Lecture 5: Metabotropic Receptors Flashcards

1
Q

How do heterotrimeric G-protein receptors work?

A

ligand binds to the receptor -> receptor interacts with heterotrimeric G-protein -> heterotrimeric G-protein dissociates and alters the function of different intracellular signalling pathways which produces changes in ion conductance

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2
Q

What is the structure of a GPCR?

A

seven transmembrane spanning l domains

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3
Q

What are the three main types of G protein?

A

Ga/Gas, Gai and Gaq

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4
Q

How do metabotropic receptors alter neuronal activity?

A

via intermediate steps between receptor and ion channels

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5
Q

What do different G-protein effectors produce?

A

different second messengers

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6
Q

What are the different ways metabotropic receptors act presynaptically?

A

presynaptic facilitation

presynaptic inhibition

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7
Q

How can changes in Ca2+ alter neuronal function?

A

via gene expression

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8
Q

How do metabotropic transmitter systems modulate postsynaptic neuronal membrane potential?

A

via second messenger pathways

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9
Q

Why do metabotropic receptors act presynaptically?

A

to modulate neurotransmitter release

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10
Q

What can second messengers derived from activation of metabotropic receptors alter?

A

neuronal gene expression

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11
Q

How is noradrenaline and adrenaline synthesised?

A

tyrosine is converted by tyrosine hydroxylase to DOPA
DOPA is converted by DOPA decarboxylase to dopamine
dopamine is converted by dopamine β hydroxylase to noradrenaline
noradrenaline is converted by phenylethanolamine-N-methyl-transferase to adrenaline

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12
Q

How is a neuron’s neurochemical phenotype determined?

A

by the presence of certain enzymes

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13
Q

What does calcium influx stimulate?

A

production of monoamines

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14
Q

Where is DBH and PNMT present?

A

within vesicles

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15
Q

Which enzymes are involved in the breakdown of monoamines?

A

monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT)

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16
Q

Which enzyme transports all monoamines into vesicles?

A

vesicular monoamine transporter (VMAT)

17
Q

How is dopamine, noradrenaline and adrenaline transported into the axon terminals?

A

dopamine - DAT (Na+ co-transporter)

NA/A - NET (also Na+ co-transporter that can take DA)

18
Q

Where are dopaminergic neurons most commonly found?

A

in the substantia nigra and ventral tegmental area of the brain

19
Q

Where are noradrenergic neurons most commonly found?

A

in the locus coeruleus