Role of adrenal in establishment and development of conceptus in unilaterally ovariectomized mated rats

The model of unilateral ovariectomy induced ovarian compensatory hypertrophy in mated bilaterally adrenalectomized rats was used to assess the role of adrenal in conceptus development. Replacement dose of dehydroepiandrosterone (DHA) or corticosterone (Comp. B) from day 2-14 post coitum was given with or without ip injections of estrogen (E, on day 2) and progesterone (P, on day 3 or 3-9). Replacement of adrenal hormones failed to support ipsilateral uterine horn (IP) pregnancy. But injections of E2 and P support IH pregnancy in variable percentages (about 38-75%) of rats depending on the type of adrenal steroids and single or multiple doses of P. Contralateral horn (CH) pregnancy developed under any of these conditions. Adrenalectomy induced reduction of fetal weight and pregnancy index (No. of fetus divided by No. of implantation sites), were not significantly improved by adrenal hormone replacement, except pregnancy index of those animals which received Comp. B and P. Adrenalectomy inhibited compensatory increase of contralateral corpus luteum (CL) volume and ovarian delta 5(3)beta-hydroxy steroid dehydrogenase (delta 5(3)beta-HSD) activity. Replacement of DHA or Comp. B induced these compensatory changes. Comp. B and P appears to be a better combination in establishment of IH pregnancy, pregnancy index maintenance and stimulation of ovarian compensatory changes. Results suggest that adrenocorticoids were not obligatory for conceptus development but were important for efficient action of ovarian steroids in establishment and maintenance of pregnancy. Relationship between nutrition or pituitary gonadotropins and adrenal steroids, having relevance to conceptus development has been discussed.