Pharmabiotic Based on Lactobacillus fermentum Strain U-21 Modulates the Toxic Effect of 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine as Parkinsonism Inducer in Mice

— The states of the intestinal microbiota and the nervous system have repeatedly been shown to affect each other in experimental and clinical studies, changes in microbiota being clearly associated with neurodegenerative processes. Microflora distortions and inflammation are thought to provoke the spread of pathological forms of α-synuclein in the nervous system, and their spread is recognized as the main cause of neurodegeneration in Parkinson’s disease (PD). The aim was to identify the effects of a pharmacobiotic based on the Lactobacillus fermentum U-21 strain in C57BL/6 mice administered with the parkinsonism inducer 1‑methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Two groups of mice were subcutaneously injected with MPTP (10 mg/kg, two injections with a 2-h interval) and received orally 0.9% NaCl or the preparation U-21 daily for 15 days, and a control group received 0.9% NaCl both as injections and orally in the same regimen. Motor and neurological impairments were assessed in the open field (OF), tapering beam (TB), and bar pull-up tests. Changes in tyrosine hydroxylase-positive (TH + ) fibers of the enteric plexus and the number of goblet cells of small intestinal villi were assessed morphologically. MPTP decreased motor activity in the OF test (ANOVA, p = 0.0039), increased the time to pass the TB test ( p = 0.0003), and induced muscle weakness on evidence of the bar pull-up test ( p = 0.0419). U-21 prevented the MPTP effects ( p < 0.05 in all tests). MPTP reduced the density of TH + fibers and the number of goblet cells (ANOVA, p < 0.05), and U-21 partly alleviated the MPTP-induced changes. High biological activity was observed for U-21 in the neurotoxic model of parkinsonism, justifying further extensive studies of its effects.