NPPA and congenital rubella syndrome: Moreover, evidence for KP activation was also indicated in the CRS mice serum, as the metabolites of the KP, including Kyn, Kyna, 3-HK, 3-HAA, Quin, and NAD+ were significantly increased or displayed an increased tendency; synchronously, the 5-HT level in the serum was obviously reduced in the CRS-treated group (Figure S3B).