CH. 5 Noradrenaline Flashcards
what are the two ways NE cells are organized
central
peripheral
central NE anatomy
cell bodies in locus coeruleus in the pons (A6)
axons extend to basically the whole forebrain, cerebellum and spinal cord
peripheral NE anatomy
sympathetic NS uses NE released from
sympathetic noradrenergic neurons
adrenal gland release
true or false; NE transmission in the brain and the body can influence each other
false; NE does not cross the BBB
why doesn’t NE cross the BBB
because it is polar and soluble non-polar atoms cross it better
what are the two main NEergic receptors?
alpha (a)
beta (b)
what are the different types of alpha NE receptors
a1
a2
what kind of receptors are all NE recpetors?
metabotropic
what 2nd messenger system do a1 receptors work on?
activates phosphoinositide
a1 agonist
phenylephrine
a1 antagonist
prazosin
what 2nd messenger system do a2 receptors work on? where?
inhibit cAMP synthesis
presynapse autoreceptors and postsynaptic
a2 agonist
clonidine
a2 antagonist
yohimbine
what 2nd messenger system do b1/b2 receptors work on?
stimulate adenylyl cyclase to enhance synthesis of cAMP
what role does the b1 receptor play in the periphery?
primary receptor found on the heart that increases heart rate when activated
b1/b2 agonist
isoprotenerol
b1/b2 antagonist
propanolol
what behaviours does NE regulate?
sleep/wake cycle
stress and cognition
emotional memory modulation
how does NE regulate the sleep wake cycle?
maintains arousal
how does locus coeruleus activity vary throughout the sleep-wake cycle?
very silent during REM
little activity during deep sleep
most activity during wakefulness
what NE projections are promoting wakefulness?
medial septal
medial preoptic
what effects do a1/b receptor agonists have on wakefullness
increases awake times
what effect do a2 agonists/ a1 antagonists have?
sedation
how does NE regulate stress?
increased NE causes increase in stress/like feelings of anxiety
how was the NE/stress relationship tested in humans
virtual version of the elevated plus maze
self-reported feelings of anxiety in open or closed arms
how does NE regulate cognition?
NE facilitates attention and working memory by activating postsynaptic a2 receptors
describe the study used to show NE’s effect on working memory
aged monkeys that received an a2 agonist did better on working memory task with a distactor than control
true or false; facilitation of PFC functin by NE seems to be because of postsynapse a2 activation rather than just NE release
true
what effect does stress have on cognition through NE regulation? why?
excessive increase in NE release by stress impairs PFC function
takes PFC ‘offline’ to prioritize sensory-motor control on behaviour
which receptor drives PFC impairments caused by stress?
a1
how is NE effect on the PFC regulated between stress and facilitation?
NE has lower affinity to a1 receptors than a2
therefore low amounts of NE facilitate, high amounts shut down
how does NE modulate memory consolidation? why?
enhances memory consolidation when in more emotional states
emotionally relevant events are more likely to be important to remember
how do b1/2 antagonists affect memory?
disrupts enhancement of memory for emotional content
no effect on neutral content
what study was performed to see how beta-blockers affect memory consolidation?
control was told a neutral story, experimental an emotional story
memory recall tested a few days later
beta blocker lowered recall of experimental to same as control
where in the brain is NE increase seen for emotional memories?
amygdala (main)
spatial and instrumental memory (side note)
what psychiatric disorder may the NE-memory relationship underlie?
PTSD
