Gestational hyperlipidemia in the rat is characterized by accumulation of n - 6 and n - 3 fatty acids, especially docosahexaenoic acid.

We have evaluated the relative and quantitative changes in long-chain fatty acids in maternal liver, serum, carcass and conceptus (fetuses plus placentae) during pregnancy in the rat, to ascertain whether previous concern over lower proportions of n - 6 and n - 3 fatty acids in maternal serum could be indicative of suboptimal n - 6 or n - 3 fatty acid status. Gestational hyperlipidemia was characterized by proportional decreases in linoleic, stearic and arachidonic acids but increases in palmitic and docosahexaenoic acids. However, the quantitative amount (microgram/ml) of linoleic, arachidonic and docosahexaenoic acids in serum lipids actually increased 2-5-fold from mid-pregnancy to term. Compared to non-pregnant rats, gestational hyperlipidemia was also associated with a lower proportion but similar quantity of linoleic acid in maternal carcass and adipose stores. We conclude that gestational hyperlipidemia in the rat is characterized by a relative but not quantitative decrease in whole-body stores of n - 6 fatty acids and a marked proportional and quantitative increase in docosahexaenoic acid in maternal organs and in the conceptus.     

Long-term calorie restriction has minimal impact on brain metabolite and fatty acid profiles in aged rats on a Western-style diet

The effect of long-term calorie restriction (CR) on metabolites, fatty acid profiles and energy substrate transporter expression in the brain was assessed in aged rats. Three groups of male Sprague–Dawley rats were studied: (i) a 2 month old ad libitum-fed (2AL group), (ii) a 19 month old ad libitum-fed (19AL group), and (iii) a 19 month old group subjected to 40% CR from the age of 7.5 to 19 months (19CR group). The diet contained high sucrose and low n-3 polyunsaturated fatty acids (PUFA) so as to imitate a Western-style diet. High resolution magic angle spinning-¹H NMR showed an effect of aging on brain cortex metabolites compared to 2AL rats, the largest differences being for myo-inositol (+251% and +181%), lactate (+203% and +188%), β-hydroxybutyrate (+176% and +618%) and choline (+148% and +120%), in 19AL and 19 CR rats, respectively. However, brain metabolites did not differ between the 19AL and 19CR groups. Cortex fatty acid profiles showed that n-3 PUFA were 35–47% lower but monounsaturated fatty acids were 40–52% higher in 19AL and 19CR rats compared to 2AL rats. Brain microvessel glucose transporter (GLUT1) was 68% higher in 19AL rats than in 2AL rats, while the monocarboxylate transporter, MCT1, was 61% lower in 19CR rats compared to 19AL rats. We conclude that on a high-sucrose, low n-3 PUFA diet, the brain of aged AL rats had higher metabolites and microvessel GLUT1 expression compared to 2AL rats. However, long-term CR in aged rats did not markedly change brain metabolite or fatty acid profile, but did reduce brain microvessel MCT1 expression.     

Survival of the fattest: fat babies were the key to evolution of the large human brain

In the past 2 million years, the hominid lineage leading to modern humans evolved significantly larger and more sophisticated brains than other primates. We propose that the modern human brain was a product of having first evolved fat babies. Hence, the fattest (infants) became, mentally, the fittest adults. Human babies have brains and body fat each contributing to 11-14% of body weight, a situation which appears to be unique amongst terrestrial animals. Body fat in human babies provides three forms of insurance for brain development that are not available to other land-based species: (1) a large fuel store in the form of fatty acids in triglycerides; (2) the fatty acid precursors to ketone bodies which are key substrates for brain lipid synthesis; and (3) a store of long chain polyunsaturated fatty acids, particularly docosahexaenoic acid, needed for normal brain development. The triple combination of high fuel demands, inability to import cholesterol or saturated fatty acids, and dependence on docosahexaenoic acid puts the mammalian brain in a uniquely difficult situation compared with other organs and makes its expansion in early humans all the more remarkable. We believe that fresh- and salt-water shorelines provided a uniquely rich, abundant and accessible food supply, and the only viable environment for evolving both body fat and larger brains in human infants.     

Regional Brain Glucose Hypometabolism in Young Women with Polycystic Ovary Syndrome: Possible Link to Mild Insulin Resistance

Objective

To investigate whether cerebral metabolic rate of glucose (CMR_glu) is altered in normal weight young women with polycystic ovary syndrome (PCOS) who exhibit mild insulin resistance.

Materials and methods

Seven women with PCOS were compared to eleven healthy female controls of similar age, education and body mass index. Regional brain glucose uptake was quantified using FDG with dynamic positron emission tomography and magnetic resonance imaging, and its potential relationship with insulin resistance assessed using the updated homeostasis model assessment (HOMA2-IR). A battery of cognitive tests was administered to evaluate working memory, attention and executive function.

Results

The PCOS group had 10% higher fasting glucose and 40% higher HOMA2-IR (p ≤ 0.035) compared to the Controls. The PCOS group had 9–14% lower CMR_glu in specific regions of the frontal, parietal and temporal cortices (p ≤ 0.018). A significant negative relation was found between the CMR_glu and HOMA2-IR mainly in the frontal, parietal and temporal cortices as well as in the hippocampus and the amygdala (p ≤ 0.05). Globally, cognitive performance was normal in both groups but scores on the PASAT test of working memory tended to be low in the PCOS group.

Conclusions

The PCOS group exhibited a pattern of low regional CMR_glu that correlated inversely with HOMA2-IR in several brain regions and which resembled the pattern seen in aging and early Alzheimer’s disease. These results suggest that a direct association between mild insulin resistance and brain glucose hypometabolism independent of overweight or obesity can exist in young adults in their 20s. Further investigation of the influence of insulin resistance on brain glucose metabolism and cognition in younger and middle-aged adults is warranted.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Long-term treadmill exercise improves spatial memory of male APPswe/PS1dE9 mice by regulation of BDNF expression and microglia activation

Increasing evidence suggests that physical activity could delay or attenuate the symptoms of Alzheimer''s disease (AD). But the underlying mechanisms are still not fully understood. To investigate the effect of long-term treadmill exercise on the spatial memory of AD mice and the possible role of β-amyloid, brain-derived neurotrophic factor (BDNF) and microglia in the effect, male APPswe/PS1dE9 AD mice aged 4 months were subjected to treadmill exercise for 5 months with 6 sessions per week and gradually increased load. A Morris water maze was used to evaluate the spatial memory. Expression levels of β-amyloid, BDNF and Iba-1 (a microglia marker) in brain tissue were detected by immunohistochemistry. Sedentary AD mice and wildtype C57BL/6J mice served as controls. The results showed that 5-month treadmill exercise significantly decreased the escape latencies (P < 0.01 on the 4th day) and improved the spatial memory of the AD mice in the water maze test. Meanwhile, treadmill exercise significantly increased the number of BDNF-positive cells and decreased the ratios of activated microglia in both the cerebral cortex and the hippocampus. However, treadmill exercise did not significantly alleviate the accumulation of β-amyloid in either the cerebral cortex or the hippocampus of the AD mice (P > 0.05). The study suggested that long-term treadmill exercise could improve the spatial memory of the male APPswe/PS1dE9 AD mice. The increase in BDNF-positive cells and decrease in activated microglia might underpin the beneficial effect.