Increasing energy expenditure through exercise and low ambient temperature offers oxidative protection to the hypothalamus after high-fat feeding to mice

The mitochondrial quality control system: a new target for exercise therapeutic intervention in the treatment of brain insulin resistance-induced neurodegeneration in obesity

Obesity is a major global health concern because of its strong association with metabolic and neurodegenerative diseases such as diabetes, dementia, and Alzheimer's disease. Unfortunately, brain insulin resistance in obesity is likely to lead to neuroplasticity deficits. Since the evidence shows that insulin resistance in brain regions abundant in insulin receptors significantly alters mitochondrial efficiency and function, strategies targeting the mitochondrial quality control system may be of therapeutic and practical value in obesity-induced cognitive decline. Exercise is considered as a powerful stimulant of mitochondria that improves insulin sensitivity and enhances neuroplasticity. It has great potential as a non-pharmacological intervention against the onset and progression of obesity associated neurodegeneration. Here, we integrate the current knowledge of the mechanisms of neurodegenration in obesity and focus on brain insulin resistance to explain the relationship between the impairment of neuronal plasticity and mitochondrial dysfunction. This knowledge was synthesised to explore the exercise paradigm as a feasible intervention for obese neurodegenration in terms of improving brain insulin signals and regulating the mitochondrial quality control system.

High-Fat Diet-Induced Obesity Increases Brain Mitochondrial Complex I and Lipoxidation-Derived Protein Damage

Obesity is a risk factor for highly prevalent age-related neurodegenerative diseases, the pathogenesis of whichinvolves mitochondrial dysfunction and protein oxidative damage. Lipoxidation, driven by high levels of peroxidizable unsaturated fatty acids and low antioxidant protection of the brain, stands out as a significant risk factor. To gain information on the relationship between obesity and brain molecular damage, in a porcine model of obesity we evaluated (1) the level of mitochondrial respiratory chain complexes, as the main source of free radical generation, by Western blot; (2) the fatty acid profile by gas chromatography; and (3) the oxidative modification of proteins by mass spectrometry. The results demonstrate a selectively higher amount of the lipoxidation-derived biomarker malondialdehyde-lysine (MDAL) (34% increase) in the frontal cortex, and positive correlations between MDAL and LDL levels and body weight. No changes were observed in brain fatty acid profile by the high-fat diet, and the increased lipid peroxidative modification was associated with increased levels of mitochondrial complex I (NDUFS3 and NDUFA9 subunits) and complex II (flavoprotein). Interestingly, introducing n3 fatty acids and a probiotic in the high-fat diet prevented the observed changes, suggesting that dietary components can modulate protein oxidative modification at the cerebral level and opening new possibilities in neurodegenerative diseases' prevention.

Walking Exercise Reduces Postprandial Lipemia but Does Not Influence Postprandial Hemorheological Properties and Oxidative Stress

A higher postprandial triglycerides response and hemorheological abnormalities may increase the incidence of metabolic disorders and negatively interfere with the aging process. A single session of preprandial endurance exercise was found to be effective in reducing triglyceride levels after a high-fat diet. However, whether the exercise-induced reduction in postprandial triglyceride levels influences hemorheological indicators remains unknown. This study aims to investigate the effects of postprandial lipemia on hemorheological properties and oxidative stress. Eight healthy young male participants completed two experimental trials. On day 1, the participants were randomly assigned to walk for 1 h at 50% VO2max (EE trial) or rest (CON trial). On day 2, participants rested and consumed a high-fat meal in the morning. Results: The postprandial area under the curve (AUC) of plasma TG concentration was significantly lower in EE compared to CON (EE: 9.2 ± 1.9; CON: 10.9 ± 1.7 mmol/L·h−1; p = 0.013; Cohen’s d = 0.036). No significant difference was observed in hemorheological properties and MDA (p > 0.05). Endurance exercise effectively decreased postprandial TG concentration but did not influence the postprandial hemorheological properties and oxidative stress indicators.

Voluntary Exercise Eliminates Maternal Gestational Hypertension-Induced Hypertensive Response Sensitization to Postweaning High-Fat Diet in Male Adult Offspring

BACKGROUND

Exercise has profound effects on cardiovascular function and metabolism in both physiological and pathophysiological states. The present study tested whether voluntary exercise would protect male offspring against maternal gestational hypertension-induced hypertensive response sensitization elicited by post-weaning high-fat diet (HFD).

METHODS AND RESULTS

On low-lard-fat diet, offspring of both normotensive and hypertensive dams had comparable resting blood pressure, but HFD feeding elicited an enhanced increase in blood pressure (ie, hypertensive response sensitization) in sedentary offspring of hypertensive dams when compared with sedentary offspring of normotensive dams. The HFD fed sedentary offspring of hypertensive dams displayed greater sympathetic activity, enhanced pressor responses to centrally administered ANG II (angiotensin II) or leptin, and greater mRNA expression of proinflammatory cytokines, leptin, and a marker of blood-brain barrier leakage in the hypothalamic paraventricular nucleus. The enhanced blood pressure and central sympathetic activity in HFD-fed sedentary offspring of hypertensive dams were significantly reduced by exercise but fell only to levels comparable to HFD-fed exercising offspring of normotensive dams. HFD-induced increases in plasma IL-6 (interleukin-6) and sympathetic activity and greater pressor responses to central TNF (tumor necrosis factor)-α in offspring from both normotensive and hypertensive dams were also maintained after exercise. Nevertheless, exercise had remarkably beneficial effects on metabolic and autonomic function, brain reactivity to ANG II and leptin and gene expression of brain prohypertensive factors in all offspring.

CONCLUSIONS

Voluntary exercise plays a beneficial role in preventing maternal hypertension-induced hypertensive response sensitization, and that this is associated with attenuation of enhanced brain reactivity and centrally driven sympathetic activity.