Katakami H, Berelowitz M, Marbach M, Frohman L A
Endocrinology. 1985 Aug;117(2):557-60. doi: 10.1210/endo-117-2-557.
The effect of exogenously administered GH on somatostatin (SRIF) receptor regulation was studied in rat anterior pituitary membranes. A single class, high affinity specific receptor for SRIF was identified by binding studies with [125I-Tyr11]SRIF [binding capacity (mean +/- SD), 129.4 +/- 23.3 fmol/mg protein; binding affinity, 2.8 +/- 0.6 X 10(10) M-1]. A single injection of rat GH (150 micrograms) caused a significant reduction in capacity, but not in affinity, of SRIF receptors 2 and 6 h after injection (mean decrease, 23% and 24%, respectively) from that in controls. In contrast, mean SRIF binding capacity 24 h after a single injection of rat GH was increased 48% above control values, but affinity was unaffected. Measurement of membrane SRIF content indicated that these changes could not be explained by alterations in receptor occupancy. When rat GH was injected repeatedly for 3 days (150 micrograms/rat X day), the mean binding capacity, though not the affinity, of SRIF receptors was decreased 23% from that in controls 24 h after the last injection. The results can be explained by stimulation of SRIF release from the hypothalamus by GH and somatomedins, with subsequent internalization of the pituitary plasma membrane SRIF receptor. They suggest yet another level of neuroendocrine regulation of GH secretion.
研究了外源性给予生长激素（GH）对大鼠垂体前叶膜中生长抑素（SRIF）受体调节的影响。通过用[125I-酪氨酸11]SRIF进行结合研究，鉴定出一类单一的、高亲和力的SRIF特异性受体[结合容量（平均值±标准差），129.4±23.3 fmol/mg蛋白质；结合亲和力，2.8±0.6×10(10) M-1]。单次注射大鼠GH（150微克）后2小时和6小时，SRIF受体的容量显著降低，但亲和力未受影响（平均降低分别为23%和24%）。相比之下，单次注射大鼠GH后24小时，SRIF结合容量比对照值增加了48%，但亲和力未受影响。膜SRIF含量的测定表明，这些变化不能用受体占有率的改变来解释。当大鼠GH连续注射3天（150微克/大鼠×天）时，末次注射后24小时，SRIF受体的平均结合容量（而非亲和力）比对照降低了23%。这些结果可以通过GH和生长调节素刺激下丘脑释放SRIF，随后垂体质膜SRIF受体内化来解释。它们提示了GH分泌神经内分泌调节的另一个层面。
