Richardson Heather N, Gore Andrea C, Venier Jane, Romeo Russell D, Sisk Cheryl L
Department of Psychology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
Mol Cell Endocrinol. 2004 Feb 12;214(1-2):63-70. doi: 10.1016/j.mce.2003.11.013.
Pubertal development is associated with increased activity of the gonadotropin releasing hormone (GnRH) neuronal system and rising gonadal steroid levels. The purpose of this study was to determine whether different circulating levels of testosterone affect GnRH mRNA and luteinizing hormone (LH) to the same degree prior to and following pubertal maturation. Pre- and post-pubertal male Syrian hamsters were gonadectomized and treated with timed-release testosterone pellets (0, 0.5, 1.5, or 2.5mg) for one week. Following treatment, three separate brain tissue dissections containing the majority of GnRH cell bodies, tenia tecta and medial septum (TT/MS), diagonal band of Broca/organum vasculosum of the lamina terminalis (DBB/OVLT), and preoptic area (POA), were analyzed for GnRH mRNA levels by RNase protection assay and terminal plasma luteinizing hormone concentrations were determined by radioimmunoassay. Pre-pubertal animals were more sensitive to testosterone negative feedback on LH. Conversely, the ability of testosterone to reduce GnRH mRNA was much greater after pubertal development. Specifically, GnRH mRNA in the TT/MS was considerably higher in adults, and testosterone reduced GnRH mRNA in a dose-dependent manner only in adults. These data indicate that although testosterone is a powerful suppressor of LH release before puberty, it does not have appreciable control over GnRH mRNA until after puberty. Furthermore, the pubertal increase in GnRH mRNA appears to occur via steroid feedback-independent mechanisms in the male Syrian hamster.
青春期发育与促性腺激素释放激素（GnRH）神经元系统活性增加以及性腺类固醇水平上升有关。本研究的目的是确定不同循环水平的睾酮在青春期成熟前后是否对GnRH mRNA和促黄体生成素（LH）产生相同程度的影响。对青春期前和青春期后的雄性叙利亚仓鼠进行去势，并使用缓释睾酮丸剂（0、0.5、1.5或2.5毫克）治疗一周。治疗后，对包含大部分GnRH细胞体、终纹床核和内侧隔（TT/MS）、布罗卡斜带/终板血管器（DBB/OVLT）以及视前区（POA）的三个独立脑组织切片进行分析，通过核糖核酸酶保护试验检测GnRH mRNA水平，并通过放射免疫测定法测定血浆终末促黄体生成素浓度。青春期前的动物对睾酮对LH的负反馈更为敏感。相反，青春期发育后睾酮降低GnRH mRNA的能力要强得多。具体而言，TT/MS中的GnRH mRNA在成年动物中明显更高，并且睾酮仅在成年动物中以剂量依赖的方式降低GnRH mRNA。这些数据表明，尽管睾酮在青春期前是LH释放的有力抑制剂，但直到青春期后它才对GnRH mRNA有明显的调控作用。此外，在雄性叙利亚仓鼠中，GnRH mRNA的青春期增加似乎是通过与类固醇反馈无关的机制发生的。
