Elevated angiotensinogen mRNA levels in rat liver by nephrectomy

The expression of the angiotensinogen gene was studied in nephrectomized rats with and without adrenal glands. Angiotensinogen mRNA was measured by a sensitive radiodensitometric hybridization assay. Angiotensinogen mRNA levels in the liver increased 5 times by nephrectomy alone and 2.6 times by nephrectomy with adrenalectomy in acute experiments. Brain mRNA levels remained the same in both groups. When nephrectomy was performed 7 days after adrenalectomy, mRNA level increased by 50%. Angiotensinogen mRNA increased 5 times in the liver and 2.3 times in the brain by the administration of dexamethasone. An additive effect on liver angiotensinogen mRNA level was observed in nephrectomy with dexamethasone treatment. These results suggest that in nephrectomy, a synergetic action of glucocorticoids and other unknown factors increase hepatic angiotensinogen mRNA levels.