Maternal and fetal tissue distribution of L-carnitine in pregnant mice: low accumulation in the brain.
The distribution of L-carnitine was studied by whole-body autoradiography in pregnant CD-1 mice at 1, 2, 3, and 6 hr after receiving L-[14C]carnitine. Highest concentrations of carnitine were found in maternal tissues including liver, placenta, kidney, myocardium, and choroid plexus. High retention of tissue carnitine in excess of blood levels suggests the existence of concentrative uptake mechanism. Labeled carnitine was not detectable in either maternal or fetal brain. This suggests that the brain barrier systems limit the access of L-carnitine to the brain. In fetus, the level of carnitine was less than that seen in the maternal tissues, however, the tissue distribution was similar. The fetal tissue carnitine concentration increased with time. These findings suggest that relief of encephalopathy due to toxic organic anions in metabolic disorders following L-carnitine supplementation appears to be peripheral metabolic effects rather than direct access to the central nervous system. However, the physiological role for the concentrative uptake of L-carnitine by the choroid plexus remains to be determined. Transport of carnitine into fetal tissues via placenta further suggests the possibility of prenatal therapy in pregnancies at risk for certain inherited metabolic disorders.
Kim
C S
CS
Biological Sciences Research Center, University of North Carolina School of Medicine, Chapel Hill 27514.
Roe
C R
CR
D000818:Animals; D001345:Autoradiography; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002331:Carnitine / Q000493:pharmacokinetics*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D008431:Maternal-Fetal Exchange; D051379:Mice; D011247:Pregnancy; D014018:Tissue Distribution
D002250:Carbon Radioisotopes; D002331:Carnitine