We utilized a mice model of Parkinsonism: (1) to evaluate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity; and (2) to evaluate whether manganese (Mn) exposure can affect MPTP-induced neurotoxicity. A 2 × 3 experimental design (MPTP ×± Mn) was as follows: SS, MPTP(-) × Mn(-); SLMn, MPTP(-) × low Mn(+); SHMn, MPTP(-) × high Mn(+); MpS, MPTP(+) × Mn(-); MpLMn, MPTP(+) × low Mn(+); MpHMn, MPTP(+) × high Mn(+). We administered MPTP (30 mg/kg per day) to male C57BL/6 mice intraperitoneally, once a day for 5 days. Subsequently, mice were treated with either 2 or 8 mg/kg of MnCl2.4H2O intraperitoneally, once a day for 3 weeks. Blood and striatal Mn levels were elevated in the Mnexposed groups. The number of tyrosine hydroxylase (TH)-immunoreactive (ir) neurons in the substantia nigra pars compacta were decreased significantly in the MPTP-exposed groups. The densities of TH-ir axon terminals in caudate-putamen (CPU) were significantly decreased in the MPTP-treated groups. However, Mn treatment did not affect MPTP neurotoxicity. The densities of glial fibrillary acidic protein (GFAP)-ir astrocytes in the CPU or globus pallidus were significantly increased in the MPTP-treated groups. Concentrations of dopamine in the striatum were decreased significantly in the MPTP-exposed groups only, but Mn had no effect.

Microcystins are one of the most frequently found hepatotoxic cyclic peptides in fresh-and brackishwater. Zebrafish (Danio rerio) were exposed to 20 ppb of microcystin-LR (MCLR) for 72 h in order to investigate the metabolic responses. Proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy was used to analyze the metabolic profiles. As a result, male and female zebrafish showed different patterns of metabolic perturbation in relation to their detoxification profiles. Glutathione was reduced for the MCLR excretion, and fumarate and creatine were increased for the energy demands required for detoxification in the male zebrafish. The correlation of metabolites in the metabolic pathway network was changed due to MCLR exposure. The correlations connected with myo-inositol, betaine, and NADPH considerably altered in the MCLR-exposed group.

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