title: Brain xanthophyll content and exploratory gene expression analysis: subspecies differences in rhesus macaque.
abstract: BACKGROUND
  The dietary xanthophylls, lutein and zeaxanthin, accumulate in primate retina and brain, and emerging evidence indicates neural lutein content may be beneficial for cognition. Neural xanthophyll content in primates varies greatly among individuals, and genetic factors are likely to be significant contributors. Subspecies of rhesus macaques originating from different geographic locations are known to differ genetically, but the effect of origin on gene expression and carotenoid status has not been determined. The study objective was to determine whether xanthophyll status and expression of carotenoid-related genes, as well as genes with known variants between subspecies, differ between the brains of adult rhesus monkeys of Indian and Chinese origin.
  
  
  METHODS
  Samples of prefrontal cortex, cerebellum, and striatum were collected from adult monkeys (n= 9) fed a standard stock diet containing carotenoids. Serum and brain carotenoids were determined using reverse-phase high-performance liquid chromatography. For each brain region, RNA sequencing and real-time quantitative polymerase chain reaction were used to determine differentially expressed genes between the subspecies.
  
  
  RESULTS
  Indian-origin monkeys had higher xanthophyll levels in brain tissue compared to Chinese-origin monkeys despite consuming similar amounts of dietary carotenoids. In a region-specific manner, four genes related to carotenoid and fatty acid metabolism (BCO2,RPE65,ELOVL4,FADS2) and four genes involved in the immune response (CD4,CD74,CXCL12 LTBR) were differentially expressed between Indian- and Chinese-origin monkeys. Expression of all four genes involved in carotenoid and fatty acid metabolism were correlated with brain xanthophyll concentration in a region-specific manner.
  
  
  CONCLUSIONS
  These results indicate that origin is related to differences in both gene expression and xanthophyll content in the brain. Findings from this study may have important implications regarding genetic diversity, lutein status, and cognition in primates.
authors.affiliation: Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA USA.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Mohn
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Erdman
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon USA.
authors.forename: Martha
authors.initials: M
authors.lastname: Neuringer
authors.affiliation: Abbott Nutrition, Columbus, Ohio USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kuchan
authors.affiliation: Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA USA.|Antioxidants Research Laboratory, 711 Washington Street, Boston, MA 02111 USA.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Johnson
keywords: Brain; Lutein; RNA-sequencing; Rhesus monkey; Subspecies; Zeaxanthin