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Updated: Aug 17, 2026

Operant Procedures for Assessing Behavioral Flexibility in Rats
Published on: February 15, 2015
Operant response suppression induced with systemic administration of 5-hydroxytryptophan is centrally mediated
E A Engleman1, J M Murphy, F C Zhou
1Indiana University School of Medicine, Department of Psychiatry, Indianapolis, USA.
Abstract:
Intracerebroventricular (ICV) administration of selective serotonergic agents was used to examine the extent of central mediation of 5-HTP-induced operant response suppression in rats. ICV administration of LY53857 (1.0, 3.75, or 7.5 micrograms/5 microliters/5 min) dose dependently blocked response suppression induced with systemically administered 5-HTP (25 mg/kg, IP), whereas ICV 0.9% saline (5 microliters over 5 min) had no significant effect on 5-HTP-induced response suppression. ICV ketanserin (7.5 micrograms/5 microliters/5 min) also blocked response suppression induced with systemically administered 5-HTP. ICV administration of the 5-HT2A/2C receptor agonist DOI (80 micrograms/5 microliters/5 min) induced significant periods of response suppression in this model, which was blocked with LY53857 (1.0 mg/kg, IP) pretreatment. These data demonstrate that central administration of 5-HT2A/2C antagonists potently attenuate operant response suppression induced with systemically administered 5-HTP or DOI and are in agreement with previous findings suggesting central mediation of 5-HTP-induced operant response suppression.
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