N-G-NITRO-L-ARGININE METHYL EATER REDUCES STRESS-RELATED FEEDING IN THE RAT TAIL-PINCH MODEL

A possible role of nitric oxide (NO) in stress-related feeding was inv estigated in male rats using the tail-pinch (TP) model, in within-subj ects experimental designs. An initial experiment demonstrated a dose-r elated reduction in TP-induced solid food intake over a 10-min test pe riod with increasing dose (10, 25, and 50 mg/kg SC) of the NO-synthase (NOS) inhibitor, N-G-nitro-L-arginine methyl ester (L-NAME), reaching statistical significance at 25 mg/kg L-NAME when compared to vehicle control (p < 0.05). Pattern analysis further revealed a decrease both in total duration of food-directed oral behavior and in percentage of longer duration (> 60 s) oral behavior bouts with increasing dose of L -NAME; both measures reached statistical significance at 50 mg/kg (p < 0.01). Pretreatment with 500 mg/kg of the NO precursor, L-arginine (L -arg), resulted in partial but not significant reversal of the attenua ting effect of 25 mg/kg L-NAME on food intake. Latency to begin eating or gnawing was not significantly affected by L-NAME. In a subsequent experiment, L-arg alone (500 and 750 mg/kg) did not significantly alte r TP-induced food intake. It is cautiously suggested that these result s implicate involvement of NO in TP-induced feeding. (C) 1998 Elsevier Science Inc.