Guémené D, Williams J B
I.N.R.A., Centre de Tours-Nouzilly, Station de Recherches Avicoles, Nouzilly, France.
Domest Anim Endocrinol. 1999 Jul;17(1):1-15. doi: 10.1016/s0739-7240(99)00020-x.
An experiment was conducted to assess the relative in vivo and in vitro activities of chicken LH-RH-I and -II in laying, incubating and out-of-lay turkey hens. The highest plasma concentrations of LH were measured in laying turkey hens, whereas hypophyseal concentrations were highest in incubating hens (I) and lowest in the laying hens at the end of the laying period (EL). Hypophyseal and plasma concentrations of LH decreased with aging in laying hens (L) and the greater decrease occurred in the hypophyses. An in vitro hypophyseal acute challenge with 2-min pulses of cLHRH I or II (10(-7) M) using a perifusion technique resulted in an increase in the release of LH in out-of-lay (OL) and incubating (I) hens, but not in laying (L) hens. Although both peptides elicited comparable responses in I hens, cLHRH II was more effective in OL hens. This difference was attributable to a greater amplitude of the response, whose duration was unchanged. Hypophyseal desensitization to a subsequent stimulation was observed in OL hens when the interval between stimulations was 30 min, but this did not occur at 60- or 120-min intervals. In vivo, the injection of cLHRH I or II, at doses of 10(-8) and 10(-10) M/kg B.W. stimulated increases in the plasma concentrations of LH, which were initiated within 1 min of injection in OL and I hens but from 5 to 20 min postinjection in L hens. The responses were dose-related and greater immediate responses were measured with cLHRH I than with cLHRH II. Also, after the injection of cLHRH II at the 10(-8) M/kg B.W. dose, the shape of the LH response consisted of an initial increase, followed by a more sustained phase during which LH concentrations were either stable (I hens) or continued to increase (L and OL hens) from 20 to 60 min after injection. In contrast, the injection of cLHRH I at doses of 10(-8) or 10(-10) M/kg or cLHRH II at a dose of 10(-10) M/kg in I and OL hens, produced a peak of LH concentrations in plasma within 5 min and thereafter declined gradually. The difference in the in vivo responses to LHRH I and II could not be attributed to a greater potency of cLHRH II, but to a more prolonged action. In summary, the responses to both forms of chicken LH-RH varies markedly with the stage of the reproductive cycle (L, I, and OL) and differs between the in vivo and in vitro situations. Although cLHRH II may be more active than cLHRH I, controversy still surrounds its precise physiological role.
进行了一项实验，以评估鸡促黄体生成素释放激素-I（cLHRH-I）和-II（cLHRH-II）在产蛋、抱窝和休产火鸡母鸡体内和体外的相对活性。在产蛋火鸡母鸡中测得的促黄体生成素（LH）血浆浓度最高，而垂体浓度在抱窝母鸡中最高（I），在产蛋期末（EL）的产蛋母鸡中最低。产蛋母鸡（L）的垂体和血浆中LH浓度随年龄增长而降低，且垂体中的降低幅度更大。使用灌流技术对垂体进行2分钟脉冲的cLHRH I或II（10⁻⁷ M）体外急性刺激，导致休产（OL）和抱窝（I）母鸡的LH释放增加，但产蛋（L）母鸡中未增加。尽管两种肽在I母鸡中引发了类似的反应，但cLHRH II在OL母鸡中更有效。这种差异归因于反应幅度更大，其持续时间不变。当刺激间隔为30分钟时，在OL母鸡中观察到垂体对后续刺激的脱敏，但在60分钟或120分钟间隔时未发生。在体内，以10⁻⁸和10⁻¹⁰ M/kg体重的剂量注射cLHRH I或II，刺激了LH血浆浓度的增加，在OL和I母鸡中注射后1分钟内开始，而在L母鸡中在注射后5至20分钟开始。反应与剂量相关，cLHRH I比cLHRH II测得的即时反应更大。此外，以10⁻⁸ M/kg体重的剂量注射cLHRH II后，LH反应的形状包括初始增加，随后是一个更持续的阶段，在此期间，LH浓度在注射后20至60分钟内要么稳定（I母鸡）要么继续增加（L和OL母鸡）。相比之下，在I和OL母鸡中以10⁻⁸或10⁻¹⁰ M/kg的剂量注射cLHRH I或以10⁻¹⁰ M/kg的剂量注射cLHRH II，在5分钟内血浆中LH浓度达到峰值，此后逐渐下降。对LHRH I和II的体内反应差异不能归因于cLHRH II的效力更大，而是归因于作用更持久。总之，对两种形式的鸡促黄体生成素释放激素的反应随生殖周期阶段（L、I和OL）有显著差异，且在体内和体外情况之间也有所不同。尽管cLHRH II可能比cLHRH I更活跃，但其确切的生理作用仍存在争议。
