Changes in the expression of markers of stem /progenitor cells linked to fluctuation in lactotroph population

VACA, AM; SOSA, LV; PETITI, JP; MUKDSI, J. H.; ALVAREZ C; TORRES, A I

Congreso; ISSCR anual meeting; 2011

The pituitary gland shows dynamic adjustments in response to hormonal fluctuations such as puberty, pregnancy and lactation. The adaptation of this gland at different physiological requirements may be due to the recruitment and differentiation of stem/progenitor cells (S/P).These cells was located in the marginal zone that limits the pituitary cleft. In previous work we demonstrated that lactotroph population exhibit significant changes during lactation. The aim of this study was to identify pituitary S/P cells and quantify pluripotency markers: Sox2 and Oct-4, evaluating possible changes during lactation and estrous cycle. We used adult Wistar female rats in oestrus and diestrus II phase of estrous cycle and active lactancy. The pituitary gland were processed for ultrastructural immunocytochemistry, which allowed us to determine the topographic location of S/P cells by detection of differentiation markers: ß-catenin and vimentin at the subcellular level and to identify markers associated with S/P cell phenotype, the membrane receptor GFRa2 and transcription factors Sox2 and Oct-4. Morphometric quantification was carried out immunostaining of Sox2 and Oct-4 by electron microscopy using software Image J. Statistics: ANOVA-Fisher. Cilliated cells of the marginal zone were negative for ß-catenin, while vimentin positive cells were localized around those like as they were supporting cells. The GFRa2 receptor was expressed in cells that limit the pituitary cleft. The transcription factors Sox2 and Oct-4 is expressed in marginal zone cells with an increase (p <0.05) during active lactation and oestrus phase compared to diestrus II phase of estrous cycle. These findings would seem to indicate the involvement of stem/progenitor cells in lactotroph population fluctuations on physiological conditions of high hormonal demand.