Poster Topical Area: Carotenoids and Retinoids
Poster Board Number: 11
Objective: Lutein selectively accumulates in primate retina and brain where it may have an essential role in ocular and cognitive health. To date, no isotopic tracer studies of lutein pharmacokinetics have been performed in a nonhuman primate model. The objective of this pilot study was to assess the distribution of lutein into tissues of an adult rhesus macaque (Macaca mulatta) after a single oral dose of isotopically-labeled lutein.
Methods: One 19-year-old female macaque was supplemented daily for a year with 1 μmol/kg/day of unlabeled lutein and subsequently provided a single dose of 1.92 mg of 13C-lutein. 65% of lutein was uniformly labeled while 35% remained unlabeled at 1 or 2 carbons. Plasma, six brain regions, retina, and other tissues were collected on the third day post-dose. Tissues from an undosed macaque were used as negative controls. Lutein accumulation was quantified by HPLC-PDA and 13C enrichment was evaluated by LC-QTOF-MS.
Results: In the control monkey, 12C-lutein, but not 13C-lutein, was detectable in serum and all tissues examined. In the 13C-dosed macaque, the highest ratio of 13C-lutein/ 12C-lutein (13C/12C) was found in the plasma (11.3%), followed by liver (10.6%), heart (6.9%), kidney (6.5%), adrenal gland (3.5%), and quadriceps (1.5%). 13C-lutein was detected in the brain and accumulated differentially across regions. The 13C/12Cratio was highest in the temporal cortex (2.4%) and lowest in the subcortical white matter (0.6%). In adipose depots, 13C-lutein was observed, with the highest 13C/12C ratio in the axillary brown adipose tissues (0.8%) and lowest in the thigh subcutaneous adipose tissues (0.1%). However, 13C-lutein was undetectable in macular and peripheral retina, despite high concentrations of 12C-lutein.
Conclusions: Three days following dosing, 13C-lutein was differentially distributed across various tissues, including multiple brain regions, but undetectable in the retina. This pilot study demonstrates that distribution of lutein in the macaque is substantially dependent on tissue type. Studies with additional time points are needed to determine if these observations indicate differences in the kinetics of tissue uptake, metabolism, or recycling into circulation.
Funding provided by Abbott Nutrition through the Center for Nutrition, Learning and Memory, University of Illinois, Urbana-Champaign and NIH Grant P51OD011092
University of Illinois at Urbana-Champaign