Gene expression profile in prepubertal bovine mammary parenchyma and epithelial cells in response to ovariectomy
B T Velayudhan, M L McGilliard, H Jiang, S E Ellis and R M Akers
This study was carried out to compare the expression profile of steroid receptors and selected genes associated with cell signaling and proliferation in Mammary parenchyma (PAR) homogenates compared with mammary epithelial cells (MEC) in response to ovariectomy. Prepubertal dairy heifers were randomly assigned to one of two treatments, ovariectomized (n = 7) or sham operated (n = 12) and tissues were harvested 30 d after surgery. Parenchymal samples were snap frozen in liquid nitrogen for total RNA isolation. Samples of MEC were prepared from cryosections of parenchymal tissues using laser assisted microdissection and capture. Coupling two precise technologies like laser capture microdissection and quantitative realtime PCR enabled measurement of transcript abundance in MEC even at a very low level. Data were analyzed using Mixed procedure of SAS and significance was declared at P d” 0.05. The data strongly indicate a disparity in the response to ovariectomy between MEC and PAR tissue and suggest that ovariectomy very strongly impacted the non-epithelial cells in the PAR rather than the MEC themselves.
Keywords: mammary parenchyma, mammary epithelial cells, laser capture microdissection.