Lectures 1 &2-CNS I & II Flashcards
State the mechanism of how Tyrosine turns into Dopamine .
Tyrosine–>DOPA–>Dopamine
True/ false: Dopamine is a stimulatory monamine neurotransmitter
True
Dopamine receptors on the postsynaptic membrane are?
G protein coupled receptors
After synthesis, dopamine is packaged into synaptic vesicles via the vesicular monoamine transporter _____ and stored there until its release into the synapse during neurotransmission.
VMAT2
Dopamine (DA) is removed from the synapse by the dopamine transporter (DAT). It can be destroyed inside the presynaptic neuron by ______. DA can be destroyed in the synapse by _____. (These can be targets of drugs).
monoamine oxidase (MAO) A/B;
catechol-o-methyltransferase (COMT)
State the 5 dopamine pathways in the brain & their general function:
Nigrastriatal- controls movement
Mesolimbic- controls reward and perception
Mesocortical -controls executive function
Tuberoinfundibular- controls pituitary prolactin function
Thalamic- ??
State the major functions of the nigrostriatal dopamine pathway.
(a) The nigrostriatal dopamine pathway, which projects from the substantia nigra to the basal ganglia or striatum, is part of the extrapyramidal nervous system and controls motor function and movement.
State the major functions of the mesolimbic dopamine pathway.
(b) The mesolimbic dopamine pathway projects from the midbrain ventral tegmental area to the nucleus accumbens, a part of the limbic system of the brain thought to be involved in many behaviors such as pleasurable sensations, the powerful euphoria of drugs of abuse, as well as delusions and hallucinations of psychosis.
State the major functions of the mesocortical dopamine pathway.
(c) A pathway related to the mesolimbic dopamine pathway is the mesocortical dopamine pathway. It also projects from the midbrain ventral tegmental area but sends its axons to areas of the prefrontal cortex, where they may have a role in mediating cognitive symptoms (dorsolateral prefrontal cortex, DLPFC) and affective symptoms (ventromedial prefrontal cortex, VMPFC) of schizophrenia.
State the major functions of the tuberoinfundibular dopamine pathway.
(d) The fourth dopamine pathway of interest, the tuberoinfundibular dopamine pathway, projects from the hypothalamus to the anterior pituitary gland and controls prolactin secretion.
Hyperfunctioning in the Mesolimbic pathway gives
addiction, hallucinations
Hyperfunctioning in the Mesocortical pathway gives
hypervigilance
Hyperfunctioning in the Nigrostriatal pathway gives
dyskinetic movement
Hyperfunctioning in the Tuberoinfundibular pathway gives
hypoprolactinemia
Hypofunctioning in the Mesolimbic pathway gives
amotivation, apathy
Hypofunctioning in the Mesocortical pathway gives
inattention
Hypofunctioning in the Nigrostriatal pathway gives
dyskinetic movement, parkinsonism
Hypofunctioning in the Tuberoinfundibular pathway gives
hyperprolactinemia
What is Levodopa? What disease is it used in? What happens if it is dosed too high?
A dopamine enhancing drug used in Parkinsons (low dopamine). Levodopa-
Is the precursor to DA and crosses blood-brain barrier (BBB).
Once in CNS it is converted to DA and can promote better movement by improving nigrostriatal functioning.
If dosed too high can create dyskinetic movement, hallucinations.
What is Carbidopa? What disease is it used in?
Carbidopa is an agent often combined with levodopa in Parkinson’s as it prevents peripheral dopamine activity and lowers fatigue, dizziness, nausea. It is an anti side effect drug.
State the side Effects of levodopa.
Overdosing = too much DA:
Psychosis, mania
Dyskinesia- abnormal, involuntary movements
Average side effects:
Hypotension, syncope
Nausea
Anxiety/agitation
Fatigue
What do l-methylfolate or s-adenosyl methionine do?
l-methylfolate & s-adenosyl methionine raise dopamine levels!
Some Depression is considered a low DA state where patients are amotivated and see no reward or enjoyment in life. By prescribing l-methylfolate or s-adenosyl methionine we can increase the 1 carbon cycle and allow DA neurons to make more DA, thus improving the patient’s apathy
l-methylfolate & s-adenosyl methionine side effects?
None, perhaps GI upset
What is bupropion(XL)?
A Norepinephrine-Dopamine Reuptake Inhibitor (NDRI)
It is an antidepressant
bupropion(XL) side effects?
Side effects include insomnia, jitteriness/hypervigilance, seizures all due to increased DA.
Any time we increase activity of norepinephrine via drugs-
think sympathetic stimulation like:
Fight flight = Insomnia, anxiety, agitation, nausea, dry mouth, sweating, palpitations, mild increases in blood pressure