The effects of N-G-nitro-L-arginine, an inhibitor of brain nitric oxide (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 obese rats. Acute administration of N-G-nitro-L-arginine reduced food intake in lean rats. However, lean rats showed tolerance to the N-G-nitro-L-arginine effects after repeated administration. N-G-Nitro-L-arginine administration significantly increased serotonin metabolism in the cortex, diencephalon and medulla-pons of obese Zucker rats after either acute or repeated administration of N-G-nitro-L-arginine. In contrast, N-G-nitro-L-arginine increased serotonin metabolism in lean rats only after acute administration, and the appearance of tolerance to N-G-nitro-L-arginine anorectic effects paralleled the failure of N-G-nitro-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 inhibitors of brain NO synthase.
CENTRAL SEROTONINERGIC SYSTEM INVOLVEMENT IN THE ANOREXIA INDUCED BY N-G-NITRO-L-ARGININE, AN INHIBITOR OF NITRIC-OXIDE SYNTHASE
SQUADRITO, Francesco;CALAPAI, Gioacchino;ALTAVILLA, Domenica;CUCINOTTA, Domenico Maria;ARCORACI, Vincenzo;CAMPO, Giuseppe Maurizio;CAPUTI, Achille
1994-01-01
Abstract
The effects of N-G-nitro-L-arginine, an inhibitor of brain nitric oxide (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 obese rats. Acute administration of N-G-nitro-L-arginine reduced food intake in lean rats. However, lean rats showed tolerance to the N-G-nitro-L-arginine effects after repeated administration. N-G-Nitro-L-arginine administration significantly increased serotonin metabolism in the cortex, diencephalon and medulla-pons of obese Zucker rats after either acute or repeated administration of N-G-nitro-L-arginine. In contrast, N-G-nitro-L-arginine increased serotonin metabolism in lean rats only after acute administration, and the appearance of tolerance to N-G-nitro-L-arginine anorectic effects paralleled the failure of N-G-nitro-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 inhibitors of brain NO synthase.Pubblicazioni consigliate
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