An 84-year-old patient suffers from parkinsonism. One of the pathogenetic development elements of this disease is defidency of a certain mediator іn some of the brain structures. Name this mediator:

Чому це правильна відповідь

Parkinsonism is a neurological syndrome characterized by rigidity, bradykinesia and resting tremor. Its main cause is the degeneration of dopaminergic neurons in the substantia nigra. These neurons send axons to the striatum (caudate nucleus and putamen), where dopamine regulates movement. Dopamine stimulates the direct pathway via D₁ receptors and inhibits the indirect pathway via D₂ receptors, facilitating voluntary movement. When dopamine is deficient, the indirect pathway prevails, the thalamus and cortex are inhibited, and movements become slow and difficult. At the same time, cholinergic interneurons of the striatum become relatively overactive, which contributes to tremor and rigidity. So the key mediator deficient in parkinsonism is dopamine, which is why levodopa and dopamine agonists are the main treatment.