Chronic Stress and Parkinson's Disease

A recent study published in Molecular Psychiatry by Hemmerle et al. addressed this point by subjecting 6‐OHDA‐lesioned rats to the chronic stress, and they found that chronic stress exacerbates the loss of dopamine neurons induced by 6‐OHDA injection. The dopamine neuron loss leads to motor behavior deficits, as reflected by the forelimb asymmetry test, because the loss of dopamine neurons would lead to impaired usage of the contralateral limb, while the severity of dopamine neuron loss was histologically examined by TH staining . [...]a recent study has shown that selective activation of midbrain dopamine neurons with optogenetic techniques could immediately restore the depressive behavior of mice in forced swimming test , revealing an unappreciated role of dopamine neurons in mood disorders. [...]the underlying mechanisms of PD progression and depression might interact with each other; for instance, antidepressant treatment was found to delay the need for dopaminergic therapy in early stage PD patients ; while selective enhancement of endogenous dopaminergic signaling (rather than pharmacology) could reverse the depression‐like behavior in animal models .