Validation of automated open field assessment for detecting anxiolytic and anxiogenic responses in developmental neurotoxicity studies

BDRP 2026 -- Developmental neurotoxicity (DNT) studies conducted under OECD TG 426 and 443 require evaluation of functional neurobehavioral endpoints, including motor activity. The open-field assessment, performed in automated chambers, is widely used to assess locomotor activity, exploration, and habituation in rodents. In addition to motor activity, regulatory guidance (e.g., EU Biocidal Product Regulation Annex II) recognizes that open-field data can provide indirect measures of anxiety-like behavior based on spatial exploration patterns. Rodents naturally exhibit thigmotaxis (peripheral preference), and reduced center exploration is interpreted as increased anxiety-like behavior. Despite its widespread use in academic settings, utilization of open-field derived anxiety-like behavior endpoints in regulatory DNT contexts remains limited. This study aims to validate an automated open-field assessment for detecting anxiolytic and anxiogenic responses and to generate positive control data using diazepam and yohimbine.