Wade G N, Schneider J E, Li H Y
Department of Psychology, University of Massachusetts, Amherst 01003-7710, USA.
Am J Physiol. 1996 Jan;270(1 Pt 1):E1-19. doi: 10.1152/ajpendo.1996.270.1.E1.
In female mammals, reproduction is extremely sensitive to the availability of oxidizable metabolic fuels. When food intake is limited or when an inordinate fraction of the available energy is diverted to other uses such as exercise or fattening, reproductive attempts are suspended in favor of processes necessary for individual survival. Both reproductive physiology and sexual behaviors are influenced by food availability. Nutritional effects on reproductive physiology are mediated by changes in the activity of gonadotropin-releasing hormone (GnRH) neurons in the forebrain, whereas the suppression of sexual behaviors appears to be due, at least in part, to decreases in estrogen receptor in the ventromedial hypothalamus. Work using pharmacological inhibitors of glucose and fatty acid oxidation indicates that reproductive physiology and behavior respond to short-term (minute-to-minute or hour-to-hour) changes in metabolic fuel oxidation, rather than to any aspect of body size or composition (e.g., body fat content or fat-to-lean ratio). These metabolic cues seem to be detected in the viscera (most likely in the liver) and in the caudal hindbrain (probably in the area postrema). This metabolic information is then transmitted to the GnRH-secreting or estradiol-binding effector neurons in the forebrain. There is no evidence to date for direct detection of metabolic cues by these forebrain effector neurons. This metabolic fuels hypothesis is consistent with a large body of evidence and seems to account for the infertility that is seen in a number of situations, including famine, eating disorders, excessive exercise, cold exposure, lactation, some types of obesity, and poorly controlled diabetes mellitus.
在雌性哺乳动物中，生殖对可氧化代谢燃料的可用性极为敏感。当食物摄入量受限，或者当可用能量的很大一部分被转移到其他用途，如运动或育肥时，生殖尝试就会暂停，转而支持个体生存所需的过程。生殖生理和性行为都会受到食物供应情况的影响。营养对生殖生理的影响是通过前脑促性腺激素释放激素（GnRH）神经元活性的变化来介导的，而性行为的抑制似乎至少部分是由于腹内侧下丘脑雌激素受体的减少。使用葡萄糖和脂肪酸氧化的药理学抑制剂进行的研究表明，生殖生理和行为对代谢燃料氧化的短期（每分钟或每小时）变化做出反应，而不是对身体大小或组成的任何方面（如体脂含量或脂肪与瘦肉比例）做出反应。这些代谢信号似乎在内脏（很可能在肝脏）和后脑尾部（可能在最后区）被检测到。然后，这种代谢信息被传递到前脑分泌GnRH或结合雌二醇的效应神经元。迄今为止，没有证据表明这些前脑效应神经元能直接检测代谢信号。这种代谢燃料假说与大量证据相符，似乎可以解释在许多情况下出现的不孕症，包括饥荒、饮食失调、过度运动、寒冷暴露、哺乳、某些类型的肥胖症以及控制不佳的糖尿病。
