Kinetic studies on the inhibition of creatine kinase activity by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one in the cerebral cortex of rats

Diquat exposure causes brainstem demyelination by upregulating the mitochondrial calcium uniporter

Diquat (DQ) is a widely used new herbicide that poses a great threat to the environment, ecological systems and human health. Although the central nervous system (CNS) is a sensitive target of DQ exposure, the major brain regions, pathological changes and underlying mechanisms of DQ damage to the CNS remain obscure. We demonstrated that the brainstem was the primary region where DQ damaged the CNS. DQ exposure damaged both neurons and glial cells and disrupted neurotransmitter metabolism. DQ caused brainstem demyelination, as indicated by the loss of myelin sheaths, decreased levels of myelination biomarkers, and abnormal myelin morphology. Mechanistically, the expression of the mitochondrial calcium uniporter (MCU) was increased in the DQ-exposed brainstem, and MCU knockdown mice were less sensitive to DQ-induced demyelination and CNS injury by attenuating disturbances in brain energy metabolism via the AMPK pathway. Moreover, the inhibition of MCU efficiently improved DQ-induced mitochondrial dysfunction in vitro. Overall, this study is the first to reveal that the brainstem is the key injured brain region and that demyelination is the prominent pathological feature induced by DQ exposure. The MCU is a potential therapeutic target for DQ-induced demyelination and CNS injury. These novel findings expand our understanding of DQ-induced CNS injury and offer a promising therapeutic strategy.

Signaling mechanisms and disrupted cytoskeleton in the diphenyl ditelluride neurotoxicity

Evidence from our group supports that diphenyl ditelluride (PhTe)₂ neurotoxicity depends on modulation of signaling pathways initiated at the plasma membrane. The (PhTe)₂-evoked signal is transduced downstream of voltage-dependent Ca²⁺ channels (VDCC), N-methyl-D-aspartate receptors (NMDA), or metabotropic glutamate receptors activation via different kinase pathways (protein kinase A, phospholipase C/protein kinase C, mitogen-activated protein kinases (MAPKs), and Akt signaling pathway). Among the most relevant cues of misregulated signaling mechanisms evoked by (PhTe)₂ is the cytoskeleton of neural cells. The in vivo and in vitro exposure to (PhTe)₂ induce hyperphosphorylation/hypophosphorylation of neuronal and glial intermediate filament (IF) proteins (neurofilaments and glial fibrillary acidic protein, resp.) in different brain structures of young rats. Phosphorylation of IFs at specific sites modulates their association/disassociation and interferes with important physiological roles, such as axonal transport. Disrupted cytoskeleton is a crucial marker of neurodegeneration and is associated with reactive astrogliosis and apoptotic cell death. This review focuses the current knowledge and important results on the mechanisms of (PhTe)₂ neurotoxicity with special emphasis on the cytoskeletal proteins and their differential regulation by kinases/phosphatases and Ca²⁺-mediated mechanisms in developmental rat brain. We propose that the disrupted cytoskeletal homeostasis could support brain damage provoked by this neurotoxicant.