Final answer:
Parkinson's disease is a neurodegenerative disorder causing loss of dopaminergic neurons in the substantia nigra, leading to motor symptoms like tremor and rigidity. Protein aggregates and mitochondrial dysfunction are central to its pathology. L-DOPA is a common treatment aimed at increasing dopamine, though its effectiveness may decrease with time.
Step-by-step explanation:
The motor impairment due to the loss of nigrostriatal dopamine neurons, as seen in Parkinson's disease (PD), is characterized by the degeneration of dopaminergic neurons within the substantia nigra pars compacta (SNc). These neurons are critical for the modulation of movement, and their loss leads to notable motor symptoms such as tremor, rigidity, bradykinesia (slowness of movement), and postural instability. Neurodegenerative aggregates, primarily made up of a-synuclein, are a hallmark of PD, accompanied by altered mitochondrial function and oxidative stress.
Treatments like L-DOPA focus on increasing dopamine levels in the striatum to mitigate these symptoms. However, the effectiveness of such treatments may diminish over time, and side effects such as psychosis can occur due to increased dopamine levels in other brain areas.