[Pharmacologic control of hypophyseal tumors: interactions of estrogens, thyroid hormones, growth and anti-growth factors]

Abstract

Estrogens are involved in anterior pituitary (AP) growth and tumor transformation of AP. Central dopaminergic and noradrenergic systems are probably most important systems in regulation of AP growth. Estrogen-induced AP growth is associated with decreased metabolism of central catecholamines and increased dopaminergic DA-2 receptors. Application of thyroid hormones or methylene blue prevents both estrogen-induced catecholaminergic inhibition and dopamine DA-2 receptors increment in the AP. The alone given methylene blue increases the dopaminergic activity and the binding sites for dopamine. The study of interaction of natural regulators or synthetic compounds with estrogen-induced pituitary growth will be of value to understand better mechanisms of pituitary tumor formation and possibly find new approaches towards treating patients with these tumors.