Psychopharmacology

, Volume 106, Issue 1, pp 102–110

Effects of diazepam on behavioural and antinociceptive responses to the elevated plus-maze in male mice depend upon treatment regimen and prior maze experience

  • R. J. Rodgers
  • C. Lee
  • J. K. Shepherd
Original Investigations

DOI: 10.1007/BF02253596

Cite this article as:
Rodgers, R.J., Lee, C. & Shepherd, J.K. Psychopharmacology (1992) 106: 102. doi:10.1007/BF02253596

Abstract

Recent studies have shown that brief exposure to an elevated plus-maze (EPM) produces non-opioid antinociception in male mice. The present experiments were designed to assess the effects of diazepam on this phenomenon. When acutely administered, low doses (0.5–1.0 mg/kg) of diazepam failed to produce an anxiolytic profile and exerted rather inconsistent effects on EPM-induced elevations in tail-flick latencies. In EPM-experienced mice, chronic treatment with higher doses of diazepam (2–4 mg/kg, 8 days) produced a weak anxiolytic action and inhibited the early phase of EPM antinociception only. However, in EPM-naive mice, 8-day diazepam pretreatment exerted a marked anxiolytic effect and completely eliminated the antinociceptive response to the maze. Together, these data support the view that anxiety is a key factor in certain forms of adaptive pain inhibition and suggest a possible mediational role for benzodiazepine receptors. Our findings also show that prior exposure to the EPM, rather than chronic handling/injection, greatly reduces the anti-anxiety effect of diazepam. Furthermore, since re-exposure to the maze, perse, decreased time spent on the open arms and central platform, a shift in behavioural baseline (“retest anxiogenesis”) may have contributed to the weak behavioural effects of diazepam in test-experienced animals. Importantly, as chronic treatment with diazepam did not influence this anxiogenic-like retest profile, our data suggest that a single prior experience of the EPM may radically alter the nature of the anxiety reaction provoked by this test.

Key words

Elevated plus-maze Anxiety Antinociception Diazepam Prior experience Treatment regimen Mice 

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • R. J. Rodgers
    • 1
  • C. Lee
    • 2
  • J. K. Shepherd
    • 1
  1. 1.Department of PsychologyUniversity of LeedsLeedsUK
  2. 2.Department of PsychologyUniversity of BradfordBradfordUK

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