Long-term Probiotics Intervention Facilitates Recovery of Motor and Non-motor Functions by Regulating Inflammation and Modulating Gut-brain Axis in 6-OHDA Rat Model of Parkinson's Disease.

Background: Parkinson's disease (PD) is a neurodegenerative disorder that affects both motor and non-motor functions of the body. Recently, scientists have attributed that gut dysbiosis plays a crucial role in the development and progression of PD.

Purpose: In this study, we aim to determine the role of probiotic supplementation on gut dysbiosis, inflammatory responses at the systemic level, neurodegeneration and motor deficits.

Methods: To develop a rat model of PD, 6-hydroxydopamine was bilaterally injected into the striatum. Starting from the first week after surgery, probiotics were administered orally for a period of four weeks. In this study, 18 rats were randomly divided into three groups (n = 6 each): the sham group, the PD group and the PD + Probiotics group. Motor function was measured using paw print analysis, while non-motor function was assessed through gastric emptying. Neuronal survival was evaluated with cresyl violet staining, and blood-based biomarkers were measured to assess inflammation. General body conditions, including body weight, food intake and water intake, were monitored daily.

Results: Probiotic supplementation significantly improved body weight, food intake, water intake and gastric emptying, along with improving gait. Additionally, probiotic supplementation reduced neuronal loss in the brains of PD rats. There was also a reduction in inflammatory markers, such as interleukin-6 and glutaminase, along with an elevation in brain-derived neurotrophic factor levels in the serum. This study is the first to demonstrate the beneficial effects of probiotics in improving motor deficits and gastric emptying in a PD model.

Conclusion: Our findings suggest that probiotic supplementation has the potential to slow down PD progression by preventing gut dysbiosis and neurodegeneration.