Figure 3.

Main pathways targeted by NU at low doses: The main discriminating metabolites identified in urine and plasma are in white boxes. They show that tryptophan and nicotinate–nicotinamide metabolism (https://smpdb.ca; 2021) represent the main targets of acute NU exposure: (a) the kynurenine pathway leading to nicotinate–nicotinamide metabolism and NAD+ synthesis and (b) the serotonin pathway are both highlighted by the metabolomic analysis of urine and plasma samples collected at different times following the exposure of rats. The heat maps associated with each discriminating metabolite show both their relative levels change (green decrease and red increase) and the corresponding time for it was identified as the most discriminating (black if not significantly discriminating).