Mood disorders in animal models of neuropathic pain

CONSTANZA ILARRAZ; FERNANDO KASANETZ; MARIA JESUS TRUJILLO

Córdoba

Congreso; XXXIII Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

Chronic pain is a debilitating neurological condition of high clinical relevance. The treatments currently available show limited efficacy. The transition to chronic pain fundamentally remodels neuronal circuits in the brain regions that mediate pain perception. In particular, in the long term it is associated with exaggerated activation of the limbic system and a highly prevalent occurrence of mood disorders such as anxiety and depression. Although this brain plasticity was initially considered to be an epiphenomenon secondary to altered nociceptive signaling in the spinal cord, studies in both patients and animals suggest that it may actively contribute to the development of chronic pain symptoms.In order to seek for a suitable animal model to study long-term pathological mechanisms in the limbic system during pain chronicity, we addressed the behavioral profiles of two mice models of neuropathic pain: chronic constriction injury and spared-nerve injury. We established a timeline of the persistence of nociceptive sensitization and the emergence of mood-disorders associated symptoms. We tested the mechanical allodynia of the injured paw (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.