title: Specific activity of brain palmitoyl-CoA pool provides rates of incorporation of palmitate in brain phospholipids in awake rats.
abstract: In vivo rates of palmitate incorporation into brain phospholipids were measured in awake rats following programmed intravenous infusion of unesterified [9,10-3H]palmitate to maintain constant plasma specific activity. Animals were killed after 2-10 min of infusion by microwave irradiation and analyzed for tracer distribution in brain phospholipid and phospholipid precursor, i.e., brain unesterified palmitate and palmitoyl-CoA, pools. [9,10-3H]Palmitate incorporation into brain phospholipids was linear with time and rapid, with > 50% of brain tracer in choline-containing glycerophospholipids at 2 min of infusion. However, tracer specific activity in brain phospholipid precursor pools was low and averaged only 1.6-1.8% of plasma unesterified palmitate specific activity. Correction for brain palmitoyl-CoA specific activity increased the calculated rate of palmitate incorporation into brain phospholipids (0.52 nmol/s/g) by approximately 60-fold. The results suggest that palmitate incorporation and turnover in brain phospholipids are far more rapid than generally assumed and that this rapid turnover dilutes tracer specific activity in brain palmitoyl-CoA pool owing to release and recycling of unlabeled fatty acid from phospholipid breakdown.
authors.affiliation: Laboratory of Neurosciences, National Institute on Aging, NIH 20892-1582, USA.
authors.forename: E
authors.initials: E
authors.lastname: Grange
authors.forename: J
authors.initials: J
authors.lastname: Deutsch
authors.forename: Q R
authors.initials: QR
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Chang
authors.forename: S I
authors.initials: SI
authors.lastname: Rapoport
authors.forename: A D
authors.initials: AD
authors.lastname: Purdon
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D006207:Half-Life; D050356:Lipid Metabolism; D008297:Male; D008959:Models, Neurological; D010168:Palmitates / Q000097:blood / Q000378:metabolism*; D010171:Palmitoyl Coenzyme A / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010168:Palmitates; D010743:Phospholipids; D010171:Palmitoyl Coenzyme A