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Block 3 Up To Quiz 1 > Glutamate and GABA Amino Acid Neurotransmitters, Receptors, and Drugs PT 2 > Flashcards

Glutamate and GABA Amino Acid Neurotransmitters, Receptors, and Drugs PT 2 Flashcards

1
Q

Benzodiazepine drugs types

A
  • allosteric agonists

- allosteric antagonists

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2
Q

allosteric agonists used clinically names and fxs

A

they are minor tranquilizers or anxiolytics

  • chlordiazepoxide (Librium)
  • Diazepam (Valium)
  • flurazepam (Dalmane)
  • Oxazepam
  • Lorazepam
  • Prazepam
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3
Q

Competitive antagonists at benzodiazepine allosteric site drug class and name

A
  • competitive antagonists

- flumazenil

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4
Q

Mechanism of action benzodiazepine

A
  • enhance inhibitory actions GABA
  • Interact with specific site on GABAa receptor-chloride channel complex associated with receptor containing gama2 subunit
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5
Q

Benzodiazepines are both

A
  • anxiolytic

- sedating

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6
Q

allosteric agonists benzodiazepines require

A

the presence of gama2 subunit

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7
Q

Benzodiazepine agonists prefer what subunits be present or not present

A
  • alpha 1,2,3,5 present

- alpha 4,6

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8
Q

Benzodiazepine antagonists prefer

A
  • alpha 1 subunits to alpha 2 and alpha 3 and they do not interact with alpha 5
  • this means they are not complete reversal agents
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9
Q

GABA bound with vs without diazepam effect

A

GABA bound opens channels, GABA and Diazepam bound -> channels open longer

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10
Q

Benzodiazepine drugs toxicity

A
  • fairly safe no remarkable acute toxicity
  • withdraw following chronic uses can -> seizures
  • use benzodiazepines with barbiturates or alcohol can -> death
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11
Q

clinical uses benzodiazepine drugs

A
  • anxiolytic (anti-anxiety) (used in combo with other CNS deprassants in pre-anesthetic protocols)
  • anti-convulsant at v high doses give IV can control status epileptics
  • muscle relaxant- increases inhibition in spinal cord
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12
Q

Excitatory animo acid neurotransmitters

A

-mainly L-glutamate
May also include
- L-asparate
- L-homocystetic acid

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13
Q

Receptor class for excititaroy amino acid neurotransmitters name

A

glutamate receptors or excitatory amino acid receptors

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14
Q

glutamate receptors and CNS

A
  • nearly all CNS neurons have excitatory glutamate receptors

- nearly 1/3 CNS neurons= glutamatergic

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15
Q

Glutamate receptors and excitatory amino acid receptors subclasses

A
  • provide some specificity and different patterns of regional distribution of different glutamate receptor subtypes occur in brain and spinal cord
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16
Q

NMDA-type glutamate receptors

A
  • pain pathways

- hippocampus (role in learning and memory)

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17
Q

synthesis of L-glutamate

A

can be:

  • by deamination L-glutamine
  • from a-ketoglutarate
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18
Q

synthesis L-aspartate

A

can be:

  • by transmission oxalacetate
  • by deacetylation of N-acetylaspartate
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19
Q

degradation L-glutamate

A

pathway unknown

20
Q

synaptic action L-glutamte stopped how?

A
  • mainly by high affinity uptake mechanisms
  • diffusion also plays a role
  • non-specific processes
21
Q

what cells have glutamate uptake systems

A

neuronal and glial cells

22
Q

Glutaminergic synapses compartments

A
  • tripartite, have 3 components
  • presynaptic terminal
  • postsynaptic button
  • enveloping astrocyte
23
Q

Astrocytes fx

A
  • pt of glutaminergic synapse

- respond to glutamate and transmit info throughout network of neurons that contact astrocyte

24
Q

Inotropic Glutamate receptors (excitatory amino acid receptors) receptor subtypes

A
  • named for agonists
  • N-methyl-D-aspartate (NMDA)
  • AMPA
  • kainate
25
Q

Ionotropic glumate receptors permeable to

A

Na+ and K+ ions, NMDA to Ca2+

26
Q

AMPA receptors important for

A

generating fast excitatory postsynaptic potentials (EPSPs) in CNS

27
Q

important binding sites on NMDA receptors

A
  1. glutamate receptor site where neurotransmitter binds
  2. Mg2+ site inside pore
  3. PCP site
28
Q

Mg2+ site at normal resting potentials

A

Mg2+ ions block flow other ions through pore

29
Q

PCP site

A

binds dissociative anesthetic drugs (ketamine and tiletamine)

30
Q

Uncompetitive antagonists

A
  • dissociate anesthetic drugs

- use-dependent antagonists of NMDA receptor-channels (aka NMDA channel blockers)

31
Q

How do uncompetitive antagonists work

A
  • they’re use depdnet so active glutamate synapses more likely to be inhibited by dissociated anesthetics than less active ones
    details:
  • drug enters binding site inside channel, channel closes drug trapped, drug can’t leave channel until its re-opened by release neurotransmitter again
32
Q

Dissociate anesthetics characterized by

A

loss of awareness accompanied by body surface analgesia

33
Q

examples drugs used in dissociative anesthesia

A
  • ketamine
  • tiletamine
  • phencyclidine (PCP)
34
Q

Ketamine

A
  • dissociative anesthetic

- preanesthetic drug

35
Q

ketamine as a preanesthetic drug

A
  • b/c it causes dysphoria use with nonadrenergic alpha-2 agonist or benzodiazepines which provide sedation or tranquilization
36
Q

noradrenergic alpha2 agonist examples

A

detomidine, medetomidine

37
Q

benzodiazepine example

A

diazepam

38
Q

Tiletamine

A
  • dissociate anesthetic drug

- can use in combo with benzodiazepine or noradrenergic alpha 2 agonist

39
Q

Phencyclidine

A
  • dissociate anesthetic drug
  • PCP
  • UK primary anesthetic US illegal street drug
40
Q

disadvantages of dissociative anesthetics

A
  • strong dysphoric rxns as drug wears off
  • uncompetitive agonist so no possibility of reversal agent (bc any drug competing for same sit will have same effect)
  • do not give as sole agent for anesthesia recovery difficult if not given with sedative or anxiolytic drug
41
Q

advantages of dissociative anesthetics

A
  • analgesia
  • cause amnesia
  • may protect brain from exotic cell death during hypoxic episodes
  • maintain or increase cardiac output
42
Q

why analgesia with dissociative anesthetics

A
  • blockade of NMDA channels (which are pt pain pathway at glutamatergic synapses)
43
Q

excitotoxic cell death with excitatory amino acid neurotransmitter

A

continuous glutamate exposure depolarizes neurons for prolonged periods b/c NMDA channels highly permeable to Ca2+; overly active NMDA channels cause sustained increase in intracellular Ca2+ concentration activating Ca2+ dependent proteases (caspases) -> mitochondrial damage and subsequently to neuronal death

44
Q

excitatory amino acid receptors aka

A

glutamate receptors

45
Q

Examples excitotoxicity

A
  1. Hypoxic/ Ischemic reprofusion damage

2. In untreated seizure disorders

46
Q

excitotoxicity hypoxic/ischemic reperfusion damage

A
  1. cerebral ischemia

2. glutamate released from injured and dying neurons goes into extracellular space and bathes nearby neurons

47
Q

excitotoxicity in untreated seizure disorder

A

excessive glutametergic stimulation kills neurons

Block 3 Up To Quiz 1 (24 decks)

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