PSYC20006 Lecture Notes - Lecture 22: Central Nervous System, Muscarinic Acetylcholine Receptor, Metabotropic Receptor
12 Jun 2018
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Lecture 22 - Tuesday 23 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
LECTURE 22
ACETYLCHOLINE: MEMORY & ALZHEIMER’S DISEASE
TODAY
ACETYLCHOLINE (ACh)
CENTRAL & PERIPHERAL
•Acetylcholine is a major
neurotransmitter of the Central
Nervous System (CNS) and
Peripheral Nervous System (PNS).
ACETYLCHOLINE
SYNTHESIS
•Acetylecholine is made from
choline (derived from the
breakdown of lipids) + acetate
(sometimes called acetic acids).
•Don’t need to
remember the
diagram.
ACETYLCHOLINE RECEPTORS
•Two types ACh Receptors – Ionotropic (Ion Channel) & metabotropic (G-protein coupled)
receptors .
•The ionotropic receptor - stimulated by nicotine so is called Nicotinic Receptor
•In the PNS - muscle fibers must be able to contract rapidly so they contain rapid, ionotropic
nicotinic receptors.
•The metabotropic receptor - stimulated by muscarine (found in the poison mushroom Amanita
muscaria) so is called the Muscarinic receptor.
•In the CNS - both nicotinic and muscarinic receptors exist but muscarinic receptors
predominate.
ACh IN THE PERIPHERY
•In peripheral nervous
system ACh is the
primary
neurotransmitter that
acts on nicotinic
receptors at the
neuromuscular !
Lecture 22 - Tuesday 23 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
!
junction.
•Ach transmits signal from the motor neuron and causes muscle to contract >> controlling
muscular movement.
•Limb movement driven by contraction and relaxation of
muscles.
ACh DRUGS IN THE PERIPHERY
•Botulinium toxin is produced by bacteria that
grows in canned food (most acutely lethal toxin
known). Causes death by paralyzing respiratory
muscles.
•Prevents the release of ACh.
•1. Synthesis
•2. Release from synaptic vesicles
•3. Binds to receptors
•4. +/- influence on post synaptic neuron
•5. Broken down by enzymes
•6. Reuptake of transmitter
•7. Formation & storage in synaptic
vesicles
•Botox is a VERY dilute solution of botulinum
toxin injected directly into muscles. Causes muscle weakening for 3-6 months!
•Can be used cosmetically to relax facial muscles (reducing wrinkles)
•Can treat spasticity (muscle tightening) in cerebral palsy (non- specific brain damage)
•The venom of the black widow spider causes death by heart attack (very rarely).
•Triggers/Stimulates the release of ACh.
•1. Synthesis
•2. Release from synaptic vesicles
•3. Binds to receptors
•4. +/- influence on post synaptic neuron
•5. Broken down by enzymes
•6. Reuptake of transmitter
•7. Formation & storage in synaptic vesicles
•Together botulinium toxin & Black Widow venom show that too much or too little both have
catastrophic consequences. A balance is required.
ACh IN THE BRAIN
•Effects of ACh in brain are generally
facilitatory (promoting neural firing)
•Different structure than other systems
(Eg. Serotonin with 1 nuclei), ACh
has multiple nuclei.
ALZHEIMER’S
DISEASE
•Systems involved
in memory
formation are
heavily implicated
in the development of alzheimer’s
disease.
