Prior exercise protects against oxidative stress and motor deficit in a rat model of Parkinson's disease

Treadmill intervention attenuates motor deficit with 6-OHDA-induced Parkinson's disease rat via changes in lipid profiles in brain and muscle

One of the key hallmarks of Parkinson's disease is the disruption of lipid homeostasis in the brain, which plays a critical role in neuronal membrane integrity and function. Understanding how treadmill training impacts lipid restructuring and its subsequent influence on motor function could provide a basis for developing targeted non-pharmacological interventions for individuals living with early stage of PD. This study aims to investigate the effects of a treadmill training intervention on motor deficits induced by 6-OHDA in rats model of PD. PD was induced by injecting 6-hydroxy dopamine (6-OHDA) into the medial forebrain bundle (MFB). For 10 weeks, rats underwent treadmill training on a four-lane motorized treadmill. Motor function deficits were evaluated through behavioral tests. Lipidomic analysis was performed through ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC MS/MS). Treadmill intervention significantly improved motor function and restored altered brain and muscle lipid profiles in PD rats. Among the lipid species identified in PD rats, brain abundance was highest for phosphatidylethanolamine (PE), correlating positively with the beam-walking scores; muscle abundance peaked with lysophosphatidylethanolamine (LysoPE), correlating positively with grip strength scores. In the brain, the levels of diacylglycerol (DG), triacylglycerol (TG), and lysophosphatidylcholine (PC) correlated positively with grip strength and rotarod scores, while only phosphatidylethanolamine (PE) linked to beam-walking scores. In the muscle, the levels of phosphatidylinositol (PI), lysophosphatidylethanolamine (PE), lysophosphatidic acid (PA), ceramide (Cer), and ganglioside were positively correlated with grip strength and rotarod scores. In conclusion, treadmill may protect the cortex, mitigating motor deficits via change lipid profiles in the brain and muscle.

Exercise training upregulates CD55 to suppress complement-mediated synaptic phagocytosis in Parkinson's disease

The primary pathological change in Parkinson's disease (PD) is the progressive degeneration of dopaminergic neurons in the substantia nigra. Additionally, excessive microglial activation and synaptic loss are also typical features observed in PD samples. Exercise trainings have been proven to improve PD symptoms, delay the disease progression as well as affect excessive microglial synaptic phagocytosis. In this study, we established a mouse model of PD by injecting mouse-derived α-synuclein preformed fibrils (M-α-syn PFFs) into the substantia nigra, and demonstrated that treadmill exercise inhibits microglial activation and synaptic phagocytosis in striatum. Using RNA-Seq and proteomics, we also found that PD involves excessive activation of the complement pathway which is closely related to over-activation of microglia and abnormal synaptic function. More importantly, exercise training can inhibit complement levels and complement-mediated microglial phagocytosis of synapses. It is probably triggered by CD55, as we observed that CD55 in the striatum significantly increased after exercise training and up-regulation of that molecule rescued motor deficits of PD mice, accompanied with reduced microglial synaptic phagocytosis in the striatum. This research elucidated the interplay among microglia, complement, and synapses, and analyzed the effects of exercise training on these factors. Our work also suggested CD55 as a complement-relevant candidate molecule for developing therapeutic strategies of PD.

Parkinson mice show functional and molecular changes in the gut long before motoric disease onset

BACKGROUND

There is increasing evidence that Parkinson's disease (PD) might start in the gut, thus involving and compromising also the enteric nervous system (ENS). At the clinical onset of the disease the majority of dopaminergic neurons in the midbrain is already destroyed, so that the lack of early biomarkers for the disease represents a major challenge for developing timely treatment interventions. Here, we use a transgenic A30P-α-synuclein-overexpressing PD mouse model to identify appropriate candidate markers in the gut before hallmark symptoms begin to manifest.

METHODS

Based on a gait analysis and striatal dopamine levels, we defined 2-month-old A30P mice as pre-symptomatic (psA30P), since they are not showing any motoric impairments of the skeletal neuromuscular system and no reduced dopamine levels, but an intestinal α-synuclein pathology. Mice at this particular age were further used to analyze functional and molecular alterations in both, the gastrointestinal tract and the ENS, to identify early pathological changes. We examined the gastrointestinal motility, the molecular composition of the ENS, as well as the expression of regulating miRNAs. Moreover, we applied A30P-α-synuclein challenges in vitro to simulate PD in the ENS.

RESULTS

A retarded gut motility and early molecular dysregulations were found in the myenteric plexus of psA30P mice. We found that i.e. neurofilament light chain, vesicle-associated membrane protein 2 and calbindin 2, together with the miRNAs that regulate them, are significantly altered in the psA30P, thus representing potential biomarkers for early PD. Many of the dysregulated miRNAs found in the psA30P mice are reported to be changed in PD patients as well, either in blood, cerebrospinal fluid or brain tissue. Interestingly, the in vitro approaches delivered similar changes in the ENS cultures as seen in the transgenic animals, thus confirming the data from the mouse model.

CONCLUSIONS

These findings provide an interesting and novel approach for the identification of appropriate biomarkers in men.