Sex-dependent effects of antenatal glucocorticoids on insulin sensitivity in adult sheep: role of the adipose tissue renin angiotensin system

摘要

Exposure to glucocorticoids in utero is associated with changes in organ function and structure in the adult. The aims of this study were to characterize the effects of antenatal exposure to glucocorticoids on glucose handling and the role of adipose tissue. Pregnant sheep received betamethasone (Beta, 0.17 mg/kg) or vehicle 24 h apart at 80 days of gestation and allowed to deliver at term. At 9 mo, male and female offspring were fed at either 100% of nutritional allowance (lean) or ad libitum for 3 mo (obese). At 1 yr, they were chronically instrumented under general anesthesia. Glucose tolerance was evaluated using a bolus of glucose (0.25 g/kg). Adipose tissue was harvested after death to determine mRNA expression levels of angiotensinogen (AGT), angiotensin-converting enzyme (ACE) I, ACE2, and peroxisome proliferator-activated receptor γ (PPAR-7). Data are expressed as means ± SE and analyzed by ANOVA. Sex, obesity, and Beta exposure had significant effects on glucose tolerance and mRNA expression. Beta impaired glucose tolerance in lean females but not males. Superimposed obesity worsened the impairment in females and unmasked the defect in males. Beta increased ACE1 mRNA in females and males and AGT in females only (P < 0.05 by three-way ANOVA). Obesity increased AGT in females but had no effect on ACE1 in either males or females. PPAR-7 mRNA exhibited a significant sex (F = 42.8; P < 0.01) and obesity (F = 6.9; P < 0.05) effect and was significantly higher in males (P < 0.01 by three-way ANOVA). We conclude that adipose tissue may play an important role in the sexually dimorphic response to antenatal glucocorticoids.