The benzodiazepine partial receptor agonist, bretazenil, provokes a strong hyperphagic response: a meal pattern...

In this report we characterize the effects of the benzodiazepine receptor partial agonist bretazenil (0.1-3mg/kg) on meal patterning and satiety sequences of male rats. Experiment 1 indicated that bretazenil (0.3-1.0mg/kg) doubled the size of the first meal; there was no concurrent increase in feeding rate and effects on water intake were smaller. Experiment 2 showed that the benzodiazepine receptor antagonist ZK93426 (10mg/kg) blocked this effect on meal size; in addition ZK93426 reduced water intake in the first 2h following drug administration, which we attribute to its weak inverse agonist action. Experiment 3 examined satiety sequences after bretazenil treatment. Food intake and feeding behaviour were enhanced; in the following behavioural sequence, active and grooming behaviour patterns were reduced and resting was greatly increased. The data are discussed in relation to current theories of benzodiazepine action on food intake and the processing of taste stimuli.