiserum to rat GRF resulted in a approximately 83% suppression of the GH surge induced by SRIF antiserum without affecting the trough GH values. GRF antiserum also significantly inhibited the spontaneous GH surge. In urethane-anaesthetized rats, as in conscious rats, an acute phasic GH release was caused by SRIF antiserum despite the interference of anaesthesia with spontaneous GH secretion. A further surge-like GH secretion was not restored during the next several hours, however, with the GH secretory profile being characterized by a tonic increase in the baseline levels of GH. In the anaesthetized rat antiserum to rat GRF, having no effect on basal GH levels, similarly inhibited by approximately 66% the acute GH surge induced by SRIF antiserum and decreased by about 30% the later sustained rise in GH.(ABSTRACT TRUNCATED AT 250 WORDS)
生长激素（GH）的分泌在两种下丘脑肽，即生长激素释放因子（GRF）和生长激素抑制因子（生长抑素，SRIF）的双重控制下以脉冲式爆发进行。最近对大鼠的研究表明，脉冲式GH分泌是由GRF的周期性释放产生的，这与SRIF分泌的同时减少有关。为了测试GRF释放是否在功能上与SRIF的减少相关，我们使用针对SRIF和大鼠GRF的高度特异性抗血清，研究了SRIF的急性减少是否能诱导大鼠下丘脑释放GRF。在清醒不受约束的大鼠中，在GH低谷期静脉注射SRIF抗血清，注射后30分钟迅速引发GH分泌高峰，峰值为309±67微克/升（平均值±标准误）。预先用大鼠GRF抗血清处理可使SRIF抗血清诱导的GH高峰抑制约83%，而不影响GH低谷值。GRF抗血清也显著抑制了自发的GH高峰。在氨基甲酸乙酯麻醉的大鼠中，与清醒大鼠一样，尽管麻醉干扰了自发的GH分泌，但SRIF抗血清仍引起了急性阶段性GH释放。然而，在接下来的几个小时内，并未恢复进一步的类似高峰的GH分泌，GH分泌曲线的特征是GH基线水平呈持续性升高。在麻醉大鼠中，大鼠GRF抗血清对基础GH水平无影响，但同样抑制了SRIF抗血清诱导的急性GH高峰约66%，并使随后GH的持续升高降低了约30%。（摘要截短于250字）
