Pain perception in neurodevelopmental animal models of schizophrenia

Animal models are important for the investigation of mechanismsand therapeutic approaches in various human diseases, includingschizophrenia. Recently, two neurodevelopmental rat models ofthis psychosis were developed based upon the use of subunitselective N-methyl-D-aspartate receptor agonists – quinolinic acid(QUIN) and N-acetyl-aspartyl-glutamate (NAAG). The aim of thisstudy was to evaluate pain perception in these models. QUIN orNAAG was infused into lateral cerebral ventricles neonatally. Inthe adulthood, the pain perception was examined. The rats withneonatal brain lesions did not show any significant differences inacute mechanical nociception and in formalin test compared tocontrols. However, the neonatally lesioned rats exhibitedsignificantly higher pain thresholds in thermal nociception.Increased levels of mechanical hyperalgesia, accompanying thesciatic nerve constriction (neuropathic pain), were also observedin lesioned rats. Although hyperalgesia was more pronounced inQUIN-treated animals, the number of c-Fos-immunoreactiveneurons of the lumbar spinal cord was similar in experimentaland control rats. We conclude that neonatal brain lesionsattenuated the thermal perception in both nociceptive andneuropathic pain whereas mechanical pain was increased in themodel of neuropathic pain only. Thus, nociceptive andneuropathic pain belongs – in addition to behavioral changes –among the parameters which are affected in described animalmodels of schizophrenia.