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Neuroscience > L20 Neurotransmitters > Flashcards

L20 Neurotransmitters Flashcards

1
Q

What are the four general classes of NTs?

A
  1. small molecule transmitters - ACh and serotonin
  2. neuropeptides - CCK, substance P, VIP, orexin (vasopressin + oxytocin)
  3. gases - CO, NO
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2
Q

what is the life cycle of NT?

A
  • synthesis
    • nerve ending cytoplasm - small mole. NT
    • in rER, Golgi and vesicles - neuropeptides
    • in synap. vesicles - NE from DA
  • storage in vesicles
  • release
  • binding to receptors
  • degradation/re-uptake/reabsorption/diffusion
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3
Q

All NTs (with the exception of ACh, NO and peptides) are removed rapidly via _______ in the nerve ending by glial cells

A

transporters

*example - glutamate is taken up by neurons _ taken into astrocytes by their glutamate transporters. Glutamate is metabolized into glutamine which has its own transporter in neurons

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4
Q

DA, E, NE and serotonin are absorbed then broken down by ___ from the outer mitochondrial membrane in the nerve ending

A

MAOs

  • there is also some degradation from COMT
  • MAO and COMT are also present in astrocytes in liver
  • some extracellular sites for MAO do exist.
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5
Q

what receptors do cholinergic neurons (ACh) use?

A

ionotropic - nicotinic

metabotropic - muscarinic

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6
Q

muscarinic M1, M3 and M5 have what type of response?

A

slow excitatory response - Gq–>PLC -> IP3 +DAG increase –> increase [Ca2+]

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7
Q

Muscarinic M2 and M4 have what type of responses?

A

inhibitory responses - Gi –> cAMP decrease –> closure of Ca2+ channels = weaker sponataneous depolarization

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8
Q

what are the major muscarinic subtypes in the brain (cerebral cortex + hippocampus)?

A

M1, M3, M4

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9
Q

what muscarinic subtype mediates gastric acid secretion?

A

M1

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10
Q

what type of actions do catecholamines (E, NE, and DA) have

A

both excitatory and inhibitory

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11
Q

what type of receptors do catecholamines use/

A

metabotropic only

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12
Q

where is DA important

A

CNS - parkinsons disease

no role in PNS

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13
Q

where is NE released from and what does it activate?

A

postganglionic sympathetic neurons

adrenoceptors in smooth n., glands and cardiac m.

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14
Q

where is E released from and what does it activate?

A

chromaffin cells

enters circulation and activates adrenoreceptosr

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15
Q

what isoproterenol?

A

synthetic form of epinephrine - similar in sutrcture to adrenaline (E), but has an additional CH3 group on the terminal N

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16
Q

where do dopaminergic cells in the substantia nigra project?

A

basal ganglia striatum (caudate nucleus + putamen)

D1 and D2 receptors on striatal neurons

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17
Q

where do dopaminergic neurons in the ventral tegmental area project?

A

hippocampus - new memory formation
nucleus accumbens
frontal lobe cortex - planning and attitude

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18
Q

how many receptors does DA have

A

5

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19
Q

what are the 2 families of DA receptors?

A

D1 - like (D1 and D5) - increase cAMP (excitatory)

D2-like (D2, D3, D4) - inhibit cAMP

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20
Q

what do postganglionic sympathetic neurons do to cardiac muscle?

A

excite!

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21
Q

what is the function of cardiac muscles beta 1 receptors?

A

increase cAMP - excite the HR and pacemaker

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22
Q

cardiac output increases in response to what stimulation?

A

sympathetic

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23
Q

what type of channels are AMPA/kainate and NMDA?

A

cation

24
Q

describe the AMPA receptor

A

typical Na+ channel

25
Q

describe the NMDA receptor

A
  • blocked by residing Mg2+ which leaves under influence of very large depolarization (due to summation of many EPSPs)
  • when it is unblocked it allows Ca2+ entry into the postsynaptic cell where the calcium plays a role in alterations of enzyme activity
26
Q

what neurotransmitters mediate synaptic inhibition

A

glycine and GABA

27
Q

what is the main inhibitory NT in the spinal cord

A

glycine

28
Q

how does the glycine work in the spinal cord?

A

ionotropic receptor selective to Cl- - has similar structure to nAChR but NEEDS 3 MOLECULES OF GLYCINE TO OPEN CHANNEL!

29
Q

how many molecules of glycine must bind to nGlyR?

A

3

30
Q

what is the main inhibitory transmitter in the brain stem and brain?

A

GABA

31
Q

what does GABAa receptor resemble

A

nAChR and glycine receptors - with two molecules of transmitter binding to alpha subunits before it can open!

32
Q

how many molecules of GABA need to bind to GABAa receptor

A

2

33
Q

what kinds of substances to glycine and GABA receptors bind?

A

anti-epileptic drugs, anti-anxiety drugs, sedatives, muscle relaxants, anesthetics

34
Q

describe GABAb receptors?

A

metabotropic receptos - indirectly cause K+ channel opening through 2nf messengers - slow inhibition of postsynatpic neuron

35
Q

how do benzodiazepines and barbiturates act on GABAa receptor channels?

A

-inhibition in the amygdala invovled with the development of fear and anxiety

36
Q

where is the binding site on GABAa for benzos?

A

gamma subunit

37
Q

where is the binding site on GABAa for barbiturates?

A

alpha and beta subunits

38
Q

cholinergic neurons in the septal nuclei, basal nucleus of Myenert and pons connect to maintain ______, regulating a high level of consciousness

A

peak excitability

39
Q

what do the ascending arousal system and cholinergic neurons also participate in?

A

raising levels of consciousness during REM sleep

40
Q

amines and peptides have crucial roles in what

A

the CNS

41
Q

the neurons in the locus ceruleus and rostral raphe nuclei innervate neurons in the

A

limbic lobe and cortex - mood, LO anxiety and optimism

42
Q

when NE and serotonin transmission is low…

A

mood = feelings of despair, fear, anxiety

43
Q

what does DA play a role in

A

depression and schizophrenia

44
Q

what are brain dopamine receptors target in tx od

A

schizophernia, parkinsons disease and huntingtons chorea

45
Q

dopamine receptor antagonist block what

A
  • neuroleptics - block hallucinations and delusions
46
Q

dopamine receptor agonists alleviate signs of what disease

A

-bromocriptine - sings of parkinsons disease

47
Q

what therapeutic drugs are used to tx clinical depression

A

1- SSRI - slow upreg of serotonin receptors

  1. noradrenaline reuptake inhibitors
  2. MAO inhibitors - reduce degradation of NE and serotonin
48
Q

what are the 3 endogenous opiod peptide families?

A
  1. beta endorphins
  2. enkephalins
  3. dynorphins

*they inhibit pain

49
Q

what does substance P do

A

information about tissue damage and substance P mediates the increased pain sensation

50
Q

what is capsaicin

A

in red hit chilli peppers - analgensic for pain = desensitize receptors and pain is reduced

prolonge capsaicin admin. downreg pain caused by death of primary afferent neurons = decreased release of substance P

51
Q

what is the MOA for pilocarpine?

A

mimics ACh - agonist for muscarinic receptors of PNS

52
Q

what is pilocarpine used to tx?

A

glaucoma - facilitates fluid drainage from eye via canal of Schlemm

53
Q

what is the MOA for beta blockers

A

anatagonists of beta 1 receptors used to treat htn

54
Q

what receptors do asthmatic bronchodilators work?

A

beta 2 agonist

55
Q

what receptors do nasal decongestants work on

A

alpha 1 agonist = phenlephrine

Neuroscience (54 decks)

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