The Behavioural Response to the 5-hydroxytryptamine1B, (5HT1B) Receptor Agonist—Ru-24969 May Exhibit a Orcadian Variation in the Mouse

Abstract

The effects of the 5-hydroxytryptamine1B receptor agonist RU-24969 on locomotor activity were examined at different times during the light-dark cycle in the mouse. A dose-dependent hyperlocomotion was observed following RU-24969 administration which was partially antagonised by the non-selective 5-hydroxytryptamine receptor antagonist metergoline. The dose ratios for RU-24969 at two different times tested (8 hr after lights-on, L8; 5 hr after lights-off, D5) were significantly different in the presence of metergoline (2 and 5 mg/kg i.p.). The data suggest that the receptor(s) involved in the behavioural response to RU-24969 in the mouse exhibit a circadian variation.