Study summary · research use only
Effects of progestagens on follicular growth and oocyte developmental competence in FSH-treated ewes
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this sheep study, the authors examined progestagen effects on follicular growth and oocyte developmental competence in FSH-treated Sarda ewes. During the breeding season, 20 ewes received cloprostenol, then 10 received a progestagen sponge and 10 remained untreated, with all given six doses of FSH (Ovagen). They report that follicles >=2mm increased in both groups without significant between-group differences in follicle dynamics, but estradiol was higher in controls, oocyte recovery rate was lower in progestagen-treated ewes (71.1 versus 83%), and cleavage rate was lower (39.1 versus 82.6%). Blastocyst output was lower with progestagen (17.3 versus 30.4%) but not significantly. The authors describe deleterious progestagen effects on oocyte competence.
Abstract
Previous research has reported evidence for negative effects of progestagens on follicular growth and oocyte competence. In the present study, negative effects of progestagens on follicular growth and oocyte developmental competence were assessed. During the breeding season, 20 Sarda ewes were treated with two doses of cloprostenol, 10 days apart, to assure the presence of a corpus luteum (CL). On day 5 after the second cloprostenol dose, 10 ewes were treated with a progestagen sponge while 10 females remained untreated. Starting on day 7 after the second cloprostenol dose, all the ewes were treated with 6 equal doses of 24 I.U. of FSH (Ovagen, ICP, NZ), every 12h. The number of follicles > or =2mm in diameter increased (P<0.0005) in all the ewes from 24 h before to 60 h after the first FSH dose (from 12.8+/-1.1 to 23.4+/-1.3 in treated and from 12+/-0.6 to 22+/-1.2 in untreated ewes, n.s.). There were no significant differences in follicle dynamics between groups, but concentrations of estradiol in control ewes were higher than in the progestagen group (P<0.05). Twelve hours after the last FSH dose, oocytes were collected by ovum pick-up. Recovery rates were lower for progestagen-treated ewes (71.1 versus 83%; P<0.001). After IVP procedure, cleavage rate was also lower in the progestagen group (39.1 versus 82.6%; P<0.001). Furthermore, blastocysts output revealed that oocyte developmental competence was lower in progestagen group (17.3 versus 30.4%; P=0.245), although differences were not significant. These results suggest deleterious effects from progestagen on oocyte developmental competence and set the basis for new protocols for in vitro embryo production.
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