Cannabis Flashcards
Cannabinoid actions are receptor-dependent because: (3)
- Modulate intracellular signal cascades
- Temperature dependent
- Saturable
If CB1 is activated on an inhibitory neuron, what happens?
It blocks the release of inhibitory neurotransmitter (double-negative), meaning something is going to be activated
What is the type 1 cannabinoid receptor (CB1R)? (2)
- G𝜶i/o-coupled G protein-coupled receptor (clasically)
- Most-abundant GPCR in the CNS
What is CB1R activated by? (3)
- 2-AG (2-arachidonyl glycerol) and AEA (anandamide)
- THC (the high)
- Spice/K-2 compounds (e.g. CP55,490 and JWH-120)
What is CB1R inhibited by? (2)
- Rimonabant (SR141716A)
- CBD (indirectly)
What is the type 2 cannabinoid receptor (CB2R)? (2)
- Also G𝜶i/o-coupled G protein-coupled receptor (classically)
- Expressed and induced at immunomodulatory cells
What is an orphan receptor?
A receptor for which we do not know the endogenous ligand
What are 3 orphan GPCRs that have been identified that respond to exogenous cannabinoids?
- GPR55 – expressed predominantly in immune cells and osteoclasts/osteoblasts. Activated by THC. Endogenous ligand may be lysophosphatidyl inositol
- GPR18 – expressed in microglia. Activated by THC and CBD. Endogenous ligand may be N-arachidonoyl glycine (related to 2-AG)
- GPR119 – expressed in pancreas and gut. Activated by derivates of 2-AG and AEA. Endogenous ligand may be N-palmitoylethanolamine
Where is the transient receptor potential vanilloid 1 (TRPV1) receptor found?
What activates it?
- Ligand-gated Ca2+ channel expressed on central and peripheral nociceptive neurons
- Activated by AEA and also capsaicin
What are some important endocannabinoid recpeptors to be aware of? (3)
- CB1
- CB2
- TRPV1
What was found in humans with FAAH (C/A or A/A) genotypes?
Humans with a C/A or A/A genotype show less anxiety, greater propensity to substance use disorder and obesity, and heightened pain perception
Where is CB1R mostly distributed in the brain? (6)
- Caudate nucleus
- Amygdala
- Hypothalamus
- Substansia nigra
- Cerebellum
- Dorsal vagal complex
Explain ‘greening out’
When you green out, there is so much THC present that it overwhelms the inhibitory process in the dorsal vagal complex and you have an overwhelming urge to vomit
At what age do we (currently) think the human brain reaches mature neuronal development?
25
How does activation of CB1 affect memory?
Activation of CB1 impairs long-term potentiation in the hippocampus and reduces short-term memory
CB1 activates neurogenesis in the _______ _____ and ___________ ____
dentate gyrus; subgranular zone
Cannabinoids can facilitate short-term depression via ___ vs. long-term depression via _____
CB1; TRPV1
Explain what happens with CB1R and the HPA axis
Activation of CB1R habituates the HPA axis
- AEA decreases corticosterone secretion
- 2-AG inhibits excessive glucocorticoid release
Activation of CB1R in the amygdala is __________. Examples? (3)
anxiolytic
1. In GABAergic neurons this improves socialization, NORT, and exploration (mice)
2. In glutamatergic neurons this reduces aggression and excessive arousal
3. 2-AG and AEA levels are also circadian, peaking during slow-wave sleep
Explain the role of cannabinoids in pain perception (3)
- CB1R activation inhibits GABAergic interneuron transmission, which disinhibits descending, pain-attenuating pathways from the brainstem
- TRPV1, GPR55, and PPAR are also involved
- One possible mechanism for acet is the inhibition of AEA catabolism (i.e., endocannabinoid augmentation)
What role do cannabinoids play in thermoregulation? (2)
- In humans and non-human primates, TRPV1 regulates temperature through hypothalamic and vasodilatory mechanisms (AEA and N-arachidonoyl dopamine)
- In other mammals, CB1R also contributes to thermoregulation, with CB1R activation –> hypothermia
Explain how cannabinoids play a role in appetite (4)
- Acute activation of CB1R stimulates appetite
- Chronic stimulation of CB1R reduces appetite
- Inhibition of CB1R reduces food intake and weight (central and peripheral mechanisms)
- The effect of CB1R inhibition on food intake has implications for addiction as well (e.g., rimonabant was used for smoking cessation, too)
What role do cannabinoids play in adipocytes? (metabolism)
Activation of CB1R increases lipogensis
What role do cannabinoids play in hepatocytes? (metabolism)
Activation of CB1R increases fatty acid oxidation, VLDL-TG clearance, de novo lipogenesis; chronic activation of CB2R stimulates fibrosis