Mechanisms of norepinephrine mediated corticotropin-releasing factor-41 release from cultured fetal hypothalamic cells.
Catecholamines have been shown to activate hypothalamic corticotropin-releasing factor-41 (CRF) synthesis and release. In order to study the mechanisms involved, fetal hypothalamic cells were cultured and CRF release was measured by radioimmunoassay. Norepinephrine (NE) induced CRF release in a dose-dependent manner. Further studies were performed with a protein kinase C inhibitor, H-7(1-(5-isoquinolinesulfonyl)-2-methylpiperazine) and a protein kinase A inhibitor, IP-20. NE-stimulated CRF release was reduced by H-7 (5 and 50 microM) in a dose-dependent fashion, while 5 microM IP-20 resulted in a small but significant inhibition. Pretreatment of the cells for 15 h with 20 and 200 nM 12-O-tetradecanoylphorbol-13-acetate, which down-regulates protein kinase C activity, blocked the release of CRF in response to NE (1 microM), further supporting protein kinase C as a mediator for NE-activated CRF release. Pretreatment with 50 and 500 ng/ml pertussis toxin (15 h) resulted in a dose-dependent inhibition of NE-activated CRF release. Both dexamethasone and aldosterone at the concentrations of 1 microM reduced NE-induced CRF release. These results suggest that CRF can be released from hypothalamic neurons in response to NE through both protein kinase C- and protein kinase A-dependent mechanisms, and that pertussis toxin-sensitive G-proteins are also involved in this response. Furthermore, glucocorticoids and mineralocorticoids can reduce NE-activated CRF release from cultured hypothalamic cells.
Hu
S B
SB
Neuroendocrinology Unit, Charing Cross and Westminster Medical School, Charing Cross Hospital, London, UK.
Tannahill
L A
LA
Lightman
S L
SL
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007031:Hypothalamus / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology; D037342:Pertussis Toxin; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007546:Isoquinolines; D010455:Peptides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D010566:Virulence Factors, Bordetella; D000450:Aldosterone; D003907:Dexamethasone; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003346:Corticotropin-Releasing Hormone; C058824:IP 20; D037342:Pertussis Toxin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D009638:Norepinephrine