Aging renders desynchronization between clock and immune genes in male Wistar rat kidney: chronobiotic role of curcumin.

Suprachiasmatic nucleus (SCN) contains the central clock that orchestrate circadian rhythms in physiology and behavior in mammals. Tightly interlocked transcriptional and translational feedback loops (TTFLs) comprising of various clock genes such as Clock, Bmal1, Periods, Cryptochromes etc. in the SCN, send the timing signals to peripheral clocks that governs local metabolism with similar TTFLs. Peripheral clocks in kidney regulates several circadian rhythms like blood pressure, immunity etc. However, aging leads to circadian and inflammatory disorders in kidney. Though there are increasing evidences on age associated perturbations, studies elucidating the rhythmic expression of clock and immune genes across aging in kidney are obscure. We therefore studied changes in daily rhythms of clock and immune genes in kidney. In this study we measured mRNA expression of clock genes rBmal1, rPer1, rPer2, rCry1, rCry2, rRev-erbα, rRorα, and inflammatory genes rNfκb1, rTnfα, rIl6, rTlr4 and rTlr9 in 3, 12 and 24 months male Wistar rat kidney using qRT-PCR. From our study, we did not observe significant changes in clock genes expression except rRorα, but immune genes showed significant phase alterations as well as increase in mean 24 h levels. Pearson correlation analysis of data showed desynchronization between immune and clock genes expression. We further studied the effect of administration of curcumin which has anti-aging, anti-inflammatory, anti-oxidant etc. properties, and evaluated its chronobiotic properties. We here report differential effects of curcumin administration on daily rhythms of clock and immune genes expression.