High-Dose Propofol Induces Cytotoxicity by Elevating Intracellular Ca(2)⁺ via GABA(A) Receptor and IP(3)R in HT22 Cells.

OBJECTIVE: Disruption of calcium (Ca(2)⁺) homeostasis has been implicated as a key pathological mechanism underlying propofol-induced neurodevelopmental and cognitive deficits. However, the mechanisms underlying propofol-induced intracellular Ca(2)⁺ dysregulation remain incompletely understood. Extending findings of anesthetic-induced metabolic disruptions in non-neuronal models to the central nervous system, this study aimed to elucidate the underlying mechanisms of the Ca(2)⁺ imbalance in neuronal cells, with implications for the safety of clinical anesthesia in pediatric populations. MATERIAL AND METHODS: Mouse hippocampal neurons (HT22 cells) served as an in vitro model. Cell viability was assessed using the CCK-8 assay. Intracellular Ca(2)⁺ dynamics were evaluated using the Fluo-4 AM Ca(2)⁺ fluorescent probe to investigate the mechanisms underlying propofol-induced Ca(2)⁺ dysregulation. RESULTS: Propofol exposure at 10 μM and 50 μM across all time points (2, 6, or 24 hours) showed no significant impact on cell viability. Similarly, 100 μM propofol lacked toxicity at 2 or 6 hours, but survival significantly declined after 24 hours exposure (P < 0.0001). Furthermore, 200 μM propofol decreased cell viability after 2 hours of treatment (P < 0.01), with further reduction following prolonged exposure (P < 0.05). A rapid increase in intracellular Ca(2)⁺ concentration was observed with 200 μM propofol (P < 0.0001), which was entirely abolished by the inhibition of the γ-aminobutyric acid type A (GABA(A)) receptor. Conversely, inhibition of the inositol trisphosphate receptor (IP(3)R) alone partially mitigated the propofol-induced Ca(2)⁺ elevation (P < 0.0001). Notably, chelation of elevated intracellular Ca(2)⁺ using BAPTA-AM fully prevented the propofol-induced decrease in cell viability (P < 0.01). CONCLUSION: Propofol induces cytotoxicity in HT22 cells in a concentration- or time-dependent manner. Notably, cytotoxicity at 100 μM propofol was observed only after 24 hours of exposure, whereas 200 μM propofol produced rapid cytotoxicity. This rapid toxicity is mediated by activation of GABA(A) receptor and IP(3)R, which triggers the endoplasmic reticulum (ER) Ca(2)⁺ release and elevating intracellular Ca(2)⁺ concentration.