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. 2012 Dec 21;7(12):e52010. doi: 10.1371/journal.pone.0052010

Figure 1. LPS-induced melatonin synthesis depends on the nuclear translocation of NF-κB in RAW 264.7 macrophages.

Figure 1

(a) The conversion of serotonin (5-HT) to N-acetylserotonin (NAS) by the enzyme arylalkylamine-N-acetyltransferase (AA-NAT) is a key step in melatonin synthesis. This conversion is followed by N-acetyl-methyltransferase (ASMT)-mediated methylation of N-acetylserotonin. Expression of AA-NAT (b) and phospho-AA-NAT (p-AA-NAT)(c) detected by immunocytochemistry in RAW 264.7 cells, incubated (gray bars) or not (white bars) with LPS (500 ng/mL, 1 h). (d) LPS-induced melatonin synthesis by RAW 264.7 cells was blocked by incubation with ALLN (50 µM) or PDTC (25 µM) 30 min prior to stimulation with LPS. Each bar represents the mean ± SEM of values obtained in 3–5 independent experiments. *,p<0.05 compared to the respective control group.