Visualization of dietary docosahexaenoic acid in whole-body zebrafish using matrix-assisted laser desorption/ionization mass spectrometry imaging.

Zebrafish models have been developed for several studies involving lipid metabolism and lipid-related diseases. In the present study, the migration of dietary docosahexaenoic acid (DHA) in whole-body zebrafish was estimated by stable-isotope tracer and matrix-assisted laser desorption/ionization mass spectrometry imaging. Administration of 1-13C-2,2-D2-labeled DHA ((+3)DHA) ethyl ester to male zebrafish was conducted to evaluate its accumulation, migration, and distribution in the body. The (+3)DHA content in the body of zebrafish after administering (+3)DHA for 10 and 15 d was significantly higher than that in the control group. (+3)DHA was observed as a constituent of phosphatidylcholine (PC) in the intestine of zebrafish that were administered (+3)DHA for 5 and 10 d. (+3)DHA-containing PC tended to accumulate in the intestines of zebrafish administered (+3)DHA for 1 d, indicating that recombination of (+3)DHA from ethyl ester to PC occurs quickly at intestine. After administration for 15 d, (+3)DHA-containing PC accumulated in the intestine, liver, and muscle of whole-body zebrafish. In contrast, (+3)DHA-containing PC was not detected in the brain. These results showed that dietary DHA is initially constructed into PC as a structural component of intestinal cell membranes and gradually migrates into peripheral tissues such as muscle.

Selective Visualization of Administrated Arachidonic and Docosahexaenoic Acids in Brain Using Combination of Simple Stable Isotope-Labeling Technique and Imaging Mass Spectrometry.

We developed a new method for monitoring the distribution of administrated fatty acids in the body by combination of a stable isotope-labeling technique and imaging mass spectrometry (IMS). The developed stable isotope-labeling technique is very simple and able to adapt to all the fatty acid species. In this study, we synthesized stable isotope-labeled arachidonic acid (AA) and docosahexaenoic acid (DHA), and they were simultaneously administrated to mice to examine their migrations and distributions in the brain. The administrated AA and DHA have two more molecular weights compared to the originals and apparently were distinguished from the originally accumulated AA and DHA in the brain using IMS. As a result, we reveal that the administered AA and DHA first accumulated in the hippocampus and cerebellar cortex in the brain. This technique does not use radio isotopes and would appear to elucidate the role of all kinds of fatty acid species in the body.