Two studies were conducted to determine if 7-d MGA or PRID treatment initiated on d 17 of the estrous cycle altered: 1) follicular development, 2) estradiol-17β (E2) and progesterone (P4) concentrations, and 3) patterns of release of luteinizing hormone (LH). In both studies, Angus, Angus x Holstein or Holstein cows 2 to 6 yr of age were randomly assigned to receive either MGA (.5 mg⋅hd⁻¹⋅d⁻¹; n = 23) or PRID (n = 26) for 7 d or to serve as untreated controls (n = 14). Real time, B-mode ultrasound, equipped with a 7.5 mHz linear-array transrectal transducer, was used to conduct daily ovarian scans beginning 3 (Study 1) or 9 d (Study 2) after onset of estrus. Jugular venous blood samples (45 ml) were collected coincident with ovarian scans. In study 2, cows were fitted with indwelling jugular catheters 17 (Control, MGA and PRID), 20 and 23 d (MGA and PRID) after onset of estrus and blood samples were collected at 15-min intervals for 6 h for determination of LH. Interestrus interval was extended (P<.05) for 3 to 5 d in MGA-treated cows exhibiting two or three dominant follicles (classified as MGA-2 and MGA-3, respectively) or PRID-treated cows compared to controls exhibiting two or three dominant follicles during the estrous cycle (control-2 and control-3, respectively). Forty-four percent of MGA-treated cows ovulated the dominant follicle present at the beginning of MGA treatment. In both studies, days from detection of the ovulatory follicle until ovulation were greater (P<.01) in MGA-2 and control-2 cows than control-3, MGA-3 and PRID cows. Diameter of the ovulatory follicle was greater (P<.01) 9 d before estrus and growth rate of the ovulatory follicle was less (P<.02) in MGA-2 and control- 2 cows than control-3, MGA-3 and PRID cows. Serum P4 decreased 3 d earlier (P<.02) during the estrous cycle of MGA-2 and control-2 cows than control-3, MGA-3 and PRID cows. Serum E2 was greater (P<.01) 7 d before estrus in MGA-2 cows than all other treatment groups. Changes in mean and baseline LH concentrations and amplitude of LH pulses on d 17, 20 and 23 after onset of estrus did not differ (P>.10) among treatments. Luteinizing hormone pulse frequency was greater (P<.03) on d-20 after onset of estrus in MGA-2 cows than MGA-3 and PRID cows (4.3 ± .6 vs 2.6 ± .3 and 3.2 ± .4, respectively). In addition, LH pulse frequency did not differ (P>.10) 17 or 23 d after onset of estrus among treatments. In conclusion, MGA treatment extended the dominance phase of development of ovulatory follicles, which resulted in the premature increase in serum E2 and frequency of LH release, whereas the dominant follicle present at the beginning of PRID treatment underwent atresia and another preovulatory follicle developed. / Ph. D.

Two commercially available progestogen products for cattle, melengestrol acetate (MGA) and norgestomet (SMB) , were evaluated for their ability to induce synchronized estrus in anovulatory ewes. Seasonally anestrous ewes (n=232; determined by blood serum progesterone concentration) of mixed breeding were randomly assigned within broad age groups to one of seven treatments: 1) control (C); 2) MGA only (OMGA); 3) MGA + zeranol (RMGA); 4) MGA + PG-600 (PMGA; 400 IU pregnant mare's serum gonadotropin + 200 IU human chorionic gonadotropin in a 5 mL dose); 5) 5MB only (OSMB); 6) 5MB + zeranol (RSMB); and 7) 5MB + PG-600 (PSMB). Beginning 10 d before breeding, OMGA, RMGA, and PMGA ewes were fed .3 mg MGA/d provided through a mixture of shelled com and a commercially prepared pelleted supplement containing MGA. Concomitantly, OSMB, RSMB, and PSMB ewes were given a 3 mg norgestomet implant inserted subcutaneously on the back of the ear. Immediately preceding initiation of the MGA and 5MB treatments, RMGA and RSMB ewes were given a single i.m. injection of 2.5 mg zeranol. At the end of the 10-d treatment period, MGA feeding was discontinued and the norgestomet implants were removed. Concomitantly, PMGA and PSMB ewes were given a single i.m. injection of PG-600 (5 mL). All treatment groups were combined into one breeding group on May 4, 1992, with a ram to ewe ratio of 1: 17 for a 30-d breeding period. Mating to synchronized estrus was greater (P < .0001) for progestogentreated ewes. Within progestogen treatments, more (P < .000 1) 5MB ewes were marked within the first 5 d of breeding than MGA ewes. Overall, there were no treatment differences in estrus response for the 30-d breeding period. Blood serum samples collected during the first 14 d of breeding were analyzed for progesterone as an indicator of corpora lutea formation. Even though a large proportion of C ewes displayed luteal activity, only 12 % exhibited behavioral estrus within the first 17 d of breeding. Progestogen treated ewes exhibited a shorter mean interval (P < .0001) from ram introduction to lambing. Fertility and prolificacy were not different for C, MGA, or 5MB ewes. Of the two progestogen treatments used alone, lambing rate was 85 and 59 % (P < .03) for OMGA and OSMB ewes, respectively. Ewes plimed with zeranol before MGA or 5MB treatment exhibited similar levels of fertility and intervals from ram introduction to lambing compared with ewes receiving an injection of PG-600 after progestogen treatment. These data indicate that progestogen products commercially available for cattle may be useful in enhancing out-of-season breeding performance in sheep. / Master of Science

Call number: LD2668 .T4 1985 M52 / Master of Science

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Medroxyprogesterone acetate (MPA) and norethisterone (NET) and its derivatives (norethisterone enanthate (NET-EN); norethisterone acetate (NET-A)), designed to mimic the actions of the endogenous hormone progesterone (Prog), are extensively used by women as contraceptives and in hormone replacement therapy (HRT). A number of reports have indicated that these synthetic progestins affect immune function in the female genital tract thereby increasing the risk of acquiring sexual transmitted infections. Despite these findings, very little is known about their mechanism of action at the cellular level, in particular their steroid receptor-mediated effects on cytokine gene expression. In the first part of this thesis, the effect of Prog, MPA and NET-A on the expression of the endogenous pro-inflammatory cytokine gene, interleukin (IL)-12p40, and anti-inflammatory cytokine gene, IL-10, was investigated in a human ectocervical epithelial cell line, Ect1/E6E7. Quantitative realtime PCR (qPCR) showed that all three ligands significantly upregulated the tumor necrosis factor alpha (TNF )-induced IL-12p40 gene expression, while IL-10 gene expression was downregulated. Moreover, by reducing the glucocorticoid receptor (GR) levels with siRNA, these effects were shown to be mediated by the GR. A more detailed investigation into the molecular mechanism of the progestogen-induced upregulation of IL-12p40 gene expression, using chromatin immunoprecipitation (ChIP), siRNA, co-immunoprecipitation and re-ChIP analyses, showed that the progestogen-bound GR is recruited to the CCAAT enhancer binding protein (C/EBP)- regulatory element of the IL-12p40 promoter, most likely via an interaction with the transcription factor C/EBP . Similar experiments for the progestogen-induced downregulation of IL-10 gene expression showed that the progestogen-bound GR is recruited to the signal transducer and activator of transcription (STAT)-3 regulatory element of the IL-10 promoter, most likely via an interaction with the transcription factor STAT-3. The second part of this study elucidated the influence of the HIV-1 accessory viral protein R (Vpr) on progestogen-induced regulation of IL-12p40, IL-12p35 and IL-10 in the Ect1/E6E7 cell line. Results showed that in these cells, the overexpression of Vpr significantly modulated the effects of Prog, MPA and NET-A on the mRNA expression of IL- 12p40 and IL-10, while only the NET-A effect was modulated on IL-12p35. Moreover, reducing the GR protein levels by siRNA suggested that the GR is required by Vpr to mediate its effects. Taken together, these results show that Prog, MPA and NET-A promote the pro-inflammatory milieu in the ectocervical environment, and that during HIV-1 infections, this milieu is modulated. Furthermore, the results suggest that the use of MPA or NET in vivo may cause chronic inflammation of the ectocervical environment, which may have important implications for ectocervical immune function, and hence susceptibility to infections such as HIV-1. / AFRIKAANSE OPSOMMING: Medroksieprogesteroon asetaat (MPA), noretisteroon (NET) en derivate daarvan noretisteroon enantaat (NET-EN); noretisteroon asetaat (NET-A), ontwerp om die funksies van die natuurlike hormone progesteroon (Prog) na te boots, word wêreldwyd deur vroue as voorbehoedmiddels sowel as vir hormoon vervangingsterapie (HVT) gebruik. Daar is verskeie aanduidings dat hierdie sintetiese progestiene die immuunfunksie in die vroulike geslagskanaal kan beïnvloed en ook die moontlike vatbaarheid van seksueel oordraagbare infeksies kan verhoog. Ten spyte hiervan, is baie min bekend oor hulle meganisme van werking op ‘n molekulêre vlak, veral in die besonder hul effek op sitokinien geenuitdrukking. Die effek van Prog, MPA en NET-A op die geenuitdrukking van ’n endogene pro-inflammatoriese sitokinien, interleukin (IL)-12, en ’n anti-inflammatoriese sitokinien, IL-10, asook die onderliggend meganisme van werking, in ’n menslike ektoservikale sellyn, Ect1/E6E7, is in die eerste deel van hierdie studie ondersoek. Kwantitatiewe “realtime” polimerisasie ketting reaksie (PKR) het getoon dat al drie die ligande die tumor nekrosis faktor alfa (TNF- )-geïnduseerde IL-12p40 geenuitdrukking opreguleer en IL-10 geenuitdrukking onderdruk. Verder is gevind dat induksie van IL-12p40 en inhibisie van IL-10 deur Prog, MPA en NET-A deur die glukokortikoïed reseptor (GR) gedryf word, aangesien volledige opheffing van die effekte op hierdie sitokinien gene waargeneem is wanneer die GR proteïen vlakke deur middel van kort inmengende ribonukleïensuur (siRNS) verminder is. 'n Meer beskrywende ondersoek in die molekulêre meganisme is uitgevoer deur gebruik te maak van chromatien immunopresipitasie (ChIP), siRNS, mede-immunopresipitasie en her-ChIP analises. Hierdie resultate het voorgestel dat die progestogeen (Prog en die sintetiese progestiene)-gebonde GR tot die CCAAT verbeterende bindings protein (C/EBP)- regulatoriese element van die IL-12p40 promotor betrek word en dat die transkripsie faktor C/EBP benodig word om transkripsie van die IL-12p40 geen te aktiveer. Met betrekking tot IL-10, het die resultate voorgestel dat die progestogeen-gebonde GR tot die sein transduksie en aktiveerder van transkripsie (STAT)-3 regulatoriese element van die IL-10 promotor betrek word en dat die transkripsie faktor STAT-3 benodig word om transkripsie van die IL-10 geen te onderdruk. Die tweede deel van die studie het die invloed van die MIV-1 aksesorale virale proteïen R (Vpr) op sitokinien geenuitdrukking, spesifiek die progestogeen-geïnduseerde regulering van IL-12p40, IL-10 en IL-12p35, in die Ect1/E6E7 sellyn ondersoek. Resultate het getoon dat ooruitdrukking van Vpr in hierdie sellyn die effekte van Prog, MPA en NET-A op die mRNS uitdrukking van IL-12p40 en IL-10, en slegs die NET-A effek op IL-12p35, aansienlik moduleer. Vermindering van die GR proteïen vlakke deur middel van siRNS het getoon dat Vpr die GR benodig om hierdie veranderinge mee te bring. In samevatting, die resultate van hierdie proefskrif stel voor dat Prog, MPA en NET-A die pro-inflammatoriese milieu in die ektoservikale omgewing bevorder, en dat hierdie milieu gedurende MIV-1 infeksies verander. Verder, die resultate van hierdie studie impliseer dat die gebruik van MPA en NET in vivo nadelige lokale immuunonderdrukkende effekte mag hê wat kan lei tot kroniese inflammasie van die ektoservikale omgewing en ‘n moontlike verhoging in die vatbaarheid van infeksies soos MIV-1.

Visando elevar a taxa de concepção das receptoras em programas de transferência de embriões (TE), pesquisadores têm buscado aumentar o perfil progesterônico visando aumentar a taxa de prenhez. Para isto, tem se utilizado fármacos, como anti-prostaglandínicos, progesterona, gonadotrofina coriônica humana (hCG) e análogos do GnRH. Estes estudos vêm apresentando resultados de grande importância, uma vez que o aumento do perfil progesterônico torna possível diminuir o número de receptoras por embrião, minimizando os custos e com isso possibilitando uma maior difusão da técnica de TE. Neste estudo a hCG foi utilizada no intuito de melhorar as condições reprodutivas de fêmeas eqüinas candidatas a receptoras de embriões. As éguas foram divididas em três grupos: G 1 (n=28)- administração, IM, de 1 mL de solução fisiológica, quando o folículo atingiu diâmetro médio &ge; 35 mm; G 2 (n=28)- administração de 2.500 UI de hCG (Vetecor&reg;), IM, quando o folículo atingiu diâmetro médio &ge; 35 mm e G 3 (n=28)- administração de 2.500 UI de hCG (Vetecort&reg;), IM, no dia seguinte a ovulação (D1). Nos três grupos foram avaliadas, no D6, por palpação retal e/ou ultra-sonografia as seguintes características reprodutivas: tônus uterino e cervical, morfoecogenicidade uterina e luteal e diâmetro do corpo lúteo. De acordo com estes dados as fêmeas eqüinas foram ordenadas como de 1&ordf;, 2&ordf;, 3&ordf; ou 4&ordf; escolha, sendo as éguas que apresentaram as características reprodutivas desejadas em receptoras foram consideradas como de 1&ordf; escolha, e as que apresentaram as características menos desejadas como 4&ordf; escolha. As concentrações plasmáticas de progesterona foram mensuradas nos dias D0, D2, D4, D6 e D8. Foi encontrada maior concentração de progesterona plasmática nos grupos tratados (G2 e G3) em relação ao controle (G1) no dia da ovulação (D0), no D4 e na concentração média total dos dias [(D0+D2+D4+D6+D8)/5] (P&lt;0,05). O tônus cervical apresentou diferença entre os grupos (P&lt;0,05), sendo que o G3 foi o melhor grupo para essa categoria reprodutiva. A ordem de escolha da receptora diferiu (P&lt;0,05) entre os grupos, sendo que o G3 apresentou uma maior porcentagem de éguas classificadas como de 1&ordf; escolha. Constatou-se correlação positiva e moderada entre o tamanho do corpo lúteo e a produção de progesterona (r=0,41) (P&lt;0,05). Neste estudo pode-se concluir que: a hCG induz aumento na concentração plasmática de progesterona e eleva a porcentagem de receptoras aptas a receberem embriões; existe correlação entre o tamanho do corpo lúteo e a produção de progesterona; e a morfoecogenicidade do corpo lúteo não influencia na concentração plasmática de progesterona em fêmeas eqüinas. / To improve the conception rates of the recipients in embryo transfer (ET) programs, researchers have studied how to increase the progesteronic profile aiming to increase the pregnancy rate. This results were reached by exogenous administration of anti-prostaglandins, progesterone, human chorionic gonadotropin (hCG) and gonadotropin (hCG) and analogs of the GnRH. These works had showed greater results, at once, the elevation of the progesteronic profile made possible the decrease in the number of recipients per embryo: reducing the costs and facilitating the diffusion of the ET technique. In this study, hCG was used in an attempt to improve the reproductive conditions of mare candidates to embryo recipients. The mares were located in three groups: G 1 (n=28) - administration IM of 1 mL of saline solution, when follicle reached mean diameter &ge; 35 mm; G 2 (n=28) - administration of 2.500 UI of hCG (Vetecort&reg;), IM, when follicle reached &ge; 35 mm mean diameter and G 3 (n=28) - administration of 2.500 UI of hCG (Vetecort&reg;), IM, on the following day of the ovulation (D1). Reproductive characteristics were assessed on the D6 by rectal palpation and/or ultrasonographic scanning: uterine and cervical tone, uterine and luteal morphoechogenicity and diameter of the corpus luteum. Based on the reproductive characteristics assessment, equine females were put into four classifications. The mares that had presented the most desirable reproductive characteristics were the 1st classification, and the ones that had presented the worst desired characteristics were the 4th choice. The plasmatic concentrations of progesterone were measured out on the days D0, D2, D4, D6 and D8. Higher plasmatic progesterone concentration was found in G2 and G3 on the day of the ovulation (D0), and on D4 (p&lt;0.05). In addition, higher plasmatic progesterone mean concentration was found for days D0, D2, D4, D6 and D8 (p&lt;0.05). Cervical tone presented difference among the groups (p&lt;0.05) in which the G3 was the best group for this reproductive characteristic. The order of choice of the recipients differed (p&lt;0.05) among the groups. The G3 showed a higher percentage of mares in the 1st choice classification. Positive and moderate correlation was evidenced between the size of the corpus luteum and the production of progesterone (r=0.41) (p&lt;0.05). In this study, it can be concluded that: hCG induces an increase in the plasmatic concentration of progesterone and raises the number of mares with the capacity to receive embryos; correlation exists between the size of the corpus luteum and the production of progesterone; and the morphoechogenicity of the corpus luteum does not influence the plasmatic concentration of progesterone in mares.

O estabelecimento e perfeito funcionamento da placenta são fatores dependentes da intensa vascularização ocorrida no órgão. Os processos de vasculogênese e angiogênese placentária são modulados por diversos fatores, incluindo o VEGF (fator de crescimento vascular endotelial) e bFGF (fator de crescimento fibroblástico básico). Apesar da importância do VEGF e bFGF durante a vascularização estar estabelecida, vários estudos indicam a participação desses fatores de crescimento como moduladores locais em outras funções fisiológicas, como por exemplo o controle da produção hormonal em tecidos esteroidogênicos. Animais clonados podem apresentar alterações na expressão de determinados genes durante seu desenvolvimento, o que pode alterar a função placentária. Os objetivos deste estudo são determinar a localização tecidual do VEGF, bFGF e seus receptores na placenta bovina e avaliar a influência destes fatores de crescimento sobre a produção de progesterona placentária em bovinos não clonados e clonados. Placentomas de 90, 150 e 210 dias de gestação foram obtidos em abatedouro e placentônios de gestações aos 270 dias provenientes de bovinos clonados e não clonados foram coletados após cesarianas. As amostras foram fixadas em formol tamponado 4%, desidratadas e incluídas em parafina. Cortes foram submetidos a imuno-histoquímica para posterior localização das proteínas do VEGF, bFGF e seus receptores. Sob condições assépticas, as células foram mecanicamente dispersas e cultivadas em placas de 96 cavidades. Os fatores foram adicionados em concentrações de 10 e 50 &#951;g/ml de bFGF e VEGF, respectivamente. Amostras de meio de cultura e as células dos grupos controle, bFGF, VEGF e VEGF mais bFGF foram coletadas 24, 48 e 96 horas após a adição dos fatores. A progesterona foi dosada por radioimunoensaio e o conteúdo protéico pelo método de Lowry. Os dados foram analisados utilizando-se o programa estatístico SAS (Statistical Analysis System), as diferenças estatísticas encontradas foram comparadas pelo teste de variação múltipla de Duncan. O VEGF, bFGF e seus receptores foram localizados em células do epitélio e estroma maternos e fetais e células endoteliais vasculares em bovinos não clonados e clonados. As células placentárias apresentaram diferentes capacidades de síntese de progesterona ao longo da gestação. Aos 90 e 210 dias de gestação o VEGF estimulou a produção de progesterona, enquanto aos 270 dias de gestação o fator inibiu a produção deste hormônio. O bFGF estimulou a produção de progesterona pelas células placentárias aos 90 dias de gestação. A adição dos dois fatores de crescimento conjuntamente determinou um estímulo na produção de progesterona aos 210 dias de gestação. A produção de progesterona pelas células de bovinos clonados foi semelhante àquela observada em células de bovinos não clonados na mesma idade gestacional e os fatores de crescimento não influenciaram essa produção. Conclui-se que o VEGF e bFGF, atuando localmente no tecido placentário, funcionam como moduladores do processo de esteroidogênese, influenciando de maneira tempo-dependente a produção de progesterona deste órgão. / Placental establishment and function are dependent on intense vascularization. Placental vasculogenesis and angiogenesis are modulated by several factors, including VEGF (vascular endothelial growth factor) and bFGF (basic fibroblast growth factor). Although the role of VEGF and bFGF during vascularization is already well established, some studies have indicated the participation of these growth factors as local modulators in other physiological functions, such as control of hormonal production in steroidogenic tissues. Cloned animals may exhibit alterations in gene expression during development modifying placental function. The aims of this study are to determine the tissue localization of VEGF, bFGF and their receptors in the bovine placenta and to evaluate the influence of bFGF and VEGF on placental progesterone production in non-cloned and cloned bovines. Placentomes from days 90, 150 and 210 of pregnancy were obtained at local slaughterhouse and placentomes from cloned and non-cloned gestations at 270 days were obtained after cesarean sections. Samples were fixed in 4% buffered formol solution, dehydrated and included in paraffin. Sections were subimitted to immunohistochemistry for subsequent localization of VEGF, bFGF and their receptors proteins. Under aseptic conditions, cells were mechanically dispersed and then cultivated in a 96-well plate. Growth factors were added at concentrations of 10 and 50 &#951;g/ml for bFGF and VEGF, respectively. Samples of culture medium and cells from control, bFGF, VEGF and bFGF plus VEGF groups were collected 24, 48 and 96 hours after growth factor addition. Progesterone concentrations were assessed by radioimmunoassay and protein content was measured by Lowry?s method. Data were analyzed by SAS (Statistical Analysis System) program, significant differences were compared by Duncan?s range multiple test. VEGF, bFGF and their receptors were localized in maternal and fetal epithelial and stromal cells and vascular endothelial cells during pregnancy in non-cloned animals and in cloned bovine placenta at 270 days of pregnancy. Bovine placental cells were able to produce different amounts of progesterone during pregnancy. Growth factors were able to influence progesterone production in placental cells only after 24 hours in culture. At 90 and 210 days of pregnancy VEGF stimulated progesterone production, while at 270 days of pregnancy the growth factor inhibited production of this hormone. bFGF stimulated progesterone production in placental cells from 90 days of pregnancy. Both growth factors together determined an increase in progesterone production in placental cells from 210 days of pregnancy. Progesterone production in placental cells from cloned cattle is similar when compared with non-cloned placental cells at the same gestational age and growth factors did not influence progesterone production in these cells. VEGF and bFGF, acting locally in the placental tissue, are modulators of the steroidogenic process, influencing in a time-dependent manner the progesterone production in this organ.

Visando elevar a taxa de concepção das receptoras em programas de transferência de embriões (TE), pesquisadores têm buscado aumentar o perfil progesterônico visando aumentar a taxa de prenhez. Para isto, tem se utilizado fármacos, como anti-prostaglandínicos, progesterona, gonadotrofina coriônica humana (hCG) e análogos do GnRH. Estes estudos vêm apresentando resultados de grande importância, uma vez que o aumento do perfil progesterônico torna possível diminuir o número de receptoras por embrião, minimizando os custos e com isso possibilitando uma maior difusão da técnica de TE. Neste estudo a hCG foi utilizada no intuito de melhorar as condições reprodutivas de fêmeas eqüinas candidatas a receptoras de embriões. As éguas foram divididas em três grupos: G 1 (n=28)- administração, IM, de 1 mL de solução fisiológica, quando o folículo atingiu diâmetro médio &ge; 35 mm; G 2 (n=28)- administração de 2.500 UI de hCG (Vetecor&reg;), IM, quando o folículo atingiu diâmetro médio &ge; 35 mm e G 3 (n=28)- administração de 2.500 UI de hCG (Vetecort&reg;), IM, no dia seguinte a ovulação (D1). Nos três grupos foram avaliadas, no D6, por palpação retal e/ou ultra-sonografia as seguintes características reprodutivas: tônus uterino e cervical, morfoecogenicidade uterina e luteal e diâmetro do corpo lúteo. De acordo com estes dados as fêmeas eqüinas foram ordenadas como de 1&ordf;, 2&ordf;, 3&ordf; ou 4&ordf; escolha, sendo as éguas que apresentaram as características reprodutivas desejadas em receptoras foram consideradas como de 1&ordf; escolha, e as que apresentaram as características menos desejadas como 4&ordf; escolha. As concentrações plasmáticas de progesterona foram mensuradas nos dias D0, D2, D4, D6 e D8. Foi encontrada maior concentração de progesterona plasmática nos grupos tratados (G2 e G3) em relação ao controle (G1) no dia da ovulação (D0), no D4 e na concentração média total dos dias [(D0+D2+D4+D6+D8)/5] (P&lt;0,05). O tônus cervical apresentou diferença entre os grupos (P&lt;0,05), sendo que o G3 foi o melhor grupo para essa categoria reprodutiva. A ordem de escolha da receptora diferiu (P&lt;0,05) entre os grupos, sendo que o G3 apresentou uma maior porcentagem de éguas classificadas como de 1&ordf; escolha. Constatou-se correlação positiva e moderada entre o tamanho do corpo lúteo e a produção de progesterona (r=0,41) (P&lt;0,05). Neste estudo pode-se concluir que: a hCG induz aumento na concentração plasmática de progesterona e eleva a porcentagem de receptoras aptas a receberem embriões; existe correlação entre o tamanho do corpo lúteo e a produção de progesterona; e a morfoecogenicidade do corpo lúteo não influencia na concentração plasmática de progesterona em fêmeas eqüinas. / To improve the conception rates of the recipients in embryo transfer (ET) programs, researchers have studied how to increase the progesteronic profile aiming to increase the pregnancy rate. This results were reached by exogenous administration of anti-prostaglandins, progesterone, human chorionic gonadotropin (hCG) and gonadotropin (hCG) and analogs of the GnRH. These works had showed greater results, at once, the elevation of the progesteronic profile made possible the decrease in the number of recipients per embryo: reducing the costs and facilitating the diffusion of the ET technique. In this study, hCG was used in an attempt to improve the reproductive conditions of mare candidates to embryo recipients. The mares were located in three groups: G 1 (n=28) - administration IM of 1 mL of saline solution, when follicle reached mean diameter &ge; 35 mm; G 2 (n=28) - administration of 2.500 UI of hCG (Vetecort&reg;), IM, when follicle reached &ge; 35 mm mean diameter and G 3 (n=28) - administration of 2.500 UI of hCG (Vetecort&reg;), IM, on the following day of the ovulation (D1). Reproductive characteristics were assessed on the D6 by rectal palpation and/or ultrasonographic scanning: uterine and cervical tone, uterine and luteal morphoechogenicity and diameter of the corpus luteum. Based on the reproductive characteristics assessment, equine females were put into four classifications. The mares that had presented the most desirable reproductive characteristics were the 1st classification, and the ones that had presented the worst desired characteristics were the 4th choice. The plasmatic concentrations of progesterone were measured out on the days D0, D2, D4, D6 and D8. Higher plasmatic progesterone concentration was found in G2 and G3 on the day of the ovulation (D0), and on D4 (p&lt;0.05). In addition, higher plasmatic progesterone mean concentration was found for days D0, D2, D4, D6 and D8 (p&lt;0.05). Cervical tone presented difference among the groups (p&lt;0.05) in which the G3 was the best group for this reproductive characteristic. The order of choice of the recipients differed (p&lt;0.05) among the groups. The G3 showed a higher percentage of mares in the 1st choice classification. Positive and moderate correlation was evidenced between the size of the corpus luteum and the production of progesterone (r=0.41) (p&lt;0.05). In this study, it can be concluded that: hCG induces an increase in the plasmatic concentration of progesterone and raises the number of mares with the capacity to receive embryos; correlation exists between the size of the corpus luteum and the production of progesterone; and the morphoechogenicity of the corpus luteum does not influence the plasmatic concentration of progesterone in mares.

Urinary steroids have been studied during early and late pregnancy in domestic horses or sporadic samples at various stages of pregnancy in wild equidae. In our studies, urinary estrone sulfate (E1S) and pregnanediol glucuronide (PdG) were monitored throughout pregnancy in six pony mares by enzyme immunoassay (EIA). Both hormones were corrected by creatinine (Cr) index to compensate for the variation in specific gravity. The mean concentration for ElS, (μg/mg Cr), was .38 ± .03 at d 0, decreased to .17 ± .04 at d 1, and maintained at less than .5 μg/mg Cr until d 30. Although, there was an apparent increase to .80 ± .34 at d 34 (NS, P = .122), the first significant increase was .69 ± .15 at d 46 (P = .0275). Mean concentrations remained relatively stable at this approximate level until d 60. This level was followed by a sustained significant increase observed from d 60 onwards. Mean concentrations of El S increased to 1.11 ± .25, 2.01 ± .45, and 5.48 ± 1.47 at d 64, d 76, and d 86, respectively. Levels of EIS further increased reaching a peak of 143.3 ± 9.51 at d 142 (P = .0006), with maximum for individual mares ranging from d 114 to 170, and also ranging from 115.4 to 286.1 pg/mg. In all cases, maximum concentrations were followed by a gradual decline toward parturition with a more rapid decrease 1 to 3 days before parturition. The first significant decrease following the maximum concentration was 91.40 ± 13.11 (P = .0024) at d 184. Estrone sulfate was 12.1 ± 3.8 one day prepartum and decreased to .4 ± .1 and .1 ± .01 at d 1 and 4 postpartum, respectively. The mean concentrations of PdG (ng/mg Cr) increased from 147 ± 4.3 at d 0 to 50.87 ± .17 (NS, P> .05), 36.8 ± 8.1 (P = .016), and 27.6 ± 7.3 (P = .049) at d 6, 8 and 10, respectively. This increase was followed by a decline and generally the levels fluctuated ranging from 20 to 30 ng/mg Cr until d 80. At d 86, the PdG levels increased to 54.7 ± 11.7 (P = .033). This was followed by a further increase to 141.8 ± 21.4 (P = .0139, compared to d 93) at d 135, then continued to increase to 213.0 ± 25.2 at d 198, and remained at this approximate level until d 303. During the last month of gestation, the mean concentrations of PdG increased from 171.8 ± 9.8 at d 29 prepartum to reach a peak of 388.4 ± 108.6 at d 7 prepartum. Maximum concentrations were followed by a slight decrease to 354.5 ± 84.0 at d 1 prepartum and then decreased to 150.6 ± 23.4 and 39.6 ± 9.3 ng/mg Cr at d 1 and 4 postpartum. In comparing the two hormones, E1S remained baseline followed by a slight increase at d 35, whereas PdG was relatively stable until both hormones increased after d 70 of gestation. This might be related to secretion of both hormones by the fetus and their rapid metabolism by placenta. Estrone sulfate reached a peak at approximately d 142 followed by a decline toward parturition while PdG showed a rapid increase from d 70 to 150, followed by a slow sustained increase to d 300 then increased dramatically again before parturition, while El S continued to decline. The profile of these urinary hormones throughout pregnancy appeared to parallel previously published concentrations in blood. Since the patterns of urinary EIS and PdG are different, their sites and mechanism of metabolism are likely different. The results indicate that the presence of the feto-placental unit is important for the secretion of both estrogens and progestins throughout pregnancy and thus could be utilized as a reliable method for pregnancy determination after three months of pregnancy. / Graduation date: 1993

Graduation date: 1993

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes results of four studies conducted at the University of Oregon. Includes bibliographical references (leaves 221-244). Also available for download via the World Wide Web; free to University of Oregon users.