Repeated intraperitoneal administration of the GABAB receptor agonist baclofen reduces body weight in the mouse.

Chronic intraperitoneal (ip) administration of the GABAB receptor agonist baclofen has been shown to reduce body weight in rats without significantly affecting daily food intake. The present study was undertaken to extend these observations to another rodent species. Male C57B/10 mice (n=27) that had free access to food and water were injected once daily for 15 days with either saline or baclofen (4 or 8 mg / kg; i.p). Body weight and food intake were measured 24h after each injection. Statistical analysis of the results revealed that the 4 mg / kg dose of baclofen significantly reduced body weight gain in the mice during the first 5 days while the 8 mg / kg dose reduced body weight gain throughout the 15 days of the study when compared with saline control animals (F(2,21)=4.88, P<0.02). Baclofen (4 or 8 mg / kg) generally had no significant effects on daily 24h food intake except on days 1 and 2 when the 8 mg / kg dose produced small but significant decreases in food intake (P<0.05) that were probably due to the initial depressant effects of the drug on behaviour. The results of this study extend previous findings in rat to another rodent species and show that systemic administration of the GABAB receptor agonist baclofen reduces body weight gain in the mouse without affecting daily food intake. These results lend further support to the hypothesis that GABAB receptor agonists decreases body weight by increasing metabolic rate.