Caffeic Acid Phenethyl Ester Enhanced the Klotho/SIRT1/Nrf2/HO-1 Axis to Protect Against Methylmercury-Induced ALS-Like Neurodegeneration.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by motor neuron degeneration, oxidative stress, and neuroinflammation. This study evaluated the neuroprotective potential of caffeic acid phenethyl ester (CAPE) against MTME + 5-induced neurotoxicity in an ALS-like pathology model. CAPE (50 and 100 mg/kg., p.o.) demonstrated significant therapeutic efficacy by improving motor and cognitive deficits, restoring oxidative balance, and mitigating neuroinflammatory and apoptotic pathways. Behavioral assessments, including the open field, grip strength, forced swim, and Morris water maze, highlighted CAPE's ability to restore neuromuscular coordination and cognitive function in a dose-dependent manner. Cellular and Molecular analyses revealed that MTME+5 exposure significantly disrupted Klotho/SIRT-1/Nrf2/HO-1 antioxidant signaling, increased pro-inflammatory cytokines (TNF-α, IL-1β), and elevated apoptotic markers (Bax, caspase-3) while depleting anti-inflammatory cytokines (IL-10) and neuroprotective proteins. Furthermore, CAPE treatment restored these parameters, reduced oxidative stress, and enhanced antioxidant defenses (SOD, CAT, r-GSH). Furthermore, CAPE normalized neurotransmitter imbalances, including acetylcholine, dopamine, GABA, serotonin, and glutamate, alleviating excitotoxicity. Histopathological and gross morphological analyses confirmed CAPE50 and CAPE100 ability to preserve neuronal and myelin integrity across key brain regions, including the cerebral cortex, hippocampus, striatum, midbrain, and cerebellum. CAPE also reduced methylmercury accumulation in the brain and cerebrospinal fluid, indicating detoxifying effects. Co-administration of vitamin B1 (VTB1(200)) further amplified CAPE's therapeutic efficacy. Complete blood count (CBC) analysis demonstrated MTME+5-induced hematological abnormalities, including reduced RBCs, hemoglobin, WBCs, and platelets, alongside elevated eosinophils and basophils. CAPE treatment normalized these parameters, indicating systemic recovery. These findings establish CAPE as a promising neuroprotective agent for ALS, capable of targeting neurocomplications.