Stimulation by thyroid hormone of renin mRNA in mouse submandibular gland

Renin in the female mouse submandibular gland (SMG) is known to increase in response to thyroid hormone. In the present study a 500 base-pair renin cDNA was used to quantify renin mRNA, the product of transcription of the Ren-2 gene, in the female mouse SMG in response to thyroid hormone to assess more directly the nature of stimulation of renin biosynthesis. After daily injection for 1 wk renin mRNA increased from control values of 36 +/- 3 SE ng/g tissue to 212 +/- 41 with triiodothyronine (T3; P less than 0.005) and to 217 +/- 33 with thyroxine (T4; P less than 0.005). Treatment of mice with propylthiouracil (PTU) decreased renin mRNA to 1.2 +/- 0.3 (P less than 0.005) and after subsequent injection of T3 for 1 wk renin mRNA increased to 289 +/- 35 ng/g tissue. The time course of the response to a single injection of thyroid hormone indicated a rapid response with significant increases in renin mRNA by 1 h, reaching values 3.5 +/- 0.4 times control (P less than 0.005) by 5 h. Such rapid effects are consistent with a direct nuclear action of thyroid hormone in stimulating transcription of the Ren-2 gene in mouse submandibular gland or in stabilization of nuclear precursor renin mRNA or both.