What is the fine-grained topic of the following text: Previous studies have shown that polyphenols from dark-colored fruits can reduce stress-mediated signaling in BV-2 mouse microglial cells, leading to decreases in nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression. Only return the topic.
Effects of polyphenols from dark-colored fruits on stress-mediated signaling in BV-2 mouse microglial cells