Recreational drugs, pt. 3
In this lesson, we'll continue our investigation of recreational drugs by covering psychedelics and cannabinoids. Again, it should be noted that some of these drugs have recognized and/or potential therapeutic uses.
1) First, watch these videos:
Psychedelics
Cannabinoids
2) Next, answer these questions to test your understanding:
1. How many major cannabinoid receptor types have been definitively identified in humans?
- A. one
- B. two
- C. three
- D. four
Show Answer
Correct answer: B
There are two known cannabinoid receptors, CB1 and CB2--both of which are g-protein coupled receptors. CB1 receptors are found throughout the nervous system, while CB2 receptors are primarily found on immune cells. THC interacts with a number of other targets as well, but it’s thought that its main psychoactive effects are mediated through its action at CB1 receptors.
2. Although we don't fully understand how LSD's mechanism of action in the brain leads to the experiences people have when taking the drug, LSD's activity at these receptors seems to be critical to the drug's psychedelic effects:
- A. dopamine
- B. serotonin
- C. glutamate
- D. GABA
Show Answer
Correct answer: B
LSD’s activity at a subtype of serotonin receptor called the 5-HT2A receptor is critical to the drug’s psychedelic effects. LSD acts as a partial agonist at the 5-HT2A receptor, which means that it binds to the 5-HT2A receptor and generates a response that is a fraction of what the natural ligand, serotonin, generates. LSD also interacts with other receptors, although the role of these receptors in the effects of LSD is less clear.
3. Although psilocybin (the main compound in psychedelic mushrooms) is not strongly psychoactive on its own, it is converted in the body into which substance that interacts with serotonin receptors to produce its effects?
- A. serotonin
- B. dimethyltryptamine (DMT)
- C. psilocin
- D. mescaline
Show Answer
Correct answer: C
Psilocybin itself is not thought to be very psychoactive, but soon after it is ingested it is metabolized into a substance called psilocin, which is highly psychoactive. We don't have a complete understanding of how psilocin produces its effects, but its action at serotonin receptors is thought to be critical to the effects of the drug.
4. The pharmacology of DMT is not fully understood, but studies suggest its action at this serotonin receptor subtype is especially important for producing its characteristically intense visual hallucinations:
- A. 5-HT1A
- B. 5-HT2A
- C. 5-HT3
- D. 5-HT7
Show Answer
Correct answer: B
Studies suggest that DMT’s action at the 5-HT2A serotonin receptor is especially important for producing its characteristically intense visual hallucinations.
5. Ayahuasca is brewed with plants that contain inhibitors of this enzyme, enabling the DMT in ayahuasca to remain active even though it’s administered orally:
- A. acetylcholinesterase
- B. monoamine oxidase (MAO)
- C. tyrosine hydroxylase
- D. choline acetyltransferase
Show Answer
Correct answer: B
Orally administered DMT is rapidly degraded by an enzyme called monoamine oxidase. Thus, ayahuasca is brewed with plants that contain inhibitors of this enzyme, enabling the DMT in ayahuasca to remain active even though it’s administered orally.
