Effects of thyroid hormone on the renal dopaminergic system

Document Type

Journal Article

Publication Date

12-10-2001

Journal

Endocrine

Volume

15

Issue

3

DOI

10.1385/ENDO:15:3:297

Keywords

2-thiouracil; Dopamine antagonists; Haloperidol; Na /K ATPase + +; Renal dopamine; SCH-23390; Sulpiride; Thyroid hormone; Urinary dopamine

Abstract

This study determined the effects of thyroid hormone on the renal dopaminergic system. Surgical thyroidectomy (Tx) and treatment with 2-thiouracil (Thio) decreased renal cortex Na +/K + ATPase activity and urinary volume. Tx also decreased urinary Na + and urinary L-DOPA without changing urinary excretion of Dopamine (DA). Thio treatment decreased slightly urinary L-DOPA and Na +, but increased urinary excretion of DA. In both models of thyroid hormone deficiency, the ratio urinary DA/DOPA increased. Changes after Thio treatment were reversed after one month of drug withdrawal. Treatment with T 3 via osmotic minipump increased Na +/K + ATPase activity and urinary L-DOPA, did not change urinary DA, and increased the ratio DA/DOPA. To further analyze the effects of thyroid hormone deficiency, we administered selective DA 1 (SCH-23390), DA 2 (Sulpiride), and a non selective (Haloperidol) DA receptor antagonists to Thio treated and control animals. The DA 1 antagonist decreased diuresis, natriuresis and urinary L-DOPA in control, but had no effect in Thio treated rats. Sulpiride had no effect in either group. The combination of SCH-23390 plus Sulpiride decreased urinary L-DOPA and urinary volume only in Thio treated animals. Haloperidol decreased urinary volume in Thio treated animals, but had no effect in controls. Our findings suggest that renal DA synthesis is to some extent dependent on thyroid hormone levels, and that the response of DA receptors is altered by thyroid hormone deficiency, indicating a role of this hormone in the regulation of the renal dopaminergic system.

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