Glutamate Receptor Agonists as Triggers of Neurotoxicity: Decoding Pathways of Five Neurotoxins and Potential Therapeutic Targets

l-Glutamate (l-Glu) is one of the primary excitatory neurotransmitters in the nervous system, functioning through both ionotropic and metabotropic receptors. The release of l-Glu into the synaptic cleft, its interaction with receptors, and its reuptake are meticulously regulated by excitatory amino acid transporters. The structural similarity of various compounds to l-glutamate is crucial to their ability to interact with NMDA, AMPA, and kainate receptors. These interactions can significantly influence neural communication and function. Overstimulation of these receptors, which operate as ion channels, results in an increased level of calcium ion influx, a phenomenon known as excitotoxicity, which is often linked to neurodegeneration. Many neurodegenerative conditions are linked to both acute and chronic exposures to neurotoxins, whether they originate within the body (endogenous) or from external sources (exogenous). These neurotoxins often function as l-glutamate receptor agonists, potentially contributing to the progression of these diseases. This perspective focuses on key neurotoxins, including β-<i>N</i>-methylamino-l-alanine (l-BMAA), quinolinic acid (QUIN), domoic acid, β-<i>N</i>-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), homocysteine (Hcy), and l-homocysteate, all of which exhibit complementary mechanisms of action. We will explore their structural characteristics and mechanisms through which they induce neurotoxicity. Understanding the neurotoxic mechanisms of these compounds is essential for elucidating the pathology of neurodegenerative diseases, such as amyotrophic lateral sclerosis, neurolathyrism, and amnesic shellfish poisoning. This review summarizes the findings of 64 studies to clarify these relationships involving classic events associated with neurodegeneration such as mitochondrial damage, oxidative stress, and activation of proapoptotic pathways. In summary, the distinctive properties of these neurotoxins provide valuable insights that could help in the development of future therapeutic drugs aimed at treating and alleviating the effects of neurodegenerative diseases. Understanding how these neurotoxins interact with neuronal pathways can guide researchers in designing more effective interventions.