Neurotransmitters: Catecholamines

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NeurotransmittersCatecholamines
AcetylcholineChapters 5 6

• Catecholamines
• Dopamine
• Norepinephrine
• Epinephrine
• Acetylcholine
• Serotonin
• Glutamate
• GABA

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Neurotransmitter Families
Neurotransmitters
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Structural features of catecholamines
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Synthesis of Catecholamines
rate-limiting enzyme
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CatecholeminesSome adjectives

• Dopamine (DA)
• dopaminergic
• Norepinephrine (NE)
• noradrenergic
• Epinephrine (EPI)
• adrenergic

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Storage of Catecholaminesvesicular monoamine
transporter protein (VMAT2)
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Behavioral effects of reserpine
http//home.caregroup.org/clinical/altmed/interact
ions/Images/Herbs/rauwolfi.gif
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Dopamine Systems in the Brain

• Mesolimbic pathway
• Reinforcement
• Mesocortical pathway
• Planning
• Nigrostriatal pathway
• Movement

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Parkinsons Disease Damage to the substantia
nigra
http//www.urmc.rochester.edu/neuroslides/slides/s
lide199.jpg
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Causes of Parkinsons Disease

• Degeneration of substantia nigra
• Less dopaminergic activity in basal ganglia
• Discovery of MPPP ? MPTP and MPP

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A typical dopaminergic neuron
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D1 and D2 receptors
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Norepinephrine
http//homepage.psy.utexas.edu/homepage/class/Psy3
01/Salinas/sec2/Brain/31.GIF
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Role of the locus coeruleus in vigilance
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Functions of Acetylcholine (ACh)

• Neuromuscular junction (movement)
• Central nervous system (learning and memory)

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Acetylcholine Receptors

• Nicotinic receptors
• Neuromuscular junctions
• Ionotropic (ion channel)
• Curare works on these receptors
• Muscarinic receptors
• Metatropic (second messengers)
• Hippocampus, striatum
• Morphine
• Also located in heart and smooth muscles
• Nightshade

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Serotonin (5-HT)

• Mood
• Appetite
• Sleep

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Features of a serotonergic neuron
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Glutamate

• Is an amino acid
• Made from breakdown of glucose
• Used for
• Making other proteins
• Metabolism (energy)
• Excitatory neurotransmitter

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Glutamate

• Excitotoxicity
• Excessive exposure to glutamate which leads to
  cell damage or cell death
• Examples
• Domoic acid
• Strokes

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GABA

• GABA is the major inhibitory neurotransmitter of
  the central nervous system.
• The GABAA receptor interacts with a number of
  drugs.

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Why is Inhibition Important?

• Tetanospasmin (tetanus toxin) hitches a ride to
  the central nervous system from a wound site
  using the retrograde transport system within
  axons.
• The toxin binds to receptor sites for
  gamma-aminobutyric acid (GABA), and cant be
  dislodged.
• Without normal inhibitory input from GABA,
  muscles begin to go into sudden, involuntary
  contractions, or spasms.