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ORIGINAL PAPER
Dietary Enrichment with Medium Chain Triglycerides (AC-1203)
Elevates Polyunsaturated Fatty Acids in the Parietal Cortex
of Aged Dogs: Implications for Treating Age-Related Cognitive
Decline
Ameer Y. Taha ÆSamuel T. Henderson Æ
W. M. Burnham
Received: 20 October 2008 / Accepted: 4 March 2009
ÓSpringer Science+Business Media, LLC 2009
Abstract Dogs demonstrate an age-related cognitive
decline, which may be related to a decrease in the con-
centration of omega-3 polyunsaturated fatty acids (n-3
PUFA) in the brain. Medium chain triglycerides (MCT)
increase fatty acid oxidation, and it has been suggested that
this may raise brain n-3 PUFA levels by increasing
mobilization of n-3 PUFA from adipose tissue to the brain.
The goal of the present study was to determine whether
dietary MCT would raise n-3 PUFA concentrations in the
brains of aged dogs. Eight Beagle dogs were randomized to
a control diet (n=4) or an MCT (AC-1203) enriched diet
(n=4) for 2 months. The animals were then euthanized
and the parietal cortex was removed for phospholipid,
cholesterol and fatty acid determinations by gas-chroma-
tography. Dietary enrichment with MCT (AC-1203)
resulted in a significant increase in brain phospholipid and
total lipid concentrations (P\0.05). In particular, n-3
PUFA within the phospholipid, unesterified fatty acid, and
total lipid fractions were elevated in AC-1203 treated
subjects as compared to controls (P\0.05). Brain cho-
lesterol concentrations did not differ significantly between
the groups (P[0.05). These results indicate that dietary
enrichment with MCT, raises n-3 PUFA concentrations in
the parietal cortex of aged dogs.
Keywords Medium chain triglycerides Brain
Omega-3 polyunsaturated fatty acids (n-3 PUFA)
Docosahexaenoic acid (DHA) Mobilization Cognition
Alzheimer’s Aging Dogs
Abbreviations
MCT Medium chain triglycerides
PUFA Polyunsaturated fatty acids
Introduction
Age-related cognitive decline is accompanied by metabolic
and structural changes in the brain, including the inefficient
utilization of glucose as an energy substrate [1]. Acute,
dietary supplementation of cognitively impaired patients
with an oil blend containing ‘medium chain triglycerides’
(MCT) has been reported to improve cognitive perfor-
mance in patients with Alzheimer’s disease [2]. This has
been thought to be due to the production of ketone body
energy substrates, such as b-hydroxybutyrate, from hepatic
oxidation of the MCT oil. These ketone bodies might
provide an alternate source of energy for the aged brain,
which utilizes glucose inefficiently [2].
We have recently tested this hypothesis using the brains
of aged Beagle dogs on a control diet or on a diet sup-
plemented with MCT oil (AC-1302, Accera Inc., CO,
USA). Dogs were used because—in contrast to other lab-
oratory animals—the aging dog undergoes cognitive and
pathological changes similar to those seen in humans [3,4].
We found that dietary supplementation with MCT oil does
A. Y. Taha (&)W. M. Burnham
Department of Pharmacology and Toxicology, Faculty of
Medicine, University of Toronto, Medical Sciences Building,
Rm 4309, 1 King’s College Circle, Toronto, ON M5S 1A8,
Canada
e-mail: a.taha@utoronto.ca
A. Y. Taha W. M. Burnham
Epilepsy Research Program, Faculty of Medicine, University of
Toronto, Toronto, ON M5S 1A8, Canada
S. T. Henderson
Accera Inc., Broomfield, CO 80021, USA
123
Neurochem Res
DOI 10.1007/s11064-009-9952-5
increase fatty acid oxidation and ketone body production in
aged dogs [5].
There is a second way, however, involving structural
modifications to the brain, in which the MCT oil might
improve cognitive performance. The aged brain suffers not
only from inefficient glucose utilization, but also from a
depletion of omega-3 polyunsaturated fatty acids (n-3
PUFA) [1]. n-3 PUFA serve as key structural components
of neuronal membranes and are involved in neurogenesis
[6,7] and cell signaling [8], Chronic dietary consumption
of n-3 PUFA has also been reported to improve cognitive
performance in patients with mild to moderate Alzheimer’s
disease [9,10].
While MCT oil does not contain n-3 PUFA, it is pos-
sible that MCT dietary supplementation might increase
brain n-3 PUFA concentrations by causing the mobilization
of n-3 PUFA from adipose tissue to the brain. It has
recently been shown that the ketogenic diet, a diet high in
saturated fats, raises n-3 PUFA in the blood of children and
in the brains of rats [10,11]. It is possible that a diet
enriched with MCT oil might have a similar effect. Thus, a
diet containing MCT might decrease age-related cognitive
decline both by elevating ketone body energy substrates,
and by increasing n-3 PUFA concentrations in the brain.
In the present study, therefore, we re-analyzed the
samples of brains we had previously harvested from aged
dogs on a control diet or on a diet supplemented with a
MCT oil blend (AC-1203) [5]. Our goal was to determine
whether MCT supplementation would increase n-3 PUFA
concentrations in the aged brain.
Materials and Methods
Subjects and Treatments
Experimental procedures were conducted in accordance to
the guidelines of the Canadian Council of Animal Care,
and approved by the Animal Care Committee of the Uni-
versity of Toronto.
Eight Beagle dogs, aged 8–11 years and weighing
7–17 kg, served as subjects. Subjects were group housed (3–4
per pen based on compatibility) in pens measuring 16 95
feet and maintained on a natural light–dark cycle. Water
was available at libitum and the dogs were fed a standard
adult dog food (Purina Pro Plan Chicken and Rice) once
daily (http://www.proplan.com/products/ChickenRice_Dry
Dog.html). The diet contained (g/kg): 250 protein, 120 fat,
550 carbohydrates, 55 fiber and 12 moisture. The fatty acid
composition of the diet (% fatty acids) was 84.7 saturated
and monounsaturated fatty acids, 11.8 n-6 PUFA and 3.5
n-3 PUFA consisting of 0.88 eicosapentaneoic acid and
0.88 docosahexaenoic acid.
After a 2 week (minimum) period of acclimatization to
the facility, the dogs were divided into two groups, which
received either 0 g or 2 g/kg (body weight) of AC-1203.
AC-1203 is a structured triglyceride containing *95%
caprylic acid (C
8
H
16
O
2
) and *5% capric acid (C
10
H
20
O
2
).
AC-1203 is 100% saturated fat. The AC-1203 was added at
increasing doses to the chow diet over a 3 day period, with
one-third of the dose being administered on the first day,
two-thirds on the second day and a full dose on the third
day. For the MCT-enriched diet, an isocaloric amount of
food was removed from the daily ration to control for
caloric effects of the MCT oil. The subjects were then
maintained on the MCT enriched or control diets for the
remainder of the study. The MCT supplement substituted
for calories instead of fatty acids, in order to maintain
constant body condition score throughout the study, and to
exclude the possibility of changes in weight gain as a
potential confounder. The overall amount of calories
substituted was relatively small (\3%) in relation to the
total amount of food consumed by the dogs.
On the day of sacrifice (days 56 or 57), the experimental
group was administered 2 g/kg of AC1203 by gavage, and
the control group was administered an isocaloric sucrose
solution to control for caloric effects. Subjects were
euthanized approximately 2 h after dosing by a lethal
injection of approximately 10 ml of T-61 (i.v.). The pari-
etal lobe was removed and immediately flash frozen using
2-methylbutane (*-40°C), and archived in an ultra-cold
freezer (-80°C) for future analysis.
Brain Lipid Analysis
Approximately 50–100 mg of the parietal lobe were used
for total lipid, phospholipid, unesterified free fatty acid and
cholesterol analysis. Total lipids were extracted from each
sample following the addition of diheptadecanoyl
L-a-phosphatidylcholine (0.1 mg), non-esterified hepta-
decaenoic acid (0.4 mg) and 5-a-cholestane (0.9 mg)
(Sigma, St. Louis, MO) in chloroform as internal standards.
The samples were homogenized in chloroform/methanol
(2:1, v/v) in order to extract total lipids [11]. Saline (0.9%)
was added an hour later in order to separate the polar
phase. The phases were allowed to separate overnight.
Following distinct separation of the non-polar lipid phase
from the aqueous phase, the lower chloroform layer was
transferred to new 15 ml glass screw cap tubes with
TeflonÒlined caps, dried under a gentle stream of nitrogen
and reconstituted in 2 ml of chloroform.
An aliquot of the total lipid extract (0.5 ml) was dried
under nitrogen and saponified in 3 ml of 1N methanolic
NaOH at 90°C for 1 h. The non-saponifiable material
containing sterols and glycerol was first separated from the
free fatty acids by adding 2 ml of saline and 5 ml of
Neurochem Res
123
hexane, centrifuging at 1,600 rpm (275 g units) for 4 min
and removing the top hexane phase containing sterols and
glycerol. The hexane extraction process and centrifugation
were repeated three times, in order to maximize the sepa-
ration of the top hexane layer containing sterols from the
bottom layer containing free fatty acids.
The sterol fraction containing cholesterol was dried
under nitrogen, and subsequently derivitized in 0.1 ml of
trimethylsilyl chloride (Pierce, Rockford, IL) at 60°C for
1h [12]. The trimethylsilyl chloride was completely
evaporated under nitrogen and the remaining derivitized
cholesterol fraction was reconstituted with approximately
100 ll of hexane for analysis by gas chromatography.
The resulting free fatty acids in the lower methanolic
sodium hydroxide layer were recovered by adding 0.3 ml
of concentrated hydrochloric acid (11 M) and 5 ml of
hexane, and then centrifuging at 1,600 rpm for 4 min. The
upper hexane layer containing the saponified free fatty
acids was transferred to 16 9125 mm Kimax tubes, dried
under nitrogen and converted to methyl esters using 3 ml
of 14% methanolic boron triflouride (Sigma Chemical Co.,
St. Louis, MO, USA) at 90°C for 30 min. The methylation
reaction was terminated by adding 2 ml of 0.9% saline and
5 ml of hexane, and then centrifuging the mixture at
1,600 rpm for 10 min. The upper hexane layer containing
the fatty acid methyl esters was separated and stored under
nitrogen until they were analyzed by gas chromatography.
Phospholipids and free fatty acids in the brain total lipid
extracts were fractionated by thin-layer chromatography
using 20 920 cm silica gel plates (Whatman LK6D plates,
precoated with 250 lm of Silica Gel 60A). Separate lanes
were spotted with phospholipid or free fatty acid standards.
The plates were developed using hexane, diethyl ether, and
acetic acid (80:20:1 by volume) in covered glass tanks for
35 min. Bands corresponding to phospholipids and free
fatty acids were viewed under ultraviolet light after lightly
spraying with 8-anilino-1-naphthalenesulfonic acid. The
bands were scraped off each plate into 15 ml glass screw
cap tubes with Teflon lined caps, and directly methylated by
incubating with hexane (2 ml) and 14% methanolic BF
3
(2 ml) at 100°C for 1 h. Deionized water (2 ml) was then
added to separate the phases. The upper hexane phase was
extracted, dried under nitrogen and reconstituted in hexane
for analysis by gas chromatography.
Fatty Acid Methyl Ester Analysis
by Gas-Chromatography
Fatty acid methyl esters (FAME) were analyzed using an
Agilient 6890 gas-chromatography system equipped with a
flame ionization detector and a fused SP2560 silica capil-
lary column (Supelco; 100 m, 0.25 lm film thickness,
0.25 mm ID, Pennsylvania, USA). One ll samples were
injected in splitless mode. The injector and detector ports
were set at 250°C. Methyl esters were eluted using a
temperature program set initially at 60°Cfor5min,10°C/min
until 170°C, 5°C/min until 175°C, 2°C/min until 185°C,
1°C/min until 190°C, and 10°C/min until 240°C.
Helium was used as a carrier gas, at a constant flow rate of
1.3 ml/min.
Cholesterol Analysis by Gas-Chromatography
Cholesterol was determined by gas-chromatography using
a30925 mm capillary column (J and W Scientific,
DB-23, Folsom, CA) in a Hewlett Packard 5890 gas
chromatograph (Palo Alto, CA) equipped with a flame
ionization detector. A two stage temperature program was
used in the gas-chromatography system to acquire the
sterol profile [13]. The initial temperature setting was
120°C with a 1 min hold followed by a ramp up at 15°C/min
to 230°C and a 12 min hold of that temperature (total of
19 min run time). Retention times for cholesterol and the
internal standard (5-a-cholestane) were compared to pure
cholesterol and 5-a-cholestane (Sigma Chemical Co.,
St. Louis, MO, USA) which were derivitized by trimeth-
ylsilyl chloride.
Statistical Analysis
All data are presented as means ±SEM. Data analysis was
performed on Sigma Stat v.3.2 (Jandel Corporation).
Despite the small sample size of each group, the data fol-
lowed normal distribution. An unpaired t-test was therefore
used to determine the effect of AC-1203 treatment on
cholesterol and fatty acid concentrations of total lipids,
phospholipids and unesterified fatty acids. Statistical sig-
nificance was accepted at PB0.05.
Results
Concentrations of Lipid Fractions in the Parietal Cortex
of Aged Dogs
The data for total non-sterol lipids, cholesterol, phospho-
lipid and unesterified fatty acid concentrations in the
parietal cortex are presented in Fig. 1. Dietary treatment
with AC-1203 elevated total non-sterol lipids, cholesterol
and phospholipids by 20, 42 and 43%, respectively, relative
to controls. These differences were statistically significant
for total non-sterol lipids and phospholipids (P\0.05), but
did not reach statistical significance for total cholesterol
(P=0.11). Total unesterified fatty acid concentrations
were not significantly elevated in the AC-1203 treated dogs
relative to controls (P[0.05).
Neurochem Res
123
Fatty Acid Concentrations Within Total Non-Sterol
Lipids in the Parietal Cortex of Aged Dogs
The fatty acid profile of each of the total lipid, phospho-
lipid and unesterfied fatty acid fraction was determined.
Fatty acid concentrations within parietal cortex total lipids
are reported in Table 1. As shown, compared to controls,
dogs that received AC-1203 had greater concentrations of
total saturated fatty acids and n-3 PUFA. The rise in total
saturates was mainly due to an increase in palmitate and
stearate concentrations, whereas the rise in total n-3 PUFA
was due to an increase in docosahexaenoic acid concen-
trations in the brains of AC-1203 treated dogs (P\0.05).
Although total n-6 PUFA did not statistically differ
between the two groups, concentrations of arachidonic acid
and n-6 docosapentaenoic acid were significantly higher in
AC-1203 treated dogs relative to controls (P\0.05).
Fatty Acid Concentrations Within Total Phospholipids
in the Parietal Cortex of Aged Dogs
The data for fatty acid concentrations within total phos-
pholipids are presented in Table 2. Dietary treatment with
AC-1203 led to a significant increase in total saturates, n-6
PUFA and n-3 PUFA (P\0.05). These changes were
mainly due to a significant increase in the saturates, pal-
mitate (16:0) and stearate (18:0), the n-6 PUFA arachidonic
and n-6 docosapentaenoic acids, and the n-3 PUFA doco-
sahexaenoic acid (P\0.05).
Unesterified Fatty Acid Concentrations in the Parietal
Cortex of Aged Dogs
Unesterified fatty acid concentrations are presented in
Table 3. Although total unesterified fatty acid concentrations
did not change as a result of AC-1203 treatment (Fig. 1), n-6
docosapentanoic and docosahexaenoic acids were signifi-
cantly higher in AC-1203 treated dogs, as compared to
controls (P\0.05). Total n-6 PUFA were also higher in the
AC-1203 treated group relative to controls (P\0.05).
Discussion
The results of the present study demonstrate for the first
time that dietary treatment with MCT oil elevates PUFA
concentrations in various lipid fractions in the parietal
cortex of aged dogs. These results suggest that a diet
containing MCT may decrease age-related cognitive
0
5
10
15
20
25
30
35
40
Total non-sterol
lipids
Cholesterol Phospholipids Unesterified fatty
acids
Concentration (mg per g)
Control
MCT
*
*
Data are mean ± SEM of n=4 / group; *P<0.05 by unpaired t-test.
Fig. 1 Effect of MCT treatment on total lipid, cholesterol, phospho-
lipid and unesterified fatty acid concentrations in parietal cortex of
aged dogs. Data are mean ±SEM of n=4/group; *P\0.05 by
unpaired t-test
Table 1 Effect of MCT treatment on total lipid fatty acid concen-
trations of dog parietal cortex
Control MCT
12:0 0.01 ±0.003 0.01 ±0.004
14:0 0.1 ±0.01 0.1 ±0.01
16:0 4.8 ±0.4 6.3 ±0.3*
18:0 4.7 ±0.3 5.9 ±0.3*
20:0 0.04 ±0.01 0.05 ±0.01
22:0 0.03 ±0.01 0.03 ±0.002
24:0 0.1 ±0.04 0.2 ±0.03
Sum SAT 10.3 ±0.7 12.9 ±0.6*
16:1 n-9 0.1 ±0.02 0.1 ±0.01
18:1 n-9 5.3 ±0.5 6.1 ±0.5
18:1 n-7 1.4 ±0.1 1.3 ±0.3
20:1 n-9 0.2 ±0.04 0.2 ±0.03
22:1 n-9 0.03 ±0.01 0.03 ±0.003
24:1 n-9 0.3 ±0.1 0.2 ±0.03
Sum MUFA 7.5 ±0.8 8.3 ±0.7
18:2 n-6 0.1 ±0.01 0.2 ±0.02
18:3 n-6 Trace Trace
20:2 n-6 0.1 ±0.01 0.1 ±0.01
20:3 n-6 0.3 ±0.04 0.4 ±0.1
20:4 n-6 2.2 ±0.2 2.7 ±0.1*
22:2 n-6 0.02 ±0.004 0.02 ±0.01
22:4 n-6 1.4 ±0.2 1.4 ±0.1
22:5 n-6 1.0 ±0.1 1.4 ±0.1*
Sum n-6 PUFA 5.2 ±0.3 6.1 ±0.3
18:3 n-3 0.1 ±0.02 0.1 ±0.01
20:3 n-3 0.03 ±0.01 0.03 ±0.003
20:5 n-3 Trace Trace
22:3 n-3 0.1 ±0.04 0.1 ±0.004
22:5 n-3 0.05 ±0.01 0.1 ±0.01
22:6 n-3 2.0 ±0.2 3.1 ±0.1*
Sum n-3 PUFA 2.4 ±0.2 3.4 ±0.2*
Data are mean ±SEM of n=4/group; Trace, \0.01 mg/g;
*P\0.05 by unpaired t-test
Neurochem Res
123
decline by increasing n-3 PUFA concentrations in the brain
as well as by elevating ketone body energy substrates [5].
The differing concentrations of arachidonic, n-6 doco-
sapentaenoic and docosahexaenoic acids in the control and
AC-1203 treated group cannot be attributed simply to the
MCT-enriched diet because these fatty acids were not
present in the MCT oil supplement. In addition, the brain is
incapable of synthesizing these fatty acids de novo [14].
The increase in brain polyunsaturated fatty acid con-
centrations in the AC-1203 group (Tables 1,2,3) is likely
due to tissue redistribution of polyunsaturates from adipose
tissue and possibly liver to the brain [15,16]. Under con-
ditions of enhanced fatty acid oxidation or ketosis,
polyunsaturated fatty acids are preferentially mobilized
from adipose tissue or liver, to other tissues, including the
brain [16]. AC-1203 has been shown to increase fatty acid
oxidation in aged dogs [17]. Thus, the rise in brain PUFA
concentrations in the MCT-treated group is likely due to a
metabolic effect of the AC-1203 on fatty acid oxidation
and subsequent redistribution of PUFA from adipose tissue
and liver to the brain. Our results are consistent with a
previous report which has shown that dietary enhancement
of fatty acid oxidation through the high-fat ketogenic diet
increases brain polyunsaturated concentrations in rats [16].
The ketogenic diet is a high fat/adequate protein/low
carbohydrate diet designed to increase free fatty acid
release from adipocytes and promote oxidation of fatty
acids in the liver. Low levels of carbohydrates in the diet
Table 2 Effect of MCT treatment on phospholipid fatty acid con-
centrations of dog parietal cortex
Control MCT
12:0 ND ND
14:0 0.04 ±0.01 0.04 ±0.04
16:0 4.4 ±0.3 5.6 ±0.4*
18:0 4.8 ±0.3 6.2 ±0.8*
20:0 0.01 ±0.01 ND
22:0 0.01 ±0.01 ND
24:0 0.1 ±0.03 0.1 ±0.1
Sum SAT 9.6 ±0.7 12.2 ±0.6*
16:1 n-9 0.1 ±0.01 0.1 ±0.1
18:1 n-9 4.3 ±0.5 5.3 ±0.8
18:1 n-7 1.2 ±0.1 1.5 ±0.2
20:1 n-9 0.2 ±0.02 0.2 ±0.1
22:1 n-9 ND ND
24:1 n-9 0.2 ±0.02 0.1 ±0.1
Sum MUFA 6.3 ±0.7 7.7 ±1.2
18:2 n-6 0.1 ±0.01 0.1 ±0.02
18:3 n-6 ND ND
20:2 n-6 0.01 ±0.01 ND
20:3 n-6 0.2 ±0.04 0.3 ±0.1*
20:4 n-6 1.8 ±0.1 2.2 ±0.1*
22:2 n-6 ND ND
22:4 n-6 1.1 ±0.1 1.2 ±0.2
22:5 n-6 0.8 ±0.1 1.2 ±0.1*
Sum n-6 PUFA 4.1 ±0.2 5.0 ±0.4*
18:3 n-3 0.1 ±0.01 0.1 ±0.03
20:3 n-3 ND ND
20:5 n-3 ND ND
22:3 n-3 0.01 ±0.01 ND
22:5 n-3 0.02 ±0.01 0.01 ±0.02
22:6 n-3 1.9 ±0.2 2.9 ±0.3*
Sum n-3 PUFA 2.1 ±0.1 3.0 ±0.3*
Data are mean ±SEM of n=4/group; ND, not detected; *P\0.05
by unpaired t-test
Table 3 Effect of MCT treatment on unesterified fatty acid con-
centrations of dog parietal cortex
Control MCT
12:0 Trace Trace
14:0 0.02 ±0.01 0.02 ±0.003
16:0 0.2 ±0.1 0.2 ±0.02
18:0 0.2 ±0.03 0.3 ±0.02
20:0 Trace Trace
22:0 Trace Trace
24:0 Trace Trace
Sum SAT 0.5 ±0.1 0.5 ±0.1
16:1 n-9 0.01 ±0.004 0.01 ±0.002
18:1 n-9 0.1 ±0.02 0.1 ±0.01
18:1 n-7 0.04 ±0.004 0.05 ±0.003
20:1 n-9 0.01 ±0.002 0.01 ±0.001
22:1 n-9 Trace Trace
24:1 n-9 Trace ND
Sum MUFA 0.2 ±0.1 0.2 ±0.02
18:2 n-6 0.02 ±0.01 0.02 ±0.01
18:3 n-6 ND ND
20:2 n-6 Trace Trace
20:3 n-6 0.01 ±0.002 0.01 ±0.002
20:4 n-6 0.1 ±0.03 0.1 ±0.01
22:2 n-6 ND ND
22:4 n-6 0.02 ±0.001 0.02 ±0.002
22:5 n-6 0.01 ±0.001 0.02 ±0.002*
Sum n-6 PUFA 0.1 ±0.02 0.2 ±0.01*
18:3 n-3 0.01 ±0.003 0.01 ±0.001
20:3 n-3 ND ND
20:5 n-3 ND Trace
22:3 n-3 Trace 0.01 ±0.01
22:5 n-3 Trace Trace
22:6 n-3 0.02 ±0.001 0.03 ±0.003*
Sum n-3 PUFA 0.04 ±0.01 0.05 ±0.01
Data are mean ±SEM of n=4/group; ND, not detected; Trace,
\0.01 mg/g; *P\0.05 by unpaired t-test
Neurochem Res
123
suppress insulin secretion, resulting in an increase in
hepatic fatty acid oxidation. The present study did not
utilize a ketogenic diet, and protein and carbohydrate levels
were maintained at adequate levels. However, as previ-
ously reported, higher rates of fatty acid oxidation were
achieved by exogenously adding MCT to the normal chow
diet [17]. This is because, in contrast to longer chain fatty
acids ([12 carbons), MCT undergo obligate hepatic oxi-
dation. Therefore, dietary MCT, in sufficient amounts,
causes a rapid rise in fatty acid oxidation [5]. This likely
contributed to a redistribution of PUFA from adipose tissue
and liver to the brain.
It is well-established that brain polyunsaturated fatty
acid concentrations decrease with age and are lower in
Alzheimer’s disease patients [18–21]. The consequences of
low n-6 fatty acid concentrations in the brain are not fully
understood. In contrast, lower concentrations of brain n-3
PUFA, such as docosahexaenoic acid (DHA), are associ-
ated with impaired learning and memory in rodents [22,
23]. Lower plasma levels in humans are likewise associated
with impaired cognitive performance [9,10,24,25].
We observed a non-significant trend towards higher
total cholesterol concentrations, and a significant increase
in saturated fatty acid concentrations in total lipids and
phospholipids of AC-1203 treated dogs. The slight
increase in brain cholesterol and saturated fatty acids may
be due to the increased availability of ketone bodies,
which were found to be elevated in our previous study
[5]. Ketone bodies are the breakdown products of medium
chain fatty acids (4–10 carbons) [26], and they serve as
substrates for cholesterol and saturated fatty acid syn-
thesis in the brain [27,28]. The possible implications of
higher cholesterol or saturated fatty acids in the brain are
not known. Similar elevations, however, have been
reported in rats on the high fat ketogenic diet [16], which
is well known for its cognitive-enhancing effects in
children with epilepsy [29,30].
In the present study, AC-1203 treatment resulted in a
significant increase in n-3 PUFA concentrations in brain
total lipids, phospholipids and unesterified fatty acids in
aged dogs. These findings suggest that compounds con-
taining MCT, like AC-1203, could be used as a dietary
strategy for raising brain n-3 PUFA concentrations. Thus,
they might be potentially useful for restoring the structural
and functional deficits associated with age-related cogni-
tive decline.
Acknowledgments We would like to thank Dr. Christa M. Stud-
zinski for her assistance and Dr. David W.L. Ma for his support and
expert advice. Financial support for this study was provided by the
Natural Sciences and Engineering Research Council and Accera Inc.
A.Y.T is a recipient of the Canadian Institutes of Health Research
Doctoral Research Award (Fredrick Banting and Charles Best Canada
Graduate Scholarships). The authors declare no conflict of interest.
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