Does estradiol treatment normalize the hypothalamic-pituitary-adrenal axis in streptozotocin-induced ovariectomized diabetic female rats?

We recently found circulating corticosterone (CS) levels to be significantly lower in diabetic female rats as compared with proestrous control animals. This reduction in CS was correlated with the hypoestrogenic state of the diabetic female. It was the purpose of this study to evaluate basal and corticotropin releasing hormone (CRH)-stimulated CS secretion in ovariectomized (OVX) control (C) and streptozotocin-induced diabetic (D) rats given blank, 5 mcg and 20 mcg estradiol (E2) implants to determine if adrenal CS secretion in the diabetic is normalized by E2 treatment. After 3 weeks of diabetes, pituitary-adrenal function was assessed in rats from each group with a CRH stimulation test. The remaining rats were sacrificed for determination of CS, E2, testosterone and fructosamine in serum. Suppressed CS secretion in OVX female diabetic rats was partially restored with E2 therapy. Basal CS levels were significantly higher in 20 mcg E2 treated C and D rats compared with OVX rats. However, C rats had significantly higher basal CS compared with D rats in similarly E2 treated groups. The CS response to CRH stimulation was not different between OVX female diabetic and control rats. Estrogen enhanced the CS response to CRH stimulation in control animals but not in diabetic animals suggesting altered estrogen action at the pituitary level in diabetic animals.