Sonntag W E, Steger R W, Forman L J, Meites J
Endocrinology. 1980 Dec;107(6):1875-9. doi: 10.1210/endo-107-6-1875.
Pulsatile release of GH was compared in young (4-5 months old) and old (18-20 months old) male Sprague-Dawley rats using indwelling atrial cannulae. More than 57% of the young rats exhibited GH pulses greater than 300 ng/ml plasma, whereas only 7% of the old animals had GH pulses of similar amplitude. Trough GH values were not different between young and old rats, but during the 10.5-h sampling period, mean GH concentrations in young male rats were significantly greater than those in old male rats (175.3 +/- 20.9 vs. 70.2 +/- 7.6 ng/ml; P < 0.01). In another experiment, pituitary GH and hypothalamic somatostatin content were measured in young and old rats. The pituitary GH content was significantly greater in young than in old males (1187 +/- 95 vs. 670 +/- 93 microgram; P < 0.01). The immunoreactive somatostatin content in caudal areas of the hypothalamus was also greater in young than in old male rats (100.2 +/- 4.2 vs. 79.0 +/- 5.1 ng; P < 0.01). These observations demonstrate that GH secretion is depressed in old male rats, and this is associated with diminished pulsatile release of GH. The results also suggest that a relationship exists among the reduction in somatostatin content, pituitary GH content, and attenuated GH secretion in old male rats.
使用留置心房插管法，比较了年轻（4 - 5个月大）和年老（18 - 20个月大）雄性Sprague-Dawley大鼠生长激素（GH）的脉冲式释放情况。超过57%的年轻大鼠血浆中GH脉冲大于300 ng/ml，而只有7%的年老动物有类似幅度的GH脉冲。年轻和年老大鼠的GH谷值没有差异，但在10.5小时的采样期内，年轻雄性大鼠的平均GH浓度显著高于年老雄性大鼠（175.3±20.9 vs. 70.2±7.6 ng/ml；P < 0.01）。在另一项实验中，测量了年轻和年老大鼠垂体GH和下丘脑生长抑素的含量。年轻雄性大鼠的垂体GH含量显著高于年老雄性大鼠（1187±95 vs. 670±93微克；P < 0.01）。年轻雄性大鼠下丘脑尾部区域的免疫反应性生长抑素含量也高于年老雄性大鼠（100.2±4.2 vs. 79.0±5.1 ng；P < 0.01）。这些观察结果表明，年老雄性大鼠的GH分泌受到抑制，这与GH脉冲式释放减少有关。结果还表明，年老雄性大鼠生长抑素含量降低、垂体GH含量降低和GH分泌减弱之间存在关联。
