reprometabolic syndrome mediates subfertility in obesity

Conditions: Obesity; Infertility; Hypogonadotropic Hypogonadotropism; Hyperinsulinemia

Summary: obesity plays an adverse role at every stage of conception and pregnancy and mounting evidence implicates relative hypogonadotropic hypogonadism, and reduced menstrual cycle hormone secretion as likely contributors to the subfertility phenotype and possible contributors to complications of pregnancy and the developmental origin of adult diseases such as diabetes and cardiovascular disease. this study will be the first comprehensive investigation to tie together the patterns of hyperinsulinemia, hyperlipidemia and inflammation, characteristic of obesity and obesity-caused relative hypogonadotropic hypogonadotropism and its potential adverse reproductive outcomes. the investigators findings will be used to inform a subsequent clinical intervention to optimize reproductive outcomes for obese women and their offspring.

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.

Eligibility criteria:
inclusion criteria: * body mass index (bmi) at least 18 but less than 25 kg/m2 * no history of chronic disease affecting hormone production, metabolism, or clearance * no use of medications known to alter or interact with reproductive hormones or insulin metabolism (e.g. thiazolidinediones, metformin) * no use of reproductive hormones within 3 months of enrollment * normal prolactin and thyroid stimulating hormone levels at screening * history of regular menstrual cycles every 25-35 days * use of a reliable method of contraception (female or male partner sterilization; intra uterine device (iud); abstinence; diaphragm) * normal hemoglobin a1c * screening hemoglobin \>11gm/dl exclusion criteria: * women with a baseline dietary assessment indicative of \>35% daily calorie consumption from fat (as calculated based upon initial screening survey) will be excluded, as the impact of increasing their dietary fat intake may be minimal. * women with fasting triglycerides \>300mg/dl at screening will be excluded, as they might be at risk for acute elevation of triglycerides and even pancreatitis if placed on a high fat diet * inability to comply with the protocol. individuals who travel frequently, or who eat most of their meals outside of their home will be excluded, as it will be difficult to impossible for them to comply with the diet, to pick up the food cartons, etc. * because high proportions of dairy fat will be needed to attain 48% calories from fat in the diet, vegans and lactose intolerant individuals will be excluded. * pregnant women or women planning to become pregnant will be excluded.