Intro CNS II: Neurotransmitters Flashcards Preview

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Flashcards in Intro CNS II: Neurotransmitters Deck (70)
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1

Noradrenergic neurons (i.e. neurons that utilize norepinephrine) are located in the

medulla oblongata, pons and midbrain called the reticular activating system

2

a prototype catecholamine

Norepinephrine

3

Very important in arousal (wakefulness) and in regulation of autonomic functions like breathing and blood pressure

Nepi

4

Nepi must be made in the brain bc

can't cross the BBB

5

Nepi is made from

tyrosine, taken across the BBB

6

tyrosine is converted to 3,4-dihydroxyphenylalanine (DOPA) by

tyrosine hydroxylase

7

DOPA is converted into dopamine by

DOPA decarboxylase
a) low substrate specificity

8

dopamine is converted into norepinephrine by

dopamine beta hydroxylase

9

Primary regulation of norepinephrine synthesis occurs via

tyrosine hydroxylase (TH)

10

TH is normally saturated with tyrosine so its activity is the rate limiting step for____ synthesis under basal conditions

DOPA

11

TH has an essential co-factor

tetrahydrobiopterine, BH4

12

Short-term regulation of tyrosine hydroxylase activity occurs via:

(1) phosphorylation at four different serine residues
(2) end-product (i.e. norepinephrine) inhibition of BH4 binding to the enzyme; this detects over-filled vesicles

13

Synthesis of Nepi is tightly regulated; seems designed to maintain a constant amount that is released:

in a single synpatic vesicle

14

Dopamine beta hydroxylase is located in______ and co released with_________

synaptic vessicles
with NE
(not well regulated)

15

DOPA decarboxylase has _____substrate specificity and is found in

LOW
serotonergic neruons like astrocytes

16

Tyrosine Hydroxylase is saturated with ______ at normal conc but not saturated with _____-

saturated with tyrosine
not saturated with tetrahydrobiopterine (BH4) co-factor

17

Activity of tyrosine hydroxylase is regulated by

binding of BH4

18

Where does the last step of synthesis of NE occur

Dopamine is taken into the vesicle, the last step of synthesis occurs there

19

Vesicular monoamine transporters are called VMAT; VMAT2 is found

in the brain

20

NE competes directly for BH4; the NE regulating BH4 binding is :

a specific regulatory pool present in cytosol

21

Neuronal activity increases _____, which then actiates CaM kinase which increases affinity for BH4

Calcium

22

What activates CaM kinsase

increase in neuronal activity--> increase in Ca++

23

What results in decreased affinity of TH for BH4

inhibition of cAMP generation and decreased PKA activity

24

Three mechanisms of norepinephrine release

a) calcium-dependent exocytosis of vesicles
b) reversal of plasma membrane transporters
c) dendritic release that is not calcium-dependent

25

Release of NE is regulated by presynaptic receptors (autoreceptors)
a) _______inhibits release
b) _______ increases releas

alpha2 receptor
beta receptor

26

alpha 2 presynaptic receptor will _____ NE release

inhibit
called feed back regulation

27

Beta receptor on the presynaptic terminal will _____ NE release

increase
called feed forward regulation

28

All transmitters can be inactivated by

diffusion

29

_____ by the presynaptic neuron is the most important: neuronal not astrocytic

Reuptake

30

During reuptake:
High affinity carrier proteins move norepinephrine from _____ to ______ compartments

from extracellular to intracellular compartments