Lavandula angustifolia Mill. inhibits high glucose and nicotine-induced Ca2+ influx in microglia and neuron-like cells via two distinct mechanisms.

ABSTRACT

Smoking remains a significant health problem in patients with type 2 diabetes mellitus. This study compared intracellular Ca2+ ([Ca2+]i) in microglia, neurons, and astrocytes in the presence of high glucose (HG) and nicotine and evaluated the effects of Lavandula angustifolia Mill. essential oil (LEO) on this process. [Ca2+]i concentrations were measured by monitoring the fluorescence of Fura-2 acetoxymethyl ester. Treatment with HG and nicotine significantly increased [Ca2+]i in both microglia and neurons through Ca2+ influx from extracellular sources. This increased Ca2+ influx in microglia, however, was significantly reduced by LEO, an effect partially inhibited by the Na+/Ca2+ exchanger (NCX) inhibitor Ni2+. Ca2+ influx in neuron-like cells pretreated with HG plus nicotine was also significantly decreased by LEO, an effect partially inhibited by the L-type Ca2+ channel blocker nifedipine and the T-type Ca2+ channel blocker mibefradil. LEO or a two-fold increase in the applied number of astrocytes attenuated Ca2+ influx caused by high glucose and nicotine in the mixed cells of the microglia, neuron-like cells and astrocytes. These findings suggest that LEO can regulate HG and nicotine-induced Ca2+ influx into microglia and neurons through two distinct mechanisms.