Neuroprotective and probiotic potential of Lactiplantibacillus plantarum AM2 in cognitive impairment

Abstract

This study aimed to isolate and characterize an acetylcholine-producing probiotic strain and to evaluate its potential anti-Alzheimer properties in D-galactose rat model. Nine Lactobacillus isolates were isolated and purified on MRS agar, with six demonstrating acetylcholine (ACh) production capability. Among these, Lactiplantibacillus sp. AM2 showed the highest ACh production (78.4 pg/mL) and was identified as Lactiplantibacillus plantarum through morphological, biochemical, 16S rRNA sequencing and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The in-vitro probiotic characterization of Lactiplantibacillus plantarum AM2 included tolerance testing for acidic conditions and bile salts, viability under simulated digestive conditions, antimicrobial activity assessment, and sensitivity testing to antibiotics. Behavioral and biochemical tests were conducted in a D-galactose-induced cognitive impairment rat model to evaluate cognitive performance, serum glucose levels, oxidative stress markers, and antioxidant capacity. Histopathological evaluations of the hippocampus were also performed. Lactiplantibacillus plantarum AM2 demonstrated strong tolerance to acidic conditions and bile salts, maintaining over 80% viability after exposure to simulated gastric and pancreatic juices. The strain showed hydrophobicity toward hexadecane, octane, and xylene. It also exhibited significant antimicrobial activity against pathogenic bacteria and was sensitive to multiple antibiotics. In cognitive impairment tests, rats administered with Lactiplantibacillus plantarum AM2 showed reduced time latency in the Morris Water Maze, suggesting cognitive enhancement. Biochemical analyses revealed improvements in serum glucose levels, reduced oxidative stress markers, and increased glutathione and total antioxidant capacity. Histopathological analyses showed mitigation of hippocampal damage, promoting recovery of normal cellular architecture. These findings highlight Lactiplantibacillus plantarum AM2 as a promising probiotic candidate with neuroprotective potential and notable ACh production. Further research is warranted to explore its application in therapeutic contexts.