Parkinson’s Disease

Question 1

What is the direct pathway?

Answer 1

Direct pathway stimulates movement;
Motor cortex stimulates the striatum (caudate and putamen) using glutamate
Substantia nigra pars nigra stimulates the striatum via D1 receptors

Striatum will use GABA to inhibit the globus pallidus internal and substantia nigra pars reticulata to remove inhibition of the thalamus and facilitate movement.

Question 2

What is the indirect pathway?

Answer 2

Indirect pathway reduces movement

Motor cortex releases signals via glutamate to the striata.

Striatum will release inhibitory GABA to block the inhibitory action of globus pallidus external on the subthalamic nucleus to facilitate movement. Subthalamic nucleus typically stimulate globus pallidus internal for reducing movement

Question 3

What is the pathophysiology of Parkinson?

Answer 3

Alpha-synuclein deposits cause degradation of the substantia nigra pars compacts which results in the reduced release of Dopamine D1 for the direct pathway to facillitate movement, which results in the rigidity and inability to perform voluntary movements. It is closely linked with Lewy-Body dementia.

Question 4

What are the signs of Parkinson’s disease?

Answer 4

TRAP
T: tremor
R: rigidity
A: akinesia
P: postural issues

Question 5

How is Parkinson’s disease treated?

Answer 5

Dopamine precursor LEVADOPA is prescribed to allow it to cross the blood-brain barrier, alongside the decarboxylase inhibitor CARBIDOPA to reduce peripheral levels of dopamine.