Figure 6.

Mitochondrial biogenesis and the accumulation of aberrant mitochondria (aMt) due to impaired mitophagy in the left ventricle of Western diet-induced obesity female mice at 20-weeks of age. Panel A illustrates the normal morphology of the alternating row of sarcomeres with usually a single row of electron-dense intermyofibrillar mitochondria (IMF Mt). Note that insert (a) depicts normal crista morphology. Panel B depicts the moderate expansion of the IMF aberrant Mt (aMt) in Western models with hypertrophic Mt and increased hyperlucency as compared to the electron-dense mitochondria in panel A. Panel C reveals the protective role of enhanced exercise (Ex) via increased heme oxygenase-1 on Mt remodeling. Panels D and E depict marked IMF Mt expansion (biogenesis) with an accumulation of aMt that are hyperlucent with attenuation and loss of crista and a loss of the electron-dense Mt matrix in obese Western models. Note that panel E is an exploded view of the IMF aMt in panel D to better demonstrate the abnormalities of the IMF aMt. Panel F is interesting as it depicts areas of mitophagy with 2 different autophagosomes (APS white arrows) amongst areas that appeared more like the control models in panel A and in the exercise (Ex) model (panel C), which suggests that exercise may improve mitophagy and limit aMt. These modified images were provided with permission by CC 4.0 [25]. Magnifications vary and scale bars are located in the lower left-hand and magnification in the upper right-hand side of each image. Cap = capillary; N = nucleus.