Capstone- Turnquist

How do S S R I S affect serotonin?

We'll be looking at the background of S S R I S and the neurotransmitter, serotonin.

Also look at the big debate between if low

levels of serotonin actually relate to uh depression.

Next, we'll look at neurotransmitters.

And last,

we'll look at the effect of serotonin

on chemistry and how structure impacts function.

So once again,

we'll first be starting by looking at the background and

overview of S S R I S starting with serotonin.

Serotonin is a mono

neurotransmitter which is driven from the amino

acid crypto.

Uh Its chemical formula is C 10 H 12 N 20.

And on the right side of the screen, we can see the

uh molecular structure

of that. Um

neurotransmitter,

it modulates multiple psychiatric and gastro

intestinal problems and it's produced in neurons located

in the midline of the brain stem.

So the big question, how do S S R I S affect serotonin?

Normally, serotonin is reabsorbed by the presynaptic neuron,

but the S S R I S block that

reuptake.

So more serotonin is available to pass

further messages to the post synaptic neuron.

As we can see in this image,

this is a zoomed in picture of two neurons uh talking to each other.

On the left, we have the presynaptic neuron.

And you can see those vesicles carrying neurotransmitters. In our case, serotonin

into that gap, which is the synaptic left

to reach the post synaptic neuron.

As on the postsynaptic neurons,

we can see some purple hot dog looking shapes which

are the receptors where the neurotransmitters are trying to reach.

So we can reach that next uh neuron and communicate the signal versus on the left,

we have um some blue hotdog shaped structures

which are where the neurotransmitters are reuptake.

So, serotonin of er yeah, serotonin affects the reuptake of the neurotransmitter.

Now we'll look at mental health.

I thought this was really interesting when I was researching the topic.

Originally,

as there are studies that argue if there is actually

a link between low serotonin and depression or anxiety disorders,

I feel like lots of times.

Um you hear about people having low serotonin that

just means that they have depression or taking um

different pills such as solo

can help bring up that serotonin.

I thought it was really interesting that this

is such a debate in the medical community.

So,

serotonin reuptake inhibitors are widely used

antidepressants used to treat depression,

O CD generalized anxiety disorder, post traumatic stress disorder,

severe phobias.

And the list continues.

Uh there is an intense debate between whether or not

lower low serotonin levels are actually connected with depression.

Some feel that the idea is used to make money in the

pharmaceutical companies and allow doctors to throw money at a larger problem.

Additionally,

the medicine could induce a placebo effect or lead to drug dependency.

So this goes back to doing blind tests and whatnot and seeing if that plus if that

drug actually helps and actually raises the serotonin

levels or if it's actually just the placebo effect

and the people taking it feel like they're doing better, feel like in a better mood,

but it's actually all in their head and it's just the placebo

on the flip side.

Another study showed that patients with major depressive disorder or depression,

um had a reduced serotonin response after being given a dose of

a, a

amphetamine.

So they were given a dose of amphetamine and then their

brain was scanned in either an MRI machine or AC machine.

And we could see

that

they had a reduced serotonin response.

Um But both of these studies need to be continued, researched,

conducted again until there's actual feasible evidence.

And until there's more because both of these

topics have just reached the surface on.

Is there actually a connection

right? Now, we look at neurotransmitters.

So a neurotransmitter is a chemical messenger

that carries signals between nerve cells.

So, as we talked about earlier, there's that synaptic clip,

the presynaptic neuron,

the post synaptic neuron and an action potential that is sent to communicate

So

um a little bit like more about neurons,

neurons are super important as they communicate messages all over our bodies.

There are action potentials that are used to

our muscles to contract, to signal our

legs to move. They're extremely important.

So how an action potential works is that neurons

send information down its axon to the terminal end.

So to that postsynaptic

or the pre synaptic cleft,

which creates a depolarizing current as the signal travels

as if it was an electricity down a wire,

the message must pass through the synaptic cleft to get to the next.

So it has to go in that space which is done by the neurotransmitter.

Um The ash potential is terminated through re reuptake by presynaptic neuron

and enzymatic Degra

within the synaptic cleft.

I know these can be really,

really hard to understand and an easier way to think about it

is with the game of telephone that you probably played in,

say your elementary school classroom.

So someone starts with a message and whispers it from

person to person until it gets to the final person.

And they try to save the message.

A chemical messenger works a lot like that

where somebody starts with the message and they're

sending it from neuron to neuron to neuron trying to get that message from your brain

to the location.

So I think that's a really,

really easy way to think about it

and helps you understand this big biological concept

So next, we have human serotonin transporter or HSE RT.

Uh HSE RT holds the instructions to making

a serotonin transporter which is responsible for the

reuptake.

So that's gonna be on the presynaptic neuron.

As we can see in the photo to our right five H T is also known as serotonin

and we can see it in those vesicles as it's trying to get to the post synaptic neuron.

Um It's hanging out in that synaptic clip and

then going back to the purple hotdog shaped transporter,

sending it back into the cell or into the neuron.

Sorry.

Um Some people work, some people's um

H C

works too quickly and may reabsorb all that serotonin

before the post synaptic neuron has read the message

S S R I S block the reuptake of the serotonin,

which therefore leaves the serotonin in the synaptic cleft for longer,

thereby increasing the chances for the postsynaptic neuron to get the message.

Once again, going back to our telephone example, for instance,

say that you have somebody who's whispering when

trying to get the message to the next person

that's not gonna be a very effective way

and that person at the end might not understand the message completely.

So

in that instance,

you'd have the person's screen so then the message can be transferred.

So for here, say someone is not their,

their um H is working too quickly and that uh serotonin

is being reabsorbed before the postsynaptic nerve can read the message

with a serotonin

that would therefore slow, that

slow that re resorption, just like addic, making someone yell.

And therefore the message is received more clearly in the postsynaptic neuron.

So, lastly, we'll touch upon chemistry and how does chemistry shape our world.

Uh First,

we'll talk about the very important relationship between structure and function.

Uh The drugs prevent serotonin reuptake by occupying the central substrate

site and stabilizes the transporter in an outward opening confrontation.

Just here,

we can see how the structure of the serotonin or of sorry

of the S S R I prevents the reuptake of serotonin.

How structure impacts function.

The transport by HSE RT is a sodium coupled active process as

it uses the energy in the sodium gradient across the cell membrane.

For every serotonin molecule, one sodium ion

and one fluoride ion are cot transported

ion channels, maintain the resting potential within a neuron.

So that is maintained through the um passive transport of sodium and

chloride and potassium to be maintained at that resting potential rate.

Um When an action potential is sent,

there is a influx of sodium

which reaches the action potential and starts the um

pathway as discussed earlier to send that chemical message.

Um As we can see in the right here,

there are multiple different S S R I S with different brain structures and

Iine groups that have different pharm

uses.

And lastly, we'll look at drug development.

So for anybody who's interested in chemistry related careers.

This is really interesting um medicinal chemistry,

which is an ever changing profession due to new technologies

and is critical to the discovery of new drugs.

High

throughput screening has defined targets for structure based drug design.

Um structure based based drug design uses

computational chemistry tools to identify the structure

of a protein that combine to the target cell and re result in inhibition

select compounds

uh for evaluation

as they could be lead compounds.

And they study the structure activity relationships

which involve the use of organic chemistry.

Um And then looking back at the um

structure based drug design and how they're talking about inhibition

um that's just a different uh

way to then, you know, stop that reaction is for um serotonin and S S R I S,

they stop the reuptake with this one.

It would um result in inhibition of some sort of message.

And lastly,

we can look at the scientific method and how it's used to uh test different theories,

uh different drug developments

and such.

So that is how S S R I S affect serotonin.

Capstone- Turnquist

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