title: Chronic administration of phencyclidine produces decreased sensitivity to mechanical stimulation in the absence of altered affective behavior: Implications for pain processing in schizophrenia.
abstract: Patients with schizophrenia have been shown to display decreased sensitivity to pain, which can severely compound the impact of injuries and illnesses. Alterations in the sensory and affective systems of pain processing have been proposed as mechanisms, but the unique contribution of each of these systems has not been elucidated. The aim of this study was to investigate these two components of pain using the NMDA receptor antagonist, phencyclidine (PCP), an established animal model of schizophrenia. Animals underwent L5 spinal nerve ligation surgery in order to provoke a condition of ongoing pain responding, followed by treatment with 2.58 mg/kg of PCP, or saline, and 20 mg/kg of the atypical antipsychotic clozapine, or vehicle, in a block design. Responses to mechanical stimuli were assessed to determine changes in sensory processing, and affective pain processing was examined with the place escape avoidance paradigm. The results showed animals receiving PCP exhibited decreased sensitivity to mechanical stimulation and unaltered behavior in the avoidance paradigm. These findings corroborate and strengthen the human literature investigating schizophrenia and alterations in pain perception. More importantly, the differential findings between the tests of sensory and affective pain processing provide a novel means of understanding schizophrenia-related pain insensitivity.
authors.affiliation: Department of Pain Medicine, M.D.Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. jbdavis@mdanderson.org
authors.forename: Jessica
authors.initials: J
authors.lastname: Boyette-Davis
authors.forename: Perry N
authors.initials: PN
authors.lastname: Fuchs
mesh_terms: D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects; D003024:Clozapine / Q000494:pharmacology; D004195:Disease Models, Animal; D004924:Escape Reaction / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology* / Q000633:toxicity; D008026:Ligation; D008297:Male; D009437:Neuralgia / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D058748:Pain Perception / Q000187:drug effects / Q000502:physiology; D010622:Phencyclidine / Q000494:pharmacology* / Q000633:toxicity; D010812:Physical Stimulation; D051381:Rats; D020318:Rats, Long-Evans; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012559:Schizophrenia / Q000503:physiopathology*; D013127:Spinal Nerves / Q000293:injuries; D013314:Stress, Mechanical
chemical_list: D014150:Antipsychotic Agents; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D010622:Phencyclidine; D003024:Clozapine