Transient prenatal androgen exposure produces metabolic syndrome in adult female rats

Abstract

Androgen exposure during intrauterine life in nonhuman primates and in sheep results in a phenocopy of the reproductive and metabolic features of polycystic ovary syndrome (PCOS). Such exposure also results in reproductive features of PCOS in rodents. We investigated whether transient prenatal androgen treatment produced metabolic abnormalities in adult female rats and the mechanisms of these changes. Pregnant dams received free testosterone or vehicle injections during late gestation, and their female offspring were fed regular or high-fat diet (HFD). At 60 days of age, prenatally androgenized (PA) rats exhibited significantly increased body weight; parametrial and subcutaneous fat; serum insulin, cholesterol and triglyceride levels; and hepatic triglyceride content (all P < 0.0125). There were no significant differences in insulin sensitivity by intraperitoneal insulin tolerance test or insulin signaling in liver or skeletal muscle. HFD had similar effects to PA on body weight and composition as well as on circulating triglyceride levels. HFD further increased hepatic triglyceride content to a similar extent in both PA and control rats. In PA rats, HFD did not further increase circulating insulin, triglyceride, or cholesterol levels. In control rats, HFD increased insulin levels, but to a lesser extent than PA alone ( approximately 2.5- vs. approximately 12-fold, respectively). We conclude that transient prenatal androgen exposure produces features of the metabolic syndrome in adult female rats. Dyslipidemia and hepatic steatosis appear to be mediated by PA-induced increases in adiposity, whereas hyperinsulinemia appears to be a direct result of PA.

Fig. 1.

Study schema with the number of animals used in each experiment.

Fig. 2.

A: body weight change with age in control (C; ▵) and prenatally androgenized (PA; ▴) rats on regular chow diet (RD). B: body weight change with age in C (□) and PA (▪) rats on a high-fat diet (HFD). Parametrial (C) and sc (D) fat pad weights in C (open bars) and PA (filled bars) rats on RD and HFD. Values are means ± SE; C RD n = 20, PA RD n = 17, C HFD n = 11, and PA HFD n = 8. **P < 0.01 vs C RD (A). *P < 0.0125 and **P < 0.005 vs C RD (C and D).

Fig. 3.

Serum insulin (A) and glucose (B) levels in C (open bars) and PA (filled bars) rats on RD and HFD. Values are means ± SE; C RD n = 9, PA RD n = 8, C HFD n = 6, and PA HFD n = 4 (samples from saline-treated rats only). *P < 0.0125 and **P < 0.005 vs C RD. †P < 0.0125 vs C HFD.

Fig. 4.

Serum triglyceride (TG; A) and total cholesterol (B) levels in C (open bars) and PA (filled bars) rats on RD and HFD. C: hepatic TG content/μg liver protein in C (open bars) and PA (filled bars) rats. D: oil red-O stain for lipids in the liver (top: C RD, PA RD; bottom: C HFD, PA HFD). Values are means ± SE; C RD n = 10, PA RD n = 8, C HFD n = 6, PA and HFD n = 4 for serum TG and cholesterol (samples from saline-treated rats only); C RD n = 15, PA RD n = 13, C HFD n = 11, and PA HFD n = 8 for hepatic TG content (samples from saline and insulin-treated rats). *P < 0.0125, **P < 0.005, and ***P < 0.001 vs C RD. ‡‡‡P < 0.001 vs PA RD.

Fig. 5.

Glucose (A) and insulin (B) levels during intraperitoneal glucose tolerance test (IPGTT); %basal glucose during intraperitoneal insulin tolerance test (IPITT; C) in C (▵) and PA (▴) rats on RD . Values are means ± SE. For IPITT, C RD n = 5 and PA RD n = 6. For IPGTT, C RD n = 4 and PA RD n = 6.

Fig. 6.

Insulin receptor substrate (IRS)-1 and IRS-2 in the liver (A and C) and the skeletal muscle (B and D) from C (open bars) and PA (black bars) rats on RD and HFD. Representative gel images are shown above each graph. Values are means ± SE; C RD n = 10, PA RD n = 8, C HFD n = 6, and PA HFD n = 4 (samples from saline-treated rats only).

Fig. 7.

Insulin signaling [represented as a phospho-protein kinase B (Akt)-to-Akt ratio] in RD and HFD rats after 10 min ± insulin (5 U) in liver (A and C, respectively) and skeletal muscle (B and D, respectively) from C (open bars) and PA (black bars) rats. Representative gel images for phospho-proteins are shown above each graph. Values are means ± SE; C RD n = 10 saline, n = 10 insulin; PA RD n = 8 saline, n = 9 insulin; C HFD n = 6 saline, n = 5 insulin; and PA HFD n = 4 saline, n = 4 insulin.