The acute neurotoxicity of inorganic mercury in Mactra chinensis philippi

• Published in: Aquatic toxicology 2024-05, Vol.270, p.106896-106896, Article 106896
• Main Authors: Ma, Bangguo, Zhao, Xiaoli, Zhang, Xiaoning, Yang, Bowen, Cai, Zimin, Xing, Zihan, Xu, Mingzhe, Mi, Liuya, Zhang, Jianning, Wang, Lei, Zhao, Yancui, Liu, Xiaoli
• Format: Article
• Language: English
• Subjects: Bivalves; Inorganic mercury; Neurotoxicity; Neurotransmitter
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2024.106896

•Inorganic mercury disturbed the metabolic pathways of M. chinensis philippi.•Inorganic mercury affected neurotransmitters and related enzymes of M. chinensis philippi.•M. chinensis philippi responded to the neurotoxicity of inorganic mercury by overload of calcium ions.•Due to the accessible ganglion of the M. chinensis philippi, it was suitable for evaluating the neurotoxicity of inorganic mercury. Inorganic mercury (IHg) is hazardous to marine organisms especially resulting in neurotoxicity, bivalves are sensitive to pollutants as “ocean sentinel”, but data on the neurotoxicity of IHg in bivalves are sparse. So we chosed M. chinensis philippi with typical neural structures in bivalves to investigate the neurotoxicity of IHg, which could be helpful to understand the specificity of neural regulation and the response characteristics of bivalves. After acute exposed to IHg (HgCl2) for 24 h, the metabolites of ganglion tissues in M. chinensis philippi were evaluated using 1H-nuclear magnetic resonance based metabolomics; Ca2+, neurotransmitters (nitric oxide, glutamate, acetylcholine) and related enzymes (calcineurin, nitric oxide synthase and acetylcholinesterase) were measured using biochemical detection. Compared to the control group, the levels of the nitric oxide (81.04 ± 12.84 μmol/g prot) and acetylcholine (30.93 ± 12.57 μg/mg prot) in M. chinensis philippi of IHg-treated were decreased, while glutamate (2.11 ± 0.61 mmol/L) increased significantly; the activity of nitric oxide synthase (679.34 ± 135.33 U/mg prot) was increased, while acetylcholinesterase (1.39 ± 0.44 U/mg prot) decreased significantly, and the activity of calcineurin (0.52 ± 0.02 U/mg prot) had a statistically insignificant increasing tendency. The concentration of Ca2+ (0.92 ± 0.46 mmol/g prot) in the IHg-treated group was significantly higher than that in the control group. OPLS-DA was performed to reveal the difference in metabolites between the control and IHg-challenged groups, the metabolites of glucose, glutamine, inosine, succinate, glutamate, homarine, and alanine were sensitive to IHg, subsequently metabolic pathways that were affected including glucose metabolism, glutamine metabolism, nucleotide metabolism, Krebs cycle, amino acid metabolism and osmotic regulation. In our study, IHg interfered with metabolites in M. chinensis philippi, thus the corresponding metabolic pathways were changed, which influenced the neurotransmitters subsequently. Furthermore, Ca2+overload affe