Gene expression in cattle reproductive organs and mammary gland
This study was divided in three experiments that aimed to: 1) investigate effects of maternal overnutrition on gonadal development and pituitary-gonadal gene expression in cattle fetuses at mid and late gestation. Twenty-seven multiparous dry cows were fed either high (ad libitum, H) or moderate (M)...
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| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | Brasil |
| Recursos: | Universidade Federal de Viçosa (UFV) |
| Repositorio: | LOCUS Repositório Institucional da UFV |
| Idioma: | inglés |
| OAI Identifier: | oai:locus.ufv.br:123456789/7932 |
| Acesso em linha: | http://www.locus.ufv.br/handle/123456789/7932 |
| Access Level: | acceso abierto |
| Palavra-chave: | Bovino - Genética Nutrição animal Regulação de expressão gênica Bovino - Reprodução Genética e Melhoramento dos Animais Domésticos |
| Resumo: | This study was divided in three experiments that aimed to: 1) investigate effects of maternal overnutrition on gonadal development and pituitary-gonadal gene expression in cattle fetuses at mid and late gestation. Twenty-seven multiparous dry cows were fed either high (ad libitum, H) or moderate (M) intake of the same diet. Twelve cows from H (n=6) and M (n=6) intake carrying females fetuses were euthanized at 199 and 268 days of gestation (DG; n=3 for H or M on each DG). Fifteen cows from H (n=6) and M intake (n=9) carrying male fetuses were euthanized at 139, 199 and 241 DG (n=2 for H and n=3 for M on each DG). 2) To evaluate effects of different planes of nutrition on mammary parenchyma (PAR) development, expression of lipogenic marks (CD36, ACCA, FASN, ADIPOR1), concentrations of blood hormones and liver GHR, IGF1, IGFPB-2 and -3 mRNA expression in prepubertal heifers. Eighteen heifers were fed 1 of 3 nutrient intake levels (n = 6/treatment) designed to sustain an average daily gain (ADG), as follows: high gain (HG-1 kg/d), low gain (LG- 0.5 kg/d) or maintenance (MA). 3) To elucidated if the expression pattern of ESR1, GDF9, FSHR, LHR, BMPR2, TGFB1, TGFB2, BMP15, BMP6, BMP7, CYP19A1, HSD3B1, IGF1, IGFR1 and IGF2 genes could be involved in modulate the timing of puberty in Brahman heifers. In the first experiment, primordial and total follicle numbers were lower in fetal ovaries from H than in M intake cows. These results were reverse for preantral and antral follicles. Volumetric proportion and diameter of seminiferous cord were lower in fetal testis of H than M intake cows. The expression level of FSHB was greater in pituitary gland of female fetus from H compared to M intake cows, irrespective of DG, whereas LHB gene expression did not differ. In males, FSHB and LHB gene expression levels were similar between maternal intake groups. Fetal ovarian expression of P450 aromatase, StAR, BMPR2, TGFBR1, GDF9, FSHR, Bax and CASP3 genes were higher in H than in M intake cows, irrespective of DG. Fetal testicular expression of StAR, HSD17B3, IGF1, IGF2 and IGF1R genes were higher in M than in H intake cows. Overall, maternal H intake seems to affect fetal ovarian follicular growth and number of follicles, which may 8 affect size of ovarian reserve in their offspring. In male fetus, maternal H intake seems to disturb testicular development and may have implications on sperm production. In the second experiment, mammary PAR weight and MA to MG ratio was lower in HG than MA and LG heifers, whereas mammary extraparenchymal fat was greater in HG heifers than other groups. Heifers fed the HG had a greatest fraction of lipids in their PAR, and smallest fraction of protein in their PAR. However, the number of intraparenchymal adipocytes was similar between the groups. Heifers fed the HG had greater serum IGF1 than others, and serum insulin was lower in MA than HG and LG heifers. The liver GHR, IGF1 and IGFBP3 mRNA was higher whereas IGFBP2 mRNA was lower in HG heifers compared to others. The expression of CD36, ACCA, FASN and ADIPOR1 were up regulated by nutrient intake level. Overall, these results demonstrated that enhancing nutrient intake favored to fat accumulation on body and mammary gland, also resulted adipocyte hypertrophy in the PAR of HG heifers, which could be a predictor of impaired mammary development. Finally, qRT-PCR data from the third experiment revealed the expression of FSHR, BMP7, CYP19A1, IGF1 and IGFR1 mRNA was greater in PRE heifers, when contrasted to POST heifers. In addition, the expression of IGF1 mRNA was positively correlated with BMP7 mRNA (P = 0.07, r = 0.84) and the expression of HSD3B1 mRNA was negatively correlated with expression of CY19A1 mRNA (P = 0.03, r = -0.90). Taken together, these results suggest that the differential expression of ovarian genes could be associated with changes in follicular dynamics and different cell populations that have emerged as consequence of puberty and the luteal phase. The emerging hypothesis is that two key regulators of ovarian activity pre-puberty, BMP7 and IGF1 modulate the expression of FSHR, LHR, IGFR1 and CYP19A1. BMP7 seems to down-regulate LHR and up-regulate FSHR and CYP19A1, which mediates the follicular dynamics in heifer ovaries. Thus, BMP7 and IGF1 seem to play synergic regulatory roles and were predicted to interact. |
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