Effects of high intensity interval training on neuro-cardiovascular dynamic changes and mitochondrial dysfunction induced by high-fat diet in rats

Abstract

Background and aims Mitochondrial swelling is involved in the pathogenesis of many human diseases associated with oxidative stress including obesity. One of the strategies for prevention of deleterious effects related to obesity and overweight is engaging in regular physical activity, of which high intensity interval training (HIIT) is efficient in promoting biogenesis and improving the function of mitochondria. Therefore, our aims were to investigate the effects of HIIT on metabolic and neuro-cardiovascular dynamic control and mitochondrial swelling induced by high-fat diet (HFD). Methods and results Twenty-three male Wistar rats (60 – 80g) were divided into 4 subgroups: control (C), HIIT, HFD and HFD+HIIT. The whole experimentation period lasted for 22 weeks and HIIT sessions were performed 5 days a week during the last 4 weeks. At the end of the experiments, fasting glucose and insulin tolerance tests were performed. Cerebral microcirculation was analyzed using cortical intravital microscopy for capillary diameter and functional density. Cardiac function and ergoespirometric parameters were also investigated. Mitochondrial swelling was evaluated on brain and heart extracts. HFD promoted an increase on body adiposity (p<0.001), fasting glucose levels (p<0.001), insulin resistance index (p<0.05), cardiac hypertrophy index (p<0.05) and diastolic blood pressure (p<0.05), along with worsened cardiac function (p<0.05), reduced functional cerebral capillary density (p<0.05) and its diameter (p<0.01), and heart and brain mitochondrial function (p<0.001). HFD did not affect any ergoespirometric parameter. After 4 weeks of training, HIIT was able to improve cardiac hypertrophy index, diastolic blood pressure, cerebral functional capillary density (p<0.01) and heart and brain mitochondrial swelling (p<0.001). Conclusion In animals subjected to HFD, HIIT ameliorated both cerebral mitochondrial swelling and functional capillary density, but it did not improve cardiovascular function suggesting that the cardiovascular dysfunction elicited by HFD was not due to heart mitochondrial swelling.

Isolation of Mitochondria From Fresh Mice Lung Tissue

“…Our method does not contemplate analyzing all 40 subtypes of cells found in the lung. However, this heterogeneity is an intrinsic part of the lung, and all methods of mitochondria isolation, for most diverse tissues, contemplate entire organ isolation, because different cells form a syncytium for the organ to work, e.g., the heart ( Gedik et al, 2017 ), kidney ( Schulz et al, 2015 ), liver ( Goudarzi et al, 2018 ), adipose tissue ( Matta et al, 2021 ), and brain ( Marques Neto et al, 2020 ).…”

“…The evaluation of mitochondrial function is usually accomplished in isolated mitochondria ( Picard et al, 2011 ; Gedik et al, 2017 ; Maciel et al, 2020 , 2021 ; Caldeira et al, 2021 ) permeabilized fibers ( Perry et al, 2013 ) or cells ( Perry et al, 2013 ). These techniques are very well-defined in several types of tissue, e.g., heart ( Gedik et al, 2017 ), kidney ( Schulz et al, 2015 ), liver ( Goudarzi et al, 2018 ), adipose tissue ( Matta et al, 2021 ), and brain ( Marques Neto et al, 2020 ), presenting peculiarities and different indications depending on the tissue and the purpose of the investigation. However, assessment of lung mitochondrial function presents difficulties associated with obtaining isolated, intact, coupled, and functional mitochondria.…”