Long-term effects of ovariectomy on pituitary-adrenal axis and specific antibody response in rats

The effects of ovariectomy on morphologically demonstrable characteristics of lymphoid tissue, pituitary, and adrenal glands as well as on plasma ACTH and corticosterone levels and humoral immunity of female Lewis rats were investigated. The present study establishes ovaries as potential regulatory organs upon thymus, pituitary, and adrenal glands in female Lewis rats. In addition to the effects on these important lymphoid organs and endocrine glands, ovariectomy influenced the time course of serum IgM antibody titres against fluorescein isothiocyanate (FITC), but had only moderate effects upon serum IgG antibody titres. In conclusion, the present results suggest that ovariectomy modifies morphological characteristics of the thymus and pituitary-adrenal axis. Furthermore, circulating corticosterone seems to play an important role in regulating antibody formation in intact compared to ovariectomized female Lewis rats, while the influence of thymic mass is far from clear.