The usefulness of olfactory fear conditioning for the study of early emotional and cognitive impairment in reserpine model

Abstract

Due to the ability for depleting neuronal storages of monoamines, the reserpine model is a suitable approach for the investigation of the neurobiology of neurodegenerative diseases. However, the behavioral effects of low doses of reserpine are not always detected by classic animal tests of cognition, emotion, and sensory ability. In this study, the effects of reserpine (0.5-1.0mg/kg) were evaluated in olfactory fear conditioning, inhibitory avoidance, open-field, elevated plus-maze, and olfactory discrimination. Possible protective effects were also investigated. We found that single administration of reserpine impaired the acquisition of olfactory fear conditioning (in both doses) as well as olfactory discrimination (in the higher dose), while no effects were seen in all other tests. Additionally, we demonstrated that prior exposure to environmental enrichment prevented effects of reserpine in animals tested in olfactory fear conditioning. Altogether, these findings suggest that a combined cognitive, emotional and sensory-dependent task would be more sensitive to the effects of the reserpine model. In addition, the present data support the environmental enrichment as an useful approach for the study of resilience mechanisms in neurodegenerative processes.

Keywords: CS; DA; EE; EPM; Environmental enrichment; Monoamines; NA; Neurodegenerative disease; OD; OF; OFC; Olfactory fear conditioning; PD; Parkinson's disease; RES; Reserpine; SDIA; SEM; US; VEH; conditioned stimulus; dopamine; elevated plus maze; enriched environment; noradrenaline; olfactory discrimination; olfactory fear conditioning; open field; reserpine; standard error of the mean; step-down inhibitory avoidance; unconditioned stimulus; vehicle solution.