Releasing hormones

from Wikipedia, the free encyclopedia

Releasing hormones , also known as liberins , are neuropeptides that are formed in certain core areas in the hypothalamus . The nerves end in the eminentia mediana (a neurohemal organ at the bottom of the hypothalamus). Here, under the control of other hormones and neurotransmitters, the releasing hormones are released into blood vessels that reach directly to the anterior pituitary gland . One speaks of a portal system . In the pituitary gland, the releasing hormones stimulate the release of other hormones . Somatostatin and dopamine are release inhibiting hormones (statins), i.e. regulators that suppress the release. The formation of the hormones of the pituitary gland is not under the control of the releasing hormones, only their release:

The human hypothalamic releasing hormones and their effects

  • TRH (thyrotropin-releasing hormone), also called thyroliberin, causes the release of thyrotropin (TSH) and prolactin .
  • CRH (Corticotropin-Releasing Hormone), also called corticoliberin, causes the release of adrenocorticotropin (ACTH).
  • GnRH (gonadotropin-releasing hormone), also known as gonadoliberin, causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
  • GHRH (Growth Hormone-Releasing Hormone), also known as somatoliberin, causes the release of somatotropin (Growth Hormone, GH).
  • PRH ( prolactin- releasing hormone) does not exist according to the state of the art. The prolactin-releasing peptides (PrRP) (from the pituitary intermediate lobe ) can indeed achieve prolactin release in cell culture, but where the remaining releasing hormones are released into the portal system in order to be transported to the pituitary gland, in the eminentia mediana, one does not find the PrRP neurons. Hence, there are great doubts whether the pituitary prolactin release is stimulated by PrRP. The prolactin release is under negative regulation of dopamine (see below).

The hypothalamic release inhibiting hormones in humans and their effects

  • Somatostatin : Together with somatoliberin (growth hormone releasing hormone), somatostatin controls the release of growth hormone. In addition, it is a regulator of further hormone releases in the islet cells of Langerhans and in the gastrointestinal tract.
  • Dopamine : Unlike the above neuropeptides, dopamine is not a neuropeptide, but a catecholamine as a derivative of tyrosine . It acts as both a neurotransmitter and a hormone. Released from the eminentia mediana and transported to the pituitary gland via the portal system, it suppresses the release of prolactin as a hormone.

Individual evidence

  1. ↑ Hnasko, R. et al. (1997): Two distinct pituitary cell lines from mouse intermediate lobe tumors: a cell that produces prolactin-regulating factor and a melanotroph. In: Endocrinology. 138 (12): 5589-5596. PMID 938954 .
  2. ↑ Maruyama, M. et al. (1999): Immunocytochemical localization of prolactin-releasing peptide in the rat brain. In: Endocrinology. 140 (5): 2326-2333. PMID 10218986 .

literature

  • Bernhard Kleine, Winfried Rossmanith: Hormones and the endocrine system . Springer Verlag, Berlin / Heidelberg 2007, ISBN 3-540-37702-6 , chap. 4.1: Protein / peptide hormones .

See also