Turnover of palmitic and arachidonic acids in the phospholipids from different brain areas of adult and aged rats

Abstract

[3H]Palmitic acid and [14C]arachidonic acid were injected together into the cerebral ventricle of 4-month and 24-month-old rats. At different time intervals from the injection, the distribution of these fatty acids in the lipids from different brain areas was examined. The fatty acids were rapidly incorporated into the lipids through different mechanisms. The time-specific activity relationship indicate that the utilization of the fatty acid differs according to the different areas and aging decreases the utilization of both the fatty acids. The decline of arachidonic acid incorporation into phospholipids is particularly evident, indicating that aging affects mainly the utilization of polyunsaturated fatty acids.

Alterations in the balance of protein kinase and phosphatase activities and age‐related impairments of synaptic transmission and long‐term potentiation

“…Parallel age-related changes in membrane composition were also observed in aged animals. In aged brains, phospholipid metabolism is decreased, fatty acid incorporation into phospholipid is decreased, and alterations in the degree of unsaturation of phospholipid fatty acyl chains have been reported (Gatti et al, 1986;Bazan, 1989;Fonlupt et al, 1994). Because the membrane bioactive lipids such as arachidonic acid and platelet-activating factor are known to play a crucial role in the regulation of membrane excitability and longterm synaptic plasticity (Clements et al, 1991;Clark et al, 1992;Kato et al, 1994;Baraňano et al, 2001), alterations in membrane lipid availability in aged animals may cause the deficit of synaptic transmission and plasticity observed in the present study.…”

Brain phospholipid arachidonic acid half-lives are not altered following 15 weeks of N-3 polyunsaturated fatty acid adequate or deprived diet

“…Past studies have examined brain AA metabolism for р 24 h following i.c.v. injection in the lateral ventricle ( 37,49 ), giving us the opportunity to measure brain phospholipid AA loss over a greater time period (4-120 days). We calculated the half-life of AA in rat brain total phospholipids to be 44 ± 4 and 46 ± 4 days for the n-3 PUFA adequate and deprived groups, respectively; these halflives represent the rate of AA metabolic consumption, and not the more rapid kinetic rate of recycling into the phospholipid membrane.…”

“…To minimize this, we used a 33 gauge needle and allowed the animal to recover for 4-120 days prior to measuring brain phospholipid radioactivity. This procedure has been widely used to deliver compounds including fatty acids to the brain ( 24,37,49,(53)(54)(55).…”

“…Dietary fatty acid composition was confi rmed by GC analysis (see below). ( 24,37 ). The radioactivity of the perfusate was confi rmed to be 94% 20:4n-6 with 6% of the radioactivity eluting at 45 min.…”

“…Rats were then anesthetized by isofl uorane inhalation, and the head was placed in a stereotaxic instrument (Stoelting, IL) and the skull exposed. A 33-gauge bevelled injection needle (World Precision Instruments, Sarasota, FL) was inserted into the right lateral cerebral ventricle (4 mm ventral to the dura) via a hole that was drilled in the cranium at 1 mm posterior and 1.5 mm lateral to the bregma ( 37,38 ). An injection (5 µL total volume, 0.175 µL/min; quintessential stereotaxic injector; Stoelting, IL) was made of 40 µCi of [ 3 H] AA.…”