Serotonin increases the phase shift of the circadian locomotor activity rhythm in mice after dark pulses in constant light conditions.
Investigations on the effects of the 5-HT agonists and antagonists on the phase of the circadian locomotor activity rhythm of animals kept in constant light conditions (LL) are rare. Therefore the influence of R-(+)-OH-DPAT (5-HT1A receptors agonist) and metergoline (5-HT1/2/7 receptors antagonist) on the phase shift of the locomotor-activity rhythm alone and when combined with dark pulses in mice kept in LL are examined. The results indicate that 8-OH-DPAT administered independently at 12.00CT (Circadian Time) shifted the phase of the circadian rhythm and reinforced the effect of dark pulses on this parameter. 12.00CT was defined arbitrarily as the onset of locomotor activity in constant conditions. Metergoline diminished the phase shifts after dark pulses compared to 8-OH-DPAT. The influence of the serotonin agonist showed that serotonin can reinforce the phase shifting effect of the locomotor activity rhythm after dark pulses in LL condition.
Bartoszewicz
Renata
R
Institute of Zoology, Department of Neurophysiology and Chronobiology, Jagiellonian University, R. Ingardena 6, 30-060 Kraków, Poland. gsuro@zuk.iz.uj.edu.pl
Barbacka-Surowiak
Grazyna
G
D000818:Animals; D002940:Circadian Rhythm; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin