Elevated zero maze: a paradigm to evaluate antianxiety effects of drugs

Elevated zero maze is a modification of the elevated plus maze model of anxiety in rodents. The novel design comprises an elevated annular platform with two opposite, enclosed quadrants and two open quadrants, removing any ambiguity in the interpretation of the time spent in the central square of the traditional design and allowing uninterrupted exploration. In the present study, we validated elevated zero maze as a tool to study antianxiety activity, using various standard anxiolytics belonging to different pharmacological groups, such as benzodiazepines, barbiturates, alcohol etc., and compared the results with elevated plus maze. Bidirectional sensitivity of the model was also assessed using picrotoxin, pentylenetetrazol and flumazenil, the modulators of GABA(A) and benzodiazepine modulators. Animals were administered different standard antianxiety and anxiogenic drugs, and were allowed to explore the elevated zero maze (time spent in open arm, latency to enter in open arm, total number of entries in open arm and number of stretch attend postures [SAPs]) and elevated plus maze (time spent in open arm, latency to enter in open arm, total number of entries in open arm, first preference of the animal [open/closed] and number of stretchings). Selected drugs and doses were then assessed on the mirror chamber paradigm. Results of the present study indicated that elevated zero maze offered a better animal model to study antianxiety activity, when compared with elevated plus maze and mirror chamber.