Changes in thrombospondin-1 levels in the endothelial cells of the anterior pituitary during estrogen-induced prolactin-secreting pituitary tumors

[~MaryO~]

http://journals.endocrinology.org/joe/fca/JOE06925.htm

Changes in thrombospondin-1 levels in the endothelial cells of the anterior pituitary during estrogen-induced prolactin-secreting pituitary tumors

Abby J Sarkar, Kirti Chaturvedi, Cui Ping Chen and Dipak K Sarkar

Endocrinology Program and Department of Animal Sciences, Rutgers, The State University of New Jersey, 84 Lipman Drive, New Brunswick, NJ 08901, USA

 

(Requests for offprints should be addressed to D K Sarkar)

Abstract

 

Thrombospondin-1 (TSP-1), a multifunctional matrix glycoprotein, has been shown to control tumor growth by inhibiting angiogenesis in various tissues. However, the role of this glycoprotein in pituitary angiogenesis is not well studied. In this report, we determined the changes in the production and action of TSP-1 on endothelial cells in anterior pituitary following estradiol treatment, which is known to increase prolactin-secreting tumor growth and vascularization in this tissue. We showed that TSP1 immunoreactive protein is distributed in the anterior pituitary, particularly in the endothelial cells. Estradiol treatment for 2 and 4 weeks decreased the total tissue immunoreactive level of TSP1 as well as the endothelial cell specific immunoreactive level of this protein in the anterior pituitary. The steroid treatment also decreased the protein levels of TSP1 in anterior pituitary tissues and in purified pituitary endothelial cells in primary cultures. Determination of the effects of TSP-1 on proliferation and migration of pituitary-derived endothelial cells in primary cultures elucidated an inhibitory action of TSP-1 on this vascular cell functions. These results suggest that locally produced TSP-1 may regulate estrogen angiogenic action on the pituitary.

 

Journal of Endocrinology

Download the ACCEPTED PREPRINT (i.e. full text) of this article in Acrobat PDF format.