Question

6. Describe why Parkinson's Disease creates a dyskinesia and how the basal ganglia pathways are involved.

Answer 1

Drug levodopa which highly effective in treating patients with Parkinson's disease results in dyskinesia. Long term use of Levodopa can cause dyskinesia.

Parkinson's disease is disease in which there is a dopaminergic neuron which results in decrease in the level of dopamine which is a neurotransmitter which regulates motor control, motivation.

So when the levels of dopamine is decreased, Levodopa is given to take the place of dopamine.

Due to Levodopa, dyskinesia is caused.

• Substantial nigra is part of basal ganglia, which is the source of dopamine, which plays major role in function of basal ganglia.

There are two pathway of basal ganglia

1. Direct ( excitatory) pathway
2. Indirect( inhibitory) pathway

The nigrostriatal pathway

This pathway projects from the substantia nigra pars compacta to the striatum, and it utilizes the neurotransmitter dopamine. This pathway has the modulatory effect on the basal ganglia, with dopamine facilitating the motor loop in these two ways:

• It excites the direct pathway
• It inhibits the indirect pathway

There are two dopamine receptor:

D1 and D2

D1- give rise to direct pathway and D2 give rise to indirect pathway.

It plays important function in motor function.