Circadian rhythm in the response of central 5-HT1A receptors to 8-OH-DPAT in rats.
Circadian rhythm in the behavioral responsiveness to the selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) was studied in rats. Rats were subcutaneously injected with 8-OH-DPAT at one of the following times of day: 0000, 0400, 0800, 1200, 1600, 2000 hours. The post-synaptic 5-HT1A receptor behavioral syndrome, that is, forepaw treading, head weaving, and flat body posture, were measured after the administration of 8-OH-DPAT. Circadian rhythms were found in each of the behavioral responses to 8-OH-DPAT. Peak responses were observed in the mid-dark phase (1200 hours) while the weakest responses were observed in the mid-light phase (0000 hours). In a subsequent experiment, 8-OH-DPAT was administered intracerebroventricularly during the mid-dark phase and the mid-light phase. The behavioral responses to the drug in the mid-dark phase were significantly higher than those in the mid-light phase. These results suggest that the function of central postsynaptic 5-HT1A receptor exhibits circadian rhythm.
Lu
J Q
JQ
Department of Neuropsychiatry, Oita Medical University, Japan.
Nagayama
H
H
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002940:Circadian Rhythm / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000502:physiology*; D013997:Time Factors
D011985:Receptors, Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin