Abstract
Polycystic ovary syndrome (PCOS) often is associated with hyperandrogenemia and an increased incidence of obesity and type 2 diabetes. To understand the separate and combined effects of androgens and obesity on reproductive and metabolic parameters, our group established a nonhuman primate model consisting of animals receiving either testosterone (T, mean value of 1.4 ng/mL), an obesogenic western-style diet (WSD, 36% of calories from fat compared to 16% in normal monkey chow), or a combination of T+WSD. T+WSD increased insulin resistance compared to WSD alone after three years of treatment and reduced fertility. Those T+WSD animals that became pregnant had a mild worsening of glucose homeostasis during pregnancy. The current study sought to determine how T+WSD affected post-pregnancy metabolic health and whether T+WSD led to the worsening of insulin resistance after pregnancy. Intravenous glucose tolerance tests (ivGTT) were performed 1) before pregnancy, 2) approximately 3-4 months after C-section, which occurred between gestational day 130-135 (3rd trimester), and 3) one year post C-section. All animal groups tended to show increases in weight, BMI, and body fat percentage after pregnancy. Both WSD groups (WSD and T+WSD) had higher overall weights, BMI, and body fat percentages. Measures of insulin sensitivity such as fasting insulin, glucose, and insulin area under the curves during an ivGTT and homeostatic model of insulin resistance (HOMA-IR) all increased over time, but there were no differences between groups. The lack of treatment effect on measures of insulin resistance may be due to the fact that animals that did not become pregnant had significantly higher indices of insulin resistance. Experimental animals underwent a second round of fertility trials thereby allowing for a comparison of glucose homeostasis for those animals that became pregnant in both the 1st and 2nd trial. The WSD group demonstrated increased fasting glucose and glucose AUC during an early third trimester ivGTT in the second pregnancy compared to the first. The control, T, and T+WSD groups did not show significant differences in glucose homeostasis between the first and second pregnancy. These findings indicate that WSD consumption may increase the risk of worsened glucose homeostasis after pregnancy and during subsequent pregnancies. Testosterone, either in isolation or in combination with WSD, did not appear to have a significant impact on post-pregnancy metabolism or worsen metabolic outcomes in a second pregnancy.
Autocrine IGF2 programmes β-cell plasticity under conditions of increased metabolic demand