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Effects of alpha-adrenoceptor agonists and antagonists in a maze-exploration model of ‘fear’-motivated behaviour

  • Sheila L. Handley
  • Siddika Mithani
Article

Summary

An elevated X-maze with alternating open and enclosed arms was investigated as a model for the study of fear-induced behaviour. As predicted, the anxiolytics diazepam and amylobarbitone increased, and the putative anxiogenics ACTH and picrotoxin decreased the proportion of open arm entries. The α1-adrenoceptor agonists phenylephrine and ST587, and the α2-adrenoceptor antagonists idazoxan, piperoxane, RS-21361 and yohimbine decreased relative open-arm entries, thus resembling the putative anxiogenics. On the other hand, azepexole, clonidine and guanabenz, agonists at α2-adrenoceptors, and the α1-adrenoceptor antagonists prazosin and thymoxamine, enhanced the proportion of open arm entries at low doses, suggesting anxiolytic-like properties. A paradoxical fall in open arm entries occurred with these agents at higher doses. These results provide further evidence for the involvement of noradrenergic systems in ‘fear’-motivated behaviour.

Key words

Anxiety Central α-adrenoceptors Clonidine Exploratory activity ‘Fear’-motivated behaviour 

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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Sheila L. Handley
    • 1
  • Siddika Mithani
    • 1
  1. 1.Pharmacology Laboratories, Department of PharmacyUniversity of AstonBirminghamUK

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