Psychopharmacology (1997) 132 : 104–106

© Springer-Verlag 1997

RAPID COMMUNICATION

Michele Arnone · Jeanne Maruani

Frederique Chaperon · Marie-Helene Thiebot Martine Poncelet · Philippe Soubrie · Gerard Le Fur

Selective inhibition of sucrose and ethanol intake by SR 141716, an antagonist of central cannabinoid (CB1) receptors

Received: 31 January 1997/Final version: 16 March 1997

Abstract SR 141716, a selective central CB1 cannabinoid receptor antagonist, markedly and selectively reduces sucrose feeding and drinking as well as neuropeptide Y-induced sucrose drinking in 141716 also decreases ethanol consumption in C57BL/6 mice. In contrast, blockade of CB1 receptors only marginally affects regular chow intake or water drinking. The active doses of SR 141716 (0.3–3 mg/kg) are in the range known to antagonize the characteristic effects induced by cannabinoid receptor agonists. These results suggest for the first time that endogenous cannabinoid systems may modulate the appetitive value of sucrose and ethanol, perhaps by affecting the activity of brain reward systems.

Key words Sucrose intake · Ethanol consumption

·

Cannabinoid receptor · SR 141716 · Rats · Mice

Introduction

Marijuana (Cannabis sativa) is one of the oldest and most widely used drugs in the world. The major psychoactive ingredient of the marijuana plant is D9tetrahydrocannabinol (D9-THC). By stimulating cannabinoid (CB1) G-protein coupled receptors (Herkenham et al. 1990), natural and synthetic cannabinoid agonists produce their characteristic motor, cognitive and analgesic effects. Cannabinoids have also been reported to possess appetite-stimulating properties in humans

J. Maruani · M. Poncelet (*) · P. Soubrie · G. Le Fur Sanofi Recherche, 371 Rue du Professeur Blayac, F-34084 Montpellier, France

M. Arnone

Sanofi Recherche, Route d’Espagne, F-31000 Toulouse, France

F. Chaperon · M.-H. Thiebot

INSERM U.288, Faculte de Medecine Pitie Salpetriere, 91 Boulevard de l’Hopital, F-75634 Paris, France

(Mattes et al. 1994) and to enhance or exacerbate sucrose consumption in rodents, even when inducing overall anorexia (Sofia and Knoblock 1976; Brown et al. 1977).

Recently, Rinaldi-Carmona et al. (1994) reported that SR 141716 [N-piperidino-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] bound with high affinity to central (CB1) but not peripheral (CB2) cannabinoid receptors and acted as an antagonist against a variety of pharmacological and behavioural cannabinoid effects in rodents. The availability of such a tool, together with the possible existence of an endogenous cannabinoid ligand (anandamide) (Devane et al. 1992), prompted us to study the effect of SR 141716 on appetitive behaviour including spontaneous or neuropeptide Y (NPY)-induced sucrose intake in rats, and ethanol consumption in C57BL/6 mice.

Materials and methods

Standard laboratory conditions

Animals were housed under standard conditions [normal 12-h lightdark cycle (rats) or a reversed light schedule (mice); constant room temperature 21°C] with food and water ad libitum except where otherwise noted. All procedures were approved by the Comite d’Experimentation Animale (Ethical Committee) of Sanofi Recherche.

Spontaneous sucrose feeding

One week prior to the beginning of the experiment, male Wistar rats (210–220 g; CERJ, France) housed eight per cage were placed on a food restriction schedule (13 g standard chow/day per rat). One group were given a small quantity of sucrose pellets (45 mg, Campden) in their home cage to familiarize them with this food. Animals (n = 12 per group) were individually tested in an open-field (76 × 76 × 50 cm) for 30 min daily (4 days) sessions, where they had free access to sucrose pellets and regular rat chow or only regular

105

t

rat chow. The amount eaten by each rat was measured by weighing separately sucrose pellets and chow before and after each session. Animals were given SR 141716 or vehicle intraperitoneally (IP, 0.5 ml/100 g) 30 min before each session.

Spontaneous sucrose drinking

One week prior to testing, male Sprague-Dawley rats (190–210 g; Charles River, France) caged individually were given access to a sucrose solution (5%) in their home-cage during daily 4 h sessions (without food and water). On the day of the test, the amount drunk by each rat (n = 6–8 per group) was measured by weighing each bottle at the start and every hour during a 4-h drinking 141716 or vehicle was given orally (PO, 0.2 ml/100 g) 60 min before the drinking session. As a control, the effect of SR 141716 (PO, 60 min before test) was also studied on water intake (4-h session) after overnight water deprivation.

NPY-induced sucrose drinking

The injection of NPY (2.5 µg/5 µl) or vehicle was made free-hand into the lateral ventricle (ICV) of non-restrained male SpragueDawley rats (120–140 g ; Charles River, France) by means of a 50 µl microsyringe and a 10 mm calibrated needle (final length below the skin:3.5 mm). The experimental conditions were as described above, except that the animals (n = 10–15 per group) were not familiarized with the 5% sucrose 141716 or vehicle was administered (PO) 60 min before NPY.

Ethanol consumption

One week before testing, 8-week-old male C57BL/6 mice (Iffa Credo, France) were singly housed in cages equipped with two bottles of tap water. Then, mice (n = 10–20 per group) were subjected to four daily 6-h test sessions in their home cage, during which they were given free access to one bottle of water and one filled with a 10% v/v ethanol solution. The quantities of water and ethanol consumed were measured by weighing the bottles before and after the 141716 or vehicle was injected by the subcutaneous route (SC, 0.4 ml/20 g) 30 min before each session.

Drugs

SR 141716 (Sanofi Recherche, Montpellier, France) was suspended with 0.1% Tween 80 in distilled water. NPY(1–36) (Neosystem) was solubilized in 0.9% NaCl with 1% bovine serum albumin.

Results and discussion

The results obtained in food-restricted rats show that SR 141716 dose-dependently reduced spontaneous sucrose eating at doses which did not modify regular food intake in the no choice situation (Table 1). Furthermore, upon repeated administration of the highest dose, tolerance developed towards the reduction of regular food intake but not for suppression of sucrose ingestion [during the four daily sessions, quantities (g) of regular chow eaten by control rats were: 3.4 ± 0.3; 3.3 ± 0.3; 2.8 ± 0.2; 2.9 ± 0.2 while for rats

)

u

d

5

l

e t

o1

s =
n y o r	,
l c o u n	g 7
S a	. 0	e
. h n t	±	c i
e o	9 .	m
i s r 3		(
o e s r e y t	k n u	n o i t p m u s n o c l o n a h t E
l 3bd
O Y U O m e a r	a s

r e t

a w

l o

e

r t

k

n

o at

C .E

n o i t u l o s l o n a h t E

l

e

,

o

r

e

r

e

s

t

o w 0

c

d

c

u

e

(

s

t

n

V

f

e

s

C

I

e

s

r

• p d

o
a • o . • j

P

M ~bN

o

e

i

±

t

g

s

f

s

n

a

n

i

e

a

r

s

h

e

m d2~

i

d

e

a

d

Yo°:d

u

n

o

a

m

i

f

t

s

a

m

e

D 0 3

t

3

.

t

g

e

a

a

c

n

i

i

r

e

k

e

r

m

n

r > 0 3

o

u

t

n

r

s

p

e

c

a

s

u

e

m

e

s

r

u

m

p

s

d

e

n

e

e

r

c

c w d o

t

• e,T

w

4

d

.

o

n

n

h

g

a

o

c

n

i

i

s

s

r

r

t

s

a

u

e

a

l

r

s

d

u

t

g

n

s

h

e

i

e

g

n i

d

k

e

n

c

i

r

u

d

d

n

e

i

s

-

o

• c

a w

l o

e

r t

k

O at

C .E

n

o i t

u l

o s

e s o r c

u S

r

a l u g e r

e

r

l o r t

w

n

o o

C hc

l
Y o 4

t

f

n

n

a

a

i

o

r

e

c

d

e

s

te

o a

•   ~ E

t

r

s

e

u

e

n

l

s

l

o

e

e

a

r

e

p

6

e

1

m

e

w

7

s

~o~k

~ w 0

S

n

s

r

u

fo d 3

g

e

c

t

wb3~

o

n

s

n

a

e

e

l

a

r %p0Y

T e •~ E

) s t a r (

e k a

t n i e s o r c u S

orf

l

c

le u

p

S

) ) ) 71   21 11 1 .   .   . 00000 00000 (((((331		) ) 3 ..	0
			= )5 5 , 4 S wN
+I +I +I +I
	±±±±±11163..... 1 1 1
1 1
) ) ) ) ) 00000 3 11 21 1( (( (( 5 . 5 * * * * = p 22 21 2.....0 ) 0 . 5 0 5 , 00   00±±±±±49310.....11111 < 4 ( F P
) ) ~ 000 54
††††427 9
..   . .0 1 10 +I +I +I ± ± ± ± 1 1 - 'Io N 6 2 .   .   .   .
1 3 8 4
) ) ) )
7 7 7 8 0 ( ( ( (
=
	cJ1.0		) 5
±	± ± ±		2
6	9 5 4		, 3 S	n
06	. ~o ~6 8		wN	n u
				D (
8			7	Y P N
(	(((****		) 1 .1(	s
			6	v
	89 .   ... 109			1
	=03 25   2)		0.	0
±				. 0
	2 ± ± ±
3				<
	02,3<( 16. 4
0	..   . 1~o r 8768FP12			P
				†
				†
				5
				0 . 0
1 (	6))))5.22220 1 1 1 ( ((			< s i s P y †lrao
2	= 2 33			n a
	.. .. ) 000 44			e l c
	+I +I   • ±± ±±   ,3			Y
O .	M O O MCon S9939(. . .			e n v
N 2	3 MNN wz 2 2 F N			i
				s d v e 1 d
				0 u
				. 0 U
) N 2	) ) ) N N N 2 2 2 3			n i <
1 (	1 1 1 9 ( ( (			n P
	. 72 * * * *			e * e *
				b
	* * = 00 N 7 2 2 4
4 .				; 5 e
	.   .   . ) 0 0 0 0
0 0				v 0 .
	. 4 0 4 ± ± ±
±				a 0
1	, 3 < 1 6 0			h <
.	.   .   .			) 5
3	1 1 2			1 P
				* =

		; n
		s ( l
6		a s t m a i r n a e n f o :-. a r s
1 7	A	E0
1	V
4 g	O	0 n
1 k /		o
g R m S	1N 3 . .3A100 0	) C n ( a

106

given SR 141716 at 3 mg/kg the corresponding values were 1.8 ± 0.3 (P < 0.01); 1.9 ± 0.2 (P < 0.01); 3.3 ± 0.3 (NS); 2.9 ± 0.3 (NS)]. In food non-restricted rats, the intense sucrose drinking that occurs after 1 week of habituation was markedly and dose-dependently reduced by SR 141716 (Table 1); in contrast, in waterdeprived rats, water drinking was not affected by SR 141716. Together, these findings show that blockade of CB1 receptors produced an elective and almost complete suppression of spontaneous sucrose intake in both solid and liquid forms and in both Wistar and SpragueDawley rat strains. This cannot be accounted for by SR 141716-induced enhanced neophobia, since rats were tested after habituation towards sucrose pellets or sucrose solution. As shown in Table 1, SR 141716 (which is devoid of affinity for NPY1 receptors) antagonized the enhancement of sucrose ingestion induced by NPY, a neuropeptide the excessive function of which has been associated with abnormal feeding behaviour and obesity (Erickson et al. 1996). Although the density of CB1 receptors in hypothalamus is not as high as that found in other brain areas (Herkenham et al. 1990), the results suggest that a reduction in NPYhypothalamic function could be one of the mechanisms involved in the suppression of sucrose craving associated with the blockade of CB1 receptors. Whatever the mechanisms involved, these observations are consonant with the reported ability of D9-THC and derivatives to enhance the preference for sweet calories (Sofia and Knobloch 1976). This, together with the fact that the doses of SR 141716 active in the present study are in the range known to block the characteristic in vivo effects of cannabinoid receptor agonists (RinaldiCarmona et al. 1994 ; Perio et al. 1996), supports the notion that an endogenous cannabinoid tone could operate to intensify the incentive properties of sucrose. A similar hypothesis has been proposed for chocolate craving following the discovery of the presence of anandamide in chocolate (di Tomaso et al. 1996). Remarkably, SR 141716 also selectively and significantly reduced ethanol ingestion in C57BL/6 mice (Table 1), a strain known for its genetic predisposition for ethanol consumption (Ng and George 1994). This antagonism was found in the 0.3–3 mg/kg dose range, was maintained upon repeated administration, and was observed whether mice were naive (not shown) or familiarized towards ethanol. In this strain of mice, water intake was not modified by SR 141716 up to 3 mg/kg (Table 1). These results suggest that endogenous

cannabinoid tone also plays a critical role in the control of ethanol intake.

In conclusion, the results obtained on both sucrose intake and ethanol consumption suggest for the first time that the activation of an endogenous cannabinoid system may alter the appetitive value of ingested substances an hypothesis consistent with the evidence in favor of a facilitatory effect of cannabinoid agonists on brain reward circuits (Gardner and Lowinson 1991; Trojniar and Wise 1991). Thus, cannabinoid receptor antagonists may have potential for the treatment of carbohydrate craving and ethanol abuse.

References

Brown JE, Kassouny M, Cross JK (1977) Kinetic studies of food intake and sucrose solution preference by rats treated with low doses of delta-9 tetrahydrocannabinol. Behav Biol 20:104–110

Devane WA, Hanus L, Breuer A, Pertwee RG, Stevenson LS, Griffin G, Gibson D, Mandelbaum A, Etinger A, Mechoulam R (1992) Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science 258:1946–1949

diTomaso E, Beltramo M, Piomelli D (1996) Brain cannabinoids in chocolate. Nature 382:677–678

Erickson JC, Hollopeter G, Palmiter RD (1996) Attenuation of the obesity syndrome of ob/ob mice by the loss of neuropeptide Y. Science 274:1704–1707

Gardner EL, Lowinson JH (1991) Marijuana’s interaction with brain reward systems: update 1991. Pharmacol Biochem Behav 40:571–580

Herkenham M, Lynn AB, Little MD, Johnson MR, Melvin LS, DeCosta BR, Rice KC (1990) Cannabinoid receptor localization in brain. Proc Natl Acad Sci USA 87:1932–1936

Mattes RD, Engelman K, Shaw LM, Elsohly MA (1994) Cannabinoids and appetite stimulation. Pharmacol Biochem Behav 49:187–195

Ng GYK, George SR (1994) Dopamine receptor agonist reduces ethanol self-administration in the ethanol-preferring C57BL/6J inbred mouse. Eur J Pharmacol Mol Pharmacol 269:365–374

Perio A, Rinaldi-Carmona M, Maruani J, Barth F, Le Fur G, Soubrie P (1996) Central mediation of the cannabinoid cue: activity of a selective CB1 antagonist, SR 141716A. Behav Pharmacol 7:65–71

Rinaldi-Carmona M, Barth F, Heaulme M, Shire D, Calandra B, Congy C, Martinez S, Maruani J, Neliat G, Caput D, Ferrara P, Soubrie P, Breliere JC, Le Fur G (1994) SR 141716A, a potent and selective antagonist of the brain cannabinoid receptor. FEBS Lett 350:240–244

Sofia RD, Knoblock LC (1976) Comparative effects of various naturally occurring cannabinoids on food, sucrose and water consumption by rats. Pharmacol Biochem Behav 4:591–599

Trojniar W, Wise RA (1991) Facilitatory effect of D9-tetrahydrocannabinol on hypothalamically induced feeding. Psychopharmacology 103:172–176