lecture 10 LOs Flashcards
dopamine receptor subtypes amount and type
five subtypes, D1-5
all metabotropic
D1 and 5 are similar, D2-4 are similar
what does D1 dopamine receptor activation stimulate
adenylyl cyclase and cAMP synthesis
what does D2 domaine receptor activation do
reduces cAMP and inhibits adenylyl cyclase
what is the difference between where D1/D2 and D3/D4 receptors are found
D1/2 found in all brain regions that get DA innervation (but not necessarily both in all areas)
D3/4 receptors show more regional variations
what do D2 type receptors function as and what do their antagonists do
function as both autoreceptor and postsynaptic receptor
D2 antagonists increase DA release (by blocking the autoreceptor) but also reduce postsynaptic DA signalling
do D1 or D2 receptors have higher affinity for DA
D2
what does it mean that some DA receptors are _____ on glutamate/GABA terminals that _____
heteroreceptors
modulate fast transmission presynaptically
what does the DA agonist apomorphine do
stimulate D1 and D2 receptors
casues behavioural activation similar to that seen w cocaine or amphetamine
DA receptor agonists are used for treatment of parkinsons
what does DA antagonist flupenthixol do
blocks both D1-D2 receptors
reduces motivaton at higher doses produces catalepsy (lack of spontaneous movement) like all D1 or D2 antagonists
what does DA antagonist haloperidol do
highly selective for D2 vs D1 but will bind to the entire D2 like family similarily
what happens if D2 antagonist is given repeatedly over 12 days
rats develop behavioural supersensitivity
after chronic treatment the dose no longer is effective at blocking AMPH
then when the antagonist treatment is stopped the DA agonist has greater locomotor response
where are norepinephrine (NE) neuron cell bodies in the central nervous system
NE neuron cell bodies resude in the pons and medulla in the brain stem
locus coeruleus in the pons is a dene collection of NE neurons
where do NE anxons of the central nervous system extend to
nearly all of the forebrain as well as the cerebellum and the spinal cord
where is NE released from in the peripheral nervous system
sympathetic noradrenergic neurons at synapse like contacts
adrenal glands and travel in the bloodstream to target organs (cannot cross blood brain barrier)
NE receptor subtypes
alpha and beta
both metabotropic
distributed widely across cortical and subcortical sites
what do alpha1 receptors for NE operate w
phosphoinositide 2nd messenger system (post synaptic)
what are the a1 NE receptor agonist and antagonist
agonist: phenylephrine
antagonist: prazosin
what does the a2 NE receptor do
reduce cAMP synthesis (like a D2 receptor) and serves as presynaptic autoreceptor and postsynaptic receptor
what is the a2 NE agonist and antagonist
agonist: clonidine
antagonists: yohimbine
what do b1 and b2 NE receptors do
stimulare adenylyl cyclase and enhance synthesis of cAMP (like D2 receptors)
what are the agonist and antagonist of b2 NE receptor
agonist: isoprotenerol (increase heart rate)
antagonist: propanolol (decrease heart rate)
NE is key for maintaining arousal, waht happens to do this
Locus coerelus neurons fire more rapidly during waking vs sleep
almost completely silent in REM tho
what NE projections promote wakefulness
to medial septal and medial preoptic areas
what does a pharmacological increase in NE promote
anxiety like feelings
