Effects of Acute and Chronic 17-β-Estradiol Administration on Rhombencephalic, Pineal and Pituitary Catecholamine Levels in Ovariectomized Rats

Abstract

In the intermediate-posterior lobe of the pituitary gland there was a 2-fold increase in both dopamine and norepinephrine concentrations 12 h following estradiol injection to ovariectomized rats. Similar, but smaller, increases in dopamine levels were noted 24 h after injection of estradiol and following chronic estradiol treatment, as well as in norepinephrine levels 24 h after estradiol. In contrast, the dopamine content of anterior pituitary decreased following estradiol treatment. Epinephrine levels were not changed in the pituitary gland. No changes in four discrete brain stem regions or pineal gland catecholamine concentrations, with the exception of a small increase in dopamine concentration in the A2 area, were observed following either acute or chronic estradiol administration. Our results suggest that estrogens can selectively modulate catecholamine metabolism in the anterior and intermediate-posterior lobes of the pituitary gland.