Parkinson’s disease in men may be linked to a sudden decline in testosterone, a study published in The Journal of Biological Chemistry suggests.

Researchers at Rush University Medical Center analyzed a number of male mice who had been castrated, dramatically decreasing their testosterone levels, and they found that the mice showed increased symptoms of Parkinson’s disease.

Dr. Kalipada Pahan, professor of neurology at the university, explains, “While scientists use different toxins and a number of complex genetic approaches to model Parkinson’s disease in mice, we have found that the sudden drop in the levels of testosterone following castration is sufficient to cause persistent Parkinson’s-like pathology and symptoms in male mice.”

However, the researchers add that when the mice were given supplementation of testosterone in the form of 5-alpha dihydrotestosterone (DHT) pellets, the symptoms of Parkinson’s disease were reversed.

According to the researchers, in healthy males, testosterone is at its maximum levels in the mid-30s, gradually decreasing each year after then by around 1%. But they add that testosterone levels could also dramatically drop as a result of stress or other sudden life-changing events.

Dr. Kalipada Pahan adds:

In men, testosterone levels are intimately coupled to many disease processes. Therefore, preservation of testosterone in males may be an important step to become resistant to Parkinson’s disease.”

Parkinson’s disease is a disorder of the nervous system, which can affect how a person moves. Symptoms are progressive, usually beginning with small tremors in one hand.

According to statistics on Parkinson’s from the Parkinson’s Disease Foundation, there are thought to be around 1 million people in the US living with the disease, and around 60,000 Americans are diagnosed with Parkinson’s every year. It is the world’s second most common neurodegenerative disease.

The study authors say that from this research, it is apparent that understanding how Parkinson’s disease works is important for developing drugs that protect the brain and halt progression.

They add the research suggests nitric oxide – a gas naturally produced in the body that communicates between cells – is an important molecule for developing these drugs.

Dr Pahan says:

When nitric oxide is produced within the brain in excess by a protein called inducible nitric oxide synthase (iNOS), neurons start dying.

After castration, levels of iNOS and nitric oxide go up in the brain dramatically. Interestingly, castration does not cause Parkinson’s-like symptoms in male mice deficient in iNOS gene, indicating that loss of testosterone causes symptoms via increased nitric oxide production.”

He adds that further research is needed to see how testosterone levels in human males could be targeted in order to find a viable treatment.

Medical News Today recently reported on a Parkinson’s discovery that yields the potential to ‘protect’ nerve cells.