Oxidative stress plays an important role in exacerbating neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. In a previous study, Lactobacillus plantarum 200655 was shown to possess probiotic and antioxidant potential. The current study aimed to evaluate the neuroprotective effects of heat-killed L. plantarum 200655. We incubated intestinal cells (HT-29) with heat-killed L. plantarum 200655 in a conditioned medium (CM) and found that the brain-derived neurotrophic factor (BDNF) mRNA level was elevated in the HT-29 cells and the CM contained high concentrations of BDNF. The CM protected neuroblastoma cells (SH-SY5Y) from hydrogen peroxide (H2O2)-induced toxicity. Moreover, the CM increased BDNF and tyrosine hydroxylase (TH) mRNA expression and significantly reduced the apoptosis-related Bax/Bcl-2 ratio in H2O2-treated SH-SY5Y cells. At the protein level, the CM resulted in downregulation of caspase-3. These results indicate that L. plantarum 200655 might be used as a prophylactic functional ingredient to prevent neurodegenerative disease.
Keywords: Brain-derived neurotrophic factor; Gut-brain-axis; Heat-killed probiotics; Neuroprotective effect; Oxidative stress; Tyrosine hydroxylase.