Circadian variation in the activity of the 5-HT(1B) autoreceptor in the region of the suprachiasmatic nucleus, measured by microdialysis in the conscious freely-moving rat.
Intracerebral microdialysis was used to examine the function of the terminal 5-hydroxytryptamine(1B) (5-HT(1B)) autoreceptor in the region of the suprachiasmatic nuclei (SCN) of freely moving conscious rats at six time points or zeitgeber times (ZTs) across the light:dark cycle. Infusion of the 5-HT(1A/1B) agonist 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridyl)-1H-indole (RU24969) (1 microM) via the microdialysis probe produced a decrease in 5-HT output when applied at ZTs 3, 6, 15 and 21 (69.8+/-11.9, 59+/-11.7, 43.9+/-17.2 and 45.7+/-17.0% respectively). At ZTs 9 and 18 RU24969 (1 microm) failed to affect the 5-HT output significantly (28.0+/-11 and 32.8+/-24.6% decrease respectively). The profile of inhibition of 5-HT output following infusion of RU24969 (1 microM) at ZT 6 was unaffected by concurrent infusion of the specific 5-HT(1A) antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohe xanecarboxamide trihydrochloride (WAY100635) (1 microM) (52.48+/-17.5% decrease). The data demonstrate a circadian rhythm in the activity of the 5-HT(1B) autoreceptor in the region of the SCN.
Garabette
M L
ML
Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY. B.T.G., 10 Fleet Place, London EC4 7SB.
Martin
K F
KF
Redfern
P H
PH
D000818:Animals; D017660:Autoreceptors / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology*; D003243:Consciousness; D007211:Indoles / Q000494:pharmacology; D008124:Locomotion; D008297:Male; D017551:Microdialysis; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D017660:Autoreceptors; D007211:Indoles; D010879:Piperazines; D011725:Pyridines; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D012701:Serotonin; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D002118:Calcium