, Volume 118, Issue 2, pp 178–182 | Cite as

Effect of SB 200646A, a 5-HT2C/5-HT2B receptor antagonist, in two conflict models of anxiety

  • G. A. Kennett
  • F. Bailey
  • D. C. Piper
  • T. P. Blackburn
Original Investigation


SB 200646A is the first selective 5-HT2C/5-HT2B receptor antagonist and has previously been observed to have anxiolytic-like properties in the rat social interaction test. In the present study the effects of the compound in two conflict models of anxiety, the rat Geller-Seifter and marmoset conflict test, were examined. In the rat Geller-Seifter test, suppressed responding was increased by all doses of SB 200646A between 5 and 40 mg/kg PO when given 1 h pretest. Unsuppressed responding was slightly increased only at 10 mg/kg PO. Suppressed responding was also increased by the benzodiazepine anxiolytic, chlordiazepoxide, at 1, 2.5 and 5 mg/kg PO 1 h pretest. Unsuppressed responding was modestly increased by chlordiazepoxide only at 5 mg/kg PO. In the marmoset conflict test marmosets were trained to lever press for a palatable food reward. Lever pressing was subsequently suppressed by air puffs. In this procedure suppressed responding was increased by both the benzodiazepine anxiolytic diazepam at 2 and 5 mg/kg PO and SB 200646A after 10 and 20 mg/kg PO. Both treatments caused small increases in unsuppressed responding at 2 and 20 mg/kg PO respectively. Taken together with the previous effects of SB 200646A in the rat social interaction test, this is compelling evidence that 5-HT2C/2B receptor antagonists may possess anxiolytic properties.

Key words

SB 200646A 5-HT2C 5-HT2B Anxiety Conflict models 


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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • G. A. Kennett
    • 1
  • F. Bailey
    • 1
  • D. C. Piper
    • 1
  • T. P. Blackburn
    • 1
  1. 1.SmithKline BeechamHarlowUK

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