Mood Disorders in Animal Models of Neuropathic Pain

ILARRAZ CONSTANZA ; TRUJILLO MARÍA JESÚS; KASANETZ FERNANDO

Congreso; XXXIII Congress of the Argentine Society for Research in Neuroscience; 2018

Chronic pain is a debilitating neurological condition of high clinical relevance. The treatmentscurrently available show limited efficacy. The transition to chronic pain fundamentallyremodels neuronal circuits in the brain regions that mediate pain perception. In particular, inthe long term it is associated with exaggerated activation of the limbic system and a highlyprevalent occurrence of mood disorders such as anxiety and depression. Although this brainplasticity was initially considered to be an epiphenomenon secondary to altered nociceptivesignaling in the spinal cord, studies in both patients and animals suggest that it may activelycontribute to the development of chronic pain symptoms.In order to seek for a suitable animal model to study long-term pathological mechanisms inthe limbic system during pain chronicity, we addressed the behavioral profiles of two micemodels of neuropathic pain: chronic constriction injury and spared-nerve injury. Weestablished a timeline of the persistence of nociceptive sensitization and the emergence ofmood-disorders associated symptoms. We tested the mechanical allodynia of the injuredpaw (Von Frey test) and the expression of anxiety (open field, elevated plus maze),depression (grooming behavior, sucrose preference) and cognitive-related (y-maze)impairments. Our preliminary results show that nerve injury induces a late onset (~4 weeks)of mood disorders that persist even after the nociceptive sensitization is reverted.