NEUROTRANSMISSION Flashcards

1
Q

What is the main excitatory neurotransmitter in the central nervous system?

A

Glutamate

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2
Q

Name four main receptor subtypes for glutamate.

A

NMDA, AMPA, Kainate, Metabotropic receptors

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3
Q

Are NMDA, AMPA, and Kainate receptors ionotropic or metabotropic?

A

Ionotropic

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4
Q

Why is glutamate recycling important for neurons?

A

It maintains optimal neurotransmitter levels in the synapse, prevents overstimulation, and prevents excitotoxicity and neuronal damage

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5
Q

What effect do NMDA antagonists have?

A

They block the activity of NMDA receptors, involved in synaptic plasticity, memory formation, and various pathological processes

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6
Q

How do NMDA antagonists affect memory function?

A

Excessive blockade of NMDA receptors can impair memory function

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7
Q

What are some clinical applications of NMDA receptor antagonists?

A

Treatment of epilepsy, schizophrenia, depression, Alzheimer’s disease

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8
Q

Which conditions is GABA important for regulating?

A

Epilepsy, anxiety disorders, certain types of movement disorders

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9
Q

How is GABA synthesized and deactivated?

A

Synthesized from glutamate by glutamic acid decarboxylase (GAD); deactivated through reuptake and degradation by GABA transaminase (GABA-T)

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10
Q

How can a drug be devised to increase GABA levels?

A

Both GABA transaminase inhibitor and GABA reuptake inhibitor would effectively increase GABA levels in the synapse, enhancing inhibitory neurotransmission

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11
Q

What conditions do benzodiazepines treat?

A

Anxiety disorders, panic attacks, insomnia, muscle spasms

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12
Q

How do benzodiazepines enhance inhibitory neurotransmission?

A

They act as positive allosteric modulators of the GABA alpha receptor, increasing the inhibitory effects of GABA on neuronal activity

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13
Q

What is the function of the GABA alpha receptor?

A

It is a ligand-gated chloride ion channel responsible for fast postsynaptic inhibition

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14
Q

How does vigabatrin affect GABA levels in the brain?

A

It inhibits GABA transaminase, thereby increasing GABA levels in the brain

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15
Q

What is the function of the GABA beta receptor?

A

It is a G-protein-coupled receptor that inhibits calcium influx, activates potassium channels, and inhibits neurotransmitter release

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16
Q

What neurotransmitter is associated with the noradrenergic system?

A

Norepinephrine (noradrenaline)

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17
Q

What functions are regulated by the noradrenergic system?

A

Attention, arousal, stress responses

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18
Q

What neurotransmitter is associated with the serotonergic system?

A

Serotonin

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19
Q

What functions are regulated by the serotonergic system?

A

Mood, sleep, appetite, various physiological functions

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20
Q

What neurotransmitter is associated with the dopaminergic system?

A

Dopamine

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21
Q

What functions are regulated by dopaminergic neurons from the substantia nigra?

A

Motor control, affected in Parkinson’s disease

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22
Q

What functions are regulated by dopaminergic neurons from the ventral tegmental area?

A

Reward, motivation, addiction

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23
Q

What neurotransmitter is associated with the cholinergic system?

A

Acetylcholine

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24
Q

What functions are regulated by the cholinergic system?

A

Memory, attention, learning

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25
Q

What are autoreceptors?

A

Receptors located on the presynaptic neuron that regulate the release of neurotransmitters

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26
Q

What is the function of autoreceptors when activated?

A

They inhibit cell firing and transmitter release at the terminal regions

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27
Q

What are the autoreceptor subtypes for serotonin (5-HT)?

A

5-HT1A, 5-HT1D (also known as 5-HT1B)

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28
Q

What are the autoreceptor subtypes for dopamine?

A

D2 or D3

29
Q

What are the autoreceptor subtypes for noradrenaline?

A

α2

30
Q

How does reserpine affect noradrenaline (NA) levels?

A

Depletes NA stores by inhibiting vesicular uptake, interfering with packaging into synaptic vesicles

31
Q

How does amphetamine affect noradrenaline (NA) levels?

A

Enters synaptic vesicles, displaces NA into cytoplasm, increases leakage of NA, elevating extracellular levels

32
Q

How does cocaine affect noradrenaline (NA) levels?

A

Blocks reuptake of NA, leading to increased levels in synaptic cleft, prolongs action and enhances effects on postsynaptic receptors

33
Q

What type of neurotransmitter is noradrenaline?

A

Monoamine

34
Q

What are the actions of noradrenaline on receptors?

A

Both inhibitory (acting on β receptors) and excitatory (acting on α and β receptors)

35
Q

How is noradrenaline terminated after release?

A

Neuronal uptake and degradation by monoamine oxidase (MAO)

36
Q

Where are the main cell bodies for noradrenergic neurons located?

A

Locus coeruleus

37
Q

During which state are noradrenergic neurons particularly active?

A

Wakefulness

38
Q

What effect do drugs like amphetamine have on noradrenaline activity?

A

Increase alertness and exploratory behavior

39
Q

In which brain regions does noradrenaline have a high density of receptors?

A

Brainstem, hypothalamus, medial temporal lobe

40
Q

What functions is noradrenaline involved in?

A

Arousal, wakefulness, exploration, mood regulation, blood pressure regulation, addiction, gambling behaviors

41
Q

What is the association between low levels of noradrenaline and depression?

A

Low levels of noradrenaline are associated with depression

42
Q

What type of neurotransmitter is dopamine?

A

Monoamine

43
Q

How does dopamine primarily affect central neurons?

A

By acting on potassium (K+) channels to inhibit them

44
Q

What are the two main families of dopamine receptors?

A

D1 receptors (including D1 and D5 subtypes) and D2 receptors (including D2, D3, and D4 subtypes)

45
Q

Where are D3 receptors primarily located?

A

In the limbic system, but not in the striatum

46
Q

How is dopamine neurotransmission terminated?

A

By degradation through the enzyme monoamine oxidase (MAO) and reuptake into presynaptic terminals

47
Q

Name two main pathways in the brain involving dopamine.

A

From the substantia nigra to the basal ganglia and from the midbrain to the limbic cortex

48
Q

What roles does dopamine play in physiological and behavioral functions?

A

Movement control, addiction, stereotypy, hormone regulation, vomiting

49
Q

What neurological disorder is associated with dysfunction in the dopamine system?

A

Parkinson’s disease

50
Q

What psychiatric disorder is associated with abnormalities in dopamine function?

A

Schizophrenia

51
Q

What type of neurotransmitter is serotonin (5-HT)?

A

Monoamine

52
Q

How many known subtypes of serotonin receptors are there?

A

14

53
Q

Which subtype of serotonin receptors is excitatory and found in the limbic system and cortex?

A

5-HT2 receptors, particularly 5-HT2A

54
Q

Where are 5-HT3 receptors located, and what are they associated with?

A

Located in the medulla and associated with vomiting

55
Q

What is the termination process for serotonin neurotransmission?

A

Degradation through the enzyme monoamine oxidase (MAO) and reuptake into presynaptic terminals

56
Q

Name three physiological and behavioral functions regulated by serotonin.

A

Mood regulation, psychosis, sleep-wake cycle

57
Q

What psychiatric disorder is associated with imbalances in serotonin levels?

A

Anxiety and depression

58
Q

Which serotonin receptor subtype is targeted by antipsychotic medications?

A

5-HT2A

59
Q

What role does serotonin play in pain pathways and migraine?

A

Inhibits pain pathways and can act synergistically with opioids to alleviate pain

60
Q

What are the main histamine receptor subtypes and their functions?

A

H1 receptors (involved in arousal) and H3 receptors (presynaptic, constitutively active)

61
Q

What are the functions of histamine in the central nervous system?

A

Regulation of sleep-wake cycles and involvement in vomiting

62
Q

Name two purines and their receptor subtypes.

A

Adenosine (acts on A1 and A2A/A2B receptors) and ATP (acts on P2X receptors)

63
Q

What are the functions of adenosine in the central nervous system?

A

Regulation of sleep, pain modulation, neuroprotection, addiction, seizures, anticonvulsant effects

64
Q

Name three types of opioid receptors and their functions.

A

μ, δ, and κ receptors. Functions include pain modulation.

65
Q

What neuropeptides act on tachykinin receptors, and what are their functions?

A

Substance P (acts on NK1 receptors), neurokinin A (acts on NK2 receptors), and neurokinin B (acts on NK3 receptors). Functions include modulation of pain pathways.

66
Q

What type of receptors do endocannabinoids act on, and what are their effects?

A

Endocannabinoids act on CB1 receptors, inhibiting GABA and glutamate release. They are involved in various functions such as vomiting, pain, anxiety, and weight loss.

67
Q

What are the receptor subtypes for melatonin, and what is its role?

A

MT1 and MT2 receptors. Melatonin is involved in regulating sleep and circadian rhythmicity.

68
Q

What are some clinical applications of melatonin agonists?

A

Melatonin agonists are used for jet lag and insomnia.