Therapeutic potential of oleanolic acid in modulation of PI3K/Akt/mTOR/STAT-3/GSK-3β signaling pathways and neuroprotection against methylmercury-induced neurodegeneration

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that gradually deteriorates motor neurons, leading to demyelination, muscle weakness, and eventually respiratory failure. The disease involves several pathological processes, such as increased glutamate levels, mitochondrial dysfunction, and persistent neuroinflammation, often exacerbated by environmental toxins like mercury. This study explores the therapeutic potential of Olea europaea active phytoconstituents oleanolic acid (OLA) against ALS by targeting the overactivated PI3K/Akt/mTOR/STAT-3/GSK-3β signalling pathways. Methods involved in-silico studies, in vitro and in vivo experiments in which varying doses of methylmercury 5 mg/kg, p.o. and OLA (100 and 200 mg/kg, i.p.) were administered to rats for 42 days. Behavioural assessments, gross morphological, histopathological, and neurochemical parameters were measured in cerebrospinal fluid (CSF), blood plasma, and brain homogenates (cerebral cortex, hippocampus, striatum, midbrain, cerebellum) along with complete blood count (CBC) analysis. Results revealed OLA's significant neuroprotective properties. OLA effectively modulated targeted pathways, reducing pro-inflammatory cytokines, restoring normal levels of myelin basic protein (MBP) and neurofilament light chain (NEFL), and reducing histopathological changes. Gross pathological studies indicated less tissue damage, while CBC analysis showed improved hematology parameters. Additionally, the combination of OLA and edaravone (10 mg/kg, i.p.) demonstrated enhanced efficacy, improving motor functions and extending survival in ALS model rats. In conclusion, OLA exhibits significant therapeutic potential for ALS, acting as a potent modulator of key pathological signaling pathways. The findings suggest the feasibility of integrating OLA into existing treatment regimens, potentially improving clinical outcomes for ALS patients. However, further research must validate these findings in human clinical trials.