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Neuroscience > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

What are the 3 classes of neurotransmitters?

A

Amino cids, amines, and peptides

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2
Q

What is Dale’s principle?

A

A neuron has only one neurotransmitter

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3
Q

What are co-transmitters:

A

2 or more transmitters released from one nerve terminal
Ex: an amino acid or amine + a peptide

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4
Q

What are examples of nomenclatures (-ergic)?

A
  • Cholinergic, noradrenergic, GABAergic, glutamatergic
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5
Q

How do we define particular transmitter systems?

A

By the molecule, synthetic machinery, packaging, reuptake and degradation, and action

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6
Q

What are the 3 scientific study criteria for establishing a neurotransmitter?

A
  1. Synthesis and storage in presynaptic neuron
  2. Released by presynaptic axon terminal
  3. When applied, mimics postsynaptic cell response produced by release of neurotransmitter from the presynaptic neuron
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7
Q

What occurs in situ hybridization?

A

Localizing synthesis of protein or peptide to a cell (detect mRNA)

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8
Q

What is the purpose of immunocytochemistry?

A

Localize molecules to cells

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9
Q

When studying synaptic mimicry, what is the qualifying condition?

A

Molecules evokes same response as as the neurotransmitter

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10
Q

What is microiontophoresis?

A

A technique in which drugs can be ejected in very small amounts to assess postsynaptic actions

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11
Q

What is the function of the microelectrode?

A

It measures effects on membrane potential

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12
Q

What are the receptor proteins present in molecular analysis?

A
  1. Transmitter-gated ion channels (ionotropic receptors)
    - GABA(a) receptors
    - 4-5 subunits, each made with various combinations of subunit polypeptides
  2. G-protein-coupled receptors (metabotropic receptors)
    - GABA(b) receptors
    - 7-transmembrane signaling molecules
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13
Q

What is the purpose and function of acetylcholine (ACh)?

A
  • ACh was the first identified neurotransmitter
  • Major neurotransmitter at vertebrate neuromuscular junctions
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14
Q

What is the purpose and function of cholinergic (ACh) neurons?

A
  • ACh synthesis requires Choline acetyltransferase (ChAT) enzyme
  • ACh degradation mediated by acetycholinesterase (AChE)
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15
Q

What is the function of catecholaminergic neurons?

A

They are involved in movement, mood, attention, and visceral function

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16
Q

What is tyrosine?

A

Tyrosine is the precursor for three amine neurotransmitters that contain catechol group
- Dopamine
- Norepinephrine
- Epinephrine (adrenaline)

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17
Q

What enzymes are involved in catecholaminergic?

A
  • Tyrosine hydroxylase (TH)
  • Dopa decarboxylase
  • Dopamine B-hydroxylase (DBH)
  • Phentolamine N-methyltransferase (PNMT)
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18
Q

What are serotonergic (5-HT) neurons?

A

They are amine neurotransmitters, derived from tryptophan
- Regulate mood, emotional behavior, and sleep; selective serotonin reuptake inhibitors (SSRIs) - antidepressants
- Synthesis of serotonin; 2-step synthesis from tryptophan; enzymes: tryptophan hydroxylase, 5-HTP decarboxylase

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19
Q

What are some amino acidergic neurons?

A
  1. Glutamate, glycine, GABA
    - Glutamate- major excitatory CNS neurotransmitter
    - GABA- majority inhibitory CNS neurotransmitter
  2. Glutamic acid decarboxylase (GAD)
    - Key enzyme in GABA synthesis
    - Good marker for GABAergic neurons
    - GABAergic neurons are major source of synaptic inhibition in the CNS
20
Q

What transporters are required to allow GABA and Glutamate to load synaptic vesicles?

A
  • Vesicular GABA transporter (vGAT)
  • Vesicular glutamate transporter (vGlut)
21
Q

What receptors does neuropharmacological analysis consist of?

A
  • Agonists and antagonists
  • ACh receptors (nicotinic, muscarinic)
  • Glutamate receptors (AMPA, NMDA, and kainate)
22
Q

What are the functions of neurotransmitter-gated ion channels?

A
  • Fast synaptic transmission
  • Turn chemical signal into an electrical signal
  • Ion selective
23
Q

What is the structure of transmitter-gated ion channels?

A
  • Tetramer: 4 protein subunits form a pore
  • Pentamer: 5 protein subunits form a pore
    Ex: a nicotinic ACh receptor at neuromuscular junction (pentamer)
24
Q

What is the composition of amino acid (glutamate) -gated channels?

A
  • AMPA NMDA, kainate receptors
  • AMPA receptors permeable to Na+ and K+
  • NMDA receptors permeable to Na+, K+, and Ca2+
25
Q

What are the functions of voltage dependent NMDA channels?

A
  • They require glutamate binding AND membrane depolarization to open channel
  • Blocked by Mg2+ ions at negative resting membrane potentials
  • Removal of Mg2+ block accomplished by membrane depolarization
26
Q

What occurs in GABA-gated and glycine-gated channels?

A
  • GABA mediates most synaptic inhibition in CNS
  • Glycine mediates non-GABA synaptic inhibition
  • Bind ethanol, benzodiazepines, barbiturates
27
Q

Endocannabinoids are…

A
  • An example of another neurotransmitter system
  • Retrograde messengers
  • Act on presynaptic G-protein coupled receptor cannabinoid receptors
28
Q

What falls under “sensory perception” family?

A
  • Visual transduction (Rhodopsin)
  • Olfactory receptors (OR)
  • Taste (TAS)
29
Q

What falls under the “neuromodulation” family?

A
  • Glutamate (mGluR1-8)
  • GABA (GABAb)
  • Acetylcholine (M1-5)
  • Dopamine (D1-5)
  • Opioids (MOR, etc.)
  • Endocannabinoid (CB1-2)
30
Q

What falls under the “development/migration” family?

A
  • Chemokines (CXCL)
  • Frizzled (FZD1-10)
31
Q

What falls under the “cellular adhesion” family?

A
  • CELSR
  • Latrophilins
  • BAI
32
Q

What is the structure of G-protein coupled receptors (GPCRs)>

A

A single polypeptide with 7 membrane spanning alpha-helices

33
Q

What are the 3 steps in transmission for GPCRs?

A
  • Binding of the neurotransmitter to the receptor protein
  • Activation of G-proteins
  • Activation of effector systems
34
Q

What are the steps for GPCR signaling?

A
  1. Inactive: 3 G-protein subunits (alpha, beta, gamma)
  2. Active: G-protein complex activated by receptor and exchanges GDP for GTP
  3. Galpha-GTP and Gby dissociated from each other - now free to influence effector proteins
  4. Galpha inactivates by hydrolysis of GTP and GDP
  5. Galpha and Gby recombine to start the cycle again
35
Q

What is the “shortcut” pathway?

A

From receptor->G-protein->ion channel
- Fast and localized

36
Q

What is the second messenger cascade pathway?

A

The G-protein couples with neurotransmitter with downstream enzyme activation

37
Q

WHat is push-pull singaling?

A

Different G-proteins stimulate or inhibit adenylyl cyclase
- Gi: adenylyl cyclase inhibitory Galpha protein
- Gs: adenylyl cyclase stimulatory Galpha protein

38
Q

Some signaling cascades branch

A

Ex: G-protein activation of phospholipase C (PLC) -> lipas that hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2), generating diacylglycerol (DAG) and inositol 1,3,5-triphosphate (IP3)-> activate different effectors
- IP2 binding t IP3 receptors at the ER to release calcium stores
- DAG helps activate protein kinase C

39
Q

G-protein-coupled receptors signaling cascades lead to…

A

Powerful signal amplification

40
Q

Phosphorylation and dephosphorylation regulation of target proteins are a common molecular mechanism

A
  • Phosphate groups added to/or removed from a protein
  • Changes conformation and biological activity
41
Q

What is divergence?

A

When one transmitter activates more than one receptor subtype
- Greater postsynaptic response

42
Q

What is convergence?

A

When different transmitters converge to affect the same effector system

43
Q

What form of neurotransmitter signaling is occuring?

A

Integrative divergence and convergence

44
Q

In summary, what is the purpose of neurotransmitters?

A
  • They transmit information between neurons
  • Essential link between neurons and effector cells (i.e the neuromuscular junction)
45
Q

In summary, what is the purpose of signaling pathways?

A
  • Signaling network within a neuron somewhat resembles brain’s neural network
  • Inputs vary temporally and spatially to increase and/or decrease drive
  • Delicately balanced
  • Drugs can shift signaling power and balance

Neuroscience (8 decks)

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