Nr. Stoddart et al., STIMULATION OF DEVELOPMENT IN-VITRO BY PLATELET-ACTIVATING-FACTOR RECEPTOR LIGANDS RELEASED BY MOUSE PREIMPLANTATION EMBRYOS, Journal of Reproduction and Fertility, 108(1), 1996, pp. 47-53
Previous reports have demonstrated that culture of mouse preimplantati
on embryos at high density stimulates their rate of development. The m
olecular basis of this phenomenon was investigated. Culture of embryos
from the four-cell stage at high density in normal medium, or at low
density either in embryo-conditioned medium or medium containing plate
let-activating factor (PAF), significantly advanced the timing of comp
action, initiation of cavitation and/or completion of zona hatching, a
nd also increased the number of cells in blastocysts. In contrast, Lys
o-PAF, an inactive metabolite of PAF, and Enantio-PAF, an enantiomer o
f PAF, did not have a stimulatory effect at low embryo density, but di
d not inhibit the stimulation of development at high embryo density. T
he stimulatory effect of culture at high density was inhibited in the
presence of either CV-3988 or SDZ 64-412, two structurally distinct co
mpetitive PAF-receptor antagonists, while the development rate at low
density was not affected. We conclude that an embryo-derived factor re
lated to PAF is secreted by blastomeres during in vitro culture and ac
ts in a receptor-mediated manner to stimulate the rate of development.