Effects of benzodiazepine receptor ligands on the ingestion of sucrose, intralipid, and maltodextrin: an investigation using a microstructural analysis of licking behavior in a brief contact test.

Microstructural analysis of licking behavior in the rat was conducted (a) to describe in detail the characteristics of benzodiazepine-induced changes in ingestion and (b) to determine if the changes are consistent with an alteration in palatability. The effects of the benzodiazepine receptor (BZR) agonist midazolam (0.3-3 mg/kg), and the partial inverse agonist Ro 15-4513 (0.3-3 mg/kg), on licking for several concentrations of sucrose, Intralipid, and maltodextrin in a brief contact test were investigated. Midazolam increased the total number of licks for all 3 fluids; conversely, Ro 15-4513 decreased the total number of licks. Midazolam increased mean bout duration for sucrose and maltodextrin drinking and there was a trend toward a similar effect with Intralipid drinking. Ro 15-4513 reduced mean bout duration for all 3 test fluids. These data are discussed in terms of bidirectional changes in fluid palatability by drug actions at BZRs.