Fast Green FCF (FD&C Green No. 3), a safe biocompatible color additive, has been suggested to mitigate chronic pain.

Instructions
I. As a histone quantitative stain
Fast Green FCF has the ability to specifically stain histones under alkaline pH conditions.
1. Solution preparation: Dissolve Fast Green FCF in an appropriate buffer (such as Tris-HCl buffer at alkaline pH), usually at a concentration of 0.01%–0.1%.
2. Experimental steps:
1) Use acid extraction to separate DNA and collect histones.
2). Mix the sample with Fast Green FCF solution and incubate for 5–15 minutes at room temperature or under appropriate conditions.
3) Use a photometer to measure the absorbance of the solution at 622–626 nm and quantify the histone concentration based on the standard curve.
II. As a protein electrophoresis stain
Fast Green FCF can be used for protein staining after SDS-PAGE or other electrophoresis techniques
1. Solution preparation: Prepare a 0.1% Fast Green FCF solution and dissolve it in a mixture of methanol, water, and acetic acid (e.g., 50% methanol, 10% acetic acid).
Staining steps:

1) Place the gel after electrophoresis in Fast Green FCF solution and stain for 30–60 minutes with gentle shaking.

2) Destain with the same methanol/acetic acid mixture until the background is clear and the bands are clearly visible.

3) Use an imaging device to record the staining results.

Pretreatment of Fast green FCF (100 mg/kg, i.p. daily for 7 days) alleviated depressive-like behavior in LPS-treated mice.?Fast green FCF suppressed the LPS-induced microglial and astrocyte activation in the hippocampus.?Fast green FCF decreased the mRNA and protein levels of Toll-like receptor 4 (TLR4) and Myeloid differentiation primary response 88 (Myd88) and suppressed the phosphorylation of nuclear factor-κB (NF-κB) in the hippocampus of LPS-treated mice.?Fast green FCF also downregulated hippocampal tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, but did not alter the level of the brain-derived neurotrophic factor (BDNF) in the hippocampus of LPS-treated mice.?The molecular docking simulation predicts that Fast green FCF may interact with TLR4 and interrupt the formation of the TLR4-MD2 complex[1].