Okadaic acid induced neurotoxicity: an emerging tool to study Alzheimer's disease pathology

Okadaic acid (OKA) is one of the main polyether toxins produced by marine microalgae which causes diarrhetic shellfish poisoning. It is a selective and potent inhibitor of serine/threonine phosphatases 1 and 2A induces hyperphosphorylation of tau in vitro and in vivo. The reduced activity of phosphatases like, protein phosphatase 2A (PP2A) has been implicated in the brain of Alzheimer's disease (AD) patients. It is reported that AD is a complex multifactorial neurodegenerative disorder and hyperphosphorylated tau proteins is a major pathological hallmark of AD. The molecular pathogenesis of AD includes an extracellular deposition of beta amyloid (Aβ), accumulation of intracellular neurofibrillary tangles (NFT), GSK3β activation, oxidative stress, altered neurotransmitter and inflammatory cascades. Several lines of evidence suggested that the microinfusion of OKA into the rat brain causes cognitive deficiency, NFTs-like pathological changes and oxidative stress as seen in AD pathology via tau hyperphosphorylation caused by inhibition of protein phosphatases. So, communal data and information inferred that OKA induces neurodegeneration along with tau hyperphosphorylation; GSK3β activation, oxidative stress, neuroinflammation and neurotoxicity which is a characteristic feature of AD pathology. Through this collected evidence, it is suggested that OKA induced neurotoxicity may be a novel tool to study Alzheimer's disease pathology and helpful in development of new therapeutic approach.