RESUMEN
AIM To study antitumor activity of melatonin in mice and its synergetic effects when MT combined with chemotherapeutic agents cytoxan(CTX). METHODS At a tolerable dose level,MT was administrated singlely or in combination with CTX to treat the transplanted murine solid tumor U 14 . The inhibition of tumor weight were observed. The weight of spleen and the hepatic cells' structure were also be measured. RESULTS The high dosed group of MT(80 mg?kg -1 ?d -1 ,sc) had a certain inhibition on the growth of the U 14 with inhibition rate of 27 1%. The low dosed group of MT(40 mg?kg -1 ?d -1 , sc) and the high dosed one combined with the CTX (25 mg?kg -1 ?d -1 ?1,ip) showed much pronounced than that of solely administration of MT. There was no significant influnce on the weight of spleen and the hepatic cells' structure. CONCLUSIONS The antitumor effect was observed by independent administration of MT. There was a synergism when MT combined with CTX but their toxicities were not obviously enhanced.