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.