Fig. 7. Model for dual effects of isoflurane on neurogenesis. (Left side ) Exposure to low and moderate concentrations of isoflurane for short durations induces moderate calcium release from the endoplasmic reticulum (ER) via  activation of inositol-1,4,5-trisphosphate receptor (InsP³R) and/or ryanodine receptor (RyR) calcium channels on ER membrane. This low or moderate increase in cytosolic calcium concentrations then promotes neurogenesis by stimulating neuronal stem cell (NSC) proliferation, thus providing neuroprotection. (Right side ) Prolonged exposures to high concentrations of isoflurane induce excessive Ca²⁺release from the ER via  overactivation of InsP³R and/or ryanodine receptors. This results in abnormally elevated cytosolic calcium concentrations and inhibition of neurogenesis by suppressing NSC proliferation, thus contributing to isoflurane-mediated neurotoxicity.