Studies were conducted to assess progesterone antagonists (PAs) and progesterone receptor modulators (PRMs) with respect to PR agonistic and antagonistic activities in vivo. These properties are not always adequately reflected in transactivation in vitro models. Studies were performed in pregnant rats, estrogen-primed rabbits (McPhail -Test), and cycling and pregnant guinea pigs. Tested compounds included mifepristone (RU486), onapristone, J867, J956, J1042, and ZK137316. J-compounds induced sub-maximum endometrial transformation and, paradoxically, inhibited effects of progesterone in rabbits. Mifepristone, onapristone, and ZK137316 behaved as 'pure' antagonists in this species. Inhibition of uterine PGF(2alpha) secretion and inhibition of luteolysis in cycling guinea pigs were more sensitive parameters of PR-agonistic and antagonistic properties. 'Pure' PAs inhibited uterine PGF(2alpha) secretion and luteal regression completely. The PR agonist R5020 reversed both effects which demonstrates a PR mediation. Agonistic PRMs (J-substances and mifepristone) showed no or blunted antiluteolytic effects compared to the 'pure' PR antagonist onapristone. When tested in pregnant guinea pigs for their labor-inducing potential, PR agonistic PRMs had much reduced or abolished abortifacient activity compared to mifepristone (mifepristone > J956 > J867/J912 > J1042). However, in cycling animals, superior antiovulatory and antiproliferative properties of the J-substances were seen. Antiovulatory effects of 'pure' and agonistic PRMs are probably due to different mechanisms. The relevance of rodent studies for antiovulatory and uterine antiproliferative effects for the human is still uncertain. The non-abortifacient PRM J1042 induced stromal compaction and inhibition of endometrial proliferation in monkeys, but this effect was not stronger than that of the 'purer' PAs. 'Pure' PAs are important pharmacological tools analogous to PRKO models to study the role of PR in the menstrual cycle and in pregnancy.

Abortion, Induced↗

PubMedDate not supplied

Influence of neuropeptides on neutrophil adhesion and transmigration through a lung fibroblast barrier in vitro.

The lung is richly supplied with peptidergic nerves that store and secrete substance P (SP), vasoactive intestinal peptide (VIP), and other neuropeptides known to potently modulate leukocyte function in vitro and airway inflammation in vivo. We examined the effect of SP, VIP and the novel sensory neuropeptide secretoneurin (SN), as well as of interleukin (IL)-8, IL-6, IL-1 beta, transforming growth factor (TGF)-beta, and tumor necrosis factor (TNF), all associated with acute lung injury, on human neutrophil migration across a 5-mu pore polycarbonate filter system covered by human lung fibroblast monolayers. Additionally, we tested the ability of these neuropeptides to elicit neutrophil adhesion to fibroblast monolayers. SP, but not VIP and SN, may be important in directly influencing neutrophil adhesion to and subsequent migration across a subendothelial barrier of fibroblasts and extracellular matrix towards lung inflammatory sites. The effect was mainly mediated by neurokinin (NK)-1 receptors, as evaluated by a specific NK-1 antagonist, [[(S,S)Pro-Leu(spiro-y-lactam)]9,10, Trp11]substance P (1-11), whereas a specific NK-2 receptor antagonist, [Tyr5, D-Trp6,8,9, Lys10]neurokinin A (4-10), was ineffective. The SP analog septide and the NK-1 receptor agonist ([Sar9 Met(O2)11)SP were comparably effective. Furthermore, the SP effect was concentration and time dependent. However, the other tested neuropeptides might also affect neutrophil recruitment in inflammatory lung by modulating other lung cell functions. Additionally, all tested cytokines stimulated neutrophil transfibroblast migration in vitro, except IL-6. In conclusion, SP in concert with proinflammatory cytokines may regulate neutrophil interstitial accumulation and their traffic to the alveolar space in lung inflammation.

Cell Adhesion↗

PubMedDate not supplied

MTD calculations on quantitative structure-activity relationships of steroids binding to the progesterone receptor.

The minimal topological difference (MTD) method is used to describe quantitative structure-activity relationships (QSAR) for the progesterone-receptor binding affinity including 59 progestational steroids. Multiple correlation coefficients of r = 0.962 and r = 0.955 are obtained by use of the MTD variable and a measure of hydrophobicity for the series of progesterone and ethisterone derivatives, respectively. Hydrophobic effects are found to strongly influence receptor binding. In accordance with the hydrogen bonding concept, the optimized MTD receptor maps indicate cavity vertices in the regions of oxygen functions at C3 and in the 17 beta position. Receptor wall vertices are attributed in the areas of 4, 10 beta, and 13 beta substituents of 4-en-3-one steroids while 17 alpha side chains additionally contain receptor cavity vertices. A comparison of corresponding receptor maps suggests in accord with X-ray crystal structure data that progesterone and ethisterone derivatives are bound in somewhat different orientations relative to the receptor surface.

Animals↗