It is well known that the plant kingdom contains numerous bioactive substances affecting the regulation of reproduction. The present study was undertaken to examine the putative contraceptive effects of three traditional plant extracts from Côte d'Ivoire Pharmacopea. It concerns Afrormosia laxiflora (Papilionacea), Pterocarpus erinaceus (Papilionacea) and Cola nitida (Sterculiacea) stem bark. Data showed that treatment of rats with these plant extracts induced ovulation and oestrous cycle blockade at the dioestrous II stage. The analysis of the principal hormones involved in oestrous cycle regulation showed that the plant extracts decreased gonadotropin release (both LH and FSH). In fact, A. laxiflora, P. erinaceus and C. nitida extracts inhibited gonadotropin release as an antiestrogen-like substance.

Estradiol (E2) effects on the pituitary and adrenal secretogranin II (SgII) and chromogranin A (CgA) proteins and mRNA levels were analyzed in the adult female rat. Animals were ovariectomized or sham-operated for 2 weeks and then daily injected with various doses of 17 beta-E2 (from 5-100 micrograms) for the following week. SgII and CgA levels were determined by Western blot analysis using two specific antisera. Messenger RNA (mRNA) levels were measured by RNA slot blot analysis using specific cDNA probes. Simultaneously, pituitary LH content and gonadotropin subunit (LH beta, FSH beta, alpha) mRNAs were quantified. Ovariectomy promoted a significant increase in pituitary SgII and CgA proteins (2-fold vs. sham-operated animals, P less than 0.01) and a concomitant rise in their mRNA levels (2.5-fold and 4.5-fold for SgII mRNA and CgA mRNA, respectively, P less than 0.01). In the same animals LH beta, FSH beta, and alpha-subunit mRNA levels increased by 20-, 12-, and 6-fold, respectively. Estrogen replacement resulted in a parallel decrease of CgA and LH beta mRNA to the control values, starting from the lowest steroid dose (5 micrograms). The SgII mRNA decrease was initiated only with a higher concentration of E2 (10 micrograms), as was that of alpha-subunit mRNA; yet, the SgII mRNA level remained significantly higher than in the control pituitary, even with the highest steroid dose (P less than 0.05) at variance with the alpha-mRNA level. Concerning protein concentration, the postcastration increase in CgA was fully reverted with 10 micrograms E2 while that of SgII remained unaffected, as was the pituitary LH content. In the adrenal gland, neither the ovariectomy nor the E2 therapy altered significantly the SgII or CgA protein and mRNA concentrations. We conclude that, in rats, 1) ovarian factors regulate the pituitary SgII and CgA protein and mRNA steady-state levels while such factors are inefficient in the adrenal gland, 2) CgA and LH beta mRNAs exhibit the same sensitivity to E2 while SgII and alpha-subunit mRNAs appear less sensitive, and 3) SgII and LH pituitary contents present a similar pattern of variations when the estrogenic status of the animal is modified.

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