2. Flow of presentation
• Introduction
• History
• Phytocannabinoids
• Endocannabinoid system
• Physiological role and pharmacological effects
• Pathological involvement
• Clinical applications
• Recent advances
3. Cannabinoids
• Originally used to describe the family of
naturally occurring chemicals found in
cannabis, of which Δ9 – tetrahydrocannabinol
(THC) is the principal member
• Current definition: All those substances
capable of activating cannabinoid receptors
4. History of Cannabinoid Research
• At least 5000 years history
• 1753-Carolus Linnaeus classified marijuana as Cannabis
sativa
• 1855- Chemical isolation of the cannabis plant by Personne
Robiquet (‘a good analysis of hemp’)
• 1899: Wood found the first natural cannabinoid called
cannabinol (CBN) which was later structurally established in
1940 by Adams
• 1941-42: Adams and Cahn founded the cannabinoid called
cannabidiol (CBD)
5. • 1964: Major psychoactive terpene Δ9 – tetrahydrocannabinol
(THC) isolated in its pure form by Gaoni and Mechoulam and then
structurally established in 1967 by Mechoulam and Gaoni
• 1969: The activity of THC was established in rhesus monkeys by
Grunfeld and Edery
• 1988- Discovery of CB1 receptors
• 1992- Identification of anandamide as an endocannabinoid
• 1993- Discovery of CB2 receptors
• 1995-Identification of 2-arachidonoylglycerol (2-AG) as another
endocannabinoid
6. Types of Cannabinoids
• Organic cannabinoids
▫ From cannabis plant (Phytocannabinoids)
▫ Synthesized in brain (Endocannabinoids)
• Synthetic cannabinoids
7. Phytocannabinoids
• Also called natural cannabinoids, plant-derived
cannabinoids, herbal cannabinoids or classical
cannabinoids
• At least 85 cannabinoids have been isolated from
Cannabis sativa (the hemp plant)
• Concentrated in a viscous resin that is produced in
glandular structures known as trichomes
8. Various forms of cannabis usage
• Bhang
▫ Dried leaves
▫ Oral route
▫ Slow action
• Ganja
▫ Dried female inflorescence
▫ Smoked
▫ Instantaneous effect
• Charas (Hashish)
▫ Dried resinous extract from the flowering tops
and leaves
▫ Smoked with tobacco
▫ Most potent
9. Important Cannabinoids from
Cannabis Plant
• Δ9 -tetrahydrocannabinol (THC)
▫ The principle psychoactive constituent
• Cannabidiol (CBD)
▫ Precursor of THC
▫ Lack psychoactive property
• Cannabinol (CBN)
▫ Breakdown product of THC
▫ Lack psychoactive property
10. Endocannabinoid system
• Consists of
▫ Cannabinoid receptors
▫ Endogenous cannabinoids (endocannabinoids)
▫ Enzymes that synthesize and degrade
endocannabinoids
11. Cannabinoid(CB) receptors
• G-protein-coupled receptors
• Contain seven transmembrane spanning domains with an
extracellular N-terminus and cytoplasmic C-terminus
• Activated by three major group of ligands
▫ Endocannabinoids
▫ Plant cannabinoids
▫ Synthetic cannabinoids
• Currently two known subtypes
▫ CB1 & CB2
• Some endocannobinoids also activate vanilloid receptors
12.
13. CB1 receptors in brain- location &
function
• Abundantly present in brain
• Not homogeneously distributed
• More concentrated in
▫ hippocampus (Memory)
▫ cerebellum (loss of coordination)
▫ hypothalamus (control of appetite, reproductive function)
▫ substantia nigra, mesolimbic dopamine pathways (psychological
'reward')
▫ Association areas of cerebral cortex
14. • Less concentrated in the brain stem (lack of
serious respiratory or cardiovascular toxicity of
the cannabinoids)
• Localised presynaptically
▫ Inhibit transmitter release
• Mediate psychotropic effects of cannabis
15.
16. CB1 receptors in periphery- location &
function
• Liver (lipogenesis)
• Blood vessels (hypotension during hemorrhagic
and septic shock)
• GIT(inhibition of intestinal motility)
• Peripheral nerve endings (pain modulation)
• Other sites: lungs, kidneys, Adipocytes
17. CB2 receptors
• Only approximately 45% amino acid homology with CB1
• Location
▫ Mainly in lymphoid tissue (spleen, tonsils and thymus as well as
circulating lymphocytes, monocytes and tissue mast cells)
▫ B lymphocytes > natural killer cells >>monocytes > neutrophils > T8
lymphocytes > T4 lymphocytes
▫ Also present on microglia
• Function
▫ Little known
▫ Inhibitory effects of cannabis on immune function
18. Signaling mechanisms
CB1 receptors
• Linked via Gi/o to adenylate cyclase
• Hyperpolarization
▫ Inhibition of adenylate cyclase
▫ Inhibition of voltage-operated calcium channels (VOC)
▫ Activation of G-protein-sensitive inward-rectifying potassium (GIRK)
channels
• Altered gene expression
▫ Activati0n of mitogen-activated protein kinase (MAPK)
▫ ↓ activity of protein kinase A (PKA)
CB2 receptors
• Similar to CB1, but not linked to voltage-operated calcium channels (VOC)
19. Cellular actions
of cannabinoids
GIRK: G-protein-
responsive
potassium channel
MAPK: mitogen-activated
protein kinase
PKA: protein kinase A
VOC: voltage-operated
calcium channel
20. Cannabinoid receptor agonists
• Classical cannabinoids
▫ Tricyclic dibenzopyran derivatives
Compounds occurring naturally in the plant C. sativa (eg: Δ9-THC) or
Synthetic analogues of these compounds (eg: HU-210)
• Non-classical cannabinoids
▫ Synthetic THC analogues that lack the dihydropyran ring (Eg:CP-55 940)
• Aminoalkylindoles
▫ Eg: WIN-55212–2
• Eicosanoids
▫ Eg: Anandamide, 2-AG
21. Cannabinoid receptor antagonists
• Diarylpyrazoles
▫ SR 141716A, SR 144528
• Substituted benzofuranes
▫ LY 320135
• Aminoalkylindoles
▫ AM 630
• Triazole derivatives
▫ LH-21
23. Endocannabinoids
• Substances produced from within the body that activate
cannabinoid receptors
• Belong to the family of eicosanoids
• Believed to play important role in almost every major life
function in the human body
• Not stored but instead are rapidly synthesized by neurons
in response to depolarization and consequent calcium
influx
• Function as ‘retrograde synaptic messengers’
25. Biosynthesis of endocannabinoids
• Synthesized 'on demand' basis
• Produced by hydrolysis of precursors derived from phospholipid
metabolism
• Anandamide
▫ Key enzyme: NAPE-PLD(N-acyl phosphatidylethanolamine-specific
phopholipase D)
• 2-AG
▫ Key enzymes - diacylglycerol lipases (DAGL-α and DAGL-β)
• Little is known about the biosynthesis of other recent endocannabinoids
26. Termination of the endocannabinoid
signal
• Diffusion through plasma membrane down a concentration
gradient
• Uptake via ‘Endocannabinoid membrane transporter (EMT)’
▫ Transports cannabinoids from postsynaptic neurons to the
synaptic cleft, where they access CB1 receptors, and into
presynaptic terminals, where 2-AG is metabolised
• Hydrolysis by specific enzymes
▫ Anandamide degraded by Fatty acid amide hydrolase (FAAH)
▫ 2-AG degarded by monoacyl glycerol lipase (MAGL)
28. Released from postsynaptic neurons
↓
Travel backwards across synapses
↓
Activation of CB1 receptors on presynaptic
neurons
↓
Suppression of transmitter release (transient or
long-lasting)
Endocannabinoids as retrograde
synaptic messengers
29.
30. Physiological role & Pharmacological
Effects
The activation of the cannabinoid system through THC ,
phytocannabinoids, synthetic cannabinoids and
endocannabinoids causes numerous actions:
Central Effects
Peripheral Effects
31. Central effects include:
Antinociceptive
Neuroprotection
Alleviation of painful spasms and spasticity
Anti emetic
Regulate food intake and energy expenditure
Effects on Reproductive system
32. Peripheral effects are:
Effect on immune system
Vasodilatation, which is particularly marked on the scleral
and conjunctival vessels
Antiproliferative
Bronchodilatation
Reduction of intraocular pressure
34. Receptors are present at all levels.
Supraspinal :Periaqueductal gray (PAG) , thalamus ,
rostral ventromedial medulla (RVM) :they participate
in descending supraspinal pain modulation
Spinal:Primary afferents neurons at pre- and post-
synaptic sites , dorsal horn , CB1receptors have been
found on interneurons
Peripheral:Cannabinoid CB1 and CB2 receptors are
also found in the DRG, primary afferent
neurons, cutaneous nerve fibers :contribute to
peripheral antinociceptive actions
35. Peripheral pain- ‘Gate mechanism’ along with opioid
peptide.
Regulate pain initiation at the site of injury CB2
receptors (anti-inflammatory)
Interaction with opioid receptors predominantly
acting via kappa, receptors producing antinociception
effect without respiratory depression
36. Neuroprotection
Short-term adaptation to neuronal stress : limiting
excitotoxicity
Longer-term adaptations : enhancing neurogenesis
Decrease excitotoxicity
Direct inhibition of the NMDA receptor
inhibition of presynaptic Ca2+ entry - suppression of
excessive glutamatergic synaptic activity
In neuroinflammation: CB2 receptors are upregulated in
microglia and astrocytes -control the local production of
proinflammatory mediators such as IL-1β &PGs
Role in chronic neurodegenerative Parkinson’s and
Alzheimer’s disease ,multiple sclerosis.
37. Alleviation of painful spasms and spasticity
Affect mediated mainly through CB1 receptors
Release serotonin
Inhibit the synthesis of prostaglandins within the CNS
and elevate brain acetylcholine and reduce its utilization
Clinical implications : Use in Multiple sclerosis ,in phase
III trial
38. Regulation of food and energy intake
Upon stimulation, it increases food intake and weight gain,
promotes lipogenesis.
Reduced levels of leptin associated with elevated levels of
endocannabinoids in the hypothalamus
Leptin reduces food intake by upregulating appetite-reducing
neuropeptides and downregulating appetite-stimulating factors
Potential pathway by which to treat obesity & type 2 diabetes
CB1 antagonists- decrease appetite & causes weight loss -
Rimonabant
39. Anti-Emetic Effects
CB1 ligands act as retrograde synaptic messengers
Post-synaptic neuron releases endocannabinoids-
diffuse back and bind to the pre-synaptic CB1
receptor-reduction of neurotransmitter release -
depolarization-induced suppression of inhibition
(DSI)
40.
41. Effect on reproductive system
In Male
It decreases
Serum Testosterone & Leutinizing Hormone levels
Spermatogenesis and motility (oligospermia)
Blockade of acrosome reaction
In Female
Disruption of menstrual cycle
Decrease in surge of LH levels: inhibiting ovulation
Inhibition of prolactin secretion
Increase the incidence of preterm birth & intrauterine foetal
growth restriction
42. Effects on Immune system
Cannabinoids impair cell-mediated and humoral immunity
in rodents
CB2 receptors :B cells > NK cells > monocytes >
polymorphonuclear neutrophils > CD8 lymphocytes > CD4
lymphocytes
Decreases the proinflammatory mediators :interferon-
gamma ,TNF, IL-1,IL-2 etc
Inhibits differentiation into macrophages & monocytes
Effective against inflammation with a strong Th1 reaction, e.g.
in multiple sclerosis, Crohn’s disease and arthritis
44. Cardiovascular system
Profound decrease in arterial blood pressure, cardiac
contractility, and heart rate :hypotension
Modulation of the autonomic outflow in both the
central and peripheral nervous systems
Direct effects on the myocardium and vasculature
CB1 receptors are present in vascular tissue as well as
the myocardium
45. Antiproliferative effect
Inhibition of proliferation
Immunosuppressant-down regulation of anti tumor
blocking factors
Induction of apoptosis
Inhibition of metastasis & angiogenesis
Prostate cancer,Breast cancer- CB1,Glioma- CB1&CB2
46. Respiratory system:
• Modulating ratio of pro- and anti-inflammation
mediators released by airway epithelial
• Alter contractility through modulation of Ca2+-
entry
Eye- reduces Intraocular pressure
48. Pathological involvement
Abnormalities of endocannabinoid signalling have
been reported in
Neurodegenerative disorders
Hypotensive shock
Advanced cirrhosis of liver
Miscarriage
Malignancy
49. Established Effects
Marino (dronabinol, ∆9-THC)
Approved for use in refractory nausea and vomiting - anti-
neoplastic drugs
Appetite loss in anorexia and cachexia of HIV/AIDS
patients.
Adverse effects: vasodilation/facial flush,Asthenia
Palpitations, tachycardia ,Conjunctivitis, hypotension
Depression, nightmares, speech difficulties,Tinnitus
50. NABILONE
Analogue of D9-THC
Treatment of the delayed stages of emesis
patients who do not respond to existing treatments
used infrequently
Adverse Reactions
drowsiness, vertigo, dry mouth, euphoria, ataxia,
headache, and concentration difficulties
51. Rimonabant
First selective CB 1 blocker
Significant reduction in waist circumference and
improvements in lipid and glycemic profiles
Adverse effects:
Nausea, mood alteration with depressive
symptoms, depressive disorders, anxiety and
dizziness
Banned because of suicidal thoughts
52. Pharmacokinetics
THC is absorbed :digestive and respiratory tract
Oral ingestion absorbed more slowly than smoking.
Terminal half life of THC in plasma ranges from 18 hrs
to 3 days
Highly lipophilic THC and its metabolites (11-OH
THC) are sequestered in the body fat and adipose
tissue
Sixty-five per cent : faeces, 20% : renal excretion.
53. TOLERANCE AND DEPENDENCE
Both occurs only to a minor degree and mainly in
heavy users
Symptoms are similar to those of ethanol or opiate
withdrawal -nausea, agitation, irritability, confusion,
tachycardia and sweating -relatively mild
Psychological dependence does occur with cannabis,
but it is less compelling than with the major drugs of
addiction
54. Adverse effects
Low doses :euphoria and drowsiness, sometimes
accompanied by sensory distortion and hallucinations
In overdose :relatively safe, producing drowsiness and
confusion but not life-threatening respiratory or
cardiovascular depression
In this respect, it is safer than most abused substances
like opiates and ethanol.
58. 1)Modulation of excitatory glutamatergic
transmissions via presynaptic CB1 receptors
2)Modulation of immune responses and the release of
inflammatory mediators by CB1 , CB2, and non CB1
/CB2 receptors on neurons, astrocytes, microglia,
macrophages, neutrophils and lymphocytes
3)Activation of cytoprotective signaling pathways,
such as protein kinase B/Akt or neurotrophic factors
PROPOSED MECHANISMS
59. 4)Modulation of excitability and calcium
homeostasis via effects on Ca2+, Na+ and K+
channels, NMDA receptors, gap junctions, and
intracellular Ca2+ stores
5)Antioxidant properties of cannabinoids
6)CB1 receptor mediated hypothermia, possibly
by reducing metabolic rate and oxygen demand
60. NEUROTRAUMA
Characterized by cerebral edema,
axonal & neuronal injury, increased
permeability of BBB
TBI also triggers glutamate induced
excitotoxicity, oxidative stress, release
of inflammatory cytokines
61. Dexanabinol (HU-211), a behaviorally inactive
cannabinoid and noncompetitive antagonist of NMDA
receptors
CLINICAL TRIAL
A multicenter, double-blind, randomized, placebo-
controlled phase II trial conducted in 67 patients with
severe closed head injury found dexanabinol
EFFECTIVE and also, safe and well tolerated
62. 2% population each year
Preclinical studies
Dexanabinol at doses of 2 to 10 mg/kg
Decreased infarct size and histological damage
and
Improved neurological score in rat and gerbil
models - both global and focal cerebral ischemia
STROKE
63. HUNTINGTON’S DISEASE
Inherited, autosomal dominant, progressive
neuropsychiatric disorder
Motor disturbances, such as chorea (involuntary
movements) and dystonia, psychiatric symptoms, and
dementia
Endocannabinoid signaling in the basal ganglia is hypofunctional
in HD, which probably contributes to the hyperkinesia associated
with the disease
Cannabinoid agonists - therapeutic benefit in HD
anthyperkinetic and
neuroprotective effects
PRECLINICAL STUDIES
Arvanil, a hybrid endocannabinoid and vanilloid compound, was
also reported to alleviate hyperkinesias in a rat model of HD
64. GILLES DE LA TOURETTE’S
SYNDROME
Neurological syndrome - evident in early
childhood and is characterized by multiple motor
and vocal tics
CLINICAL TRIAL
In 24 patients with Tourette’s syndrome, a
randomized double-blind, placebo-controlled
study
THC (5-10 mg) vs placebo
RESULTS
Significant improvement of vocal and motor tics
65. AMYOTROHIC LATERAL SCLEROSIS
Most common motor neuron disease
Effect of cannabinoids against
Oxidative cell damage
Excitotoxicity,
Antispastic effect
PRECLINICAL STUDIES
Transgenic mice experimental model of ALS have
demonstrated that either THC or WIN55,212-2
administered after the onset of the disease delayed
disease progression
66. ALZHIEMER’S DISEASE
Most common cause of dementia in elderly
CLINICAL STUDY
open-label pilot study of six patients in the late stages
of dementia
Treatment with 2.5 mg of dronabinol daily for 2
weeks significantly improved
Neuropsychiatric Inventory total score and
Subscores for agitation and aberrant motor and
nighttime behaviors
67. SCHIZOPHRENIA
Prevalance 0.2 - 2%
Hypoglutamatergic and hypodopaminergic transmission
in the prefrontal cortex is involved in the negative
symptoms,
Whereas hyperactivity of dopamine neurotransmission in
the mesencephalic projections to the nucleus
accumbens may underlie the positive symptoms
Overactivity of the endocannabinoid system may
lead to a hyperdopaminergic and hypoglutamatergic
state, which may underlie some of the symptoms
68. CLINICAL TRIAL
In a trial conducted on 481 patients of
schizophrenia with positive and negative
symptoms, a double blind placebo
controlled study
SR141716 – CB1 antagonist vs placebo
RESULTS
No improvement was seen
69. More than 1% population affected by epilepsy
PATHOGENESIS
Excitotoxicity
CLINICAL STUDY
An epidemiological study found that chronic marijuana use
is protective against seizures
To date, there have been no large-scale, controlled clinical
trials to examine the beneficial effects of cannabinoids in
various forms of epilepsy
EPILEPSY
70. CARDIOVASCULAR & RESPIRATORY
SYSTEMS
CIRCULATORY SHOCK
SR141716 – CB1 receptor antagonist
cardiodepressant and hypotensive effects of
LPS inhibited in animal models of shock
Modulation of β-adrenergic vasodilatation
rather than direct suppression of a direct
vasodilator effect by endocannabinoids
71. ISCHAEMIA REPERFUSION INJURY
Protection mediated by endocannabinoids
acting on CB2 receptors
Anandamide and HU-210 both decreased the
incidence of ventricular arrhythmias and
reduced infarct size through activation of CB2
ATHEROSCLEROSIS
Using the apolipoprotein E knockout mouse
model of atherosclerosis, orally administered
THC significantly inhibited disease
progression
72. ASTHMA
Bronchodilation without side effects was
observed in asthmatic patients after a low
dose (0.2 mg) of nebulized THC
In contrast, aerosols containing larger doses
of THC (5–20 mg) caused paradoxical
bronchoconstriction attributed to local
irritation
Anti-inflammatory properties
73. EYE DISORDERS
GLAUCOMA
THC or marijuana decreased intraocular pressure
whether administered orally, topically, or
intravenously, with no major tolerance to their effect
reported
Decrease aqueous humor production & improve the
uveoscleral outflow by dilating blood vessels of the
anterior uvea
74. LIVER CIRRHOSIS
CB1 receptor blockade with SR141716
Reversed the hypotension and low peripheral
resistance and
Decreased the elevated mesenteric blood flow and
portal pressure - with carbon tetrachloride-induced
cirrhosis
Additional benefits by slowing progression of
cirrhosis
75. RHEUMATOID ARTHRITIS
Ajulemic acid, a potent analog of the acid metabolites of
THC and cannabidiol have been shown to have analgesic,
antiinflammatory, and immunosuppressive effects in
animal models of arthritis
OSTEOPOROSIS
Selective CB2 agonist HU308, attenuated ovariectomy-
induced bone loss and markedly stimulated cortical
thickness through the suppression of osteoclast number
and stimulation of endocortical bone formation
CB2 receptors role in bone remodeling
76. DISEASE MECHANISM OF
BENEFIT
RECEPTORS DRUG EVIDENCE
Traumatic brain
injury
Suppression of
excitotoxicity, anti-
oxidant, anti-
inflammatory
CB1 agonism Dexanabinol Phase II
Stroke Suppression of
excitotoxicity, anti-
oxidant, anti-
inflammatory
CB1 agonism Dexanabinol Preclinical
Huntington’s
disease
Anti-hyperkinetic &
neuroprotective
CB1 , TRPV1
receptors
agonism
Arvanil Preclinical
Gilles de la
tourette’s
syndrome
Improvement of
vocal & motor tics
CB1 agonism THC Phase II
Amyotrophic
lateral sclerosis
Suppression of
excitotoxicity, anti-
oxidant, anti-spastic
CB1 agonism THC,
WIN55,212-2
Preclinical
77. DISEASE MECHANISM OF
BENEFIT
RECEPTORS DRUG EVIDENCE
Alzhiemer’s
disease
Anti-
inflammatory,
neuroprotective
CB1
agonism
Dronabinol Small pilot
study
Schizophrenia Reduce positive
& negative
symptoms
CB1
antagonism
SR141716 Phase II
Epilepsy Reduce
excitotoxicity
CB1
agonism
Marijuana Epidemiologi
-cal study
Circulatory
shock
Modulation of β –
adrenocreceptors
induced
vasodilatation
CB1
antagonism
SR141716 Preclinical
Ischaemia
reperfusion
injury
Reduction of
infarct size
CB2
agonism
Anandamide Preclinical
78. DISEASE MECHANISM OF
BENEFIT
RECEPTORS DRUG EVIDENCE
Atherosclerosis Anti-inflammatory,
anti-oxidant,
immunomodulatory
CB2
receptors
THC Preclinical
Asthma Bronchodilatation,
anti-inflammatory
CB1
receptors
THC Phase II
Glaucoma Decreased aqueous
production,
increased uveoscleral
outflow
CB1
receptors
THC Phase II
Liver cirrhosis Decrease elevated
mesenteric blood
flow and portal
pressure
CB1
antagonism
SR141716 Preclinical
Rheumatoid
arthritis
Analgesic, anti-
inflammtory
CB1 agonism Ajulemic
acid
Preclinical
Osteoporosis Suppression of
osteoclast number
and stimulation of
endocortical bone
formation
CB2 agonism HU-308 Preclinical
80. Pharmacol Rev 58:389–462
Rang and Dale’s pharmacology – 6th
edition
Brazilian Journal of Medical and
Biological Research (2006) 39: 421-429
Pharmacol Rev 62:588–631, 2010
REFERENCES
81. A review of nabilone in the treatment of
chemotherapy-induced nausea and vomiting.Ther Clin
Risk Manag. 2008 February; 4(1): 99–107
Alzheimer's disease; taking the edge off with
cannabinoids?Br J Pharmacol. 2007 November; 152(5):
655–662
Cardiovascular Pharmacology of Cannabinoids.Handb
Exp Pharmacol. 2007; (168): 599–625
Effect of Cannabis sativa component THC on human
reproductive events .Br J Pharmacol. 2008 January;
153(2): 189–198.