GROWTH-HORMONE PULSATILITY AND THE ENDOCRINE MILIEU DURING SEXUAL-MATURATION IN MALE AND FEMALE RATS
GROWTH-HORMONE PULSATILITY AND THE ENDOCRINE MILIEU DURING SEXUAL-MATURATION IN MALE AND FEMALE RATS
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DOI：
10.1159/000126284
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发表时间：
1992-11-01
影响因子：
4.1
通讯作者：
RUIZ, NS
中科院分区：
文献类型：
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作者：
GABRIEL, SM;RONCANCIO, JR;RUIZ, NS
虽然成年大鼠的生长激素(RGH)分泌具有性二态模式，但在年轻大鼠中，RGH的间歇性释放并不完全。在本研究中，28至113日龄的大鼠接受了颈静脉导管，并被安置在为无应激采血而设计的房间中。术后3~7d，16.00~22.00h，每10分钟采血一次，33日龄前雄性和雌性RGH搏动性分泌相似。低基线RGH分泌夹杂着不频繁、低幅度的脉冲。在青春期早期，在33至40天龄之间，RGH脉冲幅度在两性中都增加了十倍以上。此时，男性RGH脉冲的持续时间明显长于女性，这一模式一直持续到成年。到青春期晚期，在41至54天龄之间，RGH脉冲幅度在两性中类似地增加了两倍。基线RGH分泌在这个时候在两性中都增加了，女性的基线比男性高。只有在54日龄以上的成年大鼠，才有典型的基础RGH分泌减少，并伴有高幅度、低频率的RGH脉冲，雄性与雌性相比明显。体重上的性别差异，即雄性体重超过雌性，在第33天后变得明显。在这种性别差异之前，在研究的所有年龄段中，男性相对于女性的睾丸素水平都有所增加。33日龄至41日龄雌性大鼠血清17β-雌二醇浓度高于雄性大鼠，反映了发情前期第一个内分泌期延长。从第28天到第54天，两性的血浆胰岛素样生长因子-1(IGF-1)浓度都增加了三倍。然而，只有在成年人中才有显著的性别差异，男性比女性更大，注意到。此外，在33天后，雌性的血清皮质酮水平一直高于雄性。这些研究表明，在大鼠青春期前后，性二型间歇性RGH的释放逐渐发展。由于体重的性别差异在这种模式完全确立之前就已经形成，其他因素，如性腺和肾上腺类固醇，或它们与RGH的相互作用，可能会导致体重的性别差异。
Although a sexually dimorphic pattern of rat growth hormone (rGH) secretion is well recognized in adult rats, episodic rGH release has been incompletely characterized in younger rats. In the present study, 28 to 113-day-old rats received jugular catheters and were housed in chambers designed for stress-free blood sampling. Three to seven days after surgery, 300 mul of blood was withdrawn every 10 min between 16.00 and 22.00 h. Pulsatile rGH secretion before 33 days of age was similar in males and females. Low baseline rGH secretion was interspersed with infrequent, low amplitude pulses. In early puberty, between 33 and 40 days of age, rGH pulse amplitudes increased more than tenfold in both sexes. The duration of rGH pulses was significantly greater at this time in males versus females, a pattern that continued though adulthood. By late puberty, between 41 and 54 days of age, rGH pulse amplitudes similarly increased twofold in both sexes. Baseline rGH secretion increased at this time in both sexes, with females having a higher baseline compared to males. Only in adult rats over 54 days of age, was the typical pattern of low basal rGH secretion, combined with high amplitude, low frequency rGH pulses in males versus females evident. A sex difference in body weight, i.e. males weighing more than females, became evident after day 33 of age. This sex difference was preceded by an increase in testosterone in males versus females at all ages examined. Serum 17beta-estradiol concentrations were higher in female rats compared to male rats between 33 and 41 days of age, reflecting the extended first proestrus endocrine phase. Plasma insulin-like growth factor-1 (IGF-1) concentrations increased threefold in both sexes from days 28 through 54 of age. However, only in adults was a significant sex difference, males greater than females, noted. In addition, serum corticosterone levels were higher in females than in males at all times after 33 days of age. These studies suggest that sexually dimorphic episodic rGH release develops gradually during the peripubertal period in rats. Because a sex difference in body weight develops bevore this pattern is fully established, other factors, such as gonadal and adrenal steroids, or their interaction with rGH, may contribute to the sex difference in body weight.