FCGR2B and diabetes mellitus: To elucidate the regulatory role of FCGR2B in this process, we conducted a series of experiments demonstrating that FCGR2B knockdown not only ameliorated diabetes-induced reduction of dendritic spine density in hippocampal neurons (Fig. 5A) but also increased NeuN-positive cell numbers (Fig. 5B) (Fig. S3A).