CANNABINOIDS AND ENDOCANNA-BINOIDS : TWO SIDES OF ONE COIN

Report
Cannabinoids and
endocannabinoids:
two sides of one
Title
6-10 September
coin
2010
Supramolecular
Systems in
Chemistry and
Biology
Lviv,
Ukraine
Piotr BREGESTOVSKI
Mediterranean Institute of Neurobiology
Marseille, France
Euphoria
Cannabis sativa
Short history of cannabis
Marijuana (Cannabis sativa) has been
used for thousands of years. It is one of
the oldest multi-purpose commercial
plants grown for its fibre, edible seeds and
psychotropic substances.
China, India,
Greece, Roman,
Arabic countries
> 5 000 years
• Pain
• whooping cough
• asthma
• as sebative/soporific
• Euphoria
(Shen-Nung, China’s Emperor)
Avicenna - arabian physician described the medical uses of cannabis
Cannabis sativa
Bad and Good cannabis
Marijuana (Cannabis sativa) has on the
brain and human body many powerful
effects, including:
M
Bad
cannabis
Good
cannabis
?
• pain sensitivity decrease
• lowering blood pressure
• asthma
• sebative effects
• decreased intraocular pressure
• Impared motor coordination
• Tremor
• Decreased body temperature
• Altered perception, memory
• Hallucinations
Euphoria
We will discuss today:
 Evidences on existance endocannabinoid (EC) system
 Types of cannabinoid receptors (CBRs)
 Distribution of cannabinoid receptors in CNS
 Main classes of cannabinoids
 Synthesis and degradation of endocannabinoids
 Evidences on retrograde action of ECs
 Contemporary view on mechanisms of endocannabinoid
signaling in CNS
1964 - discovery of D9-Tetrahydrocannabinol (D9-THC)
the major psychoactive ingredient of Cannabis sativa
Gaoni Y. & Mechoulam
Cannabis sativa
THC
Discovery of D9-Tetrahydrocannabinol (D9-THC)
OH
O
D9-Tetrahydrocannabinol
Raphael Mechoulam
Numerous
related
compounds
have
been
synthesized or isolated, and together they form a
class of drugs called the CANNABINOIDS.
Endocannabinoid system in
biological organisms:
Main Evidences
• Specific receptors for cannabinoids (CBRs)
• Endogenous cannabinoids (ECs)
• Specific distribution of CBRs in the brain
• Formation and degradation of ECs in neurons
20 years later after discovery of D9-Tetrahydrocannabinol
Short history of cannabinoid system
1964 - discovery of D9-Tetrahydrocannabinol (D9-THC)
the major psychoactive ingredient of Cannabis sativa
Gaoni Y. & Mechoulam
1988 & 90 - identification & cloning of the first (CB1)
receptor (rat) Devane, Howlett et al., 1988; Matsuda et al., 1990
1993- cloning of the second cannabinoid receptor (CB2)
Munro et al.
CB1 & CB2 cannabinoid receptors
• Preservation in evolution: human, rat and mouse CB1
receptors have 97–99% amino acid sequence identity
• CB1 & CB2: a low (45%) overall homology
• CB1: 472 aminoacids, highly expressed in the CNS
• CB2: 360 aminoacids, mainly expressed in cells of the
immune system.
• CB1:
- adenylite cyclase inhibition;
- N/Q- Ca2+ channels inhibition;
- K+ conductance stimulation
Endocannabinoid system in
biological organisms:
Main Evidences
• Specific receptors for cannabinoids
• Endogenous cannabinoids
• Specific distribution of receptors in the brain
Major Endocannabinoids
First endocannabinoid, 1992
Anandamide - “internal bliss” (Sansrit)
Lumir O. Hanus
R. Mechoulam
Anandamide
THC & 2-AG
Main brain endocannabinoid, 1995
Plant cannabinoid
Major Endocannabinoids
Anandamide
Arachidonic acid
Lumir O. Hanus
R. Mechoulam
Anandamide
THC & 2-AG
Plant cannabinoid
Other possible endocannabinoids
KANO ET AL., 2009
Endocannabinoids regulate multiple
physiological and pathological conditions
• Suppress nociceptive processing through activation of CB1
•
•
•
•
•
and CB2 receptors
Regulates food intake
Immunomodulation
Inflammation
Addictive behavior
Epilepsy
Short history of cannabinoid system
1964 - discovery of D9-Tetrahydrocannabinol (D9-THC)
the major psychoactive ingredient of Cannabis sativa
Gaoni Y. & Mechoulam
1988 & 90 - identification & cloning of first cannabinoid
(CB1) receptor Devane et al., 1988; Matsuda et al., 1990
1993- cloning of second cannabinoid receptor (CB2)
Munro et al.
1992 - discovery of the first endocannabinoid
(anantamide)
Devane, Hanus & co-authors
1995 - identification of 2-arachidonoyl-glycerol (2-AG) main endocannabinoid in CNS Mechoulam et al.; Sugiura et al.
Endocannabinoid system in
biological organisms:
Main Evidences
• Specific receptors for cannabinoids
• Endogenous cannabinoids
• Specific distribution of receptors in the brain
How to see disribution of
receptors in the brain?
• Radioactively labeled ligands
• Specific antibodies
Distribution of cannabinoid CB1
receptors in rat brain
Revealed by an autoradiograph of thebinding of radioactively labeled CP-55940 (a high af®nity CBR ligand)
Iversen, 2003
Antibodies for CB1 receptor
Ken Mackie, Univ.Washington, Seattle
Distribution of CB1 receptors in
the brain
1mm
Kano et al.2009
Distribution of CB1 receptors in the brain
CB1 receptors are located presynaptically on axon terminals
CB1 receptors are localized presynaptically
From Katona et al (1999)
J Neurosci 19:4544-58
CB1
Endocannabinoid system in
biological organisms.
Main evidences
• Specific receptors for cannabinoids (CBRs)
• Endogenous cannabinoids (ECs)
• Specific distribution of CBRs in the brain
• Formation and degradation of ECs in neurons
Formation of 2-AG
Phosphatydilinositol (PIP2)
Phospholipase C (PLC)
Diacylglycerol (DAG)
lipase
Diacylglycerol lipaseDG
(DAG)
2-arachidonoilglycerol (2-AG)
Formation of anantamide in neurons
+
Arachidonic acid
Endocannabinoid system in
biological organisms:
Main Evidences
• Specific receptors for cannabinoids (CBRs)
• Endogenous cannabinoids (ECs)
• Specific distribution of CBRs in the brain
• Formation and degradation of ECs in neurons
1964-2009: 45 years
Main classes of cannabinoids
-Herbal cannabitoins (phytocannabinoids)
-Synthetic cannabinoids
-Endocannabinoids
Phytocannabinoids
Cannabis
sativa
Cannabis sativa:
- contains 70 phytocannabinoids
- 11 classes
Cannabidiol
THC
Agonist
Antagonist
Endocannabinoids
For CB1 EC50 = 240 nM
For CB2 EC50 = 440 nM
For CB1 EC50 = 3425 nM
For CB2 EC50 = 1200 nM
Amount of 2-AG in the brain is >100-fold higher then anandamide
Synthetic cannabinoids
Natural agonist
Agonist
Synthetic agonists and antagonists
CB1 EC50 = 40 nM
CB2 EC50 = 30 nM
Agonist
CB1 EC50 = 1.3 nM
CB2 EC50 = 1 nM
Antagonist
IC50 = 7.5 nM
Effects of cannabinoids
(human):
Psychological effects (2-10 mg):
1. Effective:
- euphoria and elation;
- cheerfulness (feeling of happiness);
- sedation
- transient hallucinations
2. Sensoric:
- increased perception of external stimuli
3. Somatic:
- feeling of the body floating or falling
4. Cognitive:
- disturbed time perception (one min like several);
- memory failure;
- troubles with concentration
Effects of cannabinoids
(human):
Psychological effects (>10 mg):
- anxiety and panic;
- impaired attention;
- disturbed coordination
- increased risk of traffic accidents
Good
cannabis
Long- lasting use:
Bad
cannabis
- increased myocardial infraction
- chronic bronchitis
- disturbance in the ability to organize complex information
- “amotivational syndrome”
- smaller whole brain volume (hippocampus, amigdala)
- worsen symptoms of schizophrenia
Therapeutic effects of cannabinoids:
Positive effects of cannabinoids:
- side effects of anti-tumor therapy (nausea and vomiting)
-increase appetite (against anorexia) - agonists
-decrease appetite (against obesity) - antagonists
-glaucoma
- antiallergic
- antiinflammation
- sleep disorders
Bad
cannabis
-anxiety disorders
Positive effects of cannabinoids:
Good
cannabis
- protective role in atherosclerosis progression
- decreased intraocular pressure
- decreasing the ischemic-reperfusion injury
Medical applications - 1
Cesamet
Lilly Indianapolis, Indiana, USA
Treatment of cancer patients after
chemotherapy:
nausea and vomiting
Marinol or Dronabinol
Solvay, Marietta, USA
- Cancer patients after chemotherapy:
nausea and vomiting.
- Appetite stimulant for treatment of
cachexia (weight loss and wasting) in
AIDS patients
Medical applications-2
Agonist
Sativex
GW pharmaceuticals,
Salisbury, Wiltshire, UK
+
Antagonist
Relief of neuropathic pain
Cannabidiol
Mechanism of cannabinoids
action in the brain
Synapses in mammalian
brain
Excitatory
Glutamate
AMPA/Kainate
Inhibitory
GABA
or/and
Glycine
GABAR
GABAAR
GlyR
NMDA r-rs
Endocannabinoid-mediated control
of synaptic transmission
Modulation of Ca2+ influx:
- Inactivation of Ca2+ channels
- Depletion of extracellular Ca2+
- Action potential failure
CB
Pre
CB
R-R
Ca2+
Post
Presynaptic receptors:
- Metabotropic
- Adeosine
- Noradrenaline
- mAChR
- Cannabinoid receptors
Modulation of postsynaptic receptors:
- Sensitivity
- Desensitization
Discovery of Depolarization-induced
Suppression of Inhibition: DSI
Stim
Whole-cell
Pre Ca2+
Post
Discovery of Depolarization-induced Suppression of Inhibition: DSI
I. Llano & A. Marty, 1991
cerebelum
Example of hippocampal DSI
Depo
Depo Depo Depo Depo Depo Depo Depo Depo
Whole-cell
Pre Ca2+
Post
Pitler and Alger, 1992, hippocampus
Depolarization-induced suppression of inhibition (DSI)
DSI Features
DSI in cerebellum & hippoampus
Llano et al, 1991 cerebelum
Stim
Pitler and Alger, 1992, hippocampus
Whole-cell
Pre Ca2+
Post
- results from decrease of neurotransmitter release
-needs elevation of Ca in postsynaptic cell
- involves retrograde signaling
Depo
Ca2+
Retrograde signals for DSI:
endocannabinoids
Wilson & Nicoll, 2001
Stim
Whole-cell
Pre Ca2+
Post
Kreitzer & Regehr, 2001
Ohno-Shosaku et al., 2001
Diana et al., 2002
Ca2+-induced retrograde signaling
by endocannabinoids
AM281 - Antagonist
B
Depolarization
Wilson & Nicoll, 2002
Short-term synaptic plasticity
Depo
Chevaleyre et al, 2006
Depo
Hippocampal DSI is absent in CB1knock-out mice
CB+/+
Depo
Depo
Depo
Depo
Depo
1mm
Depo
DSI and DES - general
phenomenon
CB1
CB1
CB1
Inhibitory synapses: GABAA- and
glycinergic
GlyR
GlyR
channels
Ionic channels are key
proteins of electrochemical
transformation
Short-term plasticity in glycinergic synapses
DSI in glycinergic synapses
Marat Mukhtarov
Mukhtarov, Ragozzino, Bregestovski, J. Physiol., 2005
Davide Ragozzino
Action of 2-AG in excitatory synapses
Presynaptic cell
AMPAR
NMDAR
mGluR
Postsynaptic cell
Synapses on dendrite & spine
organization
Sheng and Hoogenraad, 2007
Distribution of AMPA & NMDA receptors in synapses
Somogyi et al., 1998
Distribution of mGlu receptors in synapses
AMPAR
NMDAR
mGluR5
Area of perisynaptic signaling machinery
Synapses on dendrite & spine
organization
mGluR5
DG lipase
Formation of 2-AG
Phosphatydilinositol (PIP2)
Phospholipase C (PLC)
Diacylglycerol (DAG)
lipase
Diacylglycerol lipaseDG
(DAG)
2-arachidonoilglycerol (2-AG)
Low activity
Postsynapse
Presynapse
Activation of perisynapric
signaling machinery
Katona & Freund, 2008
High activity
Suggested mechanism of 2-AG action in excitatory synapses
QuickTime™ and a
Photo - JPEG decompressor
are needed to see this picture.
Remember
Bad
cannabis
Good
cannabis
Endocannabinoid system is an ubiquitous lipid signalling system
Endocannabinoids are small molecules derived from arachidonic
acid. They bind to G-protein-coupled cannabinoid receptors
Two cannabinoid receptors have been cloned, CB1R and CB2R.
Both are receptors coupled to the pertussis toxin–sensitive G
protein, Gi/o.
The CB1R are among the most highly expressed G proteincoupled receptors in the CNS, and they are responsible for most of
the psychoactive effects of cannabinoids.
Endocannabinoids regulate multiple physiological and pathological
conditions: food intake, immunomodulation, inflammation, analgesia,
cancer, addictive behavior, epilepsy and others
In the brain, most CB1Rs are found on axon terminals.
Its activation leads to presynaptic inhibition of transmitter release.
Suggested reading
Alger BE. Retrograde signa ling in the regu la tion of syn aptic trans mis sion: focus on
endoc annab inoids. Prog Neurobiol. 2002 Nov;68(4):247 -86.
Chevaleyr e V, Takaha shi KA, Castill o PE. Endo cannab inoid-me diated synap tic
plastic ity in the CNS. Annu Rev Neurosci. 2006;29:37-76
Diana MA, Breges tovski P. Calcium and endocannab inoids in the modulation o f
inhibit ory synap tic transmi ssion. Cell Calcium. 2005 May;37(5):497-505.
Howlett AC, Breivoge l CS, Chil ders SR, Deadwyler SA, Hampson RE, Porrino LJ.
Cannab inoid phys iology and pha rmacology: 30 yea rs of progre ss.
Neuropha rmacology. 2004;47 Suppl 1:345 -58.
Kano M, Ohno -Shosaku T, Hashimotodani Y, Uchigash ima M, Watanabe M.
Endocannab inoid-mediated con trol of synap tic transmi ssion . Physiol Rev. 2009
Jan;89(1):309-80.
Onaivi ES. Cann abinoid receptors in b rain: pha rmacogenetics, neu ropha rmacology,
neu rotoxicology, and po tential t herapeutic applications . Int Rev Neurobiol.
2009;88:335-69.

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