Related Experiment Video
Updated: Sep 3, 2026
Generation of Hypoparathyroid Rats via Carbon-Nanoparticle-Assisted Parathyroidectomy
Published on: July 14, 2023
Hyperthyroidism decreases thyrotropin-releasing hormone gene expression in the caudal raphe nuclei and the
1CURE: Digestive Diseases Research Center, West Los Angeles VA Medical Center, CA 90073, USA.
Abstract:
Altered thyroid statuses are associated with autonomic disorders. Medullary thyrotropin-releasing hormone (TRH) and substance P (SP) regulate autonomic nervous activity. The influences of thyroid statuses on TRH and SP gene expressions in the caudal raphe nuclei and the parapyramidal regions were studied using quantitative in situ hybridization histochemistry. In male rats thyroidectomized (Tx) for 30 days, the serum T4 levels decreased by 64% and the medullary pro-TRH mRNA signals (silver grains per neuron) significantly increased by 32-45%. These changes were prevented by daily i.p. T4 (2 microg/100 g) injection in Tx rats. In sham operated/T4 (20 microg/100 g, daily) injected rats, T4 levels significantly increased by 88% and the silver grains decreased by 38-40%. Medullary SP mRNA signals were not significantly changed by altering thyroid status. These results support the concept that thyroid hormone regulates medullary TRH gene expression by negative feedback.
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