F. Squadrito et al., CENTRAL SEROTONINERGIC SYSTEM INVOLVEMENT IN THE ANOREXIA INDUCED BY N-G-NITRO-L-ARGININE, AN INHIBITOR OF NITRIC-OXIDE SYNTHASE, European journal of pharmacology, 255(1-3), 1994, pp. 51-55
The effects of N-G-nitro-L-arginine, an inhibitor of brain nitric oxid
e (NO) synthase, on central serotoninergic system were studied in male
obese Zucker rats and in their lean age-matched controls (FA/?;FA/FA)
, both groups aged 14 weeks. Acute injection of N-G-nitro-L-arginine (
50 mg/kg i.p.) or repeated administration of N-G-nitro-L-arginine (50
mg/kg i.p. daily, for 7 days) reduced food intake and body weight in o
bese rats. Acute administration of N-G-nitro-L-arginine reduced food i
ntake in lean rats. However, lean rats showed tolerance to the N-G-nit
ro-L-arginine effects after repeated administration. N-G-Nitro-L-argin
ine administration significantly increased serotonin metabolism in the
cortex, diencephalon and medulla-pons of obese Zucker rats after eith
er acute or repeated administration of N-G-nitro-L-arginine. In contra
st, N-G-nitro-L-arginine increased serotonin metabolism in lean rats o
nly after acute administration, and the appearance of tolerance to N-G
-nitro-L-arginine anorectic effects paralleled the failure of N-G-nitr
o-L-arginine to increase serotonin metabolism. The present data extend
our previous findings indicating that N-G-nitro-L-arginine possesses
anorectic activity in obese Zucker rats, and clearly suggest that the
central serotoninergic system mediates the anorexia induced by inhibit
ors of brain NO synthase.