Okay, now we’re going to talk about receptors
and their partners: the agonist
and the antagonist.
So, those are 3 words—pause
for just a moment
and just kind of get straight in your mind.
Receptors are very uniquely shaped
and they either receive agonists
Let’s go through a little more definition.
Okay, so receptors are these really
unique protein molecules.
They receive only specific
so they have special shapes
and when they receive these signals,
it either blocks the activation
of that receptor
or it activates the reception.
Okay, so I know that I have receptors,
they’re really unique, only certain substances
will connect with them,
and either it’s an agonist which causes
that receptor to be activated,
or it’s an antagonist that will block
the activation of that.
So what types of things can be
agonists or antagonists?
Well, they can be drugs,
hormones, or neurotransmitters.
Obviously, we’re going to focus
more on drugs at this point,
but we’ll also talk a little bit about
hormones and transmitters.
Okay, so you understand what a receptor
is—it’s this special receiver.
Now, let’s go over agonists and
When an agonist connects, it’s like a
when an agonist connects or
binds to a receptor,
it activates that receptor to do
what it’s intended to do.
So, if I was trying to get into my house,
if I had the right key to my house, i
it would fit in the lock, it would be an
agonist, and it would unlock the door.
Now, if I had an antagonist, if I tried
to put the wrong key in the door,
it might fit, but it wouldn’t activate
that receptor or unlock the door.
So let’s use another example,
sometimes have you ever gotten an
advertisement from a car dealership
that they give you a key, and
says, “Hey! Bring this key
to the car dealership, and if it starts
the car, you win the car!”
Okay, yeah. I’ve never won a car
but that’s another thing.
So, let’s take a look at this.
Now, if you take a look at the
drawing that I have up here,
first of all, you see the receptor,
and see that it has a very unique opening.
Then you see all those other
keys floating around.
Those are agonists and antagonists,
but only certain ones are going to fit in.
Now, you see the agonist slide in.
See! It fits.
That’s a beautiful thing and it
will see the lightning bolts
that let you know that it
activates that receptor.
So that’s a really good thing.
You have a uniquely shaped receptor,
you have an agonist that connected,
bound to the receptor,
and then whatever that receptor is
intended to do, it will activate it.
Now, let me give you an example of
some receptors in your own body.
You have beta-1 receptors on your heart,
you have beta-2 receptors on your lung.
When an agonist hits the beta-1
receptors on your heart,
it pumps faster and harder.
When an agonist hits the beta-2
receptors on your lungs,
your lungs will bronchodilate.
Now, you need both of those responses
when adrenaline, or epinephrine,
is released in your body
because the sympathetic nervous
system is in gear.
So, that’s an agonist.
Now, let’s show you again what
happens with an antagonist.
You’ll see that we have the same receptor
(look, it’s got a similar shape),
but instead of an agonist binding
to the receptor,
you end up with an antagonist making it.
It still fits, still has a connection,
but you see like the good guy,
it can’t get in there
because the antagonist has blocked
the activation of that response.
Now, let’s go back to those beta receptors.
Remember I said that you had beta-1
receptors on your heart?
If a beta- adrenergic agonist,
or we call them beta-blocker, that’s a drug,
if we give the patient a drug, a beta-blocker
that acts just like it’s an antagonist.
So, the drug binds to the receptor,
so when epinephrine is released
into your body,
your heart rate will not go up
because there’s an antagonist blocking
the activation of that receptor.
Now, we use receptors,
agonists, and antagonists in all kinds
of treatment plans.
So, it’s really important that
you understand that.
So let’s keep talking about some
other types of drugs.
Now, we have natural agonist and
those are called endorphins.
They’re natural agonists that bind
to the opioid receptors.
Now, the opioid receptors are the feel-
good receptors of the body, right?
People swear to me that run that if
you can get a runner’s high,
if you can run long enough, but frankly,
I have never experienced a runner’s high.
Maybe I just haven’t ran long enough
to make that happen,
but when the natural agonists,
my natural endorphins connect
to my opioid receptors,
they produce pain relief and euphoria,
so you just feel good.
Now, one of our patient’s, if they
are experiencing pain,
we want to give them an agonist drug.
Hey! That’s really cool.
So, the agonist drug, morphine,
acts just like the natural substance
in my body endorphins
because in an agonist drug
like morphine also binds
to opioid receptors.
So, how am I going to feel?
Pain relief and euphoria. That’s really cool
because agonist drugs are similar enough,
the drugs that we’ve created
are similar enough,
to the natural endorphins in my body that
they will bind to the same receptors.
That, is a really cool thought.
So, let that sink in a little bit
because that’s all of what we
do in pharmacology.
We take things that normally
occur in your body
and we create a substance that,
in a way to get the effect that we want.
So, you end up with the same,
or even a little better reaction
of that pain relief and euphoria
when we give you morphine.
So, let’s talk about the reverse agonists.
Now, earlier we talked about beta-blockers,
so I want you to compare that same example
with the same drug morphine.
So, we already talked about morphine—
it’s an agonist drug that binds to
opioid receptors, right?
Agonist drugs are similar enough that
they fit and they connect,
and they produce that same or
even stronger euphoria,
but we have drugs that can
act as antagonists.
So, remember we talked about affinity,
in the beginning of the video?
Now, when I have a drug like morphine
that’s bound to those opioid receptors,
what if the patient’s received too much?
They’ve got too much morphine.
Well, it’s a respiratory depressant,
this could put the patient
in a lot of trouble.
So, we want to boom!
We want to knock that morphine
off those receptors.
What do we do?
Well, we can use a special
kind of antagonist.
We call it naloxone or Narcan.
You may have actually seen this in the news
where they’ve put it in a nose spray now
where police officers are using this
if they come against someone who
has an opioid overdose
or if you are someone who is around
people who have an addiction problems, this
is a good thing for you to have with you.
But naloxone, or Narcan, is an antagonist
to opioid receptors,
so that means it will bind to the receptor
and then morphine can no longer
bind to that receptor.
It will exactly reverse morphine or even
a heroin overdose in seconds.
Now, I have seen this happen. It is dramatic.
When you have someone that comes
in, and they’re in an opioid overdose,
and we give them Narcan—usually in the
ER, it would be, obviously, in an IV dose,
but you give them this and boom!
They wake back up, so it is
a really fast, fast reaction.
Not all antagonists are that dramatic,
but that’s a good example for you
to understand the concept
of antagonists when we do that.