, Volume 187, Issue 2, pp 138–142 | Cite as

An operant determination of the behavioral mechanism of benzodiazepine enhancement of food intake

  • E. O’HareEmail author
  • E-M. Kim
  • K. J. Tierney
Original Investigation



A recent review paper by Cooper (Appetite 44:133–150, 2005) has pointed out that a role for benzodiazepines as appetite stimulants has been largely overlooked. Cooper’s review cited several studies that suggested the putative mechanism of enhancement of food intake after benzodiazepine administration might involve increasing the perceived pleasantness of food (palatability).


The present study examined the behavioral mechanism of increased food intake after benzodiazepine administration.

Materials and methods

The cyclic-ratio operant schedule has been proposed as a useful behavioral assay for differentiating palatability from regulatory effects on food intake (Ettinger and Staddon, Physiol Behav 29:455–458, 1982 and Behav Neurosci 97:639–653, 1983). The current study employed the cyclic-ratio schedule to determine whether the effects on food intake of chlordiazepoxide (CDP) (5.0 mg/kg), sodium pentobarbital (5.0 mg/kg), and picrotoxin (1.0 mg/kg) were mediated through palatability or regulatory processes.


The results of this study show that both the benzodiazepine CDP and the barbiturate sodium pentobarbital increased food intake in a manner similar to increasing the palatability of the ingestant, and picrotoxin decreased food intake in a manner similar to decreasing the palatability of the ingestant.


These results suggest that the food intake enhancement properties of benzodiazepines are mediated through a mechanism affecting perceived palatability.


Benzodiazepines Barbiturates Palatability Cyclic-ratio Picrotoxin 



This research was supported in part by the Wellcome Trust 063938/GM/KM/RL.


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.School of PsychologyUniversity of UlsterCo. AntrimUK
  2. 2.School of PsychologyTrinity CollegeDublin 2UK

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