Please use this identifier to cite or link to this item: http://hdl.handle.net/10553/76956
DC FieldValueLanguage
dc.contributor.authorBartlewski, Pawel Mieczyslawen_US
dc.contributor.authorAravindakshan, J.en_US
dc.contributor.authorBeard, Andrew P.en_US
dc.contributor.authorNelson, M. L.en_US
dc.contributor.authorBatista Arteaga, Miguelen_US
dc.contributor.authorCook, Susan J.en_US
dc.contributor.authorRawlings, N. C.en_US
dc.date.accessioned2020-12-23T10:53:36Z-
dc.date.available2020-12-23T10:53:36Z-
dc.date.issued2001en_US
dc.identifier.issn0006-3363en_US
dc.identifier.otherWoS-
dc.identifier.urihttp://hdl.handle.net/10553/76956-
dc.description.abstractWhen ovulation is induced with gonadotrophin-releasing hormone (GnRH) in anoestrous ewes, a proportion of animals fail to form normal (full-lifespan) corpora lutea (CL). Progesterone treatment before GnRH prevents luteal inadequacy. It remains uncertain whether a similar effect, achieved with medroxyprogesterone acetate (MAP) from intravaginal sponges, is mediated by influences on growing ovarian follicles and/or secretion of gonadotrophic hormones, before and after GnRH treatment. Two experiments were performed, on 13 and 11 anoestrous Western white-faced ewes, respectively. Seven and six ewes, respectively, received MAP-containing sponges (60 mg) for 14 days; the remaining ewes served as untreated controls. To test the effect of timing of GnRH administration after pre-treatment with MAP-releasing sponges, GnRH injections (250 ng every 2 h for 24 h followed by a bolus injection of 125 μg of GnRH i.v.) were given either immediately (Experiment 1) or 24 h after sponge removal in the treated ewes (Experiment 2). Ovarian follicular dynamics (follicles reaching ≥5 mm in size) and development of luteal structures were monitored using transrectal ultrasonography. In Experiment 1, the mean ovulation rate (0.7±0.3 and 1.0±0.4) and proportion of ovulating ewes (57 and 67%, respectively) did not vary (P>0.05) between MAP-treated and control ewes. Normal (full-lifespan) CL were detected in 29% of treated and 67% of control ewes (P>0.05). In Experiment 2, the mean ovulation rate (2.3±0.2 and 1.2±0.6; P<0.05) and percentage of ewes with normal (full-lifespan) CL (100 and 40%, respectively; P<0.10) were greater in the treated compared to control ewes. In Experiment 1, the mean peak concentration of the GnRH-induced LH surge was lower (P<0.05) in MAP-treated than in control ewes. There were no significant differences between MAP-treated and control ewes in the characteristics of follicular waves, mean daily serum FSH concentrations, and secretory parameters of LH/FSH, based on intensive blood sampling conducted 1 day before sponging and 1 day before sponge removal. It is concluded that treatment with MAP has no effect on the tonic secretion of LH/FSH or follicular wave development in anoestrous ewes. However, the GnRH-stimulated LH discharge was attenuated in the ewes that received MAP-impregnated sponges for 14 days and were treated with GnRH immediately after sponge withdrawal. Ovulatory response and CL formation were increased when GnRH was administered 24 h after sponge removal.en_US
dc.languageengen_US
dc.relation.ispartofBiology of reproductionen_US
dc.sourceBiology of reproduction [ISSN 0006-3363], v. 64 (sup. 1), p. 150, (2001)en_US
dc.subject310907 Patologíaen_US
dc.subject.otherMedroxyprogesterone acetateen_US
dc.subject.otherGonadotrophin-releasing hormoneen_US
dc.subject.otherOvulationen_US
dc.subject.otherAnoestrusen_US
dc.subject.otherEween_US
dc.titleEffects of medroxyprogesterone acetate (MAP) on ovarian antral follicle development, gonadotropin secretion and response to GnRH in seasonally anovular ewesen_US
dc.typeinfo:eu-repo/semantics/conferenceObjecten_US
dc.typeConferenceObjecten_US
dc.identifier.isi000169570900167-
dc.description.lastpage150en_US
dc.description.firstpage150en_US
dc.relation.volume64en_US
dc.investigacionCiencias de la Saluden_US
dc.type2Actas de congresosen_US
dc.contributor.daisngid329584-
dc.contributor.daisngid1885802-
dc.contributor.daisngid508118-
dc.contributor.daisngid28347052-
dc.contributor.daisngid3336300-
dc.contributor.daisngid101614-
dc.contributor.daisngid133303-
dc.description.numberofpages1en_US
dc.utils.revisionen_US
dc.contributor.wosstandardWOS:Bartlewski, PM-
dc.contributor.wosstandardWOS:Aravindakshan, J-
dc.contributor.wosstandardWOS:Beard, AP-
dc.contributor.wosstandardWOS:Nelson, ML-
dc.contributor.wosstandardWOS:Batista-Arteaga, M-
dc.contributor.wosstandardWOS:Cook, SJ-
dc.contributor.wosstandardWOS:Rawlings, NC-
dc.date.coverdate2001en_US
dc.identifier.supplement1-
dc.identifier.ulpgcen_US
dc.description.jcr3,508
dc.description.jcrqQ1
dc.description.scieSCIE
item.fulltextSin texto completo-
item.grantfulltextnone-
crisitem.author.deptMedicina Veterinaria e Investigación Terapeútica-
crisitem.author.deptIU de Investigaciones Biomédicas y Sanitarias-
crisitem.author.deptPatología Animal, Producción Animal, Bromatología y Tecnología de Los Alimentos-
crisitem.author.orcid0000-0001-9753-4786-
crisitem.author.parentorgIU de Investigaciones Biomédicas y Sanitarias-
crisitem.author.fullNameBatista Arteaga, Miguel-
Appears in Collections:Actas de congresos
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