Indolic Compound Extraction and Analysis

The indolic compounds tryptophan, tryptamine, 5HTryp, NAT, serotonin, NAS, and 5MT were purchased from Sigma-Aldrich (Madrid, Spain) and Shanghai Yuanye Bio-Technology Co., Ltd (China). These indolic compounds were extracted using the method described in our previous study (Wang et al., 2020a (link)). Briefly, sample tissues (0.5g) from the CR and control (CK) groups was finely ground, followed by extraction in an 1ml buffer containing 50% methanol and 0.1% formic acid for 15min in a shaker. After ultrasound treatment for 30min in an ice bath, the mixtures were incubated at 4°C for 30min and then centrifuged for 20min at 12,000rpm. The extracts were filtered through a 0.3μm filter membrane and were analyzed using LC–MS/MS platform (Waters Iclass-AB Sciex 6500) platform at Beijing Genomics Institute (BGI)-Shenzhen (Wuhan, China) as described by Sara et al. (2019) (link).