RESUMO
The transforming growth factors beta (TGFß) are local factors produced by ovarian cells which, after binding to their receptors, regulate follicular deviation and ovulation. However, their regulation and function during corpus luteum (CL) regression has been poorly investigated. The present study evaluated the mRNA regulation of some TGFß family ligands and their receptors in the bovine CL during induced luteolysis in vivo. On day 10 of the estrous cycle, cows received an injection of prostaglandin F2α (PGF) and luteal samples were obtained from separate groups of cows (n= 4-5 cows per time-point) at 0, 2, 12, 24 or 48 h after treatment. Since TGF beta family comprises more than 30 ligands, we focused in some candidates genes such as activin receptors (ACVR-1A, -1B, -2A, -2B) AMH, AMHR2, BMPs (BMP-1, -2, -3, -4, -6 and -7), BMP receptors (BMPR-1A, -1B and -2), inhibin subunits (INH-A, -BA, -BB) and betaglycan (TGFBR3). The mRNA levels of BMP4, BMP6 and INHBA were higher at 2 h after PGF administration (P<0.05) in comparison to 0 h. The relative mRNA abundance of BMP1, BMP2, BMP3, BMP4, BMP6, ACVR1B, INHBA and INHBB was upregulated up to 12 h post PGF (P<0.05). On the other hand, TGFBR3 mRNA that codes for a reservoir of ligands that bind to TGF-beta receptors, was lower at 48 h. In conclusion, findings from this study demonstrated that genes encoding several TGFß family members are expressed in a time-specific manner after PGF administration.
RESUMO
ABSTRACT: Gestation length in swine has a considerable amplitude and both early and delayed parturition are common. This variation increases the occurrence of unassisted farrowing and could lead to a wide-ranging age at weaning for piglets born from one batch. Supervision of sow parturition is crucial to reduce mortality of neonate piglets. To facilitate assistance, induction of farrowing using prostaglandin F2α (PGF) has been widely used in batch farrowing systems, whereby synchronization would concentrate the time of farrowing, allowing for better organization of employees. However, a viable alternative method that can be implemented to manage farrowing is to sustain high progestagen levels in the final days of gestation and, consequently, prevent early parturition. Efficient techniques to delay farrowing such as using oral progestagen supplementation have been previously described, but are only recently being considered for commercial use. The present manuscript reviews publications regarding delaying parturition and discusses the use of intravaginal devices (IVDs) containing progestagen. There is limited data addressing the effect of progestagen treatment during gestation on productive and reproductive performance. Therefore, future studies should focus on improving synchronization protocols following progestagen supplementation and evaluating piglet viability and sow fertility, before widely using progestagen supplementation to manipulate parturition.
RESUMO: Como a duração da gestação de suínos pode ter ampla variação, é comum a ocorrência de partos antecipados ou gestações prolongadas. Isso aumenta as chances de partos sem assistência e leva a uma grande variação de idade dos leitões dentro do lote de produção. Portanto, a supervisão do parto é indispensável para reduzir as perdas neonatais. Para facilitar o auxílio aos leitões, a indução do parto com prostaglandina F2α (PGF) é eficaz e amplamente utilizada, sendo indicada para concentrar os partos em momentos mais adequados, preferencialmente durante o horário com maior disponibilidade de colaboradores. Uma alternativa viável é manipular o momento do parto, através da manutenção de níveis plasmáticos elevados de progestágeno durante o final da gestação, a fim de evitar partos antecipados. Formas eficientes de evitar o parto através de suplementação oral de progestágenos foram descritas há décadas, mas apenas recentemente tem sido cogitada a utilização comercial. A presente revisão aborda estudos disponíveis na literatura relacionados ao protelamento do parto, incluindo a utilização de dispositivos intravaginais (DIVs) impregnados com progestágeno. São poucos os dados disponíveis relacionados ao uso de progestágenos na gestação com índices produtivos e reprodutivos. Portanto, alguns pontos ainda devem ser melhor avaliados, especialmente com relação à determinação da sincronia dos partos após o fim da suplementação com progestágenos, à viabilidade dos neonatos e à fertilidade subsequente das fêmeas antes da ampla adoção desta técnica.
