Releasing hormone

A releasing hormone or releasing factor is a hormone whose main purpose is to stimulate the release of another hormone. The main releasing hormones secreted by the hypothalamus are:

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• Thyrotropin-releasing hormone (TRH),
• Corticotropin-releasing hormone (CRH),
• Gonadotropin-releasing hormone (GnRH),
• Growth hormone-releasing hormone (GHRH),
• Somatostatin,
• Dopamine.

Taking TRH as an example it is found that TRH is released from the Hypothalamus in response to low levels of Thyroid stimulating hormone(TSH) being produced in the pituitary gland. The TSH in turn is under feedback control by the Thyroid hormones T4 and T3. When sufficient levels of TSH are achieved it acts to shut down the secretion of TRH. Synthetic TRH is also used by Physicians as a test of TSH reserve in the pituitary gland as it should stimulate the release of TSH and Prolactin from this gland.

Related Topics:
Hypothalamus - Thyroid stimulating hormone - Pituitary gland - T4 - T3 - TSH - Prolactin

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Releasing hormone: See also ►