Aging abolishes circadian rhythms of Rora and antioxidant enzymes expression in the temporal cortex of free running rats

DEYURKA, NICOLÁS; NAVIGATORE-FONZO, LORENA; CORIA LUCERO, CINTIA; LACOSTE, MARÍA GABRIELA; ANZULOVICH, ANA CECILIA

Mendoza

Congreso; XXXVI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2018

Sociedad de Biología de Cuyo

The retinoid-related orphan receptor a (RORa) is a transcription factor that binds RORE motifs in the promoter of clock Bmal1 and other target genes. Antioxidant enzymes contribute to the cellular redox state which is crucial for the molecular clock function. Previously, we showed that antioxidant enzymes activity follows a daily variation in the temporal cortex (TC), which was abolished in aged rats. Herein our objectives were: 1) to investigate endogenous rhythms of catalase (Cat), glutathione peroxidase (Gpx) and Nrf2 genes expression as well as RORa protein levels in the rat TC, and 2) to evaluate the aging consequences on those temporal patterns. Three- and 22-month-old male Holtzman rats were maintained under constant darkness for 15 days before the experiment, in order to validate the endogenous nature of circadian rhythms. On the experiment day, TC samples were isolated every 4 h during a 24h period. RORa protein levels were assessed by immunoblotting. Cat, Gpx and Nrf2 mRNA levels were determined by RT-PCR. Specific software was used to analyze circadian rhythms. We observed circadian endogenous rhythms of RORa, Cat and Gpx expression in the TC of free running young rats (Chronos fit, p