Evidence of a role for GABA in benzodiazepine effects on food preference in rats

It has previously been shown that chronic treatment with the GABA-transaminase inhibitor ethanolamine-O-sulphate (EOS), which elevates brain GABA levels by around 200%, selectivity enhances novel food consumption in rats treated with chlordiazepoxide (CDP) and given a food preference test. To replicate and extend these findings, the effects of two doses of CDP with and without EOS pretreatment were compared with those of EOS or saline alone. EOS alone had no significant effects except to decrease eating rate but, in combination with 2.5 mg/kg CDP, it antagonised the increase in weight of familiar food eaten found with CDP alone and marginally increased weight eaten and duration of novel foot eating episodes. EOS magnified the effects of 5.0 mg/kg CDP to increase markedly the weight eaten and duration of episodes for novel chocolate drops. As no additive effects of EOS and CDP on rate of eating were found, the results are consistent with a facilitation of novel food consumption by an anxiolytic action of the two drugs, rather than by a rate-retarding action which might bias animals toward novel food. Finally, that EOS alone did not mimic the effects of CDP suggests that the role of GABA in the anxiolytic action of CDP may be indirect.