BDNF and depressive symptom measurement: In socially defeated depression models, intervention with green tea polyphenols improved behavior via the hippocampal CREB-BDNF pathway [101], promoted the morphology of hippocampal neurons, reduced cell apoptosis, and increased levels of postsynaptic density protein 95 (PSD-95), synaptophysin (SYN), and phosphorylated (p)-CREB.