The suprachiasmatic nucleus houses the central circadian clock and is 
characterized by the timely regulated expression of clock genes. However, 
neurons of the cerebellar cortex also contain a circadian oscillator with 
circadian expression of clock genes being controlled by the suprachiasmatic 
nucleus. It has been suggested that the cerebellar circadian oscillator is 
involved in food anticipation, but direct molecular evidence of the role of the 
circadian oscillator of the cerebellar cortex is currently unavailable. To 
investigate the hypothesis that the circadian oscillator of the cerebellum is 
involved in circadian physiology and food anticipation, we therefore by use of 
Cre-LoxP technology generated a conditional knockout mouse with the core clock 
gene Arntl deleted specifically in granule cells of the cerebellum, since 
expression of clock genes in the cerebellar cortex is mainly located in this 
cell type. We here report that deletion of Arntl heavily influences the 
molecular clock of the cerebellar cortex with significantly altered and 
arrhythmic expression of other central clock and clock-controlled genes. On the 
other hand, daily expression of clock genes in the suprachiasmatic nucleus was 
unaffected. Telemetric registrations in different light regimes did not detect 
significant differences in circadian rhythms of running activity and body 
temperature between Arntl conditional knockout mice and controls. Furthermore, 
food anticipatory behavior did not differ between genotypes. These data suggest 
that Arntl is an essential part of the cerebellar oscillator; however, the 
oscillator of the granular layer of the cerebellar cortex does not control 
traditional circadian parameters or food anticipation.