title: Involvement of fatty acid amide hydrolase and fatty acid binding protein 5 in the uptake of anandamide by cell lines with different levels of fatty acid amide hydrolase expression: a pharmacological study.
abstract: BACKGROUND
  The endocannabinoid ligand anandamide (AEA) is removed from the extracellular space by a process of cellular uptake followed by metabolism. In many cells, such as the RBL-2H3 cell line, inhibition of FAAH activity reduces the observed uptake, indicating that the enzyme regulates uptake by controlling the intra- : extracellular AEA concentration gradient. However, in other FAAH-expressing cells, no such effect is seen. It is not clear, however, whether these differences are methodological in nature or due to properties of the cells themselves. In consequence, we have reinvestigated the role of FAAH in gating the uptake of AEA.
  
  
  RESULTS
  The effects of FAAH inhibition upon AEA uptake were investigated in four cell lines: AT1 rat prostate cancer, RBL-2H3 rat basophilic leukaemia, rat C6 glioma and mouse P19 embryonic carcinoma cells. Semi-quantitative PCR for the cells and for a rat brain lysate confirmed the expression of FAAH. No obvious expression of a transcript with the expected molecular weight of FLAT was seen. FAAH expression differed between cells, but all four could accumulate AEA in a manner inhibitable by the selective FAAH inhibitor URB597. However, there was a difference in the sensitivities seen in the reduction of uptake for a given degree of FAAH inhibition produced by a reversible FAAH inhibitor, with C6 cells being more sensitive than RBL-2H3 cells, despite rather similar expression levels and activities of FAAH. The four cell lines all expressed FABP5, and AEA uptake was reduced in the presence of the FABP5 inhibitor SB-FI-26, suggesting that the different sensitivities to FAAH inhibition for C6 and RBL2H3 cells is not due to differences at the level of FABP-5.
  
  
  CONCLUSIONS
  When assayed using the same methodology, different FAAH-expressing cells display different sensitivities of uptake to FAAH inhibition.
authors: Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden.
authors: Emmelie
authors: E
authors: Björklund
authors: Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden.
authors: Anders
authors: A
authors: Blomqvist
authors: Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden.
authors: Joel
authors: J
authors: Hedlin
authors: Department of Radiation Sciences, Umeå University, Umeå, Sweden.
authors: Emma
authors: E
authors: Persson
authors: Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden.
authors: Christopher J
authors: CJ
authors: Fowler
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism* / Q000494:pharmacology; D045744:Cell Line, Tumor; D063388:Endocannabinoids / Q000378:metabolism* / Q000494:pharmacology; D005136:Eye Proteins / Q000378:metabolism*; D050556:Fatty Acid-Binding Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D053284:Polyunsaturated Alkamides / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D001095:Arachidonic Acids; D063388:Endocannabinoids; D005136:Eye Proteins; D050556:Fatty Acid-Binding Proteins; D009419:Nerve Tissue Proteins; D053284:Polyunsaturated Alkamides; D000099252:Fatty Acid Amide Hydrolases; C107356:Fabp5 protein, rat; C078814:anandamide