Effects of clozapine and its metabolites on the 5-HT2 receptor system in cortical and hippocampal cells in vitro.
OBJECTIVE
The goal of the present study was to determine the effects of clozapine (Cloz) and its metabolites norclozapine (Norcloz) and clozapine-N-oxide (Cloz-N-oxide) on the 5-HT(2) receptor system on the levels of protein and gene expression in in vitro systems of primary cortical cells of the rat and human hippocampal SHS5Y5 neuroblastoma cells.


METHODS
Clinically relevant concentrations of Cloz (200/400 ng/ml) and its metabolites (200 ng/ml) were used for the examination of the effects of Cloz and its metabolites on serotoninergic 5-HT(2) receptor parameters (density, affinity and mRNA levels) as well as on glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels in primary cortical cells of the rat after treatment for 24 h under in vitro conditions. To compare the results to human cells, we also measured treatment-induced changes in 5-HT(2) and GAPDH mRNA levels in human hippocampal SHS5Y5 cells.


RESULTS
A significant decrease was found in primary cortical cells for 5-HT(2) receptor density (Cloz 200/Cloz 400/Norcloz 200 and Cloz-N-oxide 200 vs. control) and 5-HT(2A) receptor mRNA levels (Cloz 200 vs. control). 5-HT(2A) receptor mRNA levels were also significantly reduced (Norcloz 200 vs. control) in SHS5Y5 cells. GAPDH mRNA levels were not affected.


CONCLUSIONS
The results of the present study show that Cloz and Norcloz induce significant alterations on the 5-HT(2) receptor system in primary cortical cells of the rat and in human hippocampal cells.
Heiser
Philip
P
Department of Child and Adolescent Psychiatry and Psychotherapy, Philipps-University, Hans-Sachs-Str. 6, Marburg 35037, Germany. heiser@mailer.uni-marburg.de
Schulte
Eva
E
Hausmann
Christiane
C
Becker
Ralf
R
Remschmidt
Helmut
H
Krieg
Jürgen-Christian
JC
Vedder
Helmut
H
D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D003024:Clozapine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis; D011869:Radioligand Assay / Q000379:methods; D051381:Rats; D044348:Receptors, Serotonin, 5-HT2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012702:Serotonin Antagonists / Q000494:pharmacology*
D012333:RNA, Messenger; D044348:Receptors, Serotonin, 5-HT2; D012702:Serotonin Antagonists; C058272:norclozapine; D003024:Clozapine; C079149:clozapine N-oxide