Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P08908 (5-HT1A)
 5,574 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of the present study was to examine the effects of serotonin agonists on three elements of the photic response in the hamster suprachiasmatic nuclei (SCN). Both serotonin and the selective 5-HT1A agonist 8-OH-DPAT inhibited field potentials recorded in the SCN in response to optic nerve stimulation in the hypothalamic slice preparation. The effects of both drugs were dose related over a concentration range of 1-50 microM, and, in both cases, a maximal inhibition of approximately 60% was achieved at a concentration of 25-50 microM. Systemic administration of 8-OH-DPAT inhibited light-stimulated Fos expression in the SCN. A regionally selective pattern of inhibition was observed, with decreases restricted predominately to the ventral and dorsal borders of the SCN. Finally, systemic administration of 8-OH-DPAT was found to dose-dependently attenuate light-induced phase shifts of the free-running activity rhythm. The effects of 8-OH-DPAT on light-induced phase advances were dose dependent. Injection of 8-OH-DPAT at a dose of 0.5 mg/kg caused 57% inhibition of light-induced phase advances, while a dose of 5 mg/kg inhibited the phase advance by 82%. Injection of 0.05 mg/kg 8-OH-DPAT did not significantly inhibit light-induced phase advances. Injection of 5 mg/kg 8-OH-DPAT alone did not significantly alter the phase of the activity rhythm. Similarly, injection of 5 mg/kg 8-OH-DPAT 30 min prior to light stimulation at CT14 completely inhibited light-induced phase delays, while this dose of the drug did not alter the phase of the activity rhythm when administered alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Serotonin modulates photic responses in the hamster suprachiasmatic nuclei. 820 78

Mammalian circadian rhythms are synchronized daily to light-dark cycles in the environment. The suprachiasmatic nucleus (SCN) is the proposed site of the major circadian pacemaker. Daily entrainment is believed to be influenced by inputs to the SCN, one of these being the dense serotonergic (5-HT) projection from the raphe nuclei. WAY-100635 is a potent and selective 5-HT1A receptor antagonist. In this study, the effects of WAY-100635 on phase-shifts of the hamster circadian pacemaker to light were investigated. Phase-delays after a light pulse administered during the early subjective night (15 min at CT14) were observed to be significantly greater following pre-treatment with WAY-100635 compared to light pulse alone (P < 0.05). However, pre-treatment with WAY-100635 had no effect on the magnitude of phase-shifts to light at CT18, late in the subjective night. Serotonin may influence the responsiveness of the circadian pacemaker to photic stimuli. Specifically, WAY-100635 administered at CT14 can augment phase-shifts to light.
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PMID:WAY-100635, a specific 5-HT1A antagonist, can increase the responsiveness of the mammalian circadian pacemaker to photic stimuli. 1135 1

3,4-Methylenedioxymethamphetamine (MDMA or 'Ecstasy') is a widely used recreational drug that damages serotonin 5-HT neurons in animals and possibly humans. Published literature has shown that the serotonergic system is involved in photic and non-photic phase shifting of the circadian clock, which is located in the suprachiasmatic nuclei. Despite the dense innervation of the circadian system by 5-HT and the known selective neurotoxicity of MDMA, little is known about the effects of MDMA on the circadian oscillator. This study investigated whether repeated exposure to the serotonin neurotoxin MDMA alters the behavioural response of the Syrian hamster to phase shift to the serotonin 5-HT1A/7 receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide (8-OH-DPAT). This agonist was administered under an Aschoff Type I (CT8) and Aschoff Type II (ZT8) paradigm (5 mg/kg) and was given before and after treatment with MDMA (10, 15 and 20 mg/kg administered on successive days). Pre-treatment with MDMA significantly attenuated phase shifts to 8-OH-DPAT. We also tested the ability of the clock to phase shift to a photic stimulus after treatment with MDMA. A 15-min light pulse (mean lux 125 at CT14 or ZT14) was administered before and after treatment with MDMA. Phase shifts to a photic stimulus were significantly attenuated by pre-treatment with MDMA. Our study demonstrates that repeated exposure to MDMA may alter the ability of the circadian clock to phase shift to a photic and non-photic stimulus in the hamster. Disruption of circadian function has been linked with a variety of clinical conditions such as sleep disorders, mood, concentration difficulties and depression, consequently outlining the potential dangers of long-term ecstasy use.
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PMID:MDMA alters the response of the circadian clock to a photic and non-photic stimulus. 1242 45