Reprometabolic Syndrome Mediates Subfertility in Obesity

Before any of the well-known adverse effects in pregnancy2,3, obesity causes a relatively hypogonadotropic hypogonadal phenotype. Reduced LH, FSH, estradiol (E2) and progesterone secretion are well documented during the menstrual cycles of obese women compared to normal weight women (NWW).4,5. Decreased gonadotropin secretion associated with obesity is related to reduced pituitary sensitivity to GnRH6. This reduction in pituitary sensitivity suggests mediation by circulating factors such as cytokines, insulin, or other pro-inflammatory signals known to be elevated in obesity. We have recently discovered that the combination of hyperinsulinemia and circulating free fatty acids (FFAs), but neither agent alone, can acutely decrease gonadotropin secretion in NWW as well as men, establishing a direct causal linkage for the central hypothesis of this proposal: that chronic pituitary suppression partially mediates obesity related subfertility. Our working model is that the combination of excess, possibly pro-inflammatory (omega-6) circulating FFAs and insulin resistance associated with obesity, cause decreased pituitary sensitivity to GnRH, with a resulting relative sex steroid deficit that further exacerbates the obese phenotype. We have named this phenotype the reprometabolic syndrome. We propose to examine the interrelationships among obesity, reproductive dysfunction and metabolic dysfunction in a mechanistic fashion. We will induce the hypogonadotropic hypogonadal phenotype of obesity in NWW, who will be primed with a high-fat diet (HFD) designed to increase circulating FFAs and produce short-term insulin resistance and higher insulin levels.1,7-11 Before and after priming, we will test the additive effects of lipid excess, insulin, and inflammation on the reproductive and metabolic axes.