Non-coplanar polychlorinated biphenyl (PCB) mixture Aroclor 1254 and polybrominated diphenyl ether (PBDE) BDE-47 are known to impede neurogenesis and neuronal development. We previously reported that exposure to PCB and PBDE leads to increased embryonic movement in zebrafish by decreasing dopamine levels. In this study, we studied the connection between the melanin and dopamine synthesis pathways in this context. Both genetic and chemical inhibition of tyrosinase, the rate-limiting enzyme in melanin synthesis, not only led to reduced pigmentation but also inhibit PCB/PBDE-induced embryonic hyperactivity. Furthermore, PCB and PBDE rarely affected tyrosinase expression in the potential pigment cells, suggesting that these compounds reduce dopamine through enzymatic regulation, including a competitive interaction for the substrate tyrosine. Our results provide new insights into the interactions between melanogenesis and dopaminergic neuronal activity, which may contribute to understanding the mechanisms underlying PCB/PBDE toxicity in developing organisms.
