|
pubmed:abstractText |
Tachykinins are a family of peptides that are able to modulate the activity of the hypothalamo-pituitary CRH-ACTH system. Mammalian tachykinins include neurokinin A (NKA), neurokinin B (NKB), neuropeptide K (NPK), and substance P (SP). We investigated by RIA the effects of tachykinins on the release of CRH and ACTH by rat adrenal medulla in vitro. NKA and NPK concentration-dependently enhanced the release of both CRH and ACTH, NPK being more active than NKA. NKB exerted only a minor stimulatory action exclusively on CRH release, and SP was ineffective. The stimulatory effect of both NKA and NPK on ACTH release was blocked by the CRH receptor antagonist alpha-helical-CRH, thereby suggesting that the increase in ACTH secretion is consequent to the stimulation of CRH release. These findings indicate that NKA and NPK are stimulators not only of the central (hypothalamo-pituitary), but also of the peripheral (intramedullary) branch of the CRH-ACTH system.
|
