Pesquisa Veterinária Brasileira (Sep 2007)
Produção de progesterona in vitro pelas células do corpo lúteo bovino ao longo da gestação In vitro progesterone production from bovine corpus luteum throughout gestation
Abstract
O presente trabalho foi desenvolvido para testar a hipótese de que células luteínicas bovinas em cultivo, provenientes dos três terços de gestação, comportam-se da mesma maneira que células in vivo em relação à produção de P4. Foram coletadas amostras de corpos lúteos (CL) de 90 (n=3), 150 (n=3) e 210 (n=3) dias de gestação obtidos em abatedouro. Sob condições assépticas, as células foram mecanicamente dispersas e cultivadas em placas de 96 poços. Após 24 horas de cultivo foram feitas a lavagem dos poços e a adição do precursor pregnenolona. Os tratamentos foram realizados em octuplicata para cada tempo de tratamento (24, 48 e 96 horas) com três repetições de cada período gestacional. As amostras de meio de cultura e as células foram coletadas 24, 48 e 96 horas após adição do precursor e acondicionadas em freezer a -20ºC até o processamento. A progesterona foi dosada através de radioimunoensaio e o conteúdo protéico pelo método de Lowry. Os resultados foram analisados estatisticamente e considerados diferentes quando pThe aim was to test the hypothesis that cultivated bovine luteal cells from three different thirds of pregnancy behave the same way as in vivo luteal cells relative to P4 production. Corpus luteum samples from days 90 (n=3), 150 (n=3) and 210 (n=3) of pregnancy were obtained at a local slaughterhouse. Under aseptic conditions cells were mechanically dispersed and cultivated in a 96 wells-plate. After 24 hours of culture, cells were washed and the precursor pregnenolone was added. Experiments were conducted eight times for each studied time period (24, 48 and 96 h) and three times for each gestational age. Culture medium and cells were collected after 24, 48 and 96 hours of precursor addition and kept frozen at -20ºC until processing. Progesterone was measured by RIA and protein content by Lowry's method. Results were statistically analyzed and considered different when p <0.05. A higher P4 production was observed on day 90 of gestation (35.277±0.075), then this production was decreased at day 150 (28.820±0.231) and increased again at day 210 (32.777±0.099). After 24 hours of culture, luteal cells P4 production reached maximum values in the group of 90 days (2.912±0.047) when compared to 150 (2.669±0.137) and 210 days (2.741±0.088). At 48 and 96 hours of culture, bovine luteal cells from day 90 of gestation produced more P4 than cells from day 210 (2.934±0.029 and 2.976±0.121 respectively x 2.760±0.059 and 2.695±0.149, respectively; p<0.05), which in turn, produced more P4 than cells from day 150 (2.334±0.084 for 48 h and 2.205±0.136 for 96 h). Luteal cells from day 150 of gestation presented a decreasing P4 production throughout the 96 hours of culture. These differences could be explained by differential gene expression of enzymes and/or factors belonging to the esteroidogenic cascade in accordance to the gestational period. The established luteal cell culture model could be used for further functional studies once P4 secretion pattern in vitroresembled what occurs in vivo.
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