HORMONAL-REGULATION OF THE ESTROGEN-RECEPTOR IN PRIMARY CULTURES OF HEPATOCYTES FROM FEMALE RATS

Estrogen treatment affects the hepatic synthesis and/or secretion of s everal proteins involved in clinically important pathological processe s such as atherosclerosis, hypertension, and thrombosis. The endocrine regulation of the estrogen receptor (ER) concentration in primary cul tures of rat hepatocytes was studied. Human growth hormone (AGH) and d examethasone (DEX) in combination increased ER concentration 6-fold an d ER mRNA levels 2.5-fold. These effects were not significantly differ ent from those observed after treatment with the purely somatogenic bo vine growth hormone (GH) in combination with DEX. Treatment with the l actogen ovine prolactin in the presence or absence of DEX did not sign ificantly affect ER or ER mRNA concentrations. Triiodothyronine treatm ent at the most effective concentration (50 nM) increased ER and ER mR NA levels twofold Medium supplementation with estradiol (0.1 nM) throu ghout the experiment did not affect the response to treatment with hGH and DEX. Treatment with high concentrations of ethinylestradiol in co mbination with AGH and DEX, however, increased the ER level twice as m uch as hGH and DEX without addition of estradiol or ethinylestradiol, whereas the ER mRNA concentration was the same in both the GH + DEX gr oup and GH + DEX + (estradiol or ethinylestradiol) groups. These data indicate the importance of CH in combination with glucocorticoids for the maintenance of ER concentrations in the rat liver. Thyroid hormone s may be of some, although minor importance, whereas the data suggest that prolactin is not directly involved in hepatic ER regulation (Ster oids 62:647-654, 1997) (C) 1997 by Elsevier Science Inc.