title: [Diphenhydramine interferes with MTT reduction assay].
abstract: OBJECTIVE
  To determine the effects of organic amine diphenhydramine on the 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide dye (MTT) reduction assay.
  
  
  METHODS
  The primarily cultured cortical astrocytes were incubated with various concentrations of diphenhydramine for 24 h. To analyze the effects of diphenhydramine and other organic amines on the MTT assay, the data obtained from the MTT assay were compared with the results obtained from morphological observation and hoechst 33342 and propidium iodide (PI) nucleus double staining.
  
  
  RESULTS
  The MTT assay showed that diphenhydramine (10(-4)mol/L), pyrilamine (10 (-4)mol/L) and zolantidine (10 (-5)mol/L) caused a significant increase in MTT reduction in astrocytes. However there was no proliferation, apoptosis or necrosis detected by hoechst and PI nucleus double staining. Light microscopy revealed that exocytosis of formazan granules was inhibited by diphenhydramine.
  
  
  CONCLUSIONS
  Diphenhydramine and other organic amines may enhance MTT reduction by suppression of MTT formazan exocytosis in astrocytes, which may affect the results of cell viability studies.
authors.affiliation: School of Biology Science, Wenzhou Medical College, Wenzhou 325035, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Shen
authors.forename: Chen-Hui
authors.initials: CH
authors.lastname: Zhang
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Hu
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D004155:Diphenhydramine / Q000494:pharmacology*; D004347:Drug Interactions; D005562:Formazans / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013778:Tetrazolium Salts / Q000493:pharmacokinetics*
chemical_list: D005562:Formazans; D013778:Tetrazolium Salts; C079782:MTT formazan; D004155:Diphenhydramine