The Positive Role and Mechanism of Herbal Medicine in Parkinson’s Disease

Figure 1

Major mechanisms involved in Parkinson’s disease. In the dopaminergic neurons in the substantia nigra pars compacta (SNpc) of the midbrain of patients with Parkinson’s disease, mutations in SNCA (coding gene of α-synuclein) or protein modification of α-synuclein induced by neurotoxicants (or reactive oxygen species) (a) leads to the α-synuclein misfolding. The misfolded α-synuclein can further aggregate into α-synuclein fibrils when the proteasome-mediated degradation system cannot fully clear the fibrils, and then contribute to the production of Lewy bodies in neurons. The inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, secreted by activated microglial cells (b) also induce the death or apoptosis of neurons. Besides, the mitochondrial dysfunction induced by L-DOPA or Fe³⁺ induces the product of ROS, which enhances death or apoptosis via causing oxidative stress (c). L-DOPA: L-levodopa; ROS: reactive oxygen species.