Per3 has a different association with CLOCK‐BMAL1 gene in obese suprachiasmatic nuclei during satiety

Body weight, food intake and energy consumption are processes characterized by circadian rhythm (CR). Obesity is associated with a desynchronization of this process. CR modulation results from expression of the clock genes CLOCK and BMAL1 which form a heterodimer that binds to E‐box on the promoter of other clock genes, such as Per3. These genes ensure the periodicities and are significantly expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus. In order to study this process in obese mouse, we used a new method of feeding behavior recording by sound and also confocal microscopy to detect the presence and contents of CLOCK, BMAL1 and Per3 in the SCN in different situations of feeding behavior. Control (C) and obese (O) mouse were studied after situations of hunger and satiety. Both groups C and O did not show difference in BMAL and CLOCK SCN content, indicating potential capacity to modulate biological rhythms. However, Per3 was less expressed in the C group with satiety, compared to O group (P <0.05). These findings show that changes of endogenous rhythms, reflected by the observed hyperphagic behavior and reduced periods of satiety, may be due a defective Per3 action in SCN. Supported by CNPq (305903/2007); FAPERJ (E‐26/110.578/2009).