Reserpine-Induced Progressive Parkinsonism in Mice Predisposed and Non-Predisposed to Depressive-Like Behavior

Abstract

Parkinson’s disease (PD) is a progressive degenerative condition that mainly affects the elderly. The disease comprises motor symptoms such as tremors at rest, loss of voluntary movement, decreased muscle strength, propensity to lean forward and acceleration of the walking pace. These signs are related to the degeneration of the nigrostriatal dopaminergic pathway. Patients also have non-motor symptoms, among which sleep alterations, cognitive deficits, fatigue, pain and depression stand out. Although depression has been described as the most prevalent non-motor symptom, it is not clear whether this mood disorder is due to PD or patients would already have a greater predisposition. The present study evaluated the relationship between the predisposition to depressive-like behavior and the development of motor alterations in a progressive pharmacological model of PD in mice. Mice were classified into groups of depressive-like propensities and submitted to the pharmacological model. Reserpine was administrated at 0.1 mg/kg on alternate days for 40 days. The catalepsy and oral movement tests were used to evaluate motor alterations, the sucrose preference test was used to evaluate anhedonia, and the open field test was applied to evaluate general activity. Reserpine promoted parkinsonian motor impairments, and there were no differences between animals from different depressive-like behavior profiles. Thus, it was not possible to find a relationship between parkinsonism and the propensity to depression based on the basal sucrose preference test. More studies with other evaluations of depressive-like behavior are needed to confirm the results found in our study.