Effect of clonidine on consummatory negative contrast and on novelty-induced stress

In Experiments 1 and 1a rats were shifted from 32% to 4% sucrose solutions. The resultant negative contrast effect in consummatory behavior was not alleviated by clonidine (3.12, 6.25, 12.5, 25.0 and 50.0 micrograms/kg). The lower dose of the drug had no effect on behavior, the higher doses reduced consumption in shifted and unshifted rats in a dose dependent fashion. In Experiment 2 clonidine (6.25, 12.5 micrograms/kg) raised plasma glucose levels in a dose dependent fashion when the animals were exposed to a novel environment. These results are at variance with those obtained with chlordiazepoxide (and other anxiolytics in the case of contrast effects) and suggest limits on the degree to which clonidine can be considered to function as an anxiolytic.