lecture 9 LOs Flashcards
how are DA/NE removed from the synaptic cleft
membrane transporter proteins
commonly referred to as DAT and NET
sloppy
in the frontal lobes most DA reuptake is done by NET
what does blocking transporters lead to
greater accumulation of extracellular NT levels
what is release of reuptake blockers dependent on
activity of the neuron
if neurons are not firing then reuptake blockers will not increase transmitter levels
what does cocaine inhibit the reuptake of
all monoamines (DA, NE, 5-HT)
what does tricyclic antidepressant inhibit the reuptake of
NE and 5-HT
what does methyphenidate (ritalin) selective for
catecholamines
what does amephtamine do to the DA/NE transporter
reverse it so it spits out moleculesm from inside the terminal into the synapse
more transmitter is released and stays out a lot longer
amphetamines are ____ of cell firing
independent
even if the neuron is not firing, amphetamines can still increase transmitter levels
are amphetamines more selective or non selective
non selective, will work on DA, NE, and 5-HT
what do amphetamines that enter the brain invariably do
increase locomotor activity
driven primarily by the increased DA in nuecleus accumbens
what do high doses of amphetamines result in
stereotyped behaviours
snigging, repetitive head/limb movements, licking, biting)
what does the continuum of beh changes from amphetamine doses come from
increase stimulation of DA receptors in the nucleus accumbens and striatum
what is sensitization
repeated exposure increases sensitivity to effects of drug at the same dose
therepeutic effects of small doses of d-amphetamine
powerful stimulat: promotes wakefulness, reduces REM sleep
cognitive enhancer: for multiple forms of cognition
DA and NE receptor subtypes
DA autoreceptor: D2 subtype
NE autoreceptor: alpha 2 subtype
where do monoamine autoreceptors reside
axon terminals (DA and NE)
cell bodies (NE)
what does activation of DA and NE receptors result in
opening of voltage gated K+ channel that shortens duration of action potentials
on terminals this reduces Ca2+ influx and transmitter exocytosis
what do autoreceptors on the cell body do
reduce neural firing
where else can D2/alpha 2 receptors reside
postsynaptic neurons
DA cell groups A1-7
nonadrenergic
DA cell groups A8-16
dopaminergic
where do A9 (nigrostriatal) axons originate from
substantia nigra and extend to caudate putamen (dorsal striatum)
what does the nigrostriatal DA facilitate
voluntary movement
parkinsons involves these neurons
6-OHDA and MPTP are used to destroy these cells in this pathway in animal models for parkinsons
what does dorsal striatum DA aide in
action selection, promotes the best action while expressing the others
