Lactotrophs: The new and major source for VEGF secretion and the influence of ECM on rat pituitary function in vitro

Abstract

Vascular endothelial growth factor (VEG F) plays a pivotal role in pituitary endocrine function by influencing fenestration and blood vessel growth. Folliculostellate (FS) cells, which represent only a small number of pituitary cells, are recognized to produce VEG F. Tissue sections and primary pituitary cell cultures from rat pituitary glands were performed to co-localize VEG F and pituitary lactotrophs, which represents nearly 50% of all pituitary cells, by immunofluorescence. VEG F is co-localized with prolactin-producing cells in vivo and in vitro. FS cells are present infrequently in vivo (1.6%) and in vitro (2.4%). Culture supernatants were analyzed for the presence of VEG F by EL ISA. VEG F levels are always significantly lower in supernatants from the cells that are seeded on Matrigel extracellular matrix (EC M) compared to the cells grown on plastic. Lower VEG F concentrations in supernatants from the pituitary cells cultured on EC M may reflect a more adequate cell environment compared to culture on plastic. These results demonstrate for the first time, that VEG F is expressed by lactotrophs, which outnumber FS cells. These results are of potential clinical relevance especially in oncology for the interpretation of studies investigating anti-angiogenic treatment of pituitary tumors.