Parkinson's Disease Flashcards
What are the main symptoms of Parkinson’s disease?
Rigidity
Akinesia
Tremor at rest
Which DA receptor type are involved in the direct nigrostriatal pathway?
D1
Which DA receptor type are involved in the indirect nigrostriatal pathway?
D2
What is tremor due to?
Increased ACh - due to decreased DA
Name the 5 dopaminergic pathways and their functions
Nigrostriatal - motor - involved in Parkinson’s
Mesolimbic - reward
Mesocortical - psychosis
Median eminence - inhibits prolactin secretion
Chemoreceptor trigger zone - nausea
Which enzymes break down DA?
MAO
COMT
What are the synthesis steps and enzymes for DA?
Tyrosine L-DOPA (tyrosine hydroxylase) DA (DOPA decarboxylase) DOPAC (MAOB) HVA (COMT)
Which enzyme converts DA to NA?
Dopamine beta hydroxylase
What does carbidopa do?
Inhibits DOPA decarboxylase - prevents DA production
What does selegiline do?
Inhibits MAOB - prevents DA breakdown
Does DA cross BBB?
No
Does carbidopa cross BBB?
No
Does selegiline cross BBB?
Yes
What is the action of domperidone?
D2R antagonist - acts at CTZ - prevents nausea
Does domperidone cross BBB?
No
Which drug is used for tremor in drug-induced Parkinson’s and why?
Benzhexol
Muscarinic antagonist - blocks ACh action in striatum - widespread side effects - may cause dementia - lower risk for younger patients
Does L-DOPA cross BBB?
Yes
Which drug is used for older patients when L-DOPA is no longer effective and what is its action?
Bromocriptine - D2R agonist
Which drug is effective in a small proportion of patients and what is its action?
Amantidine - NMDAR antagonist
