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The effect of chronic administration of the GABA-B receptor agonist baclofen on body weight and plasma leptin levels in rats Leptin is released from white adipose (fat) tissue in direct proportion to body fat mass and acts in the hypothalamus to regulate long term energy homeostasis (see Patel and Ebenezer, 2008). We have previously reported that chronic administration of baclofen (bac) reduces body weight gain in rats (Patel and Ebenezer, 2010). In the present study we investigated the effects of chronic administration of bac on body weight and plasma leptin levels in rats. Adult male Wister rats (n = 16; starting body weights: 280 – 340 g) were divided into 2 equal groups and injected i.p. with either saline (Group 1) or bac (4 mg kg-1; Group 2) on a daily basis for 28 days. Daily body weight for each rat was recorded and expressed as the percentage change relative to average body weight recorded on the 2 days preceding treatment Day 1. At the end of the study (24h after the last injection) the rats were sacrificed by cervical dislocation and trunk blood collected in EDTA tubes and centrifuged at 556 g for 15 min to separate the plasma. Leptin levels were determined using the Bio-Plex Pro diabetes multiplex assay. The body weight data were analysed by ANOVA with post-hoc Dunnett’s test and the leptin data by the Student’s t-test. In agreement with previous results (Patel and Ebenezer, 2010), chronic administration of bac reduced body weight gain (Fig. 1A). Plasma levels of leptin were also significantly lower in the rats chronically treated with bac (Fig. 1B). 
These results suggest that chronic administration of bac decreases white fat mass which is reflected by a reduction in plasma levels of leptin. Further studies on the mechanism by which bac affects white fat and plasma leptin levels are warranted. Patel, J.D. and Ebenezer, I.S. (2010). Eur. J. Pharmacol. 580, 143 – 152. Patel, S.M. and Ebenezer, I.S. (2010). Eur. J. Pharmacol. 635,129-34 The study was supported by the European Union InterReg TransChannel Neuroscience Network.
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