A modified anxious behavior test for hamsters

Abstract

BackgroundLatency to feed in a novel environment assesses anxious behavior in rodents, but it is unclear whether it distinguishes anxiety from consumption or appetite. New methodThe anxiety-related feeding/exploration conflict (AFEC) test was used here to assess anxious behavior in Syrian hamsters for which increased cheek-pouching of food, but not overconsumption of it, reflects appetitive drive, and orexigenic stimuli do not increase consumption. The setup of the test prevented cheek-pouching. Comparison with existing methodsLatency to approach test food provided an additional control for non-emotional effects of treatments. Feed and approach latencies in the test cage were normalized to those in the home cage to factor out non-emotional effects. ResultsFeed latency and the feed latency ratio (test cage/home cage) were reduced by acute treatment with benzodiazepine, diazepam, or beta-adrenergic receptor antagonist, propranolol, or chronic treatment with norepinephrine reuptake inhibitor, desipramine. Reductions of feed latency and the feed latency ratio were not associated with hyperphagia, and these behaviors were unaltered by acute treatment with opioid receptor antagonist, naltrexone. Latency to approach food in the test cage, with and without normalization, was unaltered by these treatments. Finally, overnight fasting elevated feed latency without hyperphagia, and this effect was attenuated by chronic desipramine treatment. ConclusionsThese results suggest that the AFEC test assesses anxious, but not appetitive or consummatory, behavior, and that its sensitivity increases with food deprivation of hamsters.