UNIVERSITA'di
BOLOGNA
S. ORSOLAMALPIGHI
LA CANAPA E LO STIMOLODELLA FAME:
STORIA DI AGONISMI ED ANTAGONISMI
Dr. Uberto PagottoUnità Operativa di Endocrinologia
Dip. Medicina Int. e GastroenterologiaOspedale S.Orsola-Malpighi
Bologna
The first written evidence of medical use of cannabis
sativa comes from China some 5000 years ago
The drug was introduced in
Europe by Napoleon
Bonaparte’s troops when
returning from Egypt Nowadays marijuana and its
derivatives have become the
most widely consumed illegal
drugs in western countries
1964 isolation of 9-THC (Gaoni and Mechoulam)
The discovery of Cb receptors and their endogenous ligands
suggested the existence of an
Endogenous Cannabinoid System
Both receptors belong to the G protein coupled receptor superfamily
Ion channels
Adenylate-cyclase
Intracellular signal-regulated kinases
1990 cloning of cannabinoid
receptor 1 (Cb1Cb1) (Matsuda et al.)
1993 cloning of a second cannabinoid
receptor (Cb2Cb2) (Munro et al.)
1992 purification of anandamideanandamide,
the first endogenous cannabinoid (Devane et al.)
Cb1 ligands
9-THC
Classical cannabinoids
8-THCCannabinolCannabidiolHU 210
Non classical cannabinoids CP-55,940CP-55,940
Aminoalkylindols WIN-55,212
Endocannabinoids Anandamide
2-Arachidonylglycerol
Cb1 selective Cb1 selective antagonistsantagonists
SR 141716A
AM 630
D9-TetrahydrocannabinolO
OH1964 O
OHNH
Anandamide
1992
CB1
1990
FeedingFeeding
NeuroprotectionPain perception
Locomotion
Rewarding
ThermoregulationBlood pressure
Sleep Learning & Memory
Antitumoral activity
Hormones modulation
Anorexigenic peptidesAnorexigenic peptides
• Corticotrophin-releasing hormone (CRH)
• -melanocyte-stimulating hormone (-MSH)
• Cocaine-and amphetamine regulated transcripts (CART)
Orexigenic peptidesOrexigenic peptides• Neuropeptide Y (NPY)
• Agouti-related protein (AgRP)
• Melanin-concentrating hormone (MCH)
• Orexins (Hypocretins)
• Ghrelin
Amygdala Hippocampus
Reward
GABA
DOPA DOPA
D2-R
HypothalamusVentral tegmental
region Nucleus Accumbens
Reward
enkephalin
enkephalin
DOPA
GABA
DOPA5-HT
D2-R
Blue: excitatory neurons Red: inhibitory neurons
Substantia Nigra
Role of Reward System in feeding behavior in the
mesocorticolimbic pathaways
IN 1985, THE USE OF 9-THC (DRONABINOL) WAS APPROVED BY FDA FOR TREATMENT OF
CANCER-CHEMOTHERAPY INDUCED NAUSEA AND VOMITING REFRACTORY TO OTHER
AGENTS
Number of subjects
8 Marijuana- placebo
9 Placebo- marijuana
Average gain during Marijuana
week
Average loss during Placebo
week
0.69
0.39
2.10
1.11
Average weight loss or gain during placebo and treatment periods with 9-THC (2.5 mg or 5.0 mg per os, twice per day, for 2 weeks)
Regelson et al.
IN 1992, DRONABINOL WAS THE FIRST DRUG IN 1992, DRONABINOL WAS THE FIRST DRUG APPROVED BY FDA FOR THE TREATMENT OF APPROVED BY FDA FOR THE TREATMENT OF
ANOREXIA AND WEIGHT LOSS IN AIDS PATIENTS...ANOREXIA AND WEIGHT LOSS IN AIDS PATIENTS...
Mean change in weight from baseline, evaluable AIDS patients
Mean change in weight from baseline, evaluable AIDS patients. Excludes
patients with moderate, severe, or life-threatening drug- nonrelated adverse
events
Beal et al, 1995Beal et al, 1995
Mea
n W
eigh
t ch
ange
(K
g)
Dronabinol
Placebo
-0.5
0.0
-0.1
-0.2
-0.3
-0.4
0.2
0.1
0.3
Day 0 Day 14 Day 28 Day 42
Mea
n W
eigh
t ch
ange
(K
g)
Day 42-0.5
0.5
0.0
1.0
1.5
Day 0 Day 14 Day 28
Dronabinol
Placebo
STUDIES SUPPORT LONG-TERM, SAFE USE OF DRONABINOL FOR ANOREXIA AND CACHEXIA IN
AIDS PATIENTS
10
20
30
40
% p
atie
nts
wit
h a
t le
ast
2Kg
BW
gai
n
1 6 12
month
*
Dronabinol 2.5mg os
Placebo
(Beal et al., 1997)
DRONABINOL WAS TESTED ALSO IN ALZHEIMER PATIENTS
15 PATIENTS WERE TREATED FOR 6 WEEKS WITH PLACEBO AND 6 WEEKS WITH DRONABINOL
THE RESULTS WERE…..”BODY WEIGHT OF STUDY SUBJECTS
INCREASED MORE DURING THE DRONABINOL TREATMENT
THAN DURING THE PLACEBO PERIODS..”
Volicer L et al. 1997
9-THC +SRSR141716
2-h
ours
foo
d in
tak
e (g
)
2
4
6
8
***
*
†††
10
0 0.05 0.1 0.5 1
SR141716 mg/Kg s.c.
******
Reversal of 9-THChyperphagia in pre-fed rats by CB1 selective antagonist SR141716 (Williams et al, 2002)
Hyperphagia in pre-fed rats following oral 9-THC
(Williams et al, 1998)
8
2
4
6
0
2-h
ours
foo
d in
tak
e (g
) *
*
0.06
3
0.12
5
0.25 0.5 1 2
*
9-THC mg/Kg
The selective Cb1 antagonist, SR 141716A, reduces dose-dependently sucrose and ethanol intake in rodents
Arnone et al, 1997
SR 141716
Sucrose pellets
(rats)
Sucrose solution
(rats)
NPY-induced sucrose drinking
(rats)
Ethanol solution
(mice)
vehicle 3.1 0.4 28.3 5.0 8.1 1.7 1.9 0.1
0.3 mg/Kg 2.1 0.2 16.1 3.9 3.6 1.2† 1.3 0.2
1 mg/Kg 1.6 0.2** 7.4 2.8** 1.2 0.4†† 1.1 0.2**
3 mg/Kg 1.0 0.4** 8.6 2.9** n.d. 1.0 0.2**
If you want a knockout...
The conditional mutagenesis
CRE/lox P system
Gene targeting
Feeding behavior
CB1 Null-mutation
Breeding
CB1+/+ CB1-/-
Age (week)2 4 6 8 10 12 14 16
bod
y w
eigh
t (g
)
5
10
15
20
25
30
*
** * * * * *
* *
CB1-/- mice show decreased body weight and reduced fat mass
60
65
70
75
Lean mass
*
Fat mass
% o
f b
ody
wei
ght
5
10
15
CB1+/+
CB1-/-
**
% o
f b
ody
wei
ght
T T
T
T
B
B
CB1+/+
CB1-/-
Cota D. et al., J Clin Invest 2003
CRH/PVN
a
*
CART/PVN
b
CB1 transcripts are co-localized with mRNAs of hypothalamic neuropeptidesCB1 transcripts are co-localized with mRNAs of hypothalamic neuropeptides
Pre-pro-orexin/LHA
c
*
MCH/LHA
d
Cota D. et al., J Clin Invest 2003
Age (week)3 4 5 6
Cal
oric
inta
ke
(kca
l/d
ay)
5
10
15 YoungCB1+/+ CB1-/-
CB1CB1-/--/- lean phenotype is principally related to the decreased caloric intake lean phenotype is principally related to the decreased caloric intake
20 21 22
5
10
15
20
25
30
Cal
oric
inta
ke
(kca
l/d
ay)
Age (week)
AdultCB1+/+ CB1-/-
Bod
y w
eigh
t (g
)
5
10
15
20
25
Age (week)3 4 5 6
** * *** * **** *** *** ** *
† † † † † † † †† † † † †CB1+/+ pair-fed
CB1+/+ CB1-/-
20 21 2215
20
25
30
35
40
45
Age (week)
* * * * * * * * * * * * * * * * * *
Bod
y w
eigh
t (g
)
Cota D. et al., J Clin Invest 2003
0
100
200
300
400
CT WIN WIN+SR SR
LP
L a
ctiv
ity
(%
of
con
trol
) *M CB1
+/+
Actin
1.0
0.5CB1
CB1
-/-
NC NC
Hip
poH 2
O
White adipose tissue may represent White adipose tissue may represent a novel peripheral target for a novel peripheral target for
cannabinoid actioncannabinoid action
Cota D. et al., J Clin Invest 2003
We confirm that the cannabinoid system is strongly involved in the body weight regulation
I conclusions
• CB1ko mice are lighter and leaner than their wt controls
• CB1ko mice are not different in energy expenditure, body temperature and locomotor activity from their
wt controls
• Pairfeeding studies using young animals indicate a main role of central orexigenic drive in body weight
regulation, however in adults also a food-intake-independent mechanism contributes to the lean
phenotype
•Higher expression of CRH mRNA in PVN of CB1ko mice fed ad libitum,lower expression of CART mRNA in LHA and DMN of CB1ko mice fed ad libitum
• CB1 is expressed in adipose tissue and stimulates lipogenesis
•CRH, CART, Pre-pro-orexin, MCH co-expression and CB1have been found in hypothalamus of wt fed ad libitum
We confirm that the cannabinoid system is strongly involved in the body weight regulation
II conclusions
Endogenous Cannabinoid System seems to be an ideal target for the treatment of eating disorders and obesity
Hypothalamic action of CB1 antagonists
may modulate neuropeptide network controlling food intake
CB1 antagonists acting in the limbic
system may decrease the rewarding
property of food
Blockade of gastroenteric CB1
might contribute to the therapy by
modulating feeding-related peripheral
signals
Anti-obesity action Anti-obesity action of CB1 of CB1 antagonists
could involve could involve metabolic processes metabolic processes and directly target and directly target
adipose tissueadipose tissue
The cannabinoid system is involved in several physiological functions and
might be related to a general stress-recovery system.
Such a variety of effects was concisely summarized by a recent statement by Di Marzo:
Di Marzo et al. Trends Neurosc, 1998
“…..FEEL LESS PAIN, CONTROL YOUR MOVEMENT,
RELAX, EAT, FORGET, SLEEP AND PROTECT.”