Young Bradley A, Bryan Mara B, Sower Stacia A, Scott Alexander P, Li Weiming
Department of Fisheries and Wildlife, 13 Natural Resources Building, Michigan State University, East Lansing, MI 48824-1222, USA.
Gen Comp Endocrinol. 2004 Apr;136(2):276-81. doi: 10.1016/j.ygcen.2003.12.022.
The sea lamprey (Petromyzon marinus L.) represents one of the two most ancient classes of vertebrates and possesses a functional hypothalamus-pituitary-gonadal axis. However, the presence and functionality of androgens in the sea lamprey remain elusive. Recently, 15alpha-hydroxytestosterone (15alpha-T) has been found in sea lamprey gonads and blood plasma. In this study we examined changes of circulatory concentrations of 15alpha-T in response to gonadotropin releasing hormone (GnRH) treatments. Plasma concentrations of 15alpha-T in sea lamprey increased 2-5 times for all GnRH-injected sea lamprey compared to controls (P < 0.001). However, there were no differences among responses: (1) to the two forms of GnRH (lamprey GnRH I or lamprey GnRH III), (2) to the doses delivered (50, 100, or 200 microg/kg), or (3) between post-injection sample intervals (8 or 24 h). Between lampreys from the Atlantic Ocean and Great Lakes sites, two of seven GnRH form and dosage comparisons showed between-site differences, but were not believed to represent an overall between-site difference. These are the first data to show a response of a C19 steroid to GnRH stimulation in sea lamprey.
海七鳃鳗（Petromyzon marinus L.）是两类最古老的脊椎动物之一，拥有一个功能正常的下丘脑-垂体-性腺轴。然而，海七鳃鳗中雄激素的存在及其功能仍不明确。最近，在海七鳃鳗的性腺和血浆中发现了15α-羟基睾酮（15α-T）。在本研究中，我们检测了海七鳃鳗在促性腺激素释放激素（GnRH）处理后循环中15α-T浓度的变化。与对照组相比，所有注射GnRH的海七鳃鳗血浆中15α-T的浓度增加了2至5倍（P < 0.001）。然而，在以下方面的反应中没有差异：（1）对两种形式的GnRH（七鳃鳗GnRH I或七鳃鳗GnRH III）；（2）对给药剂量（50、100或200微克/千克）；或（3）注射后采样间隔（8小时或24小时）之间。在来自大西洋和五大湖地区的七鳃鳗之间，七项GnRH形式和剂量比较中的两项显示出地区间差异，但不认为这代表总体的地区间差异。这些是首次表明C19类固醇对海七鳃鳗GnRH刺激有反应的数据。
