New research in rats has shown that alpha-synuclein, an abnormal protein normally found in brain cells affected in Parkinson's, can move rapidly from the gut to the brain. These findings support growing evidence that Parkinson’s may start in the gut rather than the brain.
A gut feeling
Evidence has been mounting over the years that some of the earliest changes that lead to Parkinson’s may actually start in the gut. Symptoms such as constipation often happen before other symptoms of Parkinson’s occur.
In 2016, studies in mice showed that alpha-synuclein could travel from the gut into the brain. And a surgical technique involving cutting the main nerve between the gut and brain can reduce the risk of Parkinson’s.
A two-way relationship
In this new study, researchers in Denmark injected alpha-synuclein into the intestines of rats already expressing higher than normal levels of the faulty protein.
The team predicted that the protein would spread to the brain, but wanted to see exactly how it would do this. Tissue was collected at 2 and 4 months after the injection of alpha-synuclein to see where the faulty protein was in the body.
At 2 months, alpha-synuclein had spread to the brain of the rats. And interestingly, the scientists found that the faulty protein could travel in both directions - from the gut to the brain and from the brain back to the stomach.
They also found that alpha-synuclein had spread to the heart in 7 out of the 8 rats. It's known that some people with Parkinson's experience heart related symptoms, such as problems with blood pressure. This study may have shed light on why.
Dr Beckie Port, research communications manager at Parkinson's UK, said:
'This new research gives us an important insight into the route the alpha-synuclein protein takes as it spreads from the gut.
'This has the potential to open the doors to developing tests to detect Parkinson's earlier, as well as treatments that may stop the protein from reaching the brain, which could help us to prevent Parkinson's in the future.'