Opioids and the Brain's Receptors
Opioids
NORTHEAST SOCIETY OF TOXICOLOGY
OCTOBER 20, 2017
JOSHUA GRAY – U.S. COAST GUARD ACADEMY
LARISSA WILLIAMS – BATES COLLEGE
photograph by Elizabeth Roy, distributed under a
CC-BY-SA 3.0 license.
History of Opium
Opium is an extract of poppy seeds which reduces pain and also
produces euphoria.
Morphine, named after the god Morpheus, is the most active
ingredient of opium.
Heroin was synthesized chemically by morphine diacetylation in the
late 1800s and was marketed as a non-addictive opiate to treat
cough and asthma. Later, it was recognized that heroin was in fact
addictive, and heroin and opium were both prohibited in 1910.
In the 1970s, it was discovered that there are particular receptors in
the brain to which morphine and heroin bind
Public domain photograph by
KGM007
photograph by Sumita Roy
Dutta, distributed under a CC-
BY-SA 4.0 license.
Vicodin and other oral opioid
medicines
Hydrocodone – semisynthetic opioid
Vicodin – combination hydrocodone and acetaminophen
Oxycodone – semisynthetic opioid
oxycodone
hydrocodone
codeine
Opioid Epidemic slide
Deaths due to all types of opioids
are rising
Fentanyl and other synthetic
opioids are rapidly becoming a
major cause of opioid deaths
Source: Centers for Disease Control
https://www.cdc.gov/mmwr/preview/
mmwrhtml/mm6450a3.htm
Why does the brain have opioid
receptors?
INSTRUCTIONS: DISCUSS WITH OTHERS WHY YOU THINK THE BRAIN HAS
RECEPTORS FOR OPIOIDS.
What kinds of behaviors do humans
do that are associated with
pleasure?
Emotions have evolved that encourage animals to engage in
behaviors with a beneficial outcome and avoid behaviors that
could reduce their chance of survival.
Positive emotions like pleasure, hedonism, or reward, when
associated with the ability to learn from experience, increase the
probability of the occurrence of a particular behavior, called
positive reinforcement.
Heroin causes a sense of pleasure,
or euphoria. What kinds of
behaviors are positively reinforced
by taking heroin?
photograph by Steve pb, distributed
under a CC0-1.0 Universal Public Domain
license.
Why do opioid users need to
escalate their dose? What
biochemical mechanism might be
playing a part?
Typically with opioid addiction, the patient escalates their dose over
time, such that a higher dose is required to achieve the same
degree of euphoria.
In order for opioids to
function, they must get to
the brain where they bind
to a receptor on the target
of the cell.
Hypothesize some ways in
which the cell might
become less sensitive to
opioids over time
When the receptor is bound
to an opioid, it activates a
signaling pathway inside
the cell, represented by a
star.
The number of receptors
bound to an opioid
molecule depends on the
amount of opioids present.
At the K
M
value, half of all of
the receptors will be bound.
Some cells require a certain
number of bound receptors
to initiate a response. This is
called a threshold
The threshold in this
example is 5.
If 5 or more receptors have
opioid bound, a positive
signal occurs
If less than 5 receptors have
opioid bound, no signal
occurs.
What happens to the
number of bound
receptors if the
concentration of opioids
changes?
The number of receptors
bound to an opioid
molecule depends on the
amount of opioids present.
At the K
M
value, half of all of
the receptors will be bound.
Some cells require a certain
number of bound receptors
to initiate a response. This is
called a threshold
The threshold in this
example is 5.
If 5 or more receptors have
opioid bound, a positive
signal occurs
If less than 5 receptors have
opioid bound, no signal
occurs.
What happens if the
number of receptors
expressed on the cell
surface drops?
To achieve the same level
of activation, what has to
happen in this case?
The magnitude of the
response is shown by the
size of the yellow star.
What happens if the cell
adapts to higher
receptor activation by
have a lower response?
Normal response
Weakened response
How would you, as a scientist,
design a drug that would help with
opioid addiction and withdrawal?
Nalaxone is a drug that
binds to the receptor but
does not activate it.
Nalaxone is indicated by a
purple circle.
What happens when
naloxone is added by
itself?
Nalaxone is a drug that
binds to the receptor but
does not activate it.
Nalaxone is indicated by a
purple circle.
Nalaxone is commonly
given to people who have
overdosed and are
comatose.
What happens when
heroin and naloxone
are administered at
the same time?
Buprenorphene is a drug
that binds to the receptor
with higher affinity but only
partially activates the
receptor . It is indicated by
a green circle.
What happens when
buprenorphine is
added?
The magnitude of the
response is shown by the
size of the yellow star.
Normal response
Weakened response
Buprenorphine is used as
an anti-opioid drug.
What happens when
heroin and
buprenorphine are
taken at the same time?
The magnitude of the
response is shown by the
size of the yellow star.
Normal response
Weakened response
References and resources for more
information
http://www.pbs.org/newshour/updates/brain-gets-hooked-opioids/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2711509/
Acknowledgements
All images used in this powerpoint are licensed under a Creative
Commons license or are in the Public Domain unless otherwise
noted.
Images were found on the Wikimedia Commons
This PowerPoint was created by Joshua Gray of the U.S. Coast
Guard Academy and Larissa Williams of Bates College.
Additional Reference Slides
Chemical structures of synthetic
opioids
photograph by V. Höllt and C. Allgaier, distributed under a CC BY-SA 3.0 license.
Opioids have a complex history, with substances like opium, morphine, and heroin playing significant roles. The opioid epidemic has highlighted the dangers associated with these drugs, including rising deaths due to fentanyl and synthetic opioids. Questions arise about why the brain has opioid receptors and how behaviors related to pleasure and positive reinforcement are connected to opioid use. Exploring these topics sheds light on the underlying mechanisms driving opioid addiction.
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Presentation Transcript
Opioids NORTHEAST SOCIETY OF TOXICOLOGY OCTOBER 20, 2017 JOSHUA GRAY U.S. COAST GUARD ACADEMY LARISSA WILLIAMS BATES COLLEGE photograph by Elizabeth Roy, distributed under a CC-BY-SA 3.0 license.
History of Opium photograph by Sumita Roy Dutta, distributed under a CC- BY-SA 4.0 license. Public domain photograph by KGM007 Opium is an extract of poppy seeds which reduces pain and also produces euphoria. Morphine, named after the god Morpheus, is the most active ingredient of opium. Heroin was synthesized chemically by morphine diacetylation in the late 1800s and was marketed as a non-addictive opiate to treat cough and asthma. Later, it was recognized that heroin was in fact addictive, and heroin and opium were both prohibited in 1910. In the 1970s, it was discovered that there are particular receptors in the brain to which morphine and heroin bind
Vicodin and other oral opioid medicines Hydrocodone semisynthetic opioid Vicodin combination hydrocodone and acetaminophen Oxycodone semisynthetic opioid oxycodone codeine hydrocodone
Opioid Epidemic slide Deaths due to all types of opioids are rising Fentanyl and other synthetic opioids are rapidly becoming a major cause of opioid deaths Source: Centers for Disease Control https://www.cdc.gov/mmwr/preview/ mmwrhtml/mm6450a3.htm
Why does the brain have opioid receptors? INSTRUCTIONS: DISCUSS WITH OTHERS WHY YOU THINK THE BRAIN HAS RECEPTORS FOR OPIOIDS.
What kinds of behaviors do humans do that are associated with pleasure? Emotions have evolved that encourage animals to engage in behaviors with a beneficial outcome and avoid behaviors that could reduce their chance of survival. Positive emotions like pleasure, hedonism, or reward, when associated with the ability to learn from experience, increase the probability of the occurrence of a particular behavior, called positive reinforcement.
Heroin causes a sense of pleasure, or euphoria. What kinds of behaviors are positively reinforced by taking heroin? photograph by Steve pb, distributed under a CC0-1.0 Universal Public Domain license.
Why do opioid users need to escalate their dose? What biochemical mechanism might be playing a part? Typically with opioid addiction, the patient escalates their dose over time, such that a higher dose is required to achieve the same degree of euphoria.
In order for opioids to function, they must get to the brain where they bind to a receptor on the target of the cell. Hypothesize some ways in which the cell might become less sensitive to opioids over time
When the receptor is bound to an opioid, it activates a signaling pathway inside the cell, represented by a star.
What happens to the number of bound receptors if the concentration of opioids changes? The threshold in this example is 5. If 5 or more receptors have opioid bound, a positive signal occurs The number of receptors bound to an opioid molecule depends on the amount of opioids present. At the KM value, half of all of the receptors will be bound. If less than 5 receptors have opioid bound, no signal occurs. Some cells require a certain number of bound receptors to initiate a response. This is called a threshold
What happens if the number of receptors expressed on the cell surface drops? The threshold in this example is 5. If 5 or more receptors have opioid bound, a positive signal occurs The number of receptors bound to an opioid molecule depends on the amount of opioids present. At the KM value, half of all of the receptors will be bound. If less than 5 receptors have opioid bound, no signal occurs. Some cells require a certain number of bound receptors to initiate a response. This is called a threshold
What happens if the cell adapts to higher receptor activation by have a lower response? The magnitude of the response is shown by the size of the yellow star. To achieve the same level of activation, what has to happen in this case? Normal response Weakened response
How would you, as a scientist, design a drug that would help with opioid addiction and withdrawal?
What happens when naloxone is added by itself? Nalaxone is a drug that binds to the receptor but does not activate it. Nalaxone is indicated by a purple circle.
What happens when heroin and naloxone are administered at the same time? Nalaxone is a drug that binds to the receptor but does not activate it. Nalaxone is indicated by a purple circle. Nalaxone is commonly given to people who have overdosed and are comatose.
What happens when buprenorphine is added? Buprenorphene is a drug that binds to the receptor with higher affinity but only partially activates the receptor . It is indicated by a green circle. The magnitude of the response is shown by the size of the yellow star. Normal response Weakened response
Buprenorphine is used as an anti-opioid drug. What happens when heroin and buprenorphine are taken at the same time? The magnitude of the response is shown by the size of the yellow star. Normal response Weakened response
References and resources for more information http://www.pbs.org/newshour/updates/brain-gets-hooked-opioids/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2711509/
Acknowledgements All images used in this powerpoint are licensed under a Creative Commons license or are in the Public Domain unless otherwise noted. Images were found on the Wikimedia Commons This PowerPoint was created by Joshua Gray of the U.S. Coast Guard Academy and Larissa Williams of Bates College.
Chemical structures of synthetic opioids photograph by V. H llt and C. Allgaier, distributed under a CC BY-SA 3.0 license.
