Inhibitory effect of imipramine on the human corticotropin-releasing-hormone gene promoter activity operates through a PI3-K/AKT mediated pathway.
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.
Laboratory of Immunoendocrinology, Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, PL 31-343 Kraków, Poland.
Agnieszka
A
Basta-Kaim
Bogusława
B
Budziszewska
Lucylla
L
Jaworska-Feil
Magdalena
M
Tetich
Marta
M
Kubera
Monika
M
Leśkiewicz
Władysław
W
Lasoń
D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D045744:Cell Line, Tumor; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D003346:Corticotropin-Releasing Hormone / Q000235:genetics*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007099:Imipramine / Q000494:pharmacology*; D051379:Mice; D009447:Neuroblastoma; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010957:Plasmids / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection / Q000379:methods
D018759:Adrenergic Uptake Inhibitors; D015500:Chloramphenicol O-Acetyltransferase; D005576:Colforsin; D003346:Corticotropin-Releasing Hormone; D004791:Enzyme Inhibitors; D007099:Imipramine; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C494918:AKT1 protein, human