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New Pain Pill Could Save Your Sperm
Research in Bioorganic & Medicinal Chemistry Letters reveals successful trials of EM-1 painkillers with minimal effects on male fertility
When a man takes a painkiller to get rid of his headache, he rarely thinks about the effects it has on his fertility. Yet painkillers such as morphine, acetaminophen, ibuprofen and aspirin act as “endocrine disrupters” and can have a significant impact on a man’s sperm – and consequently, a male baby’s sexual development.
Working with my colleagues at Lanzhou University in China, we knew that taking common pain relief pills inhibited sperm production, so we wanted to synthesize a new drug that would have the least effects on male fertility.
While there are endomorphin-1 (EM-1) painkillers that do not disrupt infertility, they are still linked to poor absorption and rarely reach the cells in the central nervous system to work properly. Our study in Bioorganic and Medicinal Chemistry Letters reveals that our version of EM-1 painkillers works well at relieving pain with minimal implications for sperm motility.
Infertility on the rise
More than one-third of infertility in couples is due to male factors. These may include genetic diseases, anatomical defects, and hormonal dysfunction. In China, for example, infertility is the third largest health issue following cancer and cardiovascular diseases and is steadily increasing. In 2012, a survey by the China Population Association showed that 12.5 percent of the childbearing population − more than 40 million Chinese − were infertile. In the 90s, infertility was much lower at 3 percent.
With the recent re-introduction of the “two child” policy, more Chinese couples are being diagnosed as infertile due to stress, unhealthy lifestyle and environmental pollutants. Others are coping with chronic disease such as cancer, which require opioids for long-term treatment. In such cases, dealing with pain while trying to conceive can decrease their sperm motility.
Our study was established to alleviate the pressure faced by these families. We hope our findings will encourage doctors and patients to opt for our chemically modified painkillers to minimize the infertility risks.
Testing out versions of EM-1
When designing a new painkiller, it is imperative that the impact on sperm motility is kept to a minimum. For this reason, we took the endomorphin-1 painkiller and made a few changes to the molecule – changing an amino acid at one end, adding a chlorine atom and switching amino acids in other places.
We tested each version of the amino acid sequences using mouse tail-flick testing, which tests the pain response to molecules in rats and mice to see how effective it is at relieving pain.
During this time, we measured how well the molecules worked using several tests called radioligand binding assay, metabolic stability, antinociception activity and sperm motility effects. We compared our results with control mice that were only treated with saline.
While the results showed no significant change in the control mice, we found that our molecule survived longer than the original EM-1 and attached more tightly to those found on human nerve cells that make painkillers work.
In other words, the tests with mice showed the new molecular version of EM-1 pain relief worked better than the original. They activated receptors on cells, relieved pain and did not affect sperm motility. In some tests, sperm motility even increased – but not by a significant amount.
Our study shows that these molecules could be developed as drugs that do not harm male fertility and could be used successfully by couples that hope to conceive in the future.
Dr. Xuehong Zhang is Vice-President of Lanzhou University’s first hospital, and President of its Reproductive Medicine center. She established the first Reproductive Medicine center in Gansu Province, and the first sperm bank in four northwestern provinces of China. She is also an expert for the National Health and Family Planning Commission Human Assisted Reproductive Technology Accreditation group. She was the first to the third Standing Committee member of China Medical Society of Reproductive Medicine Branch. She is currently a member of the China Medical Society of Menopause Group and Reproductive Endocrinology Group. Dr. Zhang has published 4 books and more than 100 research papers.
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