Endocannabinoids Flashcards
eCBs vs phyto/synthetic compounds - 2 e.g.’s + sim/diff (4)
-anandamide or AEA – partial agonist
-2-AG – full agonist
diff:
-derived from fatty acids
- can exist in aq better
similar:
-both like lipids
Biosynthesis of eCBs - EAE + 2AG
AEA:
-produced by our body
-produced by enzymatic reactions
-derived from rare fatty acid
-use N-acyl transferase + Phospholipase D
2-AG:
-produced by our body
-produced by enzymatic reactions
-derived from fatty acid
- use DGL
both enzymes sensitive to calcium levels
= difficult to control 2AG conc in body
( some GCPRs might inc ca2+ = 2AG + CB1r activation)
Production of eCBs - not stored (4)
produced due to stimuli for de novo synthesis:
* From phospholipid-derived precursors
* Activation of GPCRs, PLC, inc.[Ca2+]i, (depolarization)
Produced from:
* Neurons, cardiac myocytes, astrocytes, microglia, blood cells, vascular wall, gut etc
Target tissues:
* Neurons, cardiac myocytes, astrocytes, microglia, blood cells, vascular wall, gut etc
(prod + target = same because like autocrine/paracrine system - local (not like hormone))
How to carry out Liquid chromatography-mass spectrometry
(LC-MS/MS) (5)
to measure a lipid conc - diffi. to do
1) break down tissues/ cells = release of whatever is inside (in alc (inorganic solvent)
2) feed through chromatography column - separates chemicals
3) funnelled to MS = bombard each chemical w/ high energy= break it up
4) detector: gives chemical + precise level of each found in sample
control vs test = how much CB present in sample
Tissue content of eCBs (2)
range of conc. - maybe down to tissue type
net result - not how much is being produced etc
eCBs degradation - EAE + 2-AG:
Know they are taken up by cells - dk if by produce cells or other nearby cells
ACA- FAAH: fatty acid amide hydrolase: will be hydrolysed back to original fatty acid - then poten fed into COX system (=PGs?)
2-AG- MGL: monoacyl glycerol lipase: back to same acid ^ + glycerol = ten poten fed into COX system (=PGs?)
these degr. enxymes =inside cells
Proof of FAAH - rats studies
FAAH: 1) inject FAAH inhib invo in rats
= accum of AEA
Depression resistance effect of AEA - role of FAAH (4)
if it acts as a brake for dev depression after activation of signalling r = anxiolytic effect
= if inhib degradation = reduce anxiety + resist. to depression
studies: K/O of FAAH gene
1)massive accum of AEA
2) measured pain, anxiety etc
= more tolerant to pain = anxiolytic effect
The endocannabinoid system - future research
idea:
1) production of eCBs
2) = they can activate CB1/CB2 r’s
3)= modulate tissue function
how?
- key degradation enzyme in both = simpler pathway = target enzymes = alter levels of eCB’s
- drug that stim. eCBs prod - more complicated + not as efficacious
Retrograde signalling via eCBs (5)
- eCBs not considered neurotransmitters because they’re not even stored in vesicles
-they’re modulatory (-ve feedback: reduced the release of neurotransmitters)
- eCB’s produced by post-synap neurones
- eCB’s travel up (opposite) from post-synp to Pre: they activate CB1 in pre
Fine tuning of neuronal excitability
Hippocampus - CB1 (2)
- CB1 antagonists block depolarization =induced suppression of inhibition (DSI)
- CB1 ↓ spontaneous IPSP of GABAergic interneurons
The eCBs system at synapses (3)
Complementary localization of eCB components:
NAPE-PLD and FAAH in postsynaptic neurons
CB1 receptors in presynaptic terminals of interneurons
AEA vs 2-AG in synaptic plasticity
AEA: for glutanergic transmission
2AG: GABAergic
Neuronal functions of eCB-CB1 signalling (3)
- Fine tuning neurotransmission and synaptic plasticity
- A local endocannabinoid system vs global CB1 activation?
- What happens when eCB signalling goes wrong? Dysregulation in pathological conditions?
Therapeutic potentials of eCBs (5)
-MS - pain control
-Depression + obesity
-Painkiller
-Anti-nauseant or anti-emetic
-CB1 antagonist for addiction?
Periphery- some cell types in which eCB’s or CB1/2r expressed
- Blood vessels – endothelial cells, smooth muscle cells
- Heart
- Blood cells – platelets, monocytes, macrophages
- Adipocytes
- Liver
- Pancreas
- Gut
- Skeletal muscle
- Ovaries, placenta
- Testes, sperms
How to modulate eCBs signalling? - all 3 points (3)
CB1 and CB2 receptors
* Selective antagonists
* Non-selective antagonists
* Allosteric modulators
eCB degradation
* Selective FAAH/MGL inhibitors
* Non-selective FAAH/MGL inhibitors
* Other combined inhibitors
eCB synthesis
* Synthetic enzyme inhibitors? - potential/ trickier to target due to loads of enzymes - not just one
behavioural effects produced by CB1 agonists vs the genetic (KO) or chemical (inhibitor) inactivation of FAAH (6)
CB1 agonist : analgesia, anxiolytic, MS, anti-emesis, decrease IOP (glaucoma)
FAAH k/o: analgesia, unknown anxiolytic, unknown MS, anti-unknown emesis, unknown IOP (glaucoma)
FAAH inhib: analgesia, anxiolytic, unknown MS, unknown anti-emesis, unknown IOP (glaucoma)
side-effects: CB1 agonist: Hypomotility, hypothermia + catalepsy (may be down to selectivity)
Or design a drug that acts just in the periphery - idea + pain study
if you know the therapeutic application requires cb1r (e.g= better than brain in which it causes bad side effects - fewer side effects )+ better for patients w/o getting them high
pain control - liver = successful
Alternative targets of eCBs (4)
Transient Receptor Potential Vanilloid receptor (TRPV1)
* Sensory neurons, brain, epithelium
Peroxisome proliferator-activated receptor (PPAR)
* Adipocytes, macrophages, blood vessels, neurons
K+ channels
* KCa, Kv, TASK1
Ca2+ channels
* T-type Ca2+ channels
Non-CB1/ CB2
targets
not just CB1r
e.g. FAAH inhibitors also increase levels of other
FAAH substrates eg PEA and OEA
Summary (5)
- AEA & 2-AG are major endogenous CB1/2 agonists
- AEA & 2-AG modulate synaptic plasticity via CB1-mediated retrograde signalling
- Modulation of eCB signalling has therapeutic potentials
- FAAH inhibitors increase effects of AEA and probably structurally similar eCBs-like lipids
- eCBs can act on non-CB1/CB2 receptors and ion channels
