Behavioral effects of buspirone in the marmoset employing a predator confrontation test of fear and anxiety

Abstract

In order to further validate the recently developed marmoset ( Callithrix penicillata) predator confrontation model of fear and anxiety, we investigated the behavioral effects of buspirone with this method. The apparatus consisted of three parallel arms connected at each end to a perpendicular arm, forming a figure-eight continuous maze. A taxidermized wild oncilla cat ( Felis tigrina) was positioned facing a corner of the parallel arms, alternating between the left or right side of the maze among animals tested. All subjects were first submitted to seven 30-min maze habituation trials (HTs) in the absence of the predator, and then to five randomly assigned treatment trials (TTs) in the presence of the predator: three buspirone sessions (0.1, 0.5 and 1.0 mg/kg), saline and sham injection controls. Twenty minutes after treatment administration, the animal was released into the maze and had free access to the apparatus for 30 min. All trials were taped for later behavioral analysis. Buspirone significantly decreased the frequency of scent marking, while increasing the time spent in proximity to the ‘predator’ stimulus, indicating an anxiolytic effect. Neither locomotor activity, exposure to a novel environment, stimulus location and habituation, nor gender influenced the effects of the drug treatments. These results further validate this method and demonstrate the potential usefulness of this ethologically based paradigm to test anxiety and fear-induced avoidance in nonhuman primates and its susceptibility to anxiolytic pharmacological manipulations.