Imaging incorporation of circulating docosahexaenoic acid into the human brain using positron emission tomography.
Docosahexaenoic acid (DHA; 22:6n-3) is a critical constituent of the brain, but its metabolism has not been measured in the human brain in vivo. In monkeys, using positron emission tomography (PET), we first showed that intravenously injected [1-(11)C]DHA mostly entered nonbrain organs, with approximately 0.5% entering the brain. Then, using PET and intravenous [1-(11)C]DHA in 14 healthy adult humans, we quantitatively imaged regional rates of incorporation (K*) of DHA. We also imaged regional cerebral blood flow (rCBF) using PET and intravenous [(15)O]water. Values of K* for DHA were higher in gray than white matter regions and correlated significantly with values of rCBF in 12 of 14 subjects despite evidence that rCBF does not directly influence K*. For the entire human brain, the net DHA incorporation rate J(in), the product of K*, and the unesterified plasma DHA concentration equaled 3.8 +/- 1.7 mg/day. This net rate is equivalent to the net rate of DHA consumption by brain and, considering the reported amount of DHA in brain, indicates that the half-life of DHA in the human brain approximates 2.5 years. Thus, PET with [1-(11)C]DHA can be used to quantify regional and global human brain DHA metabolism in relation to health and disease.
Umhau
John C
JC
Laboratory of Clinical Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA. umhau@jhu.edu
Zhou
Weiyin
W
Carson
Richard E
RE
Rapoport
Stanley I
SI
Polozova
Alla
A
Demar
James
J
Hussein
Nahed
N
Bhattacharjee
Abesh K
AK
Ma
Kaizong
K
Esposito
Giuseppe
G
Majchrzak
Sharon
S
Herscovitch
Peter
P
Eckelman
William C
WC
Kurdziel
Karen A
KA
Salem
Norman
N
D000328:Adult; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D001931:Brain Mapping; D002250:Carbon Radioisotopes / Q000378:metabolism; D004281:Docosahexaenoic Acids / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D000882:Haplorhini; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000378:metabolism; D012039:Regional Blood Flow; D014018:Tissue Distribution; D055815:Young Adult
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D004281:Docosahexaenoic Acids