Dominant Role of Thyrotropin-releasing Hormone in the Hypothalamic-Pituitary-Thyroid Axis

Thyroid hormone (TH) plays a critical role in development, growth, and cellular metabolism. TH production is controlled by a complex mechanism of positive and negative regulation. Hypothalamic TSH-releasing hormone (TRH) stimulates TSH secretion from the anterior pituitary. TSH then initiates TH synthesis and release from the thyroid gland. The synthesis of TRH and TSH subunit genes is inhibited at the transcriptional level by TH, which also inhibits posttranslational modification and release of TSH. Although opposing TRH and TH inputs regulate the hypothalamic-pituitary-thyroid axis, TH negative feedback at the pituitary was thought to be the primary regulator of serum TSH levels. However, study of transgenic animals showed an unexpected, dominant role for TRH in regulating the hypothalamic-pituitary-thyroid axis and an unanticipated involvement of the thyroid hormone receptor ligand-dependent activation function (AF-2) domain in TH negative regulation. These results are summarized in the review. The thyrotropin-releasing hormone neuron is well-positioned to integrate information about the environment as well as circulating TH levels and ultimately affect metabolism in response to these physiological changes.

Download Full-text

Association of Cocaine- and Amphetamine-Regulated Transcript-Immunoreactive Elements with Thyrotropin-Releasing Hormone-Synthesizing Neurons in the Hypothalamic Paraventricular Nucleus and Its Role in the Regulation of the Hypothalamic–Pituitary–Thyroid Axis during Fasting

Journal of Neuroscience ◽

10.1523/jneurosci.20-24-09224.2000 ◽

2000 ◽

Vol 20 (24) ◽

pp. 9224-9234 ◽

Cited By ~ 111

Author(s):

Csaba Fekete ◽

Emese Mihály ◽

Lu-Guang Luo ◽

Joseph Kelly ◽

Jes Thorn Clausen ◽

...

Keyword(s):

Paraventricular Nucleus ◽

Thyrotropin Releasing Hormone ◽

Hypothalamic Paraventricular Nucleus ◽

Releasing Hormone ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

Download Full-text

Thyrotropin Releasing Hormone (TRH) Stimulation Versus T3 Suppression in Assessing the Function of the Pituitary Thyroid Axis during Antithyroid Treatment in Hyperthyroidism

Japanese Journal of Medicine ◽

10.2169/internalmedicine1962.15.317 ◽

1976 ◽

Vol 15 (4) ◽

pp. 317-321

Author(s):

Shigeyoshi YUJI ◽

Tadanobu KURIBAYASHI ◽

Yoshitada YAJIMA

Keyword(s):

Thyrotropin Releasing Hormone ◽

Releasing Hormone ◽

Trh Stimulation ◽

Pituitary Thyroid Axis ◽

Antithyroid Treatment ◽

Thyroid Axis

Download Full-text

Thyroid hormonal axis regulates protein C anticoagulation pathway in rats

Open Life Sciences ◽

10.2478/s11535-011-0031-y ◽

2011 ◽

Vol 6 (4) ◽

pp. 518-523

Author(s):

Negrin Negrev ◽

Yuri Nyagolov ◽

Margarita Stefanova ◽

Emiliya Stancheva

Keyword(s):

Protein C ◽

Activated Protein C ◽

Protein S ◽

Thyroid Stimulating Hormone ◽

Thyrotropin Releasing Hormone ◽

Receptor Protein ◽

Endothelial Protein C Receptor ◽

Releasing Hormone ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

AbstractEffects of the hormones of the hypothalamic-pituitary-thyroid axis on some basic parameters of the activity of protein C anticoagulation pathway in rats are studied. Thyrotropin-releasing hormone (0.06 mg/kg body mass), thyrotropin (1 IU/kg), triiodothyronine (T3) (0.08 mg/kg), thyroxine (T4) (0.08 mg/kg), administered subcutaneously for three consecutive days on four different groups of rats increased significantly activated protein C, free protein S and protein S activity, and reduced the soluble endothelial protein C receptor. Protein C antigen and total protein S were significantly elevated only by thyrotropin-releasing hormone and thyroid-stimulating hormone, but they were not affected by T3 and T4 treatment. The data indicate the hypothalamic-pituitary-thyroid axis is involved in the regulation of the protein C anticoagulation pathway in rats by activation of this system, suggesting a tendency of hypocoagulability.

Download Full-text