Increased nitric oxide production in eating disorders

Animal studies showed that nitric oxide (NO)/cyclic-GMP (cGMP) pathway is involved in the modulation of eating behavior. To address its role in eating disorders (ED), plasma nitrite and cGMP levels were studied in 50 ED patients (25 with Anorexia Nervosa, AN; 25 with Bulimia Nervosa, BN) and 20 sex- and age-matched controls (C). Nitrites (nmol/mg protein, mean ± S.E.M.: any ED 1.01 ± 0.29; AN 1.15 ± 0.47; BN 0.88 ± 0.36; C 0.25 ± 0.07; p < 0.01) and cGMP (nmol/ml plasma, mean ± S.E.M.: any ED 2.58 ± 0.60; AN 2.81 ± 1.10; BN 2.41 ± 0.70; C 0.11 ± 0.05; p < 0.01) were significantly higher in ED patients than in C. Nitrite and cGMP levels inversely correlated with BMI in AN patients (nitrites: r = −0.62 p < 0.01; cGMP r = −0.45 p < 0.05) but not in BN patients (nitrites: r = −0.15 p = 0.49; cGMP: r = −0.05 p = 0.13) or in control subjects (nitrites: r = 0.11 p = 0.98; cGMP r = 0.37 p = 0.32). Significant correlations were also present in bulimic patients between nitrite levels, frequency of binges and several psychopathological dimensions, as assessed through the EDE. This is the first evidence of an alteration of the NO pathway in ED patients. Further studies are needed to ascertain whether an increase in NO levels plays a possible role in the pathogenesis of ED.