Lecture 10 - Transmitter Systems II

Question 1

True or False?:

Respiratory function is highly regulated by μ opioid receptors.

Answer 1

True

Question 2

What do cocaine and amphetamine do?

Answer 2

Cocaine and amphetamine increase glutamatergic synaptic strength in the ventral tegmental area (VTA). Chronic exposure results in changes in nucleus accumbens (NAc) synaptic strength.

Question 3

How do endocannabinoids suppress transmitter release?

Answer 3

Lipid precursors are converted to endocannabinoids (calcium- or mGluR-dependent) and released from the postsynaptic cell. The metabotropic CB1 on the presynaptic cell identifies the endocannabinoids and reduces activity of presynaptic calcium channels and reduces the amount of neurotransmitter released in the same way GABA can.

Question 4

What can nitric oxide do when synthesized in a cell? What’s the main reason why this may not occur?

Answer 4

Nitric oxide can freely permeate the membrane and pass into another cell where it will interact with guanylyl cyclase to turn GTP into cGMP which can activate protein kinase G. Though, NO is unstable and will breakdown before it is able to travel far intercellular distances.

Question 5

Which opioid receptor does morphine activate?

Answer 5

μ

Question 6

What is cocaine’s mode of action?

Answer 6

Cocaine blocks the reuptake of monoamines (dopamine) between the VTA and NAc, resulting in more signaling at the synapse.

Question 7

What are hallucinogenic drugs an agonist of and anti-psychotic drugs an antagonist of?

Answer 7

5-HT_2A

Question 8

What are the 3 types of opioid receptors?

Answer 8

μ, δ, and κ

Question 9

Which type of vesicle are neuropeptides typically stored in?

Answer 9

Large Dense-Core Vesicles

Question 10

How does endocannabinoid-mediated long-term depression work?

Answer 10

Endocannabanoids signal to the CB1R on the presynaptic cell and inhibit the function of RIM1α, a protein that interacts with vesicles during priming. As such, priming is slower and less vesicles are ready to fuse at the time an action potential is recieved.

Question 11

True or False?:

MDMA (ecstacy) has an amphetamine-like action but is less hallucinogenic and more euphoric.

Answer 11

True

Question 12

Which types of opioid receptors are responsible for analgesia (the inability to feel pain)?

Answer 12

μ, δ, and κ

Question 13

True or False?:

Opioid peptides start off as small pre-cursor proteins before being modified into longer proteins.

Answer 13

False

Opioid peptides start off as large pre-cursor proteins before being split into smaller proteins.

Question 14

True or False?:

There are very few neuropeptides.

Answer 14

False

The majority of neurotransmitters are neuropeptides.

Question 15

How many metabotropic receptors are there?

Answer 15

Around 300

Question 16

What is a behavioural difference between the praire vole and the meadow vole? What is this caused by?

Answer 16

The prairie vole pair-bonds while the meadow vole does not pair-bond. This is because the praire vole has high levels of vasopressin receptors while the meadow vole does not.

Question 17

True or False?:

Oxytocin and vasopressin are very evolutionarily conserved.

Answer 17

True

Question 18

Which two neurotransmitters take part in retrograde transmission?

Answer 18

Nitric Oxide (NO) and Endocannabinoids.

Question 19

What are the three types of endogenous opioid peptides?

Answer 19

Endorphins, Enkephalins, and Dynorphins

Question 20

True or False?:

The PFC and hippocampus (among other structures) get excitatory input from the VTA and NAc.

Answer 20

False

The VTA and NAc get excitatory input from the PFC and hippocampus (among other structures).

Question 21

True or False?:

Weakening of glutamatergic synapses in the NAc suppresses cocaine-induced behaviour.

Answer 21

True

Question 22

How do V1aR microsatellites affect satisfaction in relationships?

Answer 22

Those with two long V1aR microsatellites report having more satisfying relationships than those with two short or one short and one long microsatellite. This is because V1aR is expressed more in those with larger microsatellites.

Question 23

True or False?:

Endorphins prefer μ, enkephalins prefer κ, and dynorphins prefer δ. Though, there is considerable cross-reactivity.

Answer 23

False

Endorphins prefer μ, enkephalins prefer δ, and dynorphins prefer κ. Though, there is considerable cross-reactivity.

Question 24

True or False?:

Chronic cocaine exposure results in weakening of glutamatergic synapses in the NAc.

Answer 24

False

Chronic cocaine exposure results in strenghtening of glutamatergic synapses in the NAc.

Question 25

# True or False?: Anti-depressants are very addictive because they act on the serotonin transporter (SERT).

Answer 25

False Anti-depressents are non-addictive, but can cause dependence. They have many types and modes of action, often on the serotonin transporter (SERT) or norepinephrine transporter (NET).

Question 26

Where do you see changes upon taking drugs of abuse? Where do you see changes just upon chronic use of these drugs?

Answer 26

Drugs of abuse affect the VTA. Chronic drug use affects the NAc.

Question 27

All three types of opioid receptor are involved with reward function. Which have an effect of reinforcement and which have an effect of aversion?

Answer 27

Reinforcement - μ, δ Aversion - κ

Question 28

# True or False?: Pre-propeptides become propeptides which become active peptides.

Answer 28

True

Question 29

How does endocannabinoid-mediated depolarization-dependent suppression of inhibition work?

Answer 29

When the post-synaptic cell is depolarized, it release endocannabinoids onto the presynaptic cell that suppress calcium channels, resulting in less release of inhibitory neurotransmitters.

Question 30

How many amino acids are usually found in a neuropeptide?

Answer 30

3 to 36

Question 31

What will nicotine directly stimulate in the reward circuitry?

Answer 31

Nicotine will stimulate nAChRs in the VTA causing an increase in dopamine release.

Question 32

# True or False?: Nitric oxide is synthesized from arginine via NO synthase.

Answer 32

True

Question 33

What is vasopressin responsible for?

Answer 33

Vasopressin regulates bonding and salt retention, increases pressure in blood vessels, and helps avoid dehydration.

Question 34

What is the mode of action for amphetamine and methamphetamine?

Answer 34

Amphetamine andd methamphetamine reverse the function of monoamine transporters (increase their release), making more monoamines (like dopamine) available for postsynaptic uptake.

Question 35

What do psychoactive drugs of abuse stimulate?

Answer 35

Psychoactive drugs of abuse stimulate the release of dopamine in the nucleus accumbens (NAc).

Question 36

What can endocannabinoids cause?

Answer 36

DSI (depolarization-dependent suppression of inhibition), DSE (depolarization-dependent suppression of excitation), or LTD (long-term depression)

Question 37

What do barbiturates do?

Answer 37

They increase the duration of GABA channel opening, increasing channel function.

Question 38

What are orphan receptors?

Answer 38

Orphan receptors are receptors that have been identified but do not have an identified ligand yet.

Question 39

# True or False?: Dynorphin A may regulate expression of trust and fear.

Answer 39

False Oxytocin may regulate expression of trust and fear.

Question 40

If you inhibit a GABA cell innervating the VTA, how will dopamine release be influenced?

Answer 40

GABA is inhibitory. When a GABA cell is inhibited, it increases the action of the postsynaptic cell. As such, the VTA will release more dopamine.

Question 41

What kind of peptide are leucine enkephalin, α-Endorphin, and dynorphin A?

Answer 41

Opioid Peptides

Question 42

What are PCP and ketamine though to do?

Answer 42

PCP and ketamine are thought to bind to NMDA receptors (near the magnesium site) in the NAc and inhibit them.

Question 43

Alcohol has complex, poorly understood effects. What can it do?

Answer 43

* Increase the channel function of certain GABA receptors, which mediate tonic inhibition. * At higher doses, it blocks NMDA receptors which may account for memory loss and psychotic-like effects of intoxication. * Potentiates (increases the effect of ) 5HT₃ receptors, which are excitatory channels on inhibitory neurons.