Yukai Luo’s research while affiliated with Chinese Academy of Sciences and other places

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Publications (6)


Potential health risks of hypomagnetic field for manned deep-space explorations
  • Article

November 2024

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31 Reads

National Science Review

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Jie Ren

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Yukai Luo

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[...]

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ROS changes caused by HMF at cellular level.
ROS changes caused by HMF at organism level.
Cont.
The Role of Oxidative Stress in Hypomagnetic Field Effects
  • Literature Review
  • Full-text available

August 2024

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508 Reads

Antioxidants

The geomagnetic field (GMF) is crucial for the survival and evolution of life on Earth. The weakening of the GMF, known as the hypomagnetic field (HMF), significantly affects various aspects of life on Earth. HMF has become a potential health risk for future deep space exploration. Oxidative stress is directly involved in the biological effects of HMF on animals or cells. Oxidative stress occurs when there is an imbalance favoring oxidants over antioxidants, resulting in cellular damage. Oxidative stress is a double-edged sword, depending on the degree of deviation from homeostasis. In this review, we summarize the important experimental findings from animal and cell studies on HMF exposure affecting intracellular reactive oxygen species (ROS), as well as the accompanying many physiological abnormalities, such as cognitive dysfunction, the imbalance of gut microbiota homeostasis, mood disorders, and osteoporosis. We discuss new insights into the molecular mechanisms underlying these HMF effects in the context of the signaling pathways related to ROS. Among them, mitochondria are considered to be the main organelles that respond to HMF-induced stress by regulating metabolism and ROS production in cells. In order to unravel the molecular mechanisms of HMF action, future studies need to consider the upstream and downstream pathways associated with ROS.

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Fig. 3. Dot plot representing four quadrant images by flow cytometric analysis. Q1: mitochondria active cells with low ROS levels (Mito + ROS cells), Q2: mitochondria active cells with high ROS levels (Mito + ROS + cells), Q3: mitochondria inactive cells with high ROS levels (Mito ROS + ), and Q4: mitochondria inactive cells with low ROS levels (Mito ROS ).
Fig. 4. Comparison results of the percentage of Q1 (A, C, E) and the percentage of Q2 (B, D, F) in hippocampus of mice between the GMF and HMF groups when exposed to GMF and HMF for 4, 6, and 8 weeks. Data were presented as mean ± SEM. Statistical significance was calculated by unpaired t-tests. **P < 0.01, ns means no significance.
Fig. 5. Comparison results of the percentage of Mito + cells (A) and ROS + cells (B) in hippocampus of mice when exposed to GMF and HMF for 4, 6, and 8 weeks. Data were presented as mean ± SEM with data points superimposed in the histograms. Statistical significance was calculated by unpaired t-tests. **P < 0.01, *P < 0.05, ns means no significance.
Fig. 6. Histograms with one standard error bar and each data point superimposed showing the results of relative expression levels of PINK1, LC3, Parkin, and PGC-1α genes in mouse hippocampal cells when exposed to hypomagnetic field (HMF) for eight weeks. The expression of these genes was determined by qRT-PCR analysis. The expression level of the geomagnetic field (GMF) group was set to 1. MAP1LC3A encoding LC3. PRKN encoding Parkin. PPARGC1A encoding PGC-1α. Statistical significance was calculated by unpaired t-tests. *P
The effects of different durations of exposure to hypomagnetic field on the number of active mitochondria and ROS levels in the mouse hippocampus

March 2024

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36 Reads

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1 Citation

Biochemistry and Biophysics Reports

Reactive oxygen species (ROS) are one of the potential molecules in response to a hypomagnetic field (HMF), and exposure to an HMF for eight weeks led to an increase in ROS levels in the whole hippocampus area in mice. ROS are mainly derived from the byproducts of mitochondrial metabolism. However, previous in vivo studies mostly focus on the influence of one time point of HMF exposure on the mouse hippocampus and lack comparative studies on the effects of different durations of HMF exposure on the mouse hippocampus. Here, we investigated the effects of different durations of HMF on the number of active mitochondria and ROS levels in mouse hippocampus. Compared with the geomagnetic field (GMF) group, we found that the number of active mitochondria in the hippocampus was significantly reduced during the sixth week of HMF exposure, whereas the number of active mitochondria was significantly reduced and the ROS levels was significantly increased during the eighth week of HMF exposure. The number of active mitochondria gradually decreased and ROS levels gradually increased in both GMF and HMF groups with prolonged exposure time. In addition, the expression level of the PGC-1α gene in the hippocampus, the main regulator of mitochondrial biogenesis, decreased significantly in the eighth week of HMF exposure. These results reveal that the changes in active mitochondria number and ROS levels were dependent on the durations of HMF exposure, and prolonged exposure to HMF exacerbates these changes.


Hypomagnetic Field Exposure Affecting Gut Microbiota, Reactive Oxygen Species Levels, and Colonic Cell Proliferation in Mice

November 2022

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66 Reads

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4 Citations

Bioelectromagnetics

The gut microbiota has been considered one of the key factors in host health, which is influenced by many environmental factors. The geomagnetic field (GMF) represents one of the important environmental conditions for living organisms. Previous studies have shown that the elimination of GMF, the so-called hypomagnetic field (HMF), could affect the physiological functions and resistance to antibiotics of some microorganisms. However, whether long-term HMF exposure could alter the gut microbiota to some extent in mammals remains unclear. Here, we investigated the effects of long-term (8- and 12-week) HMF exposure on the gut microbiota in C57BL/6J mice. Our results clearly showed that 8-week HMF significantly affected the diversity and function of the mouse gut microbiota. Compared with the GMF group, the concentrations of short-chain fatty acids tended to decrease in the HMF group. Immunofluorescence analysis showed that HMF promoted colonic cell proliferation, concomitant with an increased level of reactive oxygen species (ROS). To our knowledge, this is the first in vivo finding that long-term HMF exposure could affect the mouse gut microbiota, ROS levels, and colonic cell proliferation in the colon. Moreover, the changes in gut microbiota can be restored by returning mice to the GMF environment, thus the possible harm to the microbiota caused by HMF exposure can be alleviated. © 2022 Bioelectromagnetics Society.


Effects of hypomagnetic field on adult hippocampal neurogenic niche and neurogenesis in mice

November 2022

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68 Reads

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3 Citations

Frontiers in Physics

The elimination of geomagnetic field (GMF), also called hypomagnetic field (HMF), is one of the major environmental hazards faced by deep-space astronauts and the workers in magnetically shielded rooms on Earth. We previously reported that long-term HMF exposure impaired adult hippocampal neurogenesis (AHN) and cognition by reducing endogenous reactive oxygen species (ROS) levels in adult neural stem cells (aNSCs). In addition to the aNSCs themselves, adult neurogenesis is also regulated by the local environment, i.e., the neurogenic niche. Neurogenic niche is mainly composed of astrocyte, microglia, and vascular system. However, whether the HMF exposure affects the neurogenic niche in hippocampus remains unknown. In this study, we investigated the effects of the HMF exposure on the neurogenic niche and adult neurogenesis in hippocampus, as well as the cognitive function in mice. The HMF is simulated by using the newly upgraded double-wrapped coils, different with our previous coils, which are capable of providing a very low-strength static magnetic field and identical electromagnetic field background between the HMF group and the GMF group. Here, we for the first time clearly revealed that 8-week HMF exposure significantly induced microglia activation and increased the number of astrocytes in hippocampal dentate gyrus (DG), suggesting the abnormalities in the neurogenic niche. Meanwhile, 8-week HMF exposure also markedly reduced proliferation and differentiation of aNSCs in the DG, and impaired the cognitive behavior of mice, consistent with our previous findings. In addition, we also found that 8-week HMF exposure significantly induced anxiety-like behaviors of mice. In summary, this study indicates that 8-week HMF exposure induces the neurogenic niche abnormalities, contributing to the AHN impairments, thus leads to the cognitive dysfunction and anxiety-like behaviors in mice.


Figure 2. The effects of HMF treatment on ROS levels in hippocampus. (a) Representative images of hydroethidine fluorescence (red) in the dentate gyrus (DG) and cornu ammonis (CA) of the hippocampus (HIP) in GMF-and HMF-exposed mice. DAPI staining (blue) was used for distinguishing the different hippocampal regions in brain sections. HIP Scale bar = 500 μm, CA/DG Scale bar = 100 μm. (b) Quantitative analyses of hydroethidine fluorescence intensity (ROS) levels of neural cells in the dentate gyrus, cornu ammonis areas, and both hippocampus of GMF-and HMF-exposed mice. n = 4 mice. Data are presented as mean ± SEM. * p < 0.05. HIP: p = 0.0374, unpaired t-test. CA: p = 0.0481, unpaired t-test. DG: p = 0.0301, unpaired t-test.
Hypomagnetic Field Induces the Production of Reactive Oxygen Species and Cognitive Deficits in Mice Hippocampus

March 2022

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123 Reads

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13 Citations

International Journal of Molecular Sciences

Previous studies have found that hypomagnetic field (HMF) exposure impairs cognition behaviors in animals; however, the underlying neural mechanisms of cognitive dysfunction are unclear. The hippocampus plays important roles in magnetoreception, memory, and spatial navigation in mammals. Therefore, the hippocampus may be the key region in the brain to reveal its neural mechanisms. We recently reported that long-term HMF exposure impairs adult hippocampal neurogenesis and cognition through reducing endogenous reactive oxygen species (ROS) levels in adult neural stem cells that are confined in the subgranular zone (SGZ) of the hippocampus. In addition to adult neural stem cells, the redox state of other cells in the hippocampus is also an important factor affecting the functions of the hippocampus. However, it is unclear whether and how long-term HMF exposure affects ROS levels in the entire hippocampus (i.e., the dentate gyrus (DG) and ammonia horn (CA) regions). Here, we demonstrate that male C57BL/6J mice exposed to 8-week HMF exhibit cognitive impairments. We then found that the ROS levels of the hippocampus were significantly higher in these HMF-exposed mice than in the geomagnetic field (GMF) group. PCR array analysis revealed that the elevated ROS levels were due to HMF-regulating genes that maintain the redox balance in vivo, such as Nox4, Gpx3. Since high levels of ROS may cause hippocampal oxidative stress, we suggest that this is another reason why HMF exposure induces cognitive impairment, besides the hippocampal neurogenesis impairments. Our study further demonstrates that GMF plays an important role in maintaining hippocampal function by regulating the appropriate endogenous ROS levels.

Citations (4)


... ROS levels are tightly controlled by an inducible antioxidant program that responds to cellular stressors. Further, in vivo research on other hippocampal cells in the mouse hippocampus revealed that HMF (31.9 ± 4.5 nT) significantly increased its ROS levels by decreasing the expression of antioxidant genes, which may cause oxidative stress damage to the overall hippocampus and further affect anxiety and cognitive behavior in mice [44,45]. HMF can cause bone loss in mammals. ...

Reference:

The Role of Oxidative Stress in Hypomagnetic Field Effects
The effects of different durations of exposure to hypomagnetic field on the number of active mitochondria and ROS levels in the mouse hippocampus

Biochemistry and Biophysics Reports

... However, in terms of the risks that are posed by radiation on human health, we also have to consider the effects of radiation on the human microbiomes, particularly the gut microbiota. Interestingly, in mice, the gut microbiota is also influenced by hypogravity [124], therefore, it is likely that there may be interactions between radiation and magnetic fields in alterations to the gut microbiome during space flight. ...

Hypomagnetic Field Exposure Affecting Gut Microbiota, Reactive Oxygen Species Levels, and Colonic Cell Proliferation in Mice
  • Citing Article
  • November 2022

Bioelectromagnetics

... In addition, neuroinflammation regulates stem cell niches, particularly neural stem/progenitor cells in mammals. We have found that HMF (31.1 ± 2.0 nT) may also cause neuroinflammation in the hippocampus of mice, manifested by the activation of microglia and upregulation of GFAP expression in astrocytes [49]. This may be closely related to the increase in ROS in hippocampal cells [44,45]. ...

Effects of hypomagnetic field on adult hippocampal neurogenic niche and neurogenesis in mice

Frontiers in Physics

... Circadian rhythms, for instance, are sensitive to magnetic fields 4,5 . Stem cell development, both neurogenesis and other, is modulated by weak magnetic fields; a phenomenon that is thought to be mediated by reactive oxygen species (ROS) [6][7][8][9] . Magnetic fields have also been shown to be important to a number of different biological functions with further implications. ...

Hypomagnetic Field Induces the Production of Reactive Oxygen Species and Cognitive Deficits in Mice Hippocampus

International Journal of Molecular Sciences