Tandon O P, Chintala R
Department of Physiology, University College of Medical Sciences & GTB Hospital, Shahdara, Delhi-110 095.
Indian J Physiol Pharmacol. 2001 Oct;45(4):395-407.
Gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus is pivotal to the regulation of reproductive physiology in vertebrates. The characteristic periodic secretion of gonadotropin releasing hormone (GnRH) from the medial basal hypothalamus (MBH), at the rate of one pulse an hour is essential for the maintenance of the menstrual cycle. These pulses are due to oscillations in the electrical activity of the GnRH pulse generator in the MBH. The GnRH pulse generator is under the influence of an assortment of interactions of multiple neural, hormonal and environmental inputs to the hypothalamus. Hence, a number of conditions such as stress, drug intake, exercise, sleep affect the activity of this pulse generator. Any deviation of normal frequency results in disruption of normal cycle. The cycle can become anovulatory in the hypothalamic lesions and can be restored by exogenous administration of pulsatile GnRH. Of late, studies have shown that pulse generator activity is also maintained by specific metabolic signals meant for energy homeostasis. Studies are in progress to work out cellular basis of GnRH pulse generator's rhythmic activation and role of Ca++ as second messenger for GnRH stimulated gonadotropin release. New concepts are emerging to find the existence of an FSH releasing factor, which independently regulates the activity of FSH.
下丘脑促性腺激素释放激素（GnRH）的分泌对于脊椎动物生殖生理的调节至关重要。内侧基底下丘脑（MBH）以每小时一次脉冲的速率周期性分泌促性腺激素释放激素（GnRH），这对于维持月经周期至关重要。这些脉冲是由于MBH中GnRH脉冲发生器电活动的振荡所致。GnRH脉冲发生器受到下丘脑多种神经、激素和环境输入的各种相互作用的影响。因此，许多情况，如压力、药物摄入、运动、睡眠，都会影响这个脉冲发生器的活动。正常频率的任何偏差都会导致正常周期的紊乱。在下丘脑病变中，周期可能会无排卵，而通过外源性给予脉冲式GnRH可以恢复。最近，研究表明脉冲发生器的活动也由用于能量稳态的特定代谢信号维持。目前正在进行研究以阐明GnRH脉冲发生器节律性激活的细胞基础以及Ca++作为GnRH刺激促性腺激素释放的第二信使的作用。关于存在独立调节FSH活性的FSH释放因子的新观念正在出现。
