CNS Pharmacology II: Stimulants & Depressants

Question 1

What is a Psychoactive / Psychotropic drug?

Answer 1

Drugs that affects mood and behaviour

Question 2

Which neurotransmitters are Amphetamines structurally similar to?

Answer 2

Dopamine & Noradrenaline

Question 3

What are THREE ways in which Amphetamines increase DA and NA transmission?

Answer 3

1. Increase secretion of DA and NA
2. Compete with DA and NA degradative enzymes
3. Competing with DA and NA re-uptake systems

Question 4

Which neurons are mainly stimulated by amphetamines?

Answer 4

Noradrenergic neurons of the ANS

Question 5

What FOUR ways do amphetamines act on Dopamine (DA) synapses?

Answer 5

1. Compete with DA uptake carrier
2. Compete with DA uptake into synaptic vesicles
3. Inhibit DA degradation (at higher conc. via MAO)
4. Bind to DA re-uptake transporter, causing it to act in reverse and transport free DA out of the nerve terminal

Question 6

What TWO ways do amphetamines act on Noradrenaline (NA) synapses?

Answer 6

1. Increase release of NA into synaptic cleft
2. Inhibit NA re-uptake transporter

Question 7

What are the FOUR Dopamine pathways in the brain?

Answer 7

1. Nigrostriatal Pathway
2. Mesolimbic Pathway
3. Mesocortical Pathway
4. Tuberoinfundibular

Question 8

Which areas of the brain, known as the Reward Pathway, do drugs of abuse modify the action of DA in?

Answer 8

• Ventral Tegemental Area (VTA)
• Nucleus Accumbens

Question 9

Which receptor in the CNS is Nicotine an agonist for?

Answer 9

Nicotinic Acetylcholine Receptor (nACh)

Question 10

What does ACh release in DA neurons cause?

Answer 10

INCREASED DA release

Question 11

Which nACh receptor is believed to be linked with addiction?

Answer 11

a4β2

Question 12

What is the mechanism of action of Cocaine on DA or NA neurons?

Answer 12

1. Cocaine binds to DA and NA re-uptake transporters, which inhibits DA and NA removal from synaptic cleft and degradation by MAO
2. DA and NA remain in synaptic cleft activating the post-synaptic receptors and enhancing neurotransmission

Question 13

What are TWO examples of Methylxanthines?

Answer 13

1. Caffeine
2. Theophylline

Question 14

Which neurotransmitter are Methylxanthines structurally similar to?

Answer 14

Adenosine
* Inhibitory NT

Question 15

How do Caffeine and Theophylline act on Adenosine receptors?

Answer 15

Non-Selective Antagonists of the A1 and A2 receptors

Question 16

Which drug is used to treat ADHD?

Answer 16

Methylphenidate (Ritalin)

Question 17

How do CNS depressants work?

Answer 17

Increase GABA transmission, which inhibits post-synaptic neuron activity

Question 18

What is Ethanol’s effects on CNS neurons?

Answer 18

• Increase inhibitory neurotransmission: GABA, Glycine, Adenosine
• Decrease excitatory neurotransmission: Glutamate (NMDA receptors)

Question 19

What is the mechanism of action of Benzodiazepines?

Answer 19

• Benzo binds to GABAa receptor at allosteric site
• Benzo enhances affinity and response to GABA
• Benzo facilitates opening of GABA-activated Cl- channels
• Benzo increase frequency of channel opening

Question 20

What are Benzodiazepines with LONG half-lives useful for?

Answer 20

Anxiolytics
* Rapid onset of action with long lasting action

Question 21

What are Benzodiazepines with SHORT half-lives useful for?

Answer 21

Insomnia
* Rapid onset or sedative effects that dissipate with sleep

Question 22

What drug blocks the binding and action of Benzodiazepines?

Answer 22

Flumazenil
* Benzo Antagonist

Question 23

Which SIX neutron types are Opioid Receptors found?

Answer 23

1. Glutamate
2. NA
3. ACh
4. GABA
5. 5-HT
6. Substance P

Question 24

How does Morphine induce euphoria in GABA and DA neurons?

Answer 24

• Inhibits GABA release
• Reduced inhibition of DA neurons (increased DA in synaptic cleft)

Question 25

What are TWO examples of Opioid antagonists?

Answer 25

1. Naloxone 2. Naltrexone (Competitive Antagonism)