new delhi altering the levels of metabolites in the kynurenine pathway responsible for regulating eye colour has been found to impact retinal health according to a new study in fliesthe study conducted by max planck institute of molecular cell biology and genetics mpicbg in germany investigated the classic drosophila genes cinnabar cardinal white and scarlet named due to their role in eye colour pigmentation and in particular the formation of the brown pigment of the fly eyethese genes encode components of the kynurenine pathway a metabolic pathway responsible for regulating eye colour among other various biological processes changes in this pathway can impact the health of the brain including the retinametabolic pathways consist of a series of biochemical reactions in cells that convert a starting component into other productsthe scientists studied the role of these genes using flies as model in whom this metabolic pathway is conserved they used genetics dietary changes and biochemical analysis of metabolites to study different mutations of the fruit fly drosophila melanogasterthe researchers developed a biochemical analysis method which allowed them to link levels of different metabolites of the pathway to retinal healththey found through this method that absolute amounts as well as relative differences between the levels of 3hydroxykynurenine 3ohk which is toxic to retina and protective metabolites such as kynurenic acid kyna governed retinal degenerationwe also fed two of these metabolites to normal nonmutant flies and found that 3ohk enhanced stressinduced retinal damage whereas kyna protected the retina from stressrelated damage said sarita hebbar one of the lead authors of the studyaltering levels of the kynurenine pathway metabolites therefore presented one of the means to improve retinal healthfurther the scientists were also able to demonstrate that the location of these metabolites in the cell and thus their availability for further reactions too was important for retinal healththe ratio of the various metabolites and the specific sites of their accumulation and activity should be taken into account in therapeutic strategies for diseases with impaired kynurenine pathway function observed in various neurodegenerative conditions said elisabeth knust who supervised the study