Effect of 8-OH-DPAT on temporal discrimination following central 5-hydroxytryptamine depletion

S. Body, T. J. Chiang, S. Mobini, M. Y. Ho*, C. M. Bradshaw, E. Szabadi

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

17 Scopus citations

Abstract

The 5-hydroxytryptamine (5-HT)1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) alters performance in discrete-trials timing schedules. 5-HT1A receptors occur both presynaptically and postsynaptically, but it is not known which receptor population mediates the effects of 8-OH-DPAT on timing. Rats received intra-raphe injections of 5,7-dihydroxytryptamine (n=16) or sham lesions (n=14). They were trained in a discrete-trials psychophysical procedure in which levers were presented at a predetermined time after the onset of each trial (2.5, 7.5, ..., 47.5 s). A response on lever A was reinforced if lever presentation occurred <25 s after trial onset; a response on lever B was reinforced if lever presentation occurred >25 s after trial onset. After 70 preliminary sessions, the rats received 8-OH-DPAT (25, 50, 100, 200 μg kg-1 sc) and saline vehicle. The percentage of responses on lever B (%B) increased as a function of time from trial onset. Under the baseline (vehicle-treatment) condition, performance did not differ between the two groups. 8-OH-DPAT did not alter the indifference point (time corresponding to %B=50%), but dose-dependently increased the Weber fraction in both groups. Forebrain concentrations of 5-HT and 5-HIAA in the lesioned group were approximately 10% of control levels. The results suggest that the effect of 8-OH-DPAT on performance on discrete-trials timing schedules is mediated by postsynaptic 5-HT1A receptors.

Original languageEnglish
Pages (from-to)787-793
Number of pages7
JournalPharmacology, Biochemistry and Behavior
Volume71
Issue number4
DOIs
StatePublished - 2002
Externally publishedYes

Keywords

  • 5,7-dihydroxytryptamine
  • 5-HT receptors
  • 8-OH-DPAT
  • Discrete-trials psychophysical procedure
  • Timing

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