Week 5 Flashcards
List the 10 features of Parkinson’s Disease?
- Tremor at rest
- Rigidity: cogwheel, limbs>axial
- Bradykinesia
- Asymmetry
- Loss righting reflex
- 30% cognitive decline
- Hypomimia (lack facial expression)
- Glabellar tap
- Quiet Speech
- Micrographia
What neurotransmitters inhibit & excite the basal ganglia?
- INHIBIT: GABA
- EXCITE: Glutamate
What happens in the substantial nigra dopaminergic part of the corticospinal pathway?
- Turns up direct pathway
- Turns down the indirect pathway
- Increases VA/VL drive to cortex
- MORE MOTOR ACTIVITY
Describe the direct corticospinal pathway?
- Increases excitatory thalamic input to cortex
- TURNS UP MOTOR ACTIVITY
Describe the indirect corticospinal pathway?
- Decreases excitatory thalamic input to cortex
- TURNS DOWN MOTOR ACTIVITY
What happens in the Striatal interneuron cholingeric part of the corticospinal pathway?
- Turns down direct pathway
- Turns up indirect pathway
- Decreases VA/VL drive to cortex
- LESS MOTOR ACTIVITY
What happens to the corticospinal pathway in Parkinson’s disease?
- Substantia nigra dopamine cells lost, therefore indirect pathway increases
- Dopamine inhibition lost (disinhibition)
- ACh excitation unopposed
- LESS MOTOR ACTIVITY
What 9 factors can lead to Neurodegeneration?
- Toxins
- Protein handling disorders
- Lack of growth factors
- Oxidative stress
- Excitotoxicity
- Ionic disequilibrium
- Mitochondrial dysfunction
- Activation of cell death pathways
- Immune attack
What is the main strategy in drug treatment of Parkinson’s disease?
Counteract deficiency of dopamine in basal ganglia
What are the 5 different drug treatments for Parkinson’s disease?
- Levopoda (1st line)
- Dopamine agonists
- Monoamine oxidase B (MAO-B) inhibitors
- Amantadine
- Muscarinic ACh antagonists
What is Levodopa used in combination with to treat Parkinson’s disease?
Dopa decarboxylase inhibitor (carbidopa or benserazide)
What do 80% of patients on Levodopa for Parkinson’s show?
Initial improvement in rigidity & hypokinesia
What does L-dopa show no evidence of?
That it slows or accelerates neurodegeneration
What are the potential side effects of Levodopa?
- Involuntary writhing movements (dyskinesia) within 2 years (face & limbs mainly), at peak therapeutic effect
- Rapid fluctuations in clinical state
- Hypokinesia & rigidity may suddenly worsen & improve again
Give examples of Dopamine agonists?
- Pramipexole & Roprinole (D2/3 selective receptor agonists)
- Bromocriptine, Cabergoline & Pergolide (oral D1 & D2 receptors)
- Rotigotine
- Apomorphine
What 2 dopamine agonists are better tolerated?
- Pramipexole
2. Roprinole
What is the limiting side effect of Bromocriptine, Carbergoline & Pergolide dopamine agonists?
Fibrotic reactions
How is Rotigotine dopamine agonist administered?
Transdermal patch
How is Apomorphine dopamine agonist administered?
Injection, sometimes to control off effect of Levodopa
Describe the characteristics of Dopamine dysregulation syndrome?
- Sudden onset sleep
- Impulse control disorders (gambling, binge eating)
- Hypotension
- Neuroleptic malignant syndrome if stopped abruptly
Give 2 examples of MAO-inhibitors for Parkinson’s disease?
- Selegiline
2. Rasagiline
Describe Selegiline (MAO-inhibitor)?
Selective MAO-B which lacks unwanted peripheral effects of non- selective MAO inhibitors
What does inhibition of MAO-B do?
Protects dopamine from extraneuronal degradation
What does a combination of MAO-inhibitors & Levodopa provide?
More effective in relieving symptoms & prolonging life