Impact of sex, fat distribution and initial body weight on oxytocin's body weight regulation.

Obesity is considered as a worldwide problem in both males and females. Although many studies have demonstrated the efficiency of oxytocin (Oxt) as an anti-obesity peptide, there is no comparative study of its effect in males and females. This study aims to determine factors (sex, initial body weight, and fat distribution) that may affect the ability of Oxt to regulate body weight (BW). With regard to sex, Oxt reduced BW similarly in males and females under both high fat diet (HFD) and standard chow-fed condition. The BW reduction induced by Oxt correlated with initial BW in male and female mice under HFD conditions. Oxt showed an equal efficacy in fat degradation in both the visceral and subcutaneous fat mass in both males and females fed with HFD. The effect of Oxt on BW reduction was attenuated in standard chow-fed male and female mice. Therefore, our results suggest that administration of Oxt is more effective in reducing BW in subjects with a high initial BW with increased fat accumulation. The present data contains important information for the possible clinical application of Oxt for the treatment of obesity.