Search PubMed⌕ Search

Biomedical subjects

J Yardley

Publications and source records attributed to J Yardley.

23 records · Page 2Linked to original sources
PubMed1978

The anti-reproductive pharmacology of LH-RH and agonistic analogues.

LH-RH and three particular ("super") analogues were evaluated for agonistic (ovulation-induction and short-term uterotrophic properties) and postcoital contraceptive activity in rodents. Additionally, LH-RH and/or a representative analogue (D-Ala6-des Gly10-Pro9-LH-RH ethylamide) were tested for postcoital contraceptive/vaginal smear/return to fertility effects, precoital contraceptive activity, and effects on puberty in the immature female. All compounds induced ovulation and uterotrophic effects and terminated pregnancy when administered either pre- or post-implantation. LH-RH and the representative analogue, while terminating pregnancy postcoitally, produced an associated break in the characteristic leucocytic vaginal smear of pregnancy to one of cornification by day 12; at this time mating and insemination were reestablished and all rats carried to normal term. Precoitally, LH-RH administered to nembutalized (but not to unblocked) rats produced a 50% reduction in the pregnancy rate and a 38% decrease in the number of viable pups delivered. In immature rats, the representative analogue delayed puberty (i.e. vaginal canalization) and retarded the growth of the ovaries, uteri, and anterior pituitary gland. The collective data strongly support the concept that LH-RH and agonistic derivatives, in spite of their putative pro-fertility classification, are characteristically antifertility by nature. Since the latter effect appears to be the paradoxically dominant one, it is suggested that LH-RH agonism is synonymous with contraception. Furthermore, such peptides may represent a new potential approach to fertility control.

Animals↗
PubMed1977

Postcoital contraceptive effects of agonist analogs of luteinizing hormone-releasing hormone.

Various analogs of synthetic hypothalamic luteinizing hormone-releasing hormone (LH-RH) were evaluated for agonistic (ovulation-inducing), postcoital contraceptive, and direct uterotrophic activities. All analogs showing agonistic activity also possessed the ability to terminate pregnancy, as did LH-RH; there appeared to be a direct relationship between agonistic and postcoital potency and activity. The highly potent and active LH-RH agonist, D-[Ala]6-des-[Gly]10-pro9-ethylamide-LH-RH, proved to be the most potent and active postcoital preimplantational and postimplantational antifertility agent. In contrast to LH-RH, none of the analogs tested in the hypophysectomized animal produced a uterotrophic effect, revealing a selective extrapituitary effect of the parent hormone. The collective data demonstrate that peptides derived from LH-RH and bearing agonistic properties can terminate pregnancy postcoitally, via disruption of the pituitary-ovarian reproductive complex. Possible mechanisms are discussed, and the use of members of this neurohormonal class as potential profertility agents should be weighed with caution.

Animals↗
PubMed1976

Post-coital contraceptive effects of an agonistic analogue of luteinizing hormone releasing hormone.

An analogue of synthetic hypothalamic LRH, D-[ALA]6-DES-[GLY]10-PRO9-ethylamide-LRH (Wy-18,481) was evaluated for agonistic (in vivo LH-releasing and ovulation-inducing), post-coital contraceptive and reproductive target organ effects. Both LRH and the analogue terminated pregnancy; there appeared to be a direct relationship between agonistic and post-coital contraceptive potency and activity. The analogue proved to be a potent agonist and both a pre-and post-implantational post-coital anti-fertility agent. In contrast to LRH, the congener did not produce a uterotrophic effect in the hypophysectomized rat. The data suggest that agonist analogue(s) of LRH can terminate pregnancy via hyperstimulation of the pituitary-ovarian-reproductive complex and the use of members of this neurohormonal class as potential clinical pro-fertility agents should be weighted with caution.

Animals↗