Effects of ACTH, benzodiazepines and 5-HT antagonists on escape from periaqueductal grey stimulation in the rat.

1. The effects of drugs has been studied on escape behaviour of rats following electrical stimulation of the periaqueductal grey, in order to assess the feasibility of using the latency to escape as a measure of experimental anxiety. 2. Escape latencies were decreased by methysergide and cyproheptadine, whilst lorazepam and chlordiazepoxide (CDP) increased the latencies. 3. ACTH marginally decreased escape latencies, and did not alter the response to lorazepam. 4. Difficulties associated with using this paradigm to detect anxiolytic or anxiogenic effects of drugs are discussed.