Serotonin and the Mammalian Circadian System: II. Phase-Shifting Rat Behavioral Rhythms with Serotonergic Agonists
- 1 April 1993
- journal article
- Published by SAGE Publications in Journal of Biological Rhythms
- Vol. 8 (1) , 17-31
- https://doi.org/10.1177/074873049300800102
Abstract
The suprachiasmatic nuclei (SCN) receive primary afferents from the median and dorsal raphe, but the role of these projections in circadian timekeeping is poorly understood. Studies of the SCN in vitro suggest that quipazine, a general serotonin (5-HT) receptor agonist, can produce circadian time-dependent phase advances and phase delays in circadian rhythms of neuronal activity. The present study addresses whether quipazine and the selective 5-HT 1A receptor agonist 8-OH-DPAT are similarly effective in vivo. Drinking and wheel-running patterns of male Wistar rats individually housed in constant darkness were monitored before and after subcutaneous administration of quipazine (5-10 mg/kg) at either circadian time (CT) 6 or CT 18, with and without running wheels available. Dose-dependent phase advances (20-180 min) were produced at CT 6. Significant phase shifts were not observed at CT 18. CT 6 quipazine-treated animals also showed a sustained and significant shortening of rhythm period (τ) following treatment (-0.28 hr; p < 0.002). τ shortening was inconsistently observed in CT 18 quipazine-treated rats. Neither quipazine-induced phase shifts nor τ effects were dependent on wheel-running activity per se. 8-OH-DPAT delivered via intracerebral ventricular treatment into the third ventricle (5 μl at 100 μM in saline) produced slightly smaller phase advances (20-90 min) at CT 6, but did not produce phase delays at CT 18 or changes in τ. These findings support in vitro evidence that 5-HT-ergic agonists can phase-shift the circadian pacemaker.Keywords
This publication has 57 references indexed in Scilit:
- Circadian Rhythms: Influences of Internal and External Factors on the Period Measured in Constant Conditions1Zeitschrift Fur Tierpsychologie, 2010
- Geniculo-hypothalamic tract lesions block chlordiazepoxide-induced phase advances in Syrian hamstersBrain Research, 1991
- Physical exercise and brain monoamines: a reviewActa Physiologica Scandinavica, 1989
- Circadian rhythm of serotonin receptor in rat brainPharmacology Biochemistry and Behavior, 1989
- VIP neurons as prime synaptic targets for serotonin afferents in rat suprachiasmatic nucleus: a combined radioautographic and immunocytochemical studyJournal of Neurocytology, 1985
- Circadian rhythms of house sparrows are phase-shifted by pharmacological manipulation of brain serotoninJournal of Comparative Physiology A, 1985
- Neuropeptide Y: Role in light-dark cycle entrainment of hamster circadian rhythmsNeuroscience Letters, 1984
- Circadian phase response curves for dark pulses in the hamsterJournal of Comparative Physiology A, 1982
- Food availability and daily biological rhythmsNeuroscience & Biobehavioral Reviews, 1980
- Exogenous and Endogenous Components in Circadian RhythmsCold Spring Harbor Symposia on Quantitative Biology, 1960