NDP-α-MSH induces diuretic and natriuretic responses that are blocked with the MC3/4 receptor antagonist SHU9119.

(A) Time course of weight change after an intraperitoneal (i.p.) injection of saline and NDP-α-MSH (0.3 mg/kg). The values are based on a change from pretreatment weight. n = 7 per group. (B) Dose-dependent effects of NDP-α-MSH on body weight. Mice were weighed 2 hours after the injection. (C) Effect of a selective MC3/4-R antagonist (SHU9119) on NDP-α-MSH-induced diuresis. SHU9119 (1 mg/kg i.p) was given 30 min prior to administration of NDP-α-MSH (0.3 mg/kg i.p.). (D–F) 24-hour urine volume and urinary excretion of sodium (U N_aV) and potassium (U _KV) in control, NDP-α-MSH-treated and SHU9119-pretreated mice. The number of mice analyzed is shown in the graphs. Data are mean ± SEM. ** P < 0.01 versus saline, # # P < 0.01 versus NDP-α-MSH.