Cannabis

Question 1

What is an alkaloid?

Answer 1

Nitrogenous compound
Plant origin
Pronounced physiological effects

Question 2

What is the most potent cannabinoid in cannabis?

Answer 2

Delta-9-tetrahydrocannabinol (Δ9-THC)

Question 3

What can protect against the psychotic effects of Δ9-THC somewhat?

Answer 3

Cannabidiol, another cannabinoid

Question 4

Why are current brands of cannabis more pro-psychotic than they previously were?

Answer 4

The Δ9-THC:cannabidiol ratio has been increased

Question 5

What proportion of cannabis reaches the bloodstream when inhaled?

Answer 5

1/3

Question 6

Explain the pharmacokinetics of cannabis and the brain

Answer 6

Enters and leaves brain quickly and so the peak effects last for max 2 hours

Question 7

Recall the pharmacokinetics of cannabis when administered intravenously

Answer 7

Very lipid soluble so accumulates in poorly-perfused fatty tissue
Fatty acid conjugates of cannabinoids accumulate in fat and can leak into the bloodstream for up to 30 days

Question 8

Where is cannabis metabolised?

Answer 8

Liver

Question 9

What is the major metabolite of cannabis?

Answer 9

11-hydroxy-THC

Question 10

Why is serum Δ9-THC a poor measure of intoxication?

Answer 10

The 11-hydroxy-THC metabolite is more potent than Δ9-THC itself, and since it is excreted via the bile is often caught in enterohepatic cycling

Question 11

Recall the elements of the body’s endogenous cannabinoid system

Answer 11

Body produces cannabinoid-like substances and receptors:
CB1 = brain
CB2 = immune cells
Receptors are Gi-linked GPCRS

Question 12

Why is cannabis classed as a depressant?

Answer 12

Activates GPCRs that are negatively linked to adenylate cyclase

Question 13

Why does cannabis produce feelings of euphoria?

Answer 13

Agonises CB1 receptor in brain
CB1 INHIBITS GABA
GABA has a negative influence on DA release in the nucleus accumbens - so cannabis –> more DA release

Question 14

What interaction of cannabis has linked it to schizophrenia and psychosis?

Answer 14

Interactions in anterior cingulate cortex = area of brain involved in error detection

Question 15

Why does cannabis produce “the munchies”?

Answer 15

Cannabis and cannabinoids inhibits GABA in the lateral hypothalamus - which has positive effects on orexigenic and melanin-concentrating hormone neurons

Question 16

Recall the effects of cannabis on the immune system

Answer 16

Reduces B and T cell number and the cytolytic activity of NK cells

Question 17

Recall 3 additional negative effects of annabis, other than psychosis, immunosuppression and appetite stimulation

Answer 17

Memory loss
Depressed psychomotor performance
CVS effects

Question 18

Why can cannabis cause memory loss?

Answer 18

Depressive effects on hippocampus as it decreases effects of brain-derived neurotropic factor (BDNF)

Question 19

Recall and explain the 2 main CVS effects of cannabis

Answer 19

Tachycardia - due to increased Ca++ release because of TRV1 stimulation
Bloodshot eyes - due to conjunctival vasodilation

Question 20

How come an overdose on cannabis cannot kill you?

Answer 20

CB1 presence in the medulla (cardiorespiratory centre) is very low

Question 21

How might a CB receptor agonist be used therapeutically? Give 4 examples

Answer 21

1. Prevention of nausea in chemotherapy patients
2. Stimulate appetite in AIDS patients
3. Analgesic
4. Pain-relief in MS

Question 22

Give 2 examples of THC analogues

Answer 22

Dronabinol

Nabilone

Question 23

How might a CB receptor antagonist be used clinically?

Answer 23

Anti-obesity

Question 24

What is rimonabant, and what is the main issue with its clinical use?

Answer 24

CB-antagonist used to treat obesity - was linked to deppression

Question 25

Name the reward system in the brain

Answer 25

Mesolimbic system

Question 26

Describe the structure of the mesolimbic system

Answer 26

Dopaminergic neurons
Originate in VTA and project onto nucleus accumbens
DA release –> euphoria

Question 27

What is the fastest method of administration of a drug of abuse?

Answer 27

Smoking