cytochrome-c-t and decamethrin

Exposure to the pyrethroid pesticide deltamethrin has been demonstrated to cause apoptosis both in vitro and in vivo. However, the molecular pathways leading to deltamethrin-induced apoptosis have not been established. To identify these pathways, SK-N-AS neuroblastoma cells were exposed to deltamethrin (100 nM-5 μM) for 24-48 h. Deltamethrin produced a time- and dose-dependent increase (21-300%) in DNA fragmentation, an indicator of apoptosis. Data demonstrate that the initiation of DNA fragmentation resulted from interaction of deltamethrin with Na⁺ channels and consequent calcium influx, as tetrodotoxin and the intracellular Ca²⁺ chelator BAPTA-AM completely prevented apoptosis. DNA fragmentation was accompanied by increased caspase-9 and -3 activities and was abolished by specific caspase-9 and -3 inhibitors. However, deltamethrin did not increase cytosolic cytochrome c levels, indicating that the mitochondrial pathway was likely not involved. Additional studies demonstrated that deltamethrin exposure activated caspase-12 activity and that pharmacological inhibition and siRNA knockdown of calpain prevented deltamethrin-induced DNA fragmentation, thus indicating a role for the endoplasmic reticulum (ER) stress pathway. This was confirmed by the observation that inhibition of eIF2α abolished deltamethrin-induced DNA fragmentation. Together, these data demonstrate that deltamethrin causes apoptosis through its interaction with Na⁺ channels, leading to calcium overload and activation of the ER stress pathway. Because ER stress and the subsequent unfolded protein response have been observed in a number of neurodegenerative diseases, these data provide mechanistic information by which high-level exposure to pyrethroids may contribute to neurodegeneration.

Topics: Apoptosis; Calcium; Calpain; Caspase 12; Caspase 3; Caspase 9; Cell Line; Cytochromes c; DNA Fragmentation; Egtazic Acid; Endoplasmic Reticulum; Humans; Mitochondria; Nitriles; Pesticides; Pyrethrins; RNA, Small Interfering; Signal Transduction; Unfolded Protein Response

To study the effects of melatonin (MT) on nerve cell apoptosis and the expression of bcl-2 and cytochrome C genes in rat cerebrum with deltamethrin induction.. 35 male Wistar rats were randomly divided into five groups (eight rats per group): olive oil control, deltamethrin-treated (12.5 mg/kg), deltamethrin plus melatonin (25.0 mg/kg, 50 mg/kg and 100 mg/kg respectively) group. Animal models were established by intraperitoneal injection deltamethrin in rats. Nerve cell apoptosis and the protein expression of bcl-2 and cytochrome C genes were detected by flow cytometry with PI staining and immunohistochemistry respectively.. Compared with DM group (20.73 +/- 3.34), the positive expression gradation of the bcl-2 protein in nerve cell was increased significantly in MT groups (DM + MT(25) was 45.26 +/- 3.84, DM + MT(50) 39.4 +/- 4.04 and DM + MT(100) 34.4 +/- 4.52) (P < 0.05) but significantly lower than the control group (59.33 +/- 4.03). Compared with DM group (34.86 +/- 4.15), the cytochrome C protein in nerve cell was decreased significantly in MT groups (20.53 +/- 3.17, 28.73 +/- 2.61 and 28.66 +/- 4.82 respectively) (P < 0.05). Compared with DM group (23.06 +/- 3.63), the apoptotic rate in nerve cell was decreased significantly in MT groups [(15.0 +/- 1.77)%, (14.88 +/- 1.84)% and (11.75 +/- 1.93)% respectively] (P < 0.05).. MT can protect nerve cell against deltamethrin induced brain injury by inhibiting nerve cell apoptosis, downregulate the protein expression of cytochrome C gene and upregulate the protein expression of bcl-2 gene.

Topics: Animals; Apoptosis; Cells, Cultured; Cytochromes c; Female; Hippocampus; Melatonin; Neurons; Nitriles; Proto-Oncogene Proteins c-bcl-2; Pyrethrins; Rats; Rats, Wistar

To study the effects of deltamethrin (DM) on the permeability of mitochondrial membrane and the expression of cytochrome C in brain tissue of rats.. Wistar rats were randomizedly divided into five groups (including four treated groups and one control group). In the treated groups, DM of 12.5 mg/kg was administered intraperitoneally once in rats and the rats were sacrificed 5, 24, 48 and 72 hours later while in the control group, the salad oil of 5 mg/kg was administered intraperitoneally once. The mitochondria in brain tissue of rats were extracted to measure the membrane permeability and the activity of cytochrome C oxidase as well as the expression of cytochrome C in cortex and hippocampus.. After the treatment the permeability of mitochondrial membrane was significantly increased in the treated groups compared with the control group. The expression of cytochrome C was increased in cortex and hippocampus CA1 and CA2 5 h, 24 h and 48 h groups and CA4 24 h group (0.57 +/- 0.04, 0.67 +/- 0.09, 0.58 +/- 0.04) and (0.81 +/- 0.18) (P < 0.05 or P < 0.01) while there was no significant difference in the expression of cytochrome C in cortex and hippocampus CA2 72 h group and CA3 and CA4 5 h, 48 h and 72 h groups between the treated groups and the control group (P > 0.05). The activity of cytochrome C oxidase was inhibited (P < 0.01).. Deltamethrin can significantly increase the permeability of mitochondrial membrane and the expression of cytochrome C in brain tissue of rats.

Topics: Animals; Cerebral Cortex; Cytochromes c; Electron Transport Complex IV; Hippocampus; Male; Mitochondrial Membranes; Nitriles; Permeability; Pyrethrins; Random Allocation; Rats; Rats, Wistar