Although the various members of the fibroblast growth factor (FGF) family are generally mitotic, one member, FGF18, has been shown to increase the rate of apoptosis of ovarian granulosa cells. In the present study, we first determined whether granulosa cells express FGF18 and we then explored the mechanism through which FGF18 increases apoptosis in vitro. Under culture conditions that favored estradiol secretion and CYP19A1 expression, granulosa FGF18 mRNA levels were barely detectable; however, withdrawing gonadotropic support (follicle-stimulating hormone or insulin-like growth factor 1) reduced levels of CYP19A1 mRNA and increased abundance of mRNA encoding the death ligand FASLG and FGF18. Addition of FGF18, but not FGF2, FGF10, or EGF, increased the proportion of apoptotic cells and frequency of caspase 3 activation, and these effects were abrogated by coculture with estradiol. Addition of FGF18 decreased abundance of mRNA encoding the antiapoptotic proteins GADD45B and MDM2, and increased that encoding the proapoptotic protein BBC3; these effects were reversed by coculture with estradiol. The physiological relevance of FGF18 was determined using an in vivo model: injection of FGF18 directly into growing bovine dominant follicles caused cessation of follicle growth by 24 h after injection. Collectively, these data demonstrate that FGF18 is proapoptotic in vivo and may act through a mechanism involving the BBC3-MDM2 pathway.

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Contamination of animal feed with Fusarium spp results in accumulation of mycotoxins including deoxynivalenol. In animals, deoxynivalenol is metabolized to de‐epoxy deoxynivalenol (DOM‐1), which is generally considered to be a non‐toxic metabolite; however, recent studies demonstrated that DOM‐1 can reduce steroid production and induce apoptosis in the bovine ovary. The objectives of this study were to assess the effects of DOM‐1 on applied aspects of reproductive function in cattle, specifically sperm function and embryo development in vitro and follicle growth and superovulatory responses in vivo. The effect of naturally contaminated feed on superovulatory responses was assessed; a dose of 6 ppm deoxynivalenol increased blood DOM‐1 concentrations to 20 ng/ml, but this did not alter the number of viable embryos recovered on day 7. However, intrafollicular injection of DOM‐1 (100 ng/ml) directly into the growing dominant follicle resulted in cessation of follicular growth over the subsequent 3 days. Treatment with DOM‐1 reduced motility of bull spermatozoa over a 10‐h period in vitro. Addition of DOM‐1 to oocytes in vitro during IVM did not alter rates of cumulus expansion and nuclear maturation, but treatment during IVF reduced the rate of blastocyst formation. These data illustrate that DOM‐1 is more biologically active than previously thought and negatively impacted reproductive outcomes in cattle.

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O objetivo do presente trabalho foi comparar quantitativamente as fibras colágenas tipo I e tipo III pela avaliação histológicas da inserção proximal de músculo interósseo terceiro (I.P.M.I III) de equinos das raças Crioulo (n=26) e Puro Sangue de Corrida (n=6), hígidos com idade média de 5,7 anos. As lâminas foram coradas pelo método picrosirius red e examinadas em microscópio óptico sob luz polarizada. De cada lâmina foram capturadas imagens de 5 campos em aumento de 10 vezes. A porcentagem da área ocupada por cada tipo de colágeno foi determinada pelo plugin threshold colour do software Image J, por meio de análise da segmentação de cor. Pela análise da variância, a proporção de colágenos tipo I e tipo III na I.P.M.I III não diferiu significativamente entre as amostras das raças avaliadas. Entretanto, houve diferença significativa entre os dois tipos de colágeno numa mesma raça, de forma que o colágeno tipo I prevaleceu em relação ao tipo III. Ainda que possuam predisposições distintas, não houve diferença significativa na quantidade de colágeno entre a raça Crioulo e Puro Sangue de Corrida, por se tratar da mesma espécie em questão. Contudo a diferença significativa entre os colágenos tipo I e III era prevista, uma vez que a quantidade do colágeno original do tecido, tipo I deve ser maior que o colágeno de remodelação, tipo III nos casos em que se tratam de animais hígidos.