Effect of the JRH tetrapeptides on food intake (mean ± S.E.M.) in the wild type and MC4KO littermate mice (n=10–12 per group wild type and n=6 per group for the MC4KO mice). These compounds significantly decreased food intake at the wild type and MC4KO mice (p<0.0001). The tetrapeptide JRH887-9 in the wild type mice, the 0.1, 0.5, and 2.0 nmol doses statistically decreased food intake relative to saline starting at t=5h, t=4h, and t=3h, respectively (*p<0.05). In the MC4KO mice, the 0.5, and 2.0 nmol doses statistically decreased food intake relative to saline starting at t=16 h (***p<0.001). The tetrapeptide JRH322-18 in the wild type mice, the 0.1, 0.5, and 2.0 nmol doses statistically decreased food intake relative to saline starting at t=16h, t=5h, and t=4h, respectively (p<0.05). In the MC4KO mice, the 0.5 and 2.0 nmol doses statistically decreased food intake relative to saline starting at t=24h (p<0.05).