Near-infrared light increases ATP, extends lifespan and improves mobility in aged Drosophila melanogaster

Abstract

Ageing is an irreversible cellular decline partly driven by failing mitochondrial integrity. Mitochondria accumulate DNA mutations and reduce ATP production necessary for cellular metabolism. This is associated with inflammation. Near-infrared exposure increases retinal ATP in old mice via cytochrome c oxidase absorption and reduces inflammation. Here, we expose fruitflies daily to 670 nm radiation, revealing elevated ATP and reduced inflammation with age. Critically, there was a significant increase in average lifespan: 100-175% more flies survived into old age following 670 nm exposure and these had significantly improved mobility. This may be a simple route to extending lifespan and improving function in old age.

Keywords: ATP; fly; inflammation; lifespan.

Figure 1.

Exposure to 670 nm radiation increases ATP in aged flies and reduces inflammation. (a) Seven week old flies exposed to 670 nm had a significant increase in whole body ATP compared with controls, p = 0.028. n = 25 flies per group. (b) Whole body inflammation (C3) was measured in seven week flies using Western blot. This was reduced in 670 nm exposed flies by approximately 15%. Here, flies were pooled within groups as C3 protein levels were low in individuals. Hence there are no error bars. n = 15 flies per group. (Online version in colour.)

Figure 2.

Lifespan and mobility. (a) Fly numbers at progressive weeks in groups exposed to 670 nm supplemented light each day (red line) and controls (black line). Curves are averages for six independent experiments with a minimum of 40 flies per group in each experiment. Fly death rates separated between three and six weeks with fewer flies dying in 670 nm exposed animals. Reduction in the two population followed similar patterns from six weeks but with the 670 nm exposed group having greater numbers at any point until week 12. In all replicates, there was no indication that 670 nm increased absolute lifespan beyond weeks 11–12. Differences between the two groups were statistically significant (p = 0.008). (b) Inset: percentage increase of 670 nm exposed flies alive at progressive weeks. (c) Seven week old 670 nm exposed flies were more active than controls. (d) Mobility measures the percentage of flies that climbed above 90 mm in a clear 100 ml cylinder. (d) This was filmed and then the distance travelled by each fly was measured in each group. In both cases, the 670 nm exposed flies where significantly more mobile. There were 21 flies in each group in each condition. (Online verion in colour.)