Nitric oxide (NO) synthase inhibitors reduce food intake in rodents and chickens, suggesting that NO may stimulate feeding. We used two competitive, non-selective inhibitors of NO synthase (NOS), (NG-monomethyl-L-arginine ester [L-NMMA] and NG-nitro-L-arginine methyl ester [L-NAME]), to evaluate the role of NO mechanisms in the control of food intake in a marsupial model previously used in studies of appetite regulation. Adult male Sminthopsis crassicaudata (n=11-16, 15±0.3 g, mean±S.E.M.) received L-NMMA (50, 100, 200 and 1000 mg/kg), L-NAME (50, 100 and 200 mg/kg), L-arginine (L-arg) the precursor of NO (1000 and 2000 mg/kg), L-NAME (200 mg/kg) in combination with L-arg (2000 mg/kg), or saline (0.9%). All drugs were administered intraperitoneally after 24 h of food deprivation, after which food was immediately made available ad libitum. Food intake was measured 0, 0.5, 1, 2, 4 and 24 h after treatments. In addition, we studied the effect of acute L-NAME administration on hypothalamic, cortical, hepatic and cardiac NOS activity by quantifying citrulline production. L-NMMA (1000 mg/kg) and L-NAME (100 and 200 mg/kg) suppressed food intake by 25%, 21% and 30%, respectively, over 24 h after treatments (P<0.05). L-arg (1000 and 2000 mg/kg) by itself had no significant effect on food intake when compared with saline (P>0.05). When administered in combination with L-NAME (200 mg/kg), L-arg (2000 mg/kg) reversed L-NAME induced suppression of appetite (P>0.05). Furthermore, l-NAME (200 mg/kg) significantly decreased hypothalamic (P<0.01), cortical (P<0.01) and hepatic (P<0.03) NOS activity. L-NAME had no effect on cardiac NOS activity (P>0.05). These data show that peripheral administration of L-NAME has a significant central effect, particularly in brain areas involved in appetite regulation, and suggest in marsupials, as in other mammals and birds, that NO plays a role in the regulation of food intake. Copyright (C) 1999 Elsevier Science Inc.
|Number of pages||7|
|Journal||Comparative Biochemistry and Physiology - C Pharmacology Toxicology and Endocrinology|
|Publication status||Published or Issued - Jun 1999|
- Food intake
- Nitric oxide
ASJC Scopus subject areas