PMC

A) effect of SR141716A (0, 0.1, 1.0 and 3.0 mg/kg, i.p.) on responses for food; B) effect of SR141716A (0, 0.1, 1.0 and 3.0 mg/kg, i.p.) on anxiety, expressed as latency to emerge a defensive withdrawal behaviour. The figures represent a re-analysis of the data previously published . The half maximal effective concentration (EC₅₀) is 2.2 mg/kg and 2.3 mg/kg for food inhibition and induction of anxiety behavior, respectively.

Administration of ghrelin (0.5 µg, i.c.v.) increased food intake in free feeding animals. A) The subeffective dose of SR141716A (0.03 mg/kg, i.p) counteracted ghrelin-induced orexigenic effect. As expected, the ultra-low dose of SR141716A showed no effect on food intake in vehicle-treated animals. B) Pretreatment with LH-21 (3 mg/kg, i.p.) counteracted the increase in food intake induced by ghrelin and had no effect in vehicle-treated rats. Data are means ± SEM of 6–10 determinations per group. Different from vehicle-injected rats: *P<0.05. ***P<0.001; different from ghrelin treatment: ^# P<0.05, ^## P<0.01, ^### P<0.001.

Free-feeding animals (n = 9 in each group) had free access to standard pellets of food; fasted rats (n = 9 in each group) were totally deprived for food during 24 h before the experiment; and chronic food-restricted rats (n = 9 in each group) were limited daily for food intake until body weights reached 80% of free-feeding values (20–25 days). The amount of ingested food in vehicle-injected animals was higher in the food-restricted group, following by the fasted group and free feeding rats, respectively. Ghrelin administration induced hyperphagia at any dose tested exclusively in animals fed ad libitum. No effect of ghrelin administration was observed in fasted or food-restricted animals. Data are means ± SEM of accumulated food intake. Different from free feeding vehicle-injected rats: ^###P<0.001. Different from fasted vehicle-injected rats: ^£££P<0.001. Different from vehicle-injected rats in the same condition (free feeding): *P<0.05. **P<0.01. ***P<0.001.