Modulation of muscarinic receptors by anisodine hydrobromide in cerebral ischemia

Ischemic cerebrovascular diseases pose significant challenges due to their high mortality, disability rates, and recurrence risk, imposing substantial societal and healthcare burdens. Current treatment modalities, including medication and surgical interventions, have limitations. This study explores the therapeutic potential of anisodine hydrobromide, a neuroprotective compound, with a focus on its interaction with muscarinic receptors (M1-M5) in cerebral ischemic diseases, employing a middle cerebral artery occlusion (MCAO) rat model, and microglial HM cells and astrocytes SVG12 as models. Immunohistochemistry comprehensively assessed M1-M5 receptor expression in cerebral arteries, hippocampus, and parenchymal tissues in MCAO rats before and after anisodine hydrobromide administration. Additionally, a hypoxia/reoxygenation (H/R) model validated our findings using SVG12 and HM cells. M receptor mechanisms under hypoxia, including calcium ion influx, Reactive Oxygen Species (ROS) levels, and aspartate expression were explored. Anisodine hydrobromide effectively reduced exacerbated M1, M2, M4, and M5 receptor expression in hypoxia/reoxygenation (H/R)-treated brain tissues and M2 receptors in H/R-treated cells. Concentration-dependent inhibition of calcium ion influx and ROS levels was observed, elucidating its neuroprotective mechanisms. Under H/R conditions, HM cells exhibited decreased aspartate levels by anisodine hydrobromide, Atropine, and M2 inhibitor treatments. These findings shed light on the modulation of muscarinic receptors, particularly the M2 subtype, by anisodine hydrobromide in cerebral ischemia. The neuroprotective effects observed in this study highlight the promising clinical prospects of anisodine hydrobromide as a potential therapeutic agent for ischemic brain diseases, warranting further investigation into its mechanisms of action.