Folate producing Streptococcus thermophilus CRL808 decreased sympthoms of neurological damages in a mouse parkinson's disease model and exerted neuroprotector effect in vitro

Abstract

Parkinson's disease (PD) results from the dysfunction and degeneration of dopaminergic neurons within the substantia nigra pars compacta, and is characterized by persistent tremors, bradykinesia, rigidity and instability in posture. At the cellular level, the pathogenic process involves high levels of oxidative stress, mitochondrial dysfunction and apoptosis. Many studies showed that dietary factors, including B-Group vitamins, may be involved in the etiology of PD. It has been shown that patients with PD present folate deficiencies with increases in homocysteinemia. The aim of this study was to evaluate the effect of Streptococcus (S.) thermophilus CRL808, a folate-producing strain, in an animal model of PD and in vitro using neuron cell cultures. For the in vivo study, C56BL/6 mice were injected subcutaneously with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), using 5 doses of 20 mg/kg each during 4 days. Mice were also injected intraperitoneally with probenecid (250 mg/kg) to decrease the renal excretion of MPTP and achieve the chronicity. S. thermophilus CRL808 was orally administered (1x108 CFU/ml) starting 7 days before injection with MPTP until the end of the experiment. Each mouse received 100µl of the bacterial suspension daily. Control animals injected or not with MPTP received 100µl of physiological solution. Each mouse was subjected to behavior tests (vertical and horizontal bar, and the nasal bridge adhesive elimination). For the in vitro model, the mouse Neuro-2a (N2a) neuroblastoma cells were cultured in the presence and absence of folic acid. Oxidative stress was induced with MPP+ (toxic metabolite from MPTP). The intracellular extract from S. thermophilus CRL808 was added to the cell cultures and the effect was compared with commercial folic acid. Cell viability and proliferation were evaluated using the MTT assay. Results obtained in the in vivo model of PD showed that mice that received S. thermophilus CRL808 presented milder symptoms of the pathology compared to the PD control group. This effect was observed in the three evaluated behavior tests, in which on average, the time used to complete each test was reduced by half when compared with the PD control, with results close to those of healthy control animals. The in vitro assay showed that the exposure to MPP+ significantly increased the death of N2a cells. In contrast, when vitamin B9 or the intracellular extract of S. thermophilus CRL808 was added to the culture medium, this effect was reversed or significantly decreased. The results obtained demonstrate the neuroprotective properties of S. thermophilus CRL808 against the toxicity of MPTP and MPP+. This bacterial strain has an important potential for future studies in the Parkinson´s disease model.