amino acid transmitter pharma Flashcards

1
Q

what are the amino acid neurotransmitters

A

glutamate, GABA, glycine

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2
Q

how is glutamate synthesised and transported into vesicles

A

glutamate derived from food and metabolism in cells

taken up from extracellular space by reuptake via excitatory amino acid transporters (EAAT1-5)

concentrated into vesicles in glutamatergic neurones via vesicular glutmate transporter (VGLUT)

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3
Q

how is GABA synthesised and transported into vesicles

A

synthesised from glutamate by glutamic acid decarboxylase (GAD)

taken up from extracellular space by reuptake via GABA transporters (GAT1-4)

concentrated into vesicles in GABAergic neurones via vesicular inhibitory amino acid transporter (VIAAT)

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4
Q

how is glycine synthesised and transported into vesicles

A

taken up from blood or synthesised by all cells

taken up from extracellular space by reuptake via glycine transporters (GlyT-1and2)

concentrated into vesicles in glycinergic neurones via VIAAT

(some neurones release both GABA and glycine)

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5
Q

describe the structure of LGIC glutamate receptors

A

tetrameric

contain 3 transmembrane alpha helices labelled M1-4

M2 does not cross membrane entirely but is a loop that enters intracellularly and leaves intracellularly

L-glutamate is agonist of glutamate receptors, D-glutamate is not

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6
Q

describe AMPA receptors

A

GluR1-4

causes increase in sodium/potassium flux

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7
Q

describe NMDA receptors

A

NR1, NR2A, NR213, NR2C, NR2D, NR3

causes increase in sodium/potassium/calcium flux

normally blocked by magnesium. depolarisation of membrane causes unblocking, relief of Mg block leads to further depolarisation, voltage gated

presence of extracellular glycine is necessary for activation (co-agonist)

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8
Q

what types of kainate receptors are there

A

GluR5-7 and KA1-2

cause increase in sodium/potassium flux

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9
Q

describe metabotropic glutamate receptors

A

mGluR1-8

3 groups of mGluR

group 1: mGluR 1 and 5, excites phospholipase C causing increase in IP3 and DAG (Gq)

group2: mGluR2 and 3, inhibits adenylyl cyclase, Go

group 3: mGluR4 and 6-8, also causes inhibition of adenylyl cyclase, Go

(group 2 and 3 differ in agonist selectivities)

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10
Q

describe ionotropic GABA receptors

A

GABAa has variety of subunits (alpha1-6, beta1-3, gamma1-3, delta, epsilon, pi, tau and rho1-2)

pentameric LGIC

causes increase in intracellular chloride

GABAc also LGIC

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11
Q

describe metabotropic GABA receptors

A

GABAbR1-2

opens potassium channels causing decrease in intracellular potassium

reduces intracellular calcium and cAMP

Gi/o

may be pre or post synaptic receptors,

pre synaptic GABA receptors reduce calcium concentration

postsynaptic cause efflux of potassium from cell

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12
Q

describe glutamate metabolism

A

alpha-ketoglutarate is converted to glutamate via glutamate dehydrogenase

alpha-ketoglutarate is produced by citric acid cycle

glutamate is converted to glutamine via glutamine synthase

glutamine is converted to glutamate via glutaminase

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13
Q

name modulators of GABAa receptors

A

benzos, barbiturates, steroids, alcohol, anaesthetics

benzos are positive allosteric modulators of GABAa receptors

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14
Q

describe GABA metabolism

A

glutamate is converted into GABA via glutamic acid decarboxylase

GABA is converted into succinic semialdehyde via GABA transaminase

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