Hypocretin/orexin increases the expression of steroidogenic enzymes in human adrenocortical NCI H295R cells.
Hypocretins/orexins act through two receptor subtypes: OX(1) and OX(2). Outside the brain, orexin receptors are expressed in adrenal glands, where orexins stimulate the release of glucocorticoids. To further address the regulation of steroidogenesis, we analyzed the effect of orexins on the expression of steroidogenic enzymes in human adrenocortical National Cancer Institute (NCI) H295R cells by qPCR. In NCI H295R cells, OX(2) receptors were highly expressed, as they were in human adrenal glands. After treatment of NCI H295R cells with orexin A for 12-24 h, the cortisol synthesis rate was significantly increased, whereas 30 min of treatment showed no effect. While CYP11B1 and CYP11B2 mRNA levels were increased already at earlier time points, the expression of HSD3B2 and CYP21 mRNA was significantly up-regulated after treatment with orexin A for 12 h. Likewise, orexin B increased CYP21 and HSD3B2 mRNA levels showing, however, a lower potency compared with orexin A. The mRNA levels of CYP11A and CYP17 were unaffected by orexin A. OX(2) receptor mRNA levels were down-regulated after 12 and 24 h of orexin A treatment. Orexin A increased intracellular Ca(2+) but not cAMP concentrations in NCI H295R cells. Furthermore, inhibition of PKC and MAPK kinase/ERK kinase (MEK1/2) prevented the increase of HSD3B2 expression by orexin A. Accordingly, orexin A treatment of NCI H295R cells markedly enhanced ERK1/2 phosphorylation that was prevented by PKC and, in part, PKA inhibition. In conclusion, orexins may influence adrenal steroidogenesis by differential regulation of the expression of steroidogenic enzymes involving Ca(2+), as well as PKC-ERK1/2 signaling.
Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany.
Jan
J
Wenzel
Nicole
N
Grabinski
Cordula A
CA
Knopp
Andreas
A
Dendorfer
Manjunath
M
Ramanjaneya
Harpal S
HS
Randeva
Monika
M
Ehrhart-Bornstein
Peter
P
Dominiak
Olaf
O
Jöhren
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D064446:Orexin Receptors; D000068797:Orexins; D011375:Progesterone Reductase / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013256:Steroids / Q000378:metabolism*
C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D013256:Steroids; D000242:Cyclic AMP; C533068:3 beta-hydroxysteroid dehydrogenase type II; D011375:Progesterone Reductase; D013250:Steroid Hydroxylases; D011493:Protein Kinase C; D048052:Mitogen-Activated Protein Kinase 3; D002118:Calcium; D006854:Hydrocortisone