Bakker J, Baum M J
Department of Biology, Boston University, 5 Cummington St, Boston, MA 02215, USA.
J Reprod Fertil. 2000 Jul;119(2):315-21. doi: 10.1530/jrf.0.1190315.
In vitro release and content of GnRH in mediobasal hypothalamic slices are reduced by ovariectomy of female ferrets but are not affected by castration of male ferrets in breeding condition. The aim of the present study was to determine whether this sex difference reflects a sexually dimorphic effect of gonadal steroids on mediobasal hypothalamic GnRH mRNA content of male and female ferrets killed 4 weeks after gonadectomy, either with or without steroid hormone replacement. This time interval exceeds the 6-10 days needed for increments in plasma LH concentrations to stabilize after gonadectomy of ferrets of both sexes. In situ hybridization using an (35)S-labelled oligoprobe complementary to the human GnRH coding region showed that the number of mediobasal hypothalamic neurones and the cellular content of GnRH mRNA did not differ significantly among groups of male and female ferrets that were either in breeding condition or that had been gonadectomized and treated with sex steroids or oil vehicle. These results indicate that gonadal hormones regulate mediobasal hypothalamic GnRH biosynthesis and release in both sexes via post-transcriptional events that may include GnRH mRNA translation or the conversion of pre-pro GnRH precursor into mature GnRH.
雌性雪貂卵巢切除后，中基底下丘脑切片中GnRH的体外释放和含量降低，但处于繁殖状态的雄性雪貂去势后不受影响。本研究的目的是确定这种性别差异是否反映了性腺类固醇对去势4周后处死的雄性和雌性雪貂中基底下丘脑GnRH mRNA含量的性二态性作用，无论是否进行类固醇激素替代。这个时间间隔超过了两性雪貂去势后血浆LH浓度升高至稳定所需的6 - 10天。使用与人类GnRH编码区互补的(35)S标记寡核苷酸探针进行原位杂交显示，处于繁殖状态、去势并用性类固醇或油载体处理的雄性和雌性雪貂组之间，中基底下丘脑神经元数量和GnRH mRNA的细胞含量没有显著差异。这些结果表明，性腺激素通过转录后事件调节两性中基底下丘脑GnRH的生物合成和释放，这些事件可能包括GnRH mRNA翻译或前体促性腺激素释放激素前体转化为成熟的GnRH。
