Y2 OCaPE: NSB 3 Shuffling Gait

Parkinson’s Disease (1)

Name three other symptoms of this condition?

Masked faces (unable to smile/frown)

Postural stupor

Shuffling gait

Cog wheel rigidity

Balance problems

Speech Problems (3)

Which part of the brain is affected in Parkinsons?

Degeneration of the substantia nigra, in the basal ganglia, which produce dopamine (2)

Please could you explain how a lack of dopamine leads to the pathophysiology of Parkinsons?

Substantia nigra (pars compacta) cells degenerate
Loss of dopaminergic nigro-striatal neurons

• Basal ganglia direct pathway is not activated (D1 receptors)
• Basal ganglia indirect pathway is not inhibited (D2 receptors)

Leads to hypokinetic disorder  (4)

What is the first line drug treatment you would give for Parkinsons? Why?

– L-DOPA (1)

No marks for just saying ‘dopamine’

-This is a precursor to dopamine, as dopamine cannot cross the BBB (1)

What are two side effects of L-DOPA therapy?

4 marks: 2 for naming side effect, 2 for explanation

Hypotension – As NA is a product of dopamine (via Dopamine B hydroxylase), NA can
be displaced from sympathetic neurones –> can lead to HYPOTENSION (low bp)
• Psychosis– Increased dopamine in the frontal cortex can cause psychosis
•  Reduced Prolactin – prolactin is under dominant negative control of dopamine. Increasing dopamine therefore inhibits prolactin release further, which can be a problem for breastfeeding mothers
• Nausea – L DOPA can act in periperal chemoreceptors and cause nausea 

Describe what is meant by adjunct therapy for L-DOPA?

–Carbidopa blocks the peripheral conversion of L-DOPA into dopamine, meaning that more L-DOPA reaches the brain. This means you can give lower dosages, to reduce peripheral side effects.

-Dopamine can act on CTZ in the brainstem via D2 receptors and cause nausea. Domperidone is a D2 antagonist that blocks dopamine at the CTZ, and is taken alongside L-DOPA to reduce feeling sick. (4)