Rice R W, Kroning J, Critchlow V
Endocrinology. 1976 Apr;98(4):982-90. doi: 10.1210/endo-98-4-982.
The effects of surgical isolation of the medial basal hypothalamus (MBH) on linear growth and plasma growth hormone (GH) levels were studied in adult male and female rats. Whereas MBH isolation resulted in reduced linear growth in males, increased growth resulted in females. These effects were apparent in males 4 weeks after surgery and in females at 10 weeks. The altered growth rates persisted throughout the 28 weeks of the study. MBH isolation in both sexes led to increased food intake, obesity, and atrophy of reproductive tract organs. Non-stress plasma GH levels were unchanged at 4 weeks in both sexes but were elevated at 10 and 26 weeks in females and at 19 and 26 weeks in males. Serial samples of tail vein blood were obtained at 4-h intervals for 44 h from MBH-isolated and shamoperated females at 17 weeks postoperatively, and from similar groups of males at 19 weeks. GH levels were elevated in MBH-isolated rats of both sexes during the afternoons and evenings. Only sham-operated females showed evidence of a 24-h rhythmicity in circulating GH levels. The amplitudes of trough to peak excursions were similar in MBH-isolated and control females, but these excursions were reduced in MBH-isolated males. Although opposite effects on linear growth were noted in the two sexes, the resulting growth rates of operated males and females were similar, suggesting that MBH isolation disrupts mechanisms that normally regulate sex-specific growth patterns. Despite the sex difference in growth responses, MBH isolation caused an eventual increase in plasma GH levels in both sexes. Therefore, it is unlikely that the sex difference in growth responses is attributable exclusively to corresponding changes in circulating GH levels. A reduction in levels of circulating gonadal steroids may be an important factor. The elevations in plasma GH levels observed in both sexes suggest that MBH isolation interferes with mechanisms which inhibit GH secretion.
在成年雄性和雌性大鼠中研究了内侧基底下丘脑（MBH）手术分离对线性生长和血浆生长激素（GH）水平的影响。MBH分离导致雄性大鼠线性生长减少，而雌性大鼠生长增加。这些影响在手术后4周的雄性大鼠和10周的雌性大鼠中明显。在整个28周的研究中，生长速率的改变持续存在。两性的MBH分离均导致食物摄入量增加、肥胖和生殖道器官萎缩。非应激状态下，两性在4周时血浆GH水平均未改变，但雌性在10周和26周时升高，雄性在19周和26周时升高。在术后17周，从MBH分离和假手术的雌性大鼠以及术后19周的类似雄性大鼠组中，每隔4小时采集一次尾静脉血连续样本，共采集44小时。在下午和晚上，MBH分离的两性大鼠GH水平均升高。只有假手术的雌性大鼠显示出血浆GH水平有24小时的节律性。MBH分离的雌性大鼠和对照雌性大鼠从谷值到峰值的波动幅度相似，但MBH分离的雄性大鼠的这些波动幅度减小。尽管在两性中观察到对线性生长的相反影响，但手术的雄性和雌性大鼠最终的生长速率相似，这表明MBH分离破坏了正常调节性别特异性生长模式的机制。尽管生长反应存在性别差异，但MBH分离最终导致两性血浆GH水平升高。因此，生长反应的性别差异不太可能完全归因于循环GH水平的相应变化。循环性腺类固醇水平的降低可能是一个重要因素。两性中观察到的血浆GH水平升高表明，MBH分离干扰了抑制GH分泌的机制。
