Rol De Lama M A, Roest C, Rolf K, Rautenberg M, Tresguerres J A, Ariznavarreta C
Department of Physiology, Medical School, Complutense University, Madrid, Spain.
Ann Hum Biol. 2001 Jan-Feb;28(1):38-50. doi: 10.1080/03014460150201878.
A striking sex-related difference in postpubertal growth and growth hormone (GH) secretory pattern in the rat has been described. Although this sexual dimorphism seems to be determined by the neonatal effects of gonadal steroids on the hypothalamus, peripubertal exposure to steroids also plays an important role. In order to study the real influence of the hypothalamic sex and/or peripubertal gonadal steroids, the growth pattern of female and male rats in response to neonatal and peripubertal sexual steroid treatments was studied using microknemometry, a technique that allows non-invasive daily measurements of rat tibial growth rate. Neonatal steroid environment in males was modified by castration on day 1, whereas in females it was changed by a single neonatal testosterone administration on day 5 followed by castration at 13 days of age. From the onset of puberty to adulthood, both female and male animals received testosterone or estrogens, respectively. Neonatal treatment alone, i.e. androgenization of female and castration of male rats, were only able to induce a partial reversal of the original sex-dependent growth pattern. Additional peripubertal treatments achieved a complete change in the sex-linked growth pattern. Consistent with the effects observed on growth, the pituitary GH concentration was significantly increased in females, and diminished in males, when they were treated both at the neonatal and peripubertal stages. However, only this latter group, whose growth was more seriously compromised, showed decreased plasma insulin-like growth factor-I (IGF-I) levels. In conclusion, a complete feminization of male tibial growth pattern or masculinization of female pattern can only be achieved by maintaining the new steroid environment from puberty to adulthood.
已描述了大鼠青春期后生长及生长激素（GH）分泌模式中显著的性别相关差异。尽管这种性别二态性似乎由性腺类固醇对下丘脑的新生效应所决定，但青春期前后接触类固醇也起重要作用。为了研究下丘脑性别和/或青春期前后性腺类固醇的实际影响，使用微骨测量法研究了雌性和雄性大鼠在新生儿期和青春期前后接受性类固醇处理后的生长模式，该技术可对大鼠胫骨生长速率进行无创每日测量。雄性大鼠的新生儿期类固醇环境通过出生第1天去势进行改变，而雌性大鼠则通过出生第5天单次给予睾酮随后在13日龄去势来改变。从青春期开始到成年，雌性和雄性动物分别接受睾酮或雌激素处理。仅新生儿期处理，即雌性大鼠雄激素化和雄性大鼠去势，仅能诱导原始性别依赖性生长模式的部分逆转。青春期前后的额外处理实现了与性别相关的生长模式的完全改变。与对生长的影响一致，在新生儿期和青春期前后均接受处理的雌性大鼠垂体GH浓度显著升高，而雄性大鼠则降低。然而，只有后一组生长受到更严重损害的大鼠血浆胰岛素样生长因子-I（IGF-I）水平降低。总之，只有从青春期到成年维持新的类固醇环境，才能实现雄性胫骨生长模式的完全雌性化或雌性模式的雄性化。
