Bromelain mitigates monosodium glutamate-induced neurobehavioral impairment in mice by modulating AChE-MAO-GAD and...

Excessive exposure to monosodium glutamate (MSG) induces glutamate-mediated excitotoxicity, oxidative stress, and neuroinflammation, culminating in neurobehavioral impairments. Bromelain, a cysteine protease derived from Ananas comosus, exhibits potent antioxidative and anti-inflammatory properties; however, its potential to attenuate excitotoxic neuronal injury remains insufficiently characterized. This study investigated the neuroprotective effects of bromelain against MSG-induced neurotoxicity through integrated behavioral, biochemical, histological, and computational analyses. Male Swiss mice (7-8 weeks) received MSG (4 g/kg, i.p.) to induce excitotoxicity and were subsequently treated orally with bromelain (50 or 100 mg/kg) or fluoxetine (1 mg/kg) for 21 days. Behavioral tests assessed locomotor, cognitive, and affective functions, while biochemical and histological analyses evaluated oxidative stress, neuroinflammatory markers, and neurotransmitter-modulating enzyme activities. In silico AlphaFold3 modeling and protein-protein docking were employed to elucidate bromelain's interactions with acetylcholinesterase (AChE), monoamine oxidase-B (MAO-B), and glutamate decarboxylase (GAD). Bromelain treatment significantly ameliorated MSG-induced behavioral deficits, restored cortical and hippocampal redox balance, suppressed pro-inflammatory cytokines, and preserved neuronal cytoarchitecture. It normalized neurotransmitter metabolism by inhibiting AChE and MAO-B activities while enhancing GAD function. AlphaFold3 modeling revealed a compact, high-confidence bromelain conformation (pLDDT >90) with strong predicted binding affinities to catalytically active residues of AChE, MAO-B, and GAD, supporting its multi-target neuromodulatory role. Altogether, these findings provide the first integrated experimental and computational evidence that bromelain confers neuroprotection by regulating redox homeostasis, inflammation, and neurotransmitter signaling, highlighting its promise as a nutraceutical candidate for mitigating glutamate-mediated neurodegenerative disorders.