Accumulation of Exogenous Amyloid-Beta Peptide in Hippocampal Mitochondria Causes Their Dysfunction: A Protective Role for Melatonin
Figure 4
The presence of Aβ within mitochondria is related to ROS overproduction. Control brain exhibited a regular distribution of mitochondria (a) with a size of 964365 nm, according to Mitotracker Green staining, which is essentially nonfluorescent in aqueous solutions but becomes fluorescent as it accumulates in the mitochondrial membranes. Nuclei appear in blue, stained with DAPI. The amount of mitochondrial ROS in control PBS-injected brain was negligible, as inferred from CM-H2XRos staining, which specifically accumulates inside mitochondria because of the positive charge it acquires upon oxidation by intracellular ROS (b). CM-H2XRos was intraperitoneally injected in vivo 2 hours before obtaining the tissue sample. fAβ-injected brains showed a different distribution of mitochondria, predominantly perinuclear, ranging in size from 529 to 7400 nm and forming clusters (c), (d). Integrated optical density (IOD) of CM-H2XRos-stained mitochondria was significantly () elevated in fAβ- and H2O2-injected brains (e), as compared with controls (d), (f). In order to estimate how many mitochondria from the mitochondrial mass were overproducing ROS, we divide the IOD of MT-Green by IOD of CM-H2XRos for each group, and we found a significant difference between fAβ-injected brains and controls as shown in the attached graphic ().
