Alleviation of ischemic brain injury by exercise preconditioning is associated with modulation of autophagy and mitochondrial dynamics in cerebral cortex of female aged mice.

Evidence from clinical studies and preclinical studies supports that exercise preconditioning can not only reduce the risk of stroke but also improve brain tissue and functional outcome after stroke. It has been demonstrated that autophagy and mitochondrial dynamics are involved in ischemic stroke. However, it is still unclear whether exercise preconditioning-induced neuroprotection against stroke is associated with modulation of autophagy and mitochondrial dynamics. Although age and sex interactively affect ischemic stroke risk, incidence, and outcome, studies based on young male animals are most often used to explore the role of exercise preconditioning in the prevention of ischemic stroke. In the current study, we examined whether exercise preconditioning could modulate autophagy and mitochondrial dynamics in a brain ischemia and reperfusion (I/R) model of female aged mice. The results showed that exercise preconditioning reduced infarct volume and improved neurological deficits. Additionally, increased levels of autophagy-related proteins LC3-II/LC3-I, LC3-II, p62, Atg7, and mitophagy-related proteins Bnip3L and Parkin, as well as increased levels of mitochondrial fusion modulator Mfn2 and mitochondrial fission modulator Drp1 in the ischemic cortex of female aged mice at 12 h after I/R were present. Our results could contribute to a better understanding of exercise preconditioning-induced neuroprotection against ischemic stroke for the elderly.

[Spectroscopic and Molecular Characterization of Water Soluble Organic Matter from Sediments in the Macrophyte-dominated and Algae-dominated Zones of Taihu Lake].

Macrophyte- and algae-dominated lakes (zones) are the two typical states of shallow lakes, where the source and composition of organic matter are distinct. The burial of organic matter (OM) in the sediment supports the role of lakes as carbon sinks. However, organic matter in the sediments could be further processed, influencing the carbon cycle. The post-burial metabolism of the sedimentary OM relates closely to its composition. However, information on the differences in composition remains limited, especially the molecular composition of organic matter from sediments in the macrophyte-dominated and algae-dominated lakes. In this study, sediments were collected from the macrophyte-dominated and algae-dominated zones of Taihu Lake (East Taihu Lake and Meiliang Bay, respectively), and the active pool of sedimentary OM (water soluble organic matter, WSOM) was extracted and purified. The composition of the WSOM was characterized in detail via absorption spectroscopy, fluorescent spectroscopy, infrared spectroscopy, and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). The optical index of E2:E3 showed that the molecular size of WSOM in the macrophyte-dominated zone (M-WSOM) was slightly larger than that in the algae-dominated zone (A-WSOM). Consistently, the intensity-weighted molecular weights were identified as 388.9 and 379.9, respectively, via FT-ICR MS analysis. M-WSOM was more humified than A-WSOM, as evidenced by the SUVA254 and HIX values. The FT-ICR MS results showed that the relative abundance of the condensed aromatic substance and the aromatics were 6.3% (intensity-weighted) and 7.7% for M-WSOM and 1.1% and 4.4% for A-WSOM, respectively. The excitation-emission matrix fluorescence-parallel factor analysis (EEM-PARAFAC) suggested that the protein-like component was more in A-WSOM than that in M-WSOM, and the FT-ICR MS results showed that the intensity-weighted relative abundances of peptides were 35.6% and 15.6% for A-WSOM and M-WSOM, respectively. The FT-ICR MS results further showed that the heteroatom-containing molecules were abundant in the sedimentary WSOM, i.e., 82.9% and 91.7% for M-WSOM and A-WSOM, respectively. The nitrogen-containing molecules dominated, contributing to 53.5% and 78.5% of M-WSOM and A-WSOM, respectively. There were 30.4% and 41.4% phosphorus-containing molecules in M-WSOM and A-WSOM, respectively. The phosphorus-containing molecules in M-WSOM were mainly aliphatics and highly unsaturated structures with low oxygen, whereas those in A-WSOM were mainly peptides. This study elucidated the detailed molecular composition of WSOM in the macrophyte-dominated and algae-dominated zones of Taihu Lake, which aids understanding of the carbon, nitrogen, and phosphorus biogeochemical cycles in lakes.

Lysosomal Proteolysis Is Associated With Exercise-Induced Improvement of Mitochondrial Quality Control in Aged Hippocampus.

Exercise improves cognitive function in older adults, but the underlying mechanism is largely unknown. Both lysosomal degradation and mitochondrial quality control decline with age. We hypothesized that exercise ameliorates age-related cognitive decline through the improvement of mitochondrial quality control in aged hippocampus, and this effect is associated with lysosomal proteolysis. Sixteen to eighteen-month old male Sprague Dawley rats underwent swim exercise training for 10 weeks. The exercise regimen prevented cognitive decline in aged rats, reduced oxidative stress, and rejuvenated mitochondria in the aged hippocampus. Exercise training promoted mitochondrial biogenesis, increased mitochondrial fusion and fission, and activated autophagy/mitophagy in aged hippocampal neurons. Lysosomal inhibitor chloroquine partly blocked beneficial effects of exercise on cognitive function, oxidative stress, autophagy/mitophagy, and mitochondrial quality control in aged rats. These results suggest that preservation of cognitive function by long-term exercise is associated with improvement of mitochondrial quality control in aged hippocampus and that lysosomal degradation is required for this process. Our findings suggest that exercise training or pharmacological regulation of mitochondrial quality control and lysosomal degradation may be effective strategies for slowing down age-related cognitive decline.