Induced physical distension of rat mammary glands accelerates the onset of apoptosis and involution compared with milk accumulation alone

摘要

Extended periods of milk accumulation result in reduced milk secretion, increased apoptosis and eventually, involution of mammary glands. The subsequent change in epithelial cell shape from a cuboidal to a flattened morphology as the alveoli distend with milk may initiate changes in protein and gene expression (mechanotransduction) triggering the process of involution (Davis et aL, 1999). The rapid up-regulation of the pro-apoptotic and immune response marker pSTATS (Li et aL, 1997), the loss of cell-extracellular matrix (ECM) survival signalling via pl-integrin (McMahon et aL, 2004; Singh et aL, 2005) and the down-regulation of tight junction (TJ) proteins (occludin, claudin-1 and ZO-1; Cooper et aL, 2003; 2004) which occur during mammary engorgement are postulated to participate in these mechanotransduction events. Therefore, the aim of this experiment was to investigate the effect of induced physical distension of rat mammary glands on early events during mammary involution.