Lecture 24 - Peptides, Lipids, Nucleotides and Gases - The "Other" neurotransmitters

Question 1

What defines non-traditional neurotransmitters?

Answer 1

They act like a neurotransmitter, but do not satisfy the criteria for a traditional/true neurotransmitter?

Question 2

Peptides consist of 2 or more….what?

Answer 2

Amino acids

Question 3

Do we have endogenous opioids?

Answer 3

Yes.

Question 4

Where are endogenous opiate receptors most densely present?

Answer 4

In the areas of the brain associated with pain.

Question 5

Morphine, heroin, and opium are what types of drugs?

Answer 5

Opiates.

Question 6

Heroin is NOT very neurotoxic. So, why does it cause such severe problems for people with heroine attictions?

Answer 6

Heroine is not neurotoxic, as in it does not cause damage or death to neurons, but it can cause respiratory failure and have broad negative side effects, such as relationships with friends, family and self.

Question 7

Is heroine a full agonist for endogenous opiate receptors?

Answer 7

Yes.

Question 8

What does NALAXONE do?

Answer 8

Nalaxone is a full antagonist and is used to treat heroine overdose. It completely stops the action of heroine by binding to endogenous opiate receptors and blocking heroine from binding, but do not cause activate the opiate receptors.

Question 9

Certain lipids can act as neurotransmitters. What are the most well known lipid neurotransmitters?

Answer 9

Endocannabinoids.

Question 10

What are the two known cabinnoid receptors?

Answer 10

CB1 and CB2.

Question 11

Endogenous canniboid receptors modulate the neuromodulators.
How do they do this?

Answer 11

Endogenous cannibinoid receptors (when activated/bound by a correct ligand) decrease the amount of neuromodulator/transmitter that is released into the synapse. They are located on the presynaptic membrane. This is how they modulate neuromodulation!

Question 12

What is the active ingredient in marijuana?

Answer 12

THC

Question 13

Nucleosides can also act as neurotransmitters/modulators.
How?

Answer 13

They are often co-transmitted with

Question 14

Is adenosine the same as adenine?

Answer 14

No. Adenine refers to the purine base. Adenosine is made up of adenine, deoxyribose and a phosphate.

Question 15

What happens to adenosine levels in the body across the day?

Answer 15

From the time of waking adenosine levels gradually rise. Why? Adenosine is a byproduct of the breakdown of adenosine triphosphate or ATP. ATP is used for energy production. When we wake we begin to use more energy. The more energy we use the higher the levels of adenosine in the system.

Question 16

Why is adenosine a good neurotransmitter for the brain?

Answer 16

Adenosine levels give an indication of how much energy has been used and therefore also give an indication of whether rest is required. There are adenosine receptors on postsynaptic neurons which lead to the activation of neurons that tell the body to sleep and rest.
So…the more adenosine in the system the more firing of adenosine selective neurons the sleepier you will feel.

Question 17

How does caffeine work on the brain?

Answer 17

Caffeine acts as an adenosine receptor antagonist. This means that adenosine cannot bind to its receptor and induce the sleepiness signals that it normally would. Hence, the alert-making nature of caffeine.

Question 18

Can gases act as neurotransmitters?

Answer 18

Yes.

Question 19

What are two gasses that are used as neurotransmitters in the brain?

Answer 19

Nitric oxide and carbon monoxide.

Question 20

What does nitric oxide do in the tissues of the body?

Answer 20

It acts as a muscle relaxant. It is a key signalling molecule in the cardiovascular system.

Question 21

What does nitric oxide do in the brain?

Answer 21

The function of nitric oxide in the brain is still unlcear, but it is thought to play a role in memory and synaptic plasticity, as well as being responsible for expanding blood vessels in the brain around metabolically active areas of cortex.

Question 22

What amino acid is nitric oxide produced from?

Answer 22

Nitric oxide is produced from the amino acid ARGININE. And is only produced in 1-2% of neurons in the brain.

Question 23

What are some of the features of nitric oxide that make it different to other neurotransmitters?

Answer 23

It is not stored in vesicles.
It produced throughout the neuron body/soma, including dendrites and is diffuses out of the cell as soon as it is produced.
Nitric oxide does not bind to and activate receptors, it simply enters/diffuses into neighbouring cells.
Nitric oxide is very short lived.
Nitric oxide can act on neurons that aren’t neuronally connected, via axons and dendrites, as it just diffuses into cells. However, short half life means that its action is limited to the immediate surrounding area.

Question 24

Where are cannibinoid receptors found?

Answer 24

Cannibinoid receptors are found at most pre-synaptic membranes of neurons that release neurotransmitters/modulators and aid in the modulation of neural modulation.