THYROID-HORMONE STIMULATES RENIN SYNTHESIS IN RATS WITHOUT INVOLVING THE SYMPATHETIC NERVOUS-SYSTEM

The present study was performed to examine whether renal expression of the renin gene is regulated by thyroid hormone. Thirty male Sprague-D awley rats were divided into hypothyroid, control, and hyperthyroid gr oups by use of daily intraperitoneal administration of methimazole, sa line vehicle, or thyroxine, respectively. Each group was further subdi vided into sympathetic innervated and sympathetic denervated subgroups by use of intraperitoneal administration of saline vehicle or B-hydro xydopamine. Plasma renin activity and renal levels of renin were measu red by radioimmunoassays after 8 wk. Renal expression of renin mRNA wa s evaluated by a semiquantitative reverse transcriptase-polymerase cha in reaction. Compared with control animals, plasma renin activity, ren al level of renin, and renal expression of renin mRNA were reduced (82 , 94, and 71%, respectively) in hypothyroid animals and elevated (155, 1,182, and 152%, respectively) in hyperthyroid animals. Sympathetic d enervation had no independent effect on these renin values. Our result s indicate that thyroid hormone stimulates renin synthesis without inv olving the sympathetic nervous system.