NUTRITION AND REGULATION OF POSTPARTUM ANOVULATION

哺乳和营养不良抑制排卵的机制是 重要的医学意义和显著的人口学意义。 的 这里提出的实验是第一次利用卵巢切除大鼠 作为研究独立和协同作用的动物模型 慢性营养不良和哺乳对催乳素和 泌乳期间促性腺激素的释放。 实验1将检查 窝仔数和限饲对控制 促黄体生成激素（LH）、促卵泡激素（FSH）和 垂体分泌催乳素 本实验将使用3 采用膳食摄入量的x3析因设计（自由采食，85%自由采食， 70%自由采食）和窝仔数（2、5和8只幼仔）作为主要因素。 据推测，饮食限制和增加产仔数 大小将独立地和协同地影响循环LH、FSH 和催乳素浓度。 此外，我们预计这两个主要因素 独立和互动地导致抑郁的反应， 通过血浆LH和FSH测定促性腺激素释放激素（GnRH） 对GnRH挑战的反应。 母犬和幼犬的行为也会 记录并用于回归分析，以预测血浆激素 浓度的 实验2将研究食物的影响 促性腺激素释放和垂体对 GnRH和催乳素浓度。 我们假设LH，FSH 在食物限制的情况下， 哺乳期动物当再喂养时。 同样，饮食养生法对 将评估母鼠和窝仔的行为。 实验3将检查 阿片拮抗剂（纳洛酮）或催乳素抑制因子的作用 （溴隐亭）对哺乳期自由进食 和食物限制的老鼠 无论是丰衣足食还是长期营养不良， 卵巢切除的泌乳大鼠将用纳洛酮， 溴隐亭、纳洛酮和溴隐亭或盐水。 的影响 营养状况和药物治疗对血浆LH浓度的影响， 将在早期（第10天）和峰值（第14天）测定对GnRH的反应性 哺乳期 据推测，内源性阿片类物质贡献更多， 营养不良时下丘脑抑制的作用 多巴胺能通路 总之，这些实验将提供 关于生理机制的深刻信息， 哺乳、营养不良和哺乳。特征相互作用， 影响下丘脑-垂体-卵巢轴

The mechanisms by which lactation and malnutrition inhibit ovulation are important medically and have significant demographic implications. The experiments proposed here are the first to utilize the ovariectomized rat as an animal model for studying the independent and synergistic effects of chronic undernutrition and suckling on the modulation of prolactin and gonadotropin release during lactation. Experiment 1 will examine the effects of litter size and dietary restriction on the control of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin release from the pituitary. This experiment will utilize a 3 x 3 factorial design with dietary intake (ad libitum, 85% ad libitum, and 70% ad libitum) and litter size (2, 5, and 8 pups) as the main factors. It is hypothesized that both dietary restriction and increased litter size will independently and synergistically influence circulating LH, FSH and prolactin concentrations. Furthermore, we expect both main factors to independently and interactively result in depressed responsiveness to gonadotropin releasing hormone (GnRH) as measured by plasma LH and FSH responses to GnRH challenge. Maternal and pup behavior will also be documented and used in regression analyses to predict plasma hormone concentrations. Experiment 2 will study the effect of food supplementation on gonadotropin release and pituitary responsiveness to GnRH as well as prolactin concentrations. We hypothesize that LH, FSH and prolactin concentrations will be increased in food-restricted lactating animals when refed. Again, the effects of dietary regimen on dam and litter behavior will be assessed. Experiment 3 will examine the effect of an opioid antagonist (naloxone) or prolactin inhibiting factor (bromocriptine) on plasma LH concentrations in lactating ad libitum-fed and food-restricted rats. Both well -fed and chronically undernourished, ovariectomized lactating rats will be treated with either naloxone, bromocriptine, naloxone and bromocriptine, or saline. The effect of nutritional status and drug treatment on plasma LH concentrations and responsiveness to GnRH will be determined in early (d 10) and peak (d 14) lactation. It is hypothesized that endogenous opioids contribute more to hypothalamic suppression during malnutrition than does the dopaminergic pathway. In summary, these experiments will provide incisive information concerning the physiological mechanisms by which lactation, undernutrition and suckling. characteristics interact and influence the hypothalamic-pituitary-ovarian axis.