The role of Period1 in non-photic resetting of the hamster circadian pacemaker in the suprachiasmatic nucleus.

Non-photic stimuli, such as diurnal wheel running in rodents, phase shift the circadian clock and suppress the expression of Per1 in the suprachiasmatic nucleus (SCN). The goal of the present study was to directly decrease Per1 expression using antisense (AS) oligodeoxynucleotides to determine if such suppression produced non-photic phase shifts. Injections of Per1-AS suppressed expression of Per1 within the SCN and produced phase shifts similar to those resulting from other non-photic manipulation, with large phase advances to injections during the subjective day. These results indicate that the decrease in expression of Per1 is a cause rather than a consequence of non-photic phase shifts.