Regulation of the angiotensinogen gene by estrogens in rat liver and different brain regions.

Estrogens regulate the production of angiotensinogen (AOG) in liver and other tissues. However, evidence suggests that the effect is tissue specific and that it may depend on a variety of factors. We have tested the effects of ethynylestradiol (EE) on liver AOG mRNA and plasma AOG in intact male and ovariectomized female rats, as well as in hypophysectomized male rats. EE stimulated both variables to a comparable extent and in a dose-dependent manner. However, its effect on plasma AOG was significantly higher in female than in male rats. In addition, there was no response in hypophysectomized male rats; however, responsiveness was restored by pretreatment of the animals with prolactin. AOG mRNA concentration was also affected by EE in brain, but there were striking time- and region-specific differences. These results indicate that cell-specific factors also modulate the response of the AOG gene to EE in extrahepatic tissues.