Dose dependent effects of S-20098, a melatonin agonist, on direction of re-entrainment of rat circadian activity rhythms.
The chronobiotic properties of melatonin are well documented. For example, following an 8-h phase advance of the light-dark cycle daily injections of melatonin administered at the pre-shift dark onset alter the direction of re-entrainment of rat activity rhythms. Using this 8-h phase advance paradigm, the effects of the melatonin agonist S-20098 (1 mg/kg and 3 mg/kg) on the rat circadian system were compared with those of melatonin. S-20098 altered the direction of re-entrainment in the same manner as melatonin. A study using lower doses of S-20098 showed that the effect on direction of re-entrainment was dose-dependent, with 100% of rats responding at a dose of 100 micrograms/kg. S-20098 may, therefore, have therapeutic potential as a chronobiotic in the treatment of circadian disorders in humans.
Redman
J R
JR
Department of Psychology, Monash University, Clayton, Victoria, Australia.
Guardiola-Lemaitre
B
B
Brown
M
M
Delagrange
P
P
Armstrong
S M
SM
D000081:Acetamides / Q000494:pharmacology*; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000819:agonists* / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D009281:Naphthalenes
D000081:Acetamides; D006993:Hypnotics and Sedatives; D008550:Melatonin; C084711:agomelatine; D009281:Naphthalenes