June 25, 2024

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Air pollution causes brain inflammation and reduces sperm count

Air pollution causes brain inflammation and reduces sperm count


New research finds: air pollution causes brain inflammation and reduces sperm count

Air pollution, especially fine particulate matter (PM2.5), has always been considered a major global public health problem. PM2.5 refers to the particulate matter in the ambient air with an aerodynamic equivalent diameter less than or equal to 2.5 microns. It can be suspended in the air for a longer time, and the higher its concentration in the air, the more serious the air pollution.


Compared with the coarser atmospheric particulate matter, PM2.5 has a small particle size, a large area, strong activity, easy to carry toxic and harmful substances (for example, heavy metals, microorganisms, etc.), and has a long residence time in the atmosphere and a long transportation distance. Therefore, it has a greater impact on human health and the quality of the atmospheric environment.


Many previous studies have found that air pollution can increase the risk of obesity, diabetes and other diseases, and even affect fertility, but the exact mechanism of how air pollution causes these health conditions is not very clear.


Recently, Zhekang Ying’s team at the University of Maryland School of Medicine published a research paper titled PM2.5 Exposure of Mice during Spermatogenesis: A Role of Inhibitor κB Kinase 2 in Pro-Opiomelanocortin Neurons in the Journal of Environmental Health Perspectives.


The study revealed that air pollution (PM2.5) can cause an inflammatory response in hypothalamic neurons, leading to a decrease in sperm count. The removal of inflammatory markers in hypothalamic neurons can prevent or reverse the decrease in sperm count caused by air pollution.


Air pollution causes brain inflammation and reduces sperm count


Under stress conditions, the brain directly affects the reproductive organs, thereby affecting fertility and sperm count. Women’s emotional stress can also lead to skipping menstrual periods.


Some previous studies have shown that the sperm count of mice exposed to air pollution will decrease, but they do not necessarily have testicular inflammation, which means that there may be other mechanisms that cause the sperm count to decrease. Because of the direct connection between the brain and reproductive organs, the research team began to test whether air pollution would increase brain inflammation.


The research team conducted experiments on healthy mice and mice lacking the neuro-specific inflammation marker IKK2 in the brain. They were placed in filtered air or polluted air, and the sperm count was measured.


The results of the experiment showed that the number of sperm in healthy mice was reduced when exposed to the polluted air, while the mice without the inflammatory marker IKK2 in the neurons did not show a reduction in sperm in the polluted air. The research team further knocked out IKK2 in specific neurons of healthy mice, and they began to show a decrease in sperm counts when they were exposed to polluted air.


The research team found that a specific type of neuron usually associated with sleep cycles and obesity is responsible for the reduction in sperm count due to air pollution. These neurons are usually found in the hypothalamus, which is part of the brain and is responsible for controlling hunger and mouth. For thirst and sexual desire, the hypothalamus also works with the pituitary gland, which produces hormones that communicate directly with the reproductive organs.


The corresponding author of the study, Professor Ying Zhekang, said that the hypothalamus is the main bridge between the brain and the reproductive system, so the neuronal inflammation in the hypothalamus is the culprit leading to the decrease in sperm count, which is completely reasonable.


Professor Ying Zhekang also said that the results of this study show that air pollution can cause damage to sperm counts, but this damage can be compensated by removing inflammatory markers in hypothalamic neurons, which shows that we can target therapies. Prevent or reverse the impact of air pollution on fertility.


Approximately 92% of the world’s population lives in areas where the PM2.5 level in the air exceeds the minimum safety standards set by the World Health Organization. These PM2.5 may come from automobile exhaust, factory emissions, wildfires, burning biomass fuels, and so on.

These air pollution can cause brain inflammation, thereby increasing the risk of high blood pressure, diabetes, obesity and heart disease, and now has also found an impact on fertility. It is important to further explore the mechanisms by which air pollution affects physical health, which will help us find ways to prevent or eliminate these effects.



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Air pollution causes brain inflammation and reduces sperm count

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