Growth factors and steroidogenesis in the bovine placenta

The control of placental hormone biosynthesis is critical during gestation, since their coordinated action is essential for the normal progress of pregnancy. Hormonal synthesis regulation in placenta is still not elucidated and differs from that observed in other steroidogenic tissues since specific tropic hormones have not yet been identified. Cellular localization of growth factors in the placenta, including VEGF, EGVEGF and bFGF, points that these factors have additional roles in the organ besides their well known modulation on cell proliferation and angiogenesis. In vitro experiments bring new evidence that growth factors play regulatory roles modulating processes related to steroid hormone secretion in the placenta. Importance of local estrogen function has been highlighted and a key enzyme for its synthesis is aromatase cytochrome P450. The objective of this review was to describe some aspects of placental steroidogenesis, mainly focusing on aromatase cytochrome P450 steroidogenic enzyme expression and growth factors as others potential modulators of hormonal synthesis in the orga

Envolvimento da subfamília do fator de crescimento fibroblástico 7 (FGF7) no controle da foliculogênese antral em bovinos

The mechanisms that coordinate follicular development are not well known and are, therefore, target of numerous investigations for facilitateing the understanding of physiology or as promising tools for assisted reproduction. Recently, several ovarian peptides with local action have been reported to participate in the control of follicular development in all stages and modulation of gonadotropins andovarian steroid hormones. In this context, fibroblast growth factors (FGFs) have been extensively investigated in different stages of follicular development and seem to control processes such as follicular atresia, steroidogenesis, and pre-antral follicle development, where FGF7 subfamily is one of the most investigated. Therefore, the objective of this review is to summarize the participation of the FGF7 subfamily in the control of bovine antral folliculogenesis.Os mecanismos que coordenam o desenvolvimento folicular ainda não são completamente conhecidos e, portanto, constituem o alvo de numerosas investigações, seja por facilitarem a compreensão da fisiologia ou por serem promissoras ferramentas para a reprodução assistida. Recentemente, diversos peptídeos ovarianos de ação local têm sido descritos por participarem do controle de todas as fases do desenvolvimento folicular, bem como da modulação de hormônios esteróides ovarianos e gonadotrofinas; entre esses peptídeos estão os fatores de crescimento fibroblástico (FGFs). Os FGFs têm sido extensamente investigados em diversas fases do desenvolvimento folicular e parecem controlar processos como atresia folicular, esteroidogênese, bem como o desenvolvimento folicular pré-antral, sendo a subfamília do FGF7 uma das mais investigadas neste contexto. Assim, esta revisão tem como objetivo sumarizar a participação da subfamília do FGF7 no controle da foliculogênese antral de bovinos

Luteinizing Hormone Receptor (LHR): basic concepts in cattle and other mammals. a review

Acquisition of the luteinizing hormone receptor (LHR) on granulosa cells of the dominant follicle is essential to physiological LH-mediated effects on the final stages of follicular growth, final maturation of the oocyte, ovulation and luteinization of the follicular wall. Therefore, LHR plays a key role in the final maturation of the dominant follicle from follicular dominance to ovulation. In this review, the basic molecular aspects of LHR (gene structure, alternative splicing and ligand mediated activation) and the physiological regulatory aspects (changes in LHR expression during antral follicle growth and a post-transcriptional model for downregulation of LHR transcripts) are addressed. Despite the accumulation of considerable amounts of information about LHR, a comprehensive and broad model for the role of LHR in bovine antral follicle growth is missing. Questions such as the function for alternative LHR transcripts, their transcriptional and translational regulation, and how the transcripts go to the cell surface and interact with ligands remain to be elucidated in bovine and other species.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Immunohistochemical detection of receptors for oestrogen and progesterone in endometrial glands and stroma during the oestrous cycle in Nelore (Bos taurus indicus) cows

The aim of the present study was to monitor endometrial distribution and concentrations of oestrogen receptors 'alfa' (ER'alfa') and progesterone receptors (PR) by immunohistochemistry in Nelore cows (Bos taurus indicus) during the oestrous cycle. Blood samples were collected for progesterone measurement and endometrial samples were taken from the uterine horn contra lateral to the corpus luteum in 16 cows at days 0 (ovulation), 5, 9, 13 and 19 of the oestrous cycle. Immunostaining evaluation for ER'alfa' and PR in the glandular epithelium and uterine stroma was performed by two methods: positive nuclei counting and staining intensity of the nuclei. Specific positive staining reactions for both receptors were limited to cell nuclei and they were not identified in the cytoplasm. The proportion of ER'alfa' positive nuclei had a temporal variation throughout the oestrous cycle in both cell types evaluated and was higher in uterine stroma than the glandular epithelium (p < 0.05). The greatest proportion of ER'alfa' stained nuclei was observed at oestrus and during the initial and mid luteal phase (days 5, 9 and 13) (p < 0.05) in the glandular epithelium and at days 0, 5 and 9 in the uterine stroma (p < 0.01).The proportion of PR positive nuclei remained constant throughout the entire oestrous cycle for both cell types evaluated (p > 0.05). A higher proportion of PR positive nuclei was measured in the uterine stroma compared with the glandular epithelium (p < 0.05). Intensity of staining for ER'alfa' and PR varied throughout the oestrous cycle (p < 0.01). There was a higher staining intensity at days 0 and 5 in the stroma for ER'alfa' (p < 0.01) and PR (p < 0.01) and in the glandular epithelium at days 0, 5, 9 and 13 for ER'alfa' (p < 0.01) and at days 0, 5 and 9 for PR (p < 0.01) when compared with the other evaluated days. These data demonstrate that ER'alfa' and PR expression varied throughout the oestrous cycle in Nelore cows, in general with highest concentrations at oestrus and the lowest during the luteal phase. This is similar to patterns observed in Bos taurus tauru