| To investigate the uptake, distribution, and excretion patterns of bisphenol A (BPA) in the primary metabolic organs of economically important fish, grass carp (Ctenopharyngodon idella) were exposed to 8 mg/L BPA for 5 days, followed by a 5-day depuration period. Concentration of BPA and its metabolites (BPAG, BPAS, and MBP) in metabolism-related tissues (gill, kidney, liver, bile, and intestine) were quantified using solid-phase extraction coupled with high-performance liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS). Expression of genes encoding metabolic enzymes and ABC transporters was analyzed by RT-PCR. Results showed that the gill was the primary site of BPA accumulation and clearance (peak concentration: 4601.58 ± 77.76 ng/g; T1/2 = 0.8 h). BPA exposure significantly upregulated UGT1A7, SULT1ST1, ABCB4, and ABCC2 expression in the gill. During the exposure phase, in metabolism-related tissues, the conversion efficiencies of BPA to BPAG, BPAS, and MBP accounted for approximately 47.86%, 0.89%, and 0.03%, respectively, of BPA-related compounds (including BPA, BPAG, BPAS, and MBP) detected in grass carp tissues. The formation of BPAG, BPAS, and MBP was primarily associated with hepatic UGT1A7, renal SULT1ST1, and hepatic CYP3A65, respectively. The conversion efficiency of the metabolites followed the order BPAG > BPAS > MBP. During depuration, BPAG and BPAS were rapidly eliminated from tissues (T1/2 < 8 h and < 71 h, respectively). In contrast, MBP exhibited slow clearance (T1/2 > 110 h). Furthermore, BPA and its metabolites could not be excreted from the bile due to the absence of genes encoding BPA-metabolizing enzymes and ABC transporters in the bile. |
