Drugs of Abuse 1 – General/Cannabis Flashcards Preview

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Flashcards in Drugs of Abuse 1 – General/Cannabis Deck (37)
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1

Generally speaking, how do the drugs of abuse cause the feeling of euphoria?

The hijack the mesolimbic dopaminergic pathway – the central reward pathway

2

Describe the structure of the central reward pathway.

The dopaminergic neurones project from the ventral tegmental area to the nucleus accumbens
Dopamine release into the nucleus accumbens will stimulate the feeling of euphoria

3

Put the routes of administration of drugs in order of speed of absorption.

Smoking > IV > Snorting > Oral

4

Why is smoking slightly quicker than IV injections?

Smoking brings the drug to the alveoli where it easily crosses the alveoli and enters the pulmonary circulation
There is a shorter distance from the pulmonary circulation to the heart and then to the brain than from the site of IV injection to the heart and then to the brain

5

What are the different classes of the drugs of abuse?

Narcotics/painkillers – e.g. opiate like drugs
Depressants – e.g. alcohol
Stimulant – e.g. cocaine, caffeine
Miscellaneous

6

What is an alkaloid?

Any class of nitrogenous organic compound of plant origin that has profound physiological actions on humans

7

What are the active components of the Cannabis sativa plant?

Cannabinoids (there are over 60 of them in the plant)

8

What is the most potent cannabinoid in the plant?

Delta-9-tetrahydrocannabinol (Delta-9-THC)

9

What is another important cannabinoid that appears to counteract some of the negative effects of the potent cannabinoid?

Cannabidiol

10

How has cannabis production changed over the last 10-15 years?

There has been an increase in the amount of 9-THC in the cigarette meaning that there is less cannabidiol
This suggests that cannabis production is heading towards being morepro-psychotic

11

What percentage of smoked cannabis will reach the blood stream?

Around 30%

12

Describe the accumulation of cannabis in the brain following administration.

Cannabis levels in the brain rise very quickly after administration but, because the brain is highly perfused, the cannabis levels in the brainfall rapidly as well

13

Describe the accumulation of cannabis in fat following administration.

Cannabis is very lipid soluble so it slowly accumulates in the fat
This means that cannabis will leak from the store in the fat for a long time after administration

14

How long will the effects of cannabis last after smoking a joint?

Around 30 days (because of the storage in adipocytes)

15

What is an important metabolite of cannabis?

11-hydroxy THC (this is more potent than Delta-9-THC)

16

What happens to this metabolite once it has been produced?

It is excreted in the bile into the GI tract but then it undergoes enterohepatic cycling and re-enters the blood stream where it can exert its physiological effects
Because of this, plasma Delta-9-THC levels are a poor measure of intoxication

17

Where are the different cannabinoid receptors found?

CB1 – brain
CB2 – peripheral immune cells

18

What type of receptor is the cannabinoid receptor?

G protein coupled receptor – negatively coupled with adenylate cyclase

19

Name one endogenous cannabinoid.

Anandamide

20

Describe how cannabis causes euphoria.

Cannabis binds to CB1 receptors on GABA neurones and inhibits the GABA neurones
This means that they remove the inhibitory influence of GABA neurones on the dopaminergic neurones of the rewards pathway, hence there is increased firing of the dopaminergic neurones --> euphoria

21

What area of the brain does cannabis interact with that is linked to its psychotic effects?

Anterior Cingulate Cortex
There is hypoactivity in the anterior cingulate cortex in chronic cannabis users

22

What is this part of the brain responsible for?

Performance monitoring and behavioural adjustment

23

Which part of the brain does cannabis act on to stimulate food intake?

Lateral hypothalamus

24

What are the two main groups of neurones that are involved in stimulating appetite?

MCH (melanin concentrating hormone) neurones
Orexin neurones

25

What effect does cannabis have on these neurones?

Cannabis inhibits the inhibitory effect of GABA on MCH neurones, thus leading to increased MCH firing
Cannabis also directly stimulates orexin production
This leads to hunger

26

Describe the effect of cannabis on the immune system.

Cannabis is a powerful immunosuppressant

27

How does cannabis cause memory loss?

It inhibits the production of BDNF (brain derived neurotrophic factor), which is important in the hippocampus in forming memories
In general, cannabis has a depressant effect on the hippocampus

28

How does cannabis cause impaired psychomotor performance?

It depresses the cerebral cortex

29

How does cannabis cause cardiovascular effects?

Cannabis acts via the TRPV1 receptor to cause calcium influx

30

What are the cardiovascular effects of cannabis?

Activating the TRPV1 receptor leads to calcium influx --> tachycardia