title: The neurotoxic effects of amitriptyline are mediated by apoptosis and are effectively blocked by inhibition of caspase activity.
abstract: Oral tricyclic antidepressants, widely used as adjuncts in the treatment of chronic pain, block sodium channels in vitro and nerve conduction in vivo. However, toxicity of amitriptyline has been observed after neural application. We therefore investigated the mechanism and possible prevention of amitriptyline neurotoxicity. To assess dose-dependent neurotoxicity of amitriptyline, we incubated neuron cultures from adult rat dorsal root ganglia with amitriptyline and quantified neuronal survival. Additionally, we investigated accepted markers of apoptosis (mitochondrial membrane potential, cytosolic cytochrome c, and activated caspase-3) and co-incubated amitriptyline with an inhibitor of caspase activity, z-vad-fmk, to assess the effect on cell survival. We found a dose-dependent neurotoxic effect of amitriptyline. Neurons incubated with amitriptyline exhibited loss of mitochondrial membrane potential, release of cytochrome c into the cytoplasm, and activation of caspase-3. Co-incubation with z-vad-fmk substantially improved neuronal survival in culture. In conclusion, amitriptyline-induced neurotoxicity is mediated by apoptosis and is attenuated by inhibition of caspase activity, suggesting that inhibition of apoptotic pathways may be efficient at alleviating local anesthetic-induced neurotoxicity. In vivo studies will have to corroborate whether the co-injection of anti-apoptotic drugs with local anesthetics decreases neurotoxic side effects.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Austria. philipp.lirk@uibk.ac.at
authors.forename: Philipp
authors.initials: P
authors.lastname: Lirk
authors.forename: Ingrid
authors.initials: I
authors.lastname: Haller
authors.forename: Barbara
authors.initials: B
authors.lastname: Hausott
authors.forename: Shota
authors.initials: S
authors.lastname: Ingorokva
authors.forename: Martina
authors.initials: M
authors.lastname: Deibl
authors.forename: Peter
authors.initials: P
authors.lastname: Gerner
authors.forename: Lars
authors.initials: L
authors.lastname: Klimaschewski
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000639:Amitriptyline / Q000031:analogs & derivatives / Q000633:toxicity*; D000779:Anesthetics, Local / Q000633:toxicity; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000633:toxicity; D017209:Apoptosis; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology; D008564:Membrane Potentials; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051381:Rats
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000779:Anesthetics, Local; D000929:Antidepressive Agents, Tricyclic; D061945:Caspase Inhibitors; D004792:Enzyme Precursors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000639:Amitriptyline; D045304:Cytochromes c; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases