Wade G N, Schneider J E, Friedman M I
Department of Psychology, University of Massachusetts, Amherst 01003.
Am J Physiol. 1991 Jan;260(1 Pt 2):R148-52. doi: 10.1152/ajpregu.1991.260.1.R148.
In Syrian hamsters, reproduction is sensitive to the availability of metabolic fuels. Estrous cycles can be interrupted by brief periods of food deprivation, by pharmacological inhibition of glycolysis and fatty acid oxidation, or by increasing energy demands for thermoregulation. We predicted that manipulations that divert an excessive portion of the metabolic fuel supply into storage also should inhibit reproduction. Redirection of metabolic fuels from oxidation to storage was accomplished by treatment with protamine zinc insulin suspension (PZI). Syrian hamsters treated with PZI and fed ad libitum increased their food intake by approximately equal to 40% and body fat stores, but there was no effect on estrous cycles. When PZI-treated hamsters were limited to approximately equal to 110% of their preinjection food intake, they still fattened, and there was a significant inhibition of estrous cyclicity. Thus, in the absence of overeating, PZI-enhanced energy storage may lead to a shortage of oxidizable metabolic fuels with the result that reproduction is inhibited in favor of processes essential for survival (e.g., cellular maintenance, thermoregulation). It is unlikely that insulin-induced anestrus is due to actions of PZI unrelated to metabolic fuel partitioning, because the hormone had no effects on estrous cyclicity in ad libitum-fed hamsters. These findings are inconsistent with the hypothesis that nutritional infertility is due to the failure to maintain a minimum body fat content and raise the possibility that the infertility associated with some types of obesity could be due in part to a disorder of macronutrient partitioning.
在叙利亚仓鼠中，繁殖对代谢燃料的可利用性很敏感。短暂的食物剥夺、糖酵解和脂肪酸氧化的药理学抑制，或增加体温调节的能量需求，都可能中断发情周期。我们预测，将过多的代谢燃料供应转移到储存中的操作也应该会抑制繁殖。通过用精蛋白锌胰岛素悬液（PZI）处理，可实现代谢燃料从氧化向储存的重新定向。用PZI处理并随意进食的叙利亚仓鼠，其食物摄入量增加了约40%，体脂储备也增加了，但对发情周期没有影响。当用PZI处理的仓鼠被限制在其注射前食物摄入量的约110%时，它们仍然会发胖，并且发情周期受到显著抑制。因此，在没有暴饮暴食的情况下，PZI增强的能量储存可能会导致可氧化代谢燃料短缺，结果是繁殖受到抑制，转而有利于生存所必需的过程（如细胞维持、体温调节）。胰岛素诱导的发情停止不太可能是由于PZI与代谢燃料分配无关的作用，因为该激素对随意进食的仓鼠的发情周期没有影响。这些发现与营养性不育是由于未能维持最低体脂含量这一假设不一致，并增加了某些类型肥胖相关不育可能部分归因于常量营养素分配紊乱的可能性。
