A widely used diabetes medication may offer a novel avenue for inhibiting the onset and progression of Parkinson's disease, according to a recent study.

Researchers from Severance Hospital, Yonsei Severance Hospital, and Yonsei University College of Medicine—including Professors Phil Hyu Lee, Seong Ho Jeong, and Yeon Ju Kim—have confirmed that sitagliptin, an oral Dipeptidyl Peptidase-4 (DPP-4) inhibitor commonly prescribed for type 2 diabetes, blocks the accumulation of Parkinson's-inducing proteins in the gut, thereby suppressing the disease's development and advancement.

Parkinson's disease, a neurodegenerative disorder, is fundamentally characterized by the buildup of alpha-synuclein protein in the midbrain's dopamine-producing neurons. While the precise cause of this accumulation remains elusive, the 'gut-brain axis' hypothesis has gained significant traction. This theory posits that aggregates of the alpha-synuclein protein originate in the intestines and travel up the vagus nerve to the brain.

The research team, recognizing that sitagliptin—in addition to its primary function of increasing insulin secretion and lowering blood sugar—possesses neuroprotective effects, designed an animal model study to investigate its potential in this context.

The team first induced Parkinson's in laboratory mice by administering rotenone, a compound known to damage dopamine nerve cells. Mice continuously exposed to rotenone developed alpha-synuclein aggregates that spread along the gut-brain axis. After six months, these mice exhibited typical Parkinson's symptoms such as tremors, rigidity, and significant dopamine neuron loss.

Crucially, when the diabetes drug sitagliptin was co-administered to the rotenone-treated mice, a dramatic reversal was observed. Sitagliptin not only mitigated inflammation in the gut but also reduced the accumulation of alpha-synuclein aggregates. The resulting damage to dopamine nerve cells was halved, and the mice showed marked improvements in motor function.

The findings strongly suggest that sitagliptin's efficacy against Parkinson's stems from its ability to sever the pathological link of the gut-brain axis, thereby inhibiting disease progression.

"This research demonstrates that an existing diabetes drug can be repurposed as a potent inhibitor of Parkinson's disease progression," the researchers explained. "It opens the door not just to slowing the disease but offers the potential for prevention as well."

The study's results were published in the esteemed international academic journal, Gut. The successful application of a safe, already-approved drug to target a critical pathway in Parkinson's pathology represents an exciting and clinically relevant advance in the fight against neurodegeneration.