The light-enhanced startle paradigm as a putative animal model for anxiety: Effects of chlordiazepoxide, flesinoxan and fluvoxamine

Rationale: Recently, a new putative animal model of anxiety, "light-enhanced startle" was introduced. By placing a rat in a brightly lit environment, which is a naturally aversive stimulus to rats, the amplitude of the startle response to a startle-eliciting noise burst is increased. Objectives: The present study aimed to determine the predictive validity of the light-enhanced startle as a putative model for anxiety. Methods: The effects of the GABA_A-benzodiazepine receptor agonist chlordiazepoxide (CDP), the 5-HT_1A receptor agonist flesinoxan and the specific 5-HT reuptake inhibitor fluvoxamine on light-enhanced startle were studied. Results: Both CDP and flesinoxan decreased startle potentiation, whereas fluvoxamine was devoid of any effects on potentiation. Effects on baseline startle amplitude were only seen after CDP administration. Conclusions: The present experiment provides evidence for the predictive validity of the light-enhanced startle as an animal model for anxiety. Due to the use of an unconditioned anxiogenic stimulus, the light-enhanced startle offers several benefits over animal models that depend on conditioning. Drug effects can be ascribed more directly to effects on anxiety, as opposed to memory retrieval and, as shown in this study, non-specific drug effects can easily be detected without the interference of contextual fear.