The effects of acute multiple intraperitoneal injections of the GABAB receptor agonist baclofen on food intake in rats

This study was undertaken to examine the effects of acute repeated administration of the GABAB receptor agonist baclofen on food intake in rats. In Experiment 1, the effects of repeated intraperitoneal (i.p.) injections of the GABAB receptor agonist baclofen (1 and 2 mg/kg) at 2 h intervals were investigated on food intake in non-deprived male Wistar rats. Both doses of baclofen significantly increased food intake after the 1st injection (P < 0.05), but had no effects on intake following the 2nd and 3rd injections. By contrast, in Experiment 2, diazepam (1 and 2 mg/kg, i.p.) significantly increased food intake (at least, P < 0.05) after each of 3 injection separated by 2 h in non-deprived rats. These data show that tolerance occurs to the hyperphagic effects of baclofen with acute multiple injections, and may have important implications for future studies investigating the effects of GABAB receptor agonists on food intake and energy homeostasis.