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37 Cards in this Set

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Catacholamines include (3)


Rate limiting step?


oxidation of tyrosine to L-DDPA
What do catecholamines do?
Affect mood, attentiveness and emotion by effecting the function of point to point neurotransmission.
Review figure 12-1
Golan Page 186
What is required to get DA into synaptic vesicles? (2)
Proton ATPase to concentrate protons in the vesicle
Electropositive vesicle interior
The dopamine transporter (also dopamine active transporter, DAT, SLC6A3) is a membrane-spanning protein that binds the neurotransmitter dopamine; DAT provides the primary mechanism through which dopamine is cleared from synapses, transporting dopamine from the synapse into a neuron. DAT is present in the peri-synaptic area of dopaminergic neurons in areas of the brain where dopamine signaling is common.
Once dopamine is released into the postsynaptic cleft, what may occur (2)?
Dopamine may be reabsorbed by the presynaptic neuron or it is broken down by MAO or COMT
Where does MAO work, CNS or PNS?
Both CNS (MAO-B) & PNS (MAO-A)

* MAO-B is often used in the CNS, however, MAO-A retards the breakdown of ALL central and peripheral catecholamines which can be life-threatening.
The sequential action of the COMT and MAO degrades DA to the stable metabolite __________ ____ (HVA) which is excrreted in the _______
Homovanillic acid
_________ is expressed in the brain, liver, kidney and heart, and it inactivates catecholamines by adding a methyl group to the hydroxyl group at the 3 position of a benzene ring.
D1 Class receptors
D2 Class receptors
(Golan page 189)
D1 lead to increased cAMP (2 receptors 1,5)

D2 class receptors inhibits cAMP generation (3 receptors 2,3,4)
Dopamine receptors in striatum, playing a role in motor control by basal ganglia and nucleus accumbens and olfactors tubercle.
D1 and D2
Dopamine receptors in anterior pituitary gland lactotrophs, regulate prolactin.
What is required for synaptic vesicle trafficking to and fusion with the presynaptic membrane.
Drugs that block dopamine ___ receptors are used to treat nausea and vomiting.
Primary input

Primary output
Striatum (caudate and putamen)

Globus pallidus pars interna and substantia nigra pars reticula
Cortical inputs to basal gangial are _________ and use ___________ as a transmitter.

(medium spiny neurons)
The medium spiney neurons release the inhibitory transmitter GABA and send their projections to tow downstream targets.
Direct pathway-
Indirect pathway-
Direct pathway-(D1) stimulates movement
Indirect pathway-(D2) - inhibits the thalamus therefore inhibiting movement.
Increased levels of dopamine in the striatum tend to activate D1 expressing neurons of the direct pathway while inhibiting the D2 expressing movement. So,
both of these effects promote movement.

**It is the opposite in Parkinson's (it is thought that the indirect pathway is overactive- surgery to subthalamic nucleus)
In parkinson's disease there is a selective loss of dopaminergic neurons in the
substantia nigra pars compatcta
(70% of neurons lost by time of onset of symptoms, 95% loss on autopsy)
Typical presentation of parkinson's diesease:

May be due to exposure to:
Bradykinesis (slow movement)
Impaired postural balance
Tremor when limbs are at rest

Certain pesticides, mutations, mostly unknown multifactorial
Treatment of Parkinson's Disease:

Current goal is:
Mainly symptomatic control, safe, but disease will take its course especially cognitively (dimentia)

Neuroprotective and neurorestorative
3 categories of Parkinson's Disease therapeutic treatment:
1 DA precursors
2 DA receptor agonists
3 Inhibitors of DA degradation
Most effective treatment for PD is:
How come DA cannot be used?
DA cannot cross the BBB, but L-DOPA can is is converted to DA by AADC once in the CNS.
Why must Levodopa be co-administered with carbidopa?
Carbidopa will inhibit AADC so Levodopa has a chance to cross the BBB before it is made into DA, but still only 10%. However, this decreases adverse effects of peripheral DA (nausea)
Problems with Levodopa
Effects at early stage
Patients develop tolerance thus requiring larger doses
*Cause dyskinesias of head and trunk @ max levodopa concentrations
Chronic therapy causes adaptations in post syn neurons in striatum (pg 194 golan)
Explain on and off periods due to Levodopa
ON: normal to dyskinetic, shortly after administration, can be overcome by lowering dose
OFF: Periods of freezing and increased rigidity, occur as plasma levels of levodopa decrease.
Symptoms get worse over time
Dopamine precursor: transported across BBB by neutral AA transporter and then made into DA by AADC via decarboxylation.
DA receptor agonist advantages:

Disadvantages are excessive sedation, vivid dreams, and hallucinations.
Delay onset of "off" periods
Nonpeptide, so do not compete with Levodopa to cross BBB
Do not require AADC so remain effective late in disease process
Longer 1/2 life than Levodopa (less frequent dosing and more uniform response to drug)
Dopamine Receptor Agonists (4):
Ergot derivatives bind to and activate postsyn dopamine receptors directly.
Bromocriptine (ergot derivative:*n/v, edema, HTN)
Pergolide (ergot derivative:*n/v, edema, HTN)
Pramipexole (used more often than ergot derivatives)
Ropinirole (used more often than ergot derivatives)
Clinical applications of Pramipexole &
Ropinirole, and adverse effects.
Restless Leg Syndrome
(Extrapyramidal movements, somolence, dizziness, hallucinations, dream disorder, asthenia, amnesia)
*don't use with other sedating meds
Adverse effects and contraindications of Levodopa
AE: Dyskinesia, heart disease, orthostatic hypotension, psychotic disorder, loss of appetite, n/v
contrain: Hx of melenoma, narrow angle glaucoma, simultaneous use of MAO inhibitors.
Inhibitors of Levodopa or Dopamine metabolism (4): Inhibits breakdown of DA in CNS by inhibiting MAO-B or COMT, or inhibits breakdown by COMT in periphery
Rasagiline (CNS)
Selegiline (CNS)
Tolcapone (periphery)
Entacapone (periphery)
Misc Anti-PD medications (3):
Amantidine is used for PD and _________.
This drug is contraindicated if there is a:
Influenza A

Hypersensitivity to Amantidine
Adverse effects of amantidine:
Neuroleptic malignat syndrome, exacerbations of mental disorder, insomnia, dizziness, hallucinations, agitation, orthostatic hypotension, pertipheral edema, dyspepsia, livedo reticularis (vascular prob characterized by purplish mottling of skin)
What are the treatments for parkinsons's disease?

bromocriptine is also marketed for amenorrhea
Amantidine is more effective than anticholinergics and less effective than L-dopa. It is also used to treat:
A2 influenza prophylactically