An experiment in mice revealed a way that air pollution could impact male fertility in mammals.
Although it is not clear whether the results apply to humans, the mouse model suggests that inhaling fine particulate matter less than 2.5 micrometres (PM2.5), can cause inflammation and decreased sperm count.
Recent research has revealed that air pollution can have a devastating and fatal effect on our health. It causes changes in our lungs and hearts as well as our brains. Although the effects of air pollution on the reproductive system are likely to be similar, it remains unclear how they are affected.
Currently, there is an infertility crisis in some parts of the globe. For example, the sperm count of Western men has fallen by half in the past few decades. However, it is not clear what is driving these changes.
Numerous studies involving animals and humans have shown a correlation between air pollution, sperm production declines, and numerous other factors.
The main cause of infertility is therefore air pollution. However, some studies on animals have shown that PM2.5 exposure can lead to testicular inflammation. Others have not found such symptoms.
These cases indicate that something else is causing the loss of sperm. New research on mice suggests that it may be our brains.
Similar to other research, healthy mice were exposed in ambient air to PM2.5. They showed significant inflammation in the hypothalamus, a part of their brain that is responsible for sperm count and inflammation.
This is the region of the brain that connects with the pituitary and gonadal glands. It has a significant impact on hormone production and reproduction.
The authors discovered that special mice were better able to cope with the physiological effects of air pollution when they were not bred without Inhibitor Kappa B Kinase 2, a key marker for inflammation in the hypothalamus. Normal mice had sperm impairment that was stopped.
All these findings strongly support the hypothesis that hypothalamic inflammation is responsible for the impairment in sperm production due to PM2.5 exposure," argue the authors. "This provides a deep mechanistic insight into the growing public health concern caused by PM2.5."
Our current evidence on air pollution and mammalian reproduction is strong thanks to the research done on mice. We are far from understanding the mechanism or finding a solution.
Zhekang Yang, who studies the effects of pollution on health at the University of Maryland, said that "our findings showed that the damage caused by air pollution at most to the sperm count can be remedied using a single inflammation marker found in the brains of mice."
Their findings are expected to have an impact on not only fertility research but also how inflammation in our hypothalamus due to air pollution could impact our heart health and lung health. This research has been long overdue.
The study was published by Environmental Health Perspectives.
