Inhibition of casein kinase I epsilon/delta produces phase shifts in the circadian rhythms of Cynomolgus monkeys.
BACKGROUND
Circadian rhythms in mammals depend upon the cyclic oscillations of transcriptional/translational feedback loops in pacemaker cells of the suprachiasmatic nucleus. The rise and fall of clock-related proteins is a function of synthesis and degradation, the latter involving phosphorylation by casein kinase Iepsilon and delta.


OBJECTIVE
Earlier studies by our lab described the actions of a selective CKIepsilon/delta inhibitor, PF-670462, on circadian behavior in rats; the present work extended these studies to a diurnal species, Cynomolgus monkeys.


METHODS
General cage activity was used to estimate the circadian rhythms of eight telemeterized monkeys under baseline conditions and following s.c. doses of PF-670462.


CONCLUSIONS
Consolidated bouts of activity were noted during periods of light with a repeating period length of roughly 24 h based on their onset. Reassessment in constant dim light (42 vs. 450 lx) again yielded period lengths of 24 h, in this instance revealing the animals' endogenous rhythm. PF-670462 (10-100 mg/kg s.c.) produced a dose-dependent phase delay in much the same manner as that observed previously in rats. Dosing occurred 1.5 h prior to lights-off, roughly coincident with peaking levels of PER protein, a primary substrate of CKIepsilon/delta.


CONCLUSIONS
These findings suggest that the time of dosing, when held constant in both the monkey and rat studies, produced nearly identical effects despite the subjects' diurnal or nocturnal preference. Importantly, these changes in rhythm occurred in the presence of light, revealing the drug as a powerful zeitgeber in a non-human primate and, by extension, in man.
Sprouse
Jeffrey
J
CNS Discovery, Pfizer Global Research & Development, Groton, CT 06340, USA. JSPR@Lundbeck.com
Reynolds
Linda
L
Swanson
Terri A
TA
Engwall
Michael
M
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D048149:Casein Kinase 1 epsilon / Q000037:antagonists & inhibitors*; D048148:Casein Kinase Idelta / Q000037:antagonists & inhibitors*; D002940:Circadian Rhythm; D004305:Dose-Response Relationship, Drug; D007279:Injections, Subcutaneous; D008027:Light; D008252:Macaca fascicularis; D008297:Male; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology*; D013045:Species Specificity; D013686:Telemetry
D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; C522839:PF-670462; D048149:Casein Kinase 1 epsilon; D048148:Casein Kinase Idelta