Resumo
Events leading to maturation of the equine preovulatory and ovulation resemble those present in an inflammatory reaction. Once ovulation takes place, luteinizing granulosa cells quickly continue to undergo functional and structural changes that results in a remarkable growth of the luteal gland and increasing output of progesterone. The developing corpus luteum requires the establishment of a robust development of extracellular matrix and vascular network (angiogenesis). This development and regulation is governed by several growth factors, cytokines, polymorphonuclear leukocytes, and prostaglandins that work in and autocrine and paracrine to achieve successful luteal function, especially if pregnancy is taking place. Most of the information available regarding early development of the corpus luteum and its regulation derive from studies in humans, ruminants and laboratory animals. Recently, considerable attention has been given to elucidating these events in the equine corpus luteum. While much of the available research conducted in other species can be extrapolated to equine species, it is critical that we continue to learn more about the intrinsic peculiarities about the CL formation and regulation in horses.(AU)
Assuntos
Animais , Feminino , Corpo Lúteo/anormalidades , Corpo Lúteo/lesões , Cavalos/anormalidades , Cavalos/lesões , Citocinas/análiseResumo
Events leading to maturation of the equine preovulatory and ovulation resemble those present in an inflammatory reaction. Once ovulation takes place, luteinizing granulosa cells quickly continue to undergo functional and structural changes that results in a remarkable growth of the luteal gland and increasing output of progesterone. The developing corpus luteum requires the establishment of a robust development of extracellular matrix and vascular network (angiogenesis). This development and regulation is governed by several growth factors, cytokines, polymorphonuclear leukocytes, and prostaglandins that work in and autocrine and paracrine to achieve successful luteal function, especially if pregnancy is taking place. Most of the information available regarding early development of the corpus luteum and its regulation derive from studies in humans, ruminants and laboratory animals. Recently, considerable attention has been given to elucidating these events in the equine corpus luteum. While much of the available research conducted in other species can be extrapolated to equine species, it is critical that we continue to learn more about the intrinsic peculiarities about the CL formation and regulation in horses.
Assuntos
Feminino , Animais , Cavalos/anormalidades , Cavalos/lesões , Citocinas/análise , Corpo Lúteo/anormalidades , Corpo Lúteo/lesõesResumo
A busca por melhores resultados reprodutivos nos sistemas de produção atuais está diretamente ligada ao retorno econômico para o produtor. Desse modo, a maximização da produção é um fator muito importante. Aliado a isso, existe uma grande preocupação atual em relação aos resíduos hormonais utilizados em protocolos de reprodução, como os ésteres de estradiol. Primeiramente no artigo 1 objetivou-se fazer uma revisão dos principais hormônios utilizados como indutores da ovulação em protocolos de inseminação artificial em tempo fixo. A prostaglandina a qual é amplamente utilizada com objetivo de luteólise tem apresentado efeitos positivos em relação a ovulação em fêmeas bovinas e pode ser uma alternativa aos ésteres de estradiol já proibidos em alguns países. Posteriormente e com base no exposto acima, o presente estudo objetivou avaliar 1) o efeito da prostaglandina F2 intramuscular (i.m) durante o processo ovulatório, em comparação com o GnRH e 2) se o tratamento com PGF é capaz de reverter os efeitos inibitórios de um antiinflamatório não esteroidal (AINE) na cascata ovulatória induzida pelo GnRH, testando-se a hipótese de que a aplicação i.m de prostaglandina F2 altera o processo ovulatório em bovinos afetando a luteinização e a vascularização no folículo. Vacas (n=19) tiveram a onda folicular sincronizada com benzoato de estradiol (D0), dispositivo intravaginal de progesterona (DIVP4; 9 dias) e aplicação de PGF (241µg; i.m.) no D8. No experimento 1, após 12h da retirada do DIVP4, as vacas foram alocadas em três grupos: controle: solução salina 0,9% i.m (n=6); GnRH: 100µg de acetato de gonadorelina i.m (n=7); e PGF: 500µg de cloprostenol sódico i.m. (n=6). Os folículos foram aspirados 24 h após os tratamentos, não houve diferença significativa (P>0,05) nas concentrações de P4 e E2 no fluido folicular (FF), mas os níveis de E2 foram menores no grupo GnRH (P<0,05). No experimento 2, aplicou-se GnRH (acetato de gonadorelina; 100µg i.m.) 20h após a remoção do DIVP4 (hora 0), em todos os animais. Imediatamente após, as vacas foram alocadas em três grupos: controle: solução salina 0,9% i.m (n=6); AINE: 2,2mg/kg i.m. de flunixin meglumine (FM) 17h após GnRH (n=6); e grupo AINE+PGF, 2,2mg/kg i.m. de FM 17h após aplicação de GnRH e 25mg i.m. de PGF 23h após GnRH (n=6). O grupo AINE+PGF obteve menor concentração de P4 no FF e menor vascularização da parede folicular (P<0,05) 24h após GnRH. Não houve diferença significativa nos níveis de E2 intrafolicular. Conclui-se que a aplicação i.m de PGF não induz os mesmos efeitos observados sobre a esteroidogênese após o tratamento com GnRH.
The search for better reproductive outcomes in current production systems is directly linked to the economic return to the producer. In this way, maximizing production is a very important factor. Allied to this, there is a great current concern regarding the hormonal residues used in reproduction protocols, such as esters of estradiol. Firstly, in article 1 we aimed to review the main hormones used as ovulation inducers in fixedtime artificial insemination protocols. Prostaglandin, which is widely used for the purpose of luteolysis, has shown positive effects on ovulation in bovine females and may be an alternative to estradiol esters already banned in some countries. Subsequently and based on the above, the present study aimed to evaluate 1) the effect of intramuscular prostaglandin F2 (im) during the ovulatory process, compared to GnRH and 2) if PGF treatment is able to reverse the inhibitory effects of a nonsteroidal anti-inflammatory drug (NSAID) in the ovulatory cascade induced by GnRH, testing the hypothesis that the im application of prostaglandin F2 alters the ovulatory process in bovines affecting luteinization and vascularization in the follicle. Cows (n = 19) had the follicular wave synchronized with estradiol benzoate (D0), intravaginal progesterone device (DIVP4; 9 days) and application of PGF (241 g; i.m.) at D8. In experiment 1, after 12 h of DIVP4 withdrawal, the cows were allocated into three groups: control: saline solution 0.9% i.m (n = 6); GnRH: 100g gonadorelin acetate i.m (n = 7); and PGF: 500g sodium cloprostenol i.m. (n = 6). The follicles were aspirated 24 h after the treatments, there was no significant difference (P> 0.05) in the concentrations of P4 and E2 in the follicular fluid (FF), but E2 levels were lower in the GnRH group (P <0.05 ). In experiment 2, GnRH (gonadorelin acetate, 100g i.m.) was applied after removal of DIVP4 (time 0) in all animals. Immediately after, the cows were allocated in three groups: control: saline solution 0.9% i.m (n = 6); NSAID: 2.2mg / kg i.m. of flunixin meglumine (FM) 17 h after GnRH (n = 6); and AINE + PGF group, 2.2mg / kg i.m. of FM 17h after application of GnRH and 25mg i.m. of PGF 23h after GnRH (n = 6). The AINE + PGF group had a lower concentration of P4 in the FF and less vascularization of the follicular wall (P <0.05) 24h after GnRH. There was no significant difference in intrafollicular E2 levels. It is concluded that the i.m application of PGF does not induce the same effects observed on steroidogenesis after GnRH treatment.