PSYC20006 Lecture Notes - Lecture 18: Nitric Oxide, Axon Terminal, Opioid Receptor
12 Jun 2018
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Lecture 18 - Tuesday 9 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
LECTURE 18
PEPTIDES, LIPIDS, NUCLEOTIDES & GASSES
TODAY
•Peptides > Opioids
•Lipids > Endocannabinoids
•Nucleosides > Adenosine
•Gasses > Nitric Oxide
NON TRADITIONAL NEUROTRANSMITTERS
•Non traditional NTs DO NOT satisfy ALL criteria for a Neurotransmitter:
•Present in presynaptic terminals
•Released from presynaptic terminals after neuron fires
•Existence of receptors on postsynaptic neurons
PEPTIDES
•Peptides consist of 2 or more amino acids
•(note proteins also consist of amino acids but are normally
much larger with many more amino acids, Some amino
acids are produced in the body others need to be eaten -
these are the essential amino acids)
•Called peptides because they have peptide bonds.
•In the brain most peptides are NOT synthesized from
smaller compounds but are the product of larger
compounds (poly-peptides) being broken down into
peptides within the neuron before release at the terminal
button. This is different to most NTs.
•Most peptides serve as modulators, however many peptides
known to be hormones also act as neurotransmitters and are often co-release with other
neurotransmitters.
•This is a good example of the same compound having multiple roles and different functions in
different contexts or brain regions!
OPIOIDS
•Best known family of peptide neurotransmitters are the endogenous opioids
•Endogenous Opioids = “originating internally” +“like opium”
•Opiates = drugs such as morphine, heroin and opium
Lecture 18 - Tuesday 9 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
•3 types of opioid receptors.
•One type of opiate receptor the Mu (μ) receptor is
associated with Analgesia, euphoria, sedation,
constipation, addiction and hormonal changes
•In the brain the highest density of opiate receptors
are in areas involved in pain.
OPIATE DRUGS
•Opiates are most known for their analgesic (pain relief) and euphoric properties.
•Heroin doesn’t influence your brain; you can die because it sedates you but your
brain looks completely normal.
•Heroin is highly addictive - not particularly neurotoxic – but can cause death by
respiratory failure. Can destroy your life (or lifestyle) without destroying your
brain!!
•Buprenorphine is a partial agonist at the
receptors used as a treatment for heroin
dependence.
•Naloxone is a full antagonist and can be
used to rapidly block the effect of heroin
and prevent overdose.
•Methadone is also an agonist (like Heroin)
and is used in treatment of dependence
because it has a much slower time course
than Heroin.
LIPIDS
STRUCTURE
•Naturally occurring molecules that include
fats, waxes and many others .... They are
hydrophobic = “Water Fear”
•Main biological function is energy storage,
signaling and provide the structural
components of the cell membranes
•Synthesis pathways remain unclear for
many lipids that serve as
neurotransmitters/modulators
•Function as a structural component for
energy storage.
•Some can act as signalling pathways
ENDOCANNABINOIDS
•In the brain the best known lipid neurotransmitters are the endocannabinoids
(“endogenous cannabis-like substances”).
•2 known cannabinoid receptors CB1 & CB2 - Both are G-protein receptors.
•CB1 is found in the brain and is believed to be responsible for
the main psychological effects (CB2 is found in peripheral
tissue).
•CB1 receptors found on terminal buttons of Neurons that
release most of the major neurotransmitters/modulators.
•CB1 receptor activation >> shortens the duration of action
potentials in the presynaptic neuron >> decreasing amount of
neurotransmitter released
Document Summary
Today: peptides > opioids, lipids > endocannabinoids, nucleosides > adenosine, gasses > nitric oxide. Non traditional neurotransmitters: non traditional nts do not satisfy all criteria for a neurotransmitter, present in presynaptic terminals, released from presynaptic terminals after neuron fires, existence of receptors on postsynaptic neurons. Opioids: best known family of peptide neurotransmitters are the endogenous opioids, endogenous opioids = originating internally + like opium , opiates = drugs such as morphine, heroin and opium. Structure: naturally occurring molecules that include fats, waxes and many others Psyc20006 - biological psychology: by regulating the activity of those neurons and release of neuromodulators these receptors act to modulate the modulators!! Cannabis/marijuana: thc (tetrahydrocannabinol) is the active compound in marijuana. The plant is dried and consumed by inhalation: effects range from changes in appetite, time perception, arousal (relaxation/anxiety) and have also been linked to states of apathy and.
