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neurobiology > Neurotransmitters > Flashcards

Neurotransmitters Flashcards

1
Q

glutamatergic signaling fast facts:

A

100 billion neurons in the brain
100 trillion- 1 quadrillion synapses
each neuron fires 5-50 hz
involved in all excitatory processes in the nervous system
both psychological and pathophysiological roles
glutamate 90% of these synapses (vast majority of excitatory transmission)
have a number of molecular targets

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2
Q

what are some molecular targets of glutamatergic signaling?

A

AMPA and kainite receptors (Electrical mediators), Na+ permeable
NMDA receptor (chemical and electrical mediators), Na+ and Ca2+ permeable
metabolic receptors

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3
Q

What are AMPA receptors?

A

gluatmate-responsive, ligand gated ion channels. are able to provide enough depolarization to allow for an action potential to fire. activate and desensitize fast (<10 ms) mainly permeable to sodium, only slightly permeable to calcium (<4% of total current carried)

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4
Q

what do AMPA receptors function as?

A

an electrical conductor along dendrites to depolarize the membrane

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5
Q

what do NMDA receptors require?

A

binding of glutamate and glycine

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6
Q

what are NMDA receptors?

A

high permeability to Ca2+ (~20% of total current carried, electrical and chemical signaling). can only be open once the membrane has been depolarized (otherwise Mg2+ ions block the channel pore, voltage relieves Mg2+ block around -40 mV) remains active for a prolonged period of time compared to AMPA receptors during a single synaptic event

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7
Q

what are GIRK channels activated by?

A

directly activated by G proteins or second messengers

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8
Q

what is the point of GIRK channels?

A

they can lower the membrane potential of a cell by hyperpolarizing

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9
Q

what are the two groups of metabotropic glutamate receptors (mGluRs)

A

increase NMDA receptor activity/risk for excitotoxicity (mGluR1/mGluR5)
decrease NMDA receptor activity/risk for excitotoxicity (all other mGluRs)

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10
Q

what do phosphorylation (kinases) do?

A

increase activity

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11
Q

what do dephosphorylation (phosphates) do?

A

decrease activity

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12
Q

what does PKA major kinase do?

A

increase NMDA receptor activity

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13
Q

what does calcineurin major phosphate do?

A

decreases NMDA receptor activity

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14
Q

what is GABA?

A

a primary inhibitory neurotransmitter of the brain
synthesized directly form glutamate by glutamate decarboxylase
ionotropic (GABAA) and metabotropic (GABAB) functions

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15
Q

what is GABAA’s role in physiology?

A

primary inhibitory neurotransmitter in brain-> make it more difficult to fire action potential
permeable to Cl- (hyperpolarizing)
located synaptically
number of allosteric sites for a number of drugs and modulators including ethanol, benzodiazepins -> potentiate current (anxiolytic/sedative/anticonvulsant effects)

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16
Q

what is GABAB?

A

receptor is metabotropic
inhibitory
initiates GI signaling
beta/gamma subunits directly modulate potassium and calcium channel activity

17
Q

what is glycine?

A

amino acid neurotransmitter, major inhibitory neurotransmitter of the spinal cord/brain stem
primarily iontropic

18
Q

what are glycine receptors?

A

sensitive to strychnine
positively allosterically modulated by ethanol

19
Q

acetylcholine receptors can be??

A

ionotopic (nicotinic) or metabotropic (muscarinic)

20
Q

where are nicotinic acetylcholine receptors found?

A

at neuromuscular junction for muscle contraction (on muscles)

21
Q

what do nicotinic acetylcholine receptors do?

A

moves sodium ions into the cell (changes excitability)
some are permeable to the second messenger Ca2+
desensitizes greatly (PKA and PKC phosphorylation leads to desensitization)
needs constant stimulation for continued contraction

22
Q

how long do nicotinic acetylcholine receptors typically remain open?

A

until agonist diffuses away within 1 ms

23
Q

what is acetylcholine broken down in the synapse by?

A

acetylcholinesterase into choline and acetate

24
Q

why is acetylcholinesterase a common pharmacological drug target?

A

because it’s inhibition increases the amount of acetylcholine available at a synapse

25
Q

what do muscarinic acetylcholine receptors do?

A

pathway acts on calcium and potassium channels
hyperpolarizing
inhibited for treatment of Parkinson’s

26
Q

what is serotonin synthesized from?

A

tryptophan

27
Q

what is serotonin involved in?

A

mood, appetite and sleep

28
Q

how is serotonin removed?

A

via synapse by synaptic reuptake

29
Q

serotonin receptors can be??

A

metabotropic and ionitropic

30
Q

serotonin is permeable to?

A

cations

31
Q

describe 5HT3 (serotonin) receptors functionally

A

little pharmacological differences known between subunits
permeable to cations, including Ca2+, however Ca2+ also blocks the channel as it permeates

32
Q

describe 5HT3 (serotonin) receptors physiologically

A

receptors distributed throughout the CNS and PNS, mediated excitatory transmission in the amygdala, hippocampus and visual cortex

33
Q

describe 5HT3 (serotonin) receptors pathologically

A

activation can lead to anxiety, increased seizure propensity, nausea and vomiting

34
Q

describe metabotropic serotonin receptors

A

various subtypes
either increase or decrease cAMP
cAMP activates PKA, which can activate potassium channels

35
Q

catecholamine neurotransmitters include?

A

dopamine, norepinephrine, and epinephrine

36
Q

what kind of receptors are dopamine receptors?

A

metabotropic

37
Q

describe dopamine’s involvement in circuitry of the mid brain and basal nuclei

A

motor behavior (dysfunctional in parkinson’s and huntington’s)
involved in reward
initially thought to play a role in schizophrenia

38
Q

D1 dopamine receptors are?

A

Gs stimulatory

39
Q

D2 dopamine receptors are?

A

Gi inhibitory

neurobiology (5 decks)

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