Estradiol and calcium affect the growth hormone producing cells in female middle-aged rats

The effects of multiple doses of estradiol dipropionate (EDP) or calcium glucoheptonate (Ca) on the growth and function of pituitary somatotropes (GH cells) were studied. Female middle-aged rats were receiving i.p. EDP (0.625 mg i.p./kg b.w), or Ca (11.4 mg/kg b.w) every day for two weeks. Blood samples were collected for hormone analyses and pituitaries dissected for histological and morphometric evaluation 24 h after the last injection. GH-producing cells were examined using the peroxidase-antiperoxidase (PAP) immuno-histochemical procedure. Both EDP- and Ca-treatment significantly decreased all morphometric parameters of GH cells (p<0.05) in comparison with the corresponding controls. Serum concentration of growth hormone (GH) in EDP- or Ca-treated groups was lower by 65% and 13% (p<0.05) respectively comparing to the controls. The difference between all morphometric parameters of EDP- and Ca-treated rats was statistically significant (p<0.05) in relation to the controls. These findings suggest that multiple EDP, or Ca application affects (directly or indirectly) the control of growth and secretory activity of GH cells in middle-aged female rats.