MSG ip increased the weight of body fat and induced hyperleptinemia. MSG or NS treatments were performed using intraperitoneal injections (ip) in mice from the first postnatal day (d0) to 14 days, who were called 14MSG or 14NS mice; to 28 days, who were called 28MSG or 28NS mice; or to 56 days, who were called 56MSG or 56NS mice. These selected times are representative of prepuberty, puberty and adulthood, respectively. The epididymal adipose was obtained from each MSG and NS-treated group (A). The leptin levels in the plasma of MSG or NS- treated mice (B). The rate of increased leptin level was assessed using MSG-treated mice compared with the corresponding NS-treated mice and dividing by the leptin concentration of NS-treated mice (C).