Mycotoxin Alternariol Induces Ca²⁺ Dysregulation and Cell Death in Astrocytes: Mechanistic Toxicological Insights

Alternariol (AOH) is a low-molecular-weight mycotoxin produced by Alternaria species, frequently found in cereal grains, tomatoes, and processed foods. While its genotoxic and endocrine-disrupting effects are well established, emerging studies suggest a neurotoxic potential that remains poorly understood. Astrocytes-key regulators of neuronal support and calcium (Ca²⁺) balance in the central nervous system (CNS)-are an underexplored target of AOH toxicity. Here, we investigated the effects of AOH on Ca²⁺ signaling and viability in human astrocytes (Gibco Human Astrocyte, GHA cells). AOH exposure (25-125 μM) caused a concentration-dependent rise in cytosolic Ca²⁺ concentrations ([Ca²⁺]ᵢ) and induced significant cytotoxicity. These effects were reversed by the intracellular Ca²⁺ chelator BAPTA-AM, suggesting a Ca²⁺-dependent mechanism. Mechanistically, AOH mobilized Ca²⁺ from the endoplasmic reticulum (ER), as shown by thapsigargin blockade, and facilitated extracellular influx via store-operated calcium entry (SOCE), inhibited by 2-APB (a SOCE inhibitor) and GF109203X (a protein kinase C, PKC inhibitor). Notably, inhibition of phospholipase C (PLC) by U73122 completely abolished the Ca²⁺ rise, implicating the PLC-ER axis as a key upstream trigger. Together, our findings reveal a novel Ca²⁺-dependent mechanism by which AOH disrupts astrocyte homeostasis, providing new insights into its neurotoxic potential and highlighting Ca²⁺ signaling as a potential therapeutic target in glial toxicology.