Inhibitory effect of imipramine on the human corticotropin-releasing-hormone gene promoter activity operates through a PI3-K/AKT mediated pathway

Neuropharmacology. 2005 Aug;49(2):156-64. doi: 10.1016/j.neuropharm.2005.02.008. Epub 2005 Apr 1.


Antidepressant drugs inhibit the corticotropin-releasing-hormone (CRH) gene promoter activity in the differentiated Neuro-2A cells, but a molecular mechanism of their action has been poorly recognized. The aim of the present study was to elucidate the involvement of some intracellular signal transduction pathways in imipramine-induced inhibition of CRH gene activity in the differentiated Neuro-2A cells, stably transfected with a human CRH promoter fragment linked to the chloramphenicol acetyltransferase (CAT) reporter gene. It was found that wortmannin (0.1muM), an inhibitor of phosphatidylinositol 3-kinase (PI3-K) and forskolin (10, 25muM), an activator of adenylate cyclase enhanced the basal activity of CRH gene promoter, whereas inhibitors of protein kinase A, calcium/calmodulin kinase (CaMK) and mitogen-activated protein kinase (MAPK) had opposite effects. Moreover, wortmannin at a low concentration (0.01muM) significantly reversed the inhibitory effect of imipramine on CRH-CAT activity, whereas other protein kinase inhibitors were inactive or even enhanced the imipramine effects. The involvement of PI3-K/Akt pathway in the imipramine action was confirmed by Western blot study, which showed that this drug increased phospho-Ser-473 Akt level, but had no effect on total Akt and glycogen synthase kinase (GSK-3beta) levels. These results indicate that the inhibitory effect of imipramine on the CRH gene promoter activity in Neuro-2A cells is mainly connected with enhancement of PI-3K/Akt pathway.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic Uptake Inhibitors / pharmacology*
  • Animals
  • Blotting, Western / methods
  • Cell Line, Tumor
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Colforsin / pharmacology
  • Corticotropin-Releasing Hormone / genetics*
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Humans
  • Imipramine / pharmacology*
  • Mice
  • Neuroblastoma
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Plasmids / physiology
  • Promoter Regions, Genetic / drug effects*
  • Protein Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Transfection / methods


  • Adrenergic Uptake Inhibitors
  • Enzyme Inhibitors
  • Proto-Oncogene Proteins
  • Colforsin
  • Corticotropin-Releasing Hormone
  • Chloramphenicol O-Acetyltransferase
  • AKT1 protein, human
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Imipramine