FFA and Acyl-CoA concentrations in brain -
Competition seems likely between n-3 and n-6 polyunsaturated fatty acids at certain elongation/desaturation steps, particularly delta6-desaturase. In contrast, cycles of de-esterification/re-esterification of 22:6n-3 and 20:4n-6 operate independently and are not likely sites of n-3/n-6 competition. Contreras MA, Rapoport SI. Recent studies on interactions between n-3 and n-6 polyunsaturated fatty acids in brain and other tissues. Curr Opin Lipidol 2002 Jun;13(3):267-72.
Pyrene labeled phosphatidylcholine allows a rapid, continuous assay of phospholipase A(2) (PLA(2)) activity in mouse brain cytosol (CB-57). Bromoenol lactone inhibited up to 58% of the PLA(2) activity with an IC(50) of 0.5 microM. Yarger DE, Patrick CB, Rapoport SI, Murphy EJ. A continuous fluorometric assay for phospholipase A(2) activity in brain cytosol. J Neurosci Methods 2000 Jul 31;100(1-2):127-33
The total acylcarnitine concentration from control rat brains equaled 7-8 nmol/g wet weight brain, about one-fourth the total concentration of long-chain acyl-CoA, indicating a small role in buffering the total acyl-CoA pool concentration. Also, acylcarnitine in ischemic and control rat brain had similar concentrations of molecular species. Deutsch J, Kalderon B, Purdon AD, Rapoport SI. Evaluation of brain long-chain acylcarnitines during cerebral ischemia. Lipids 2000 Jun;35(6):693-6.
Previous estimates of energy requirements for phospholipid metabolism in mammalian brain were 2% or less of total ATP consumption (consistent with long half-lives reported). However, we saw half-lives 100 times shorter (min-h), making energy requirements for reacylation of fatty acids into lysophospholipids be 5% of net brain ATP consumption. ATP requirements for translocase-maintained asymmetry of phosphatidylserine and phosphatidylethanolamine across brain membrane bilayers was calculated to be 8% of total ATP consumed. Purdon AD, Rapoport SI. Energy requirements for two aspects of phospholipid metabolism in mammalian brain. Biochem J 1998 Oct 15;335 ( Pt 2):313-8.
Unesterified fatty acid concentrations increased significantly after decapitation, most dramatically for arachidonic acid (76-fold at 15 min) followed by docosahexaenoic acid. Of the acyl-CoA molecular species only the concentration of arachidonoyl-CoA was increased at 3 min and 15 min after decapitation, by 3-4 fold compared with microwaved brain. Deutsch J, Rapoport SI, Purdon AD. Relation between free fatty acid and acyl-CoA concentrations in rat brain following decapitation. Neurochem Res 1997 Jul;22(7):759-65
The common carotid arteries in awake gerbils were tied for 5 min, after which the ligatures were released for 5 min and the animals were killed by microwave irradiation. Brain unesterified fatty acid concentration increased 4.4-fold in the ischemic-reperfused animals, with stearic acid and arachidonic acid increasing the most. In 2 of 10, brain unesterified arachidonic acid concentration was not elevated beyond that in controls. The total acyl-CoA concentration remained unaffected, but there was a substantial increase in the stearoyl- and arachidonoyl-CoA and a marked decrease in palmitoyl- and docosahexaenoyl-CoA. Rabin O, Deutsch J, Grange E, Pettigrew KD, Chang MC, Rapoport SI, Purdon AD. Changes in cerebral acyl-CoA concentrations following ischemia-reperfusion in awake gerbils. J Neurochem 1997 May;68(5):2111-8