Molecular Mechanisms of Reduced Nerve Toxicity by Titanium Dioxide Nanoparticles in the Phoxim-Exposed Brain of Bombyx mori

Abstract

Bombyx mori (B. mori), silkworm, is one of the most important economic insects in the world, while phoxim, an organophosphorus (OP) pesticide, impact its economic benefits seriously. Phoxim exposure can damage the brain, fatbody, midgut and haemolymph of B. mori. However the metabolism of proteins and carbohydrates in phoxim-exposed B. mori can be improved by Titanium dioxide nanoparticles (TiO2 NPs). In this study, we explored whether TiO2 NPs treatment can reduce the phoxim-induced brain damage of the 5th larval instar of B. mori. We observed that TiO2 NPs pretreatments significantly reduced the mortality of phoxim-exposed larva and relieved severe brain damage and oxidative stress under phoxim exposure in the brain. The treatments also relieved the phoxim-induced increases in the contents of acetylcholine (Ach), glutamate (Glu) and nitric oxide (NO) and the phoxim-induced decreases in the contents of norepinephrine (NE), Dopamine (DA), and 5-hydroxytryptamine (5-HT), and reduced the inhibition of acetylcholinesterase (AChE), Na+/K+-ATPase, Ca2+-ATPase, and Ca2+/Mg2+-ATPase activities and the activation of total nitric oxide synthase (TNOS) in the brain. Furthermore, digital gene expression profile (DGE) analysis and real time quantitative PCR (qRT-PCR) assay revealed that TiO2 NPs pretreatment inhibited the up-regulated expression of ace1, cytochrome c, caspase-9, caspase-3, Bm109 and down-regulated expression of BmIap caused by phoxim; these genes are involved in nerve conduction, oxidative stress and apoptosis. TiO2 NPs pretreatment also inhibited the down-regulated expression of H+ transporting ATP synthase and vacuolar ATP synthase under phoxim exposure, which are involved in ion transport and energy metabolism. These results indicate that TiO2 NPs pretreatment reduced the phoxim-induced nerve toxicity in the brain of B. mori.

Studies on combined effect of Aeromonas hydrophila and cadmium on lipid peroxidation and antioxidant status in selected tissues of Indian freshwater major carp, Catla catla: role of silver nanoparticles

“…Previously, we demonstrated that citrate-coated AgNPs plays an important role in energy metabolism as evidenced by a balance between aerobic to anaerobic marker enzymes succinate dehydrogenase and lactate dehydrogenase, respectively in AH infected fishes (8). Further, titanium dioxide nanoparticles protect silkworm, Bombyx mori against phoxim induced oxidative stress and neurotoxicity (24,25). Thus, it seems obvious that response of biological systems towards different combinations of NPs differ at the perspective of toxicological aspects.…”

“…Recently, studies of Xie et al and Su et al (24,25) reported that Titanium dioxide nanoparticles (TiO 2 NPs) protected brain tissue from oxidative stress induced by organophosphorus pesticide, phoxim in silk worm, Bombyx mori. The same authors indicated that TiO 2 NPs suppressed oxidative stress in selected tissues of insects might be due to regulation of expression of genes such as caspases which are believed to be important in oxidative stress and mitochondria and respiratory chain (24,25). Recently, studies of Oliveira et al (34), indicated that AgNPs with organic additives such as (1) 5-Aminoisoquinoline, (2) 7-amino-4-methylcoumarin, and (3) 2-Aminoanthraceneas did not elicit same responses in pro-(malondialdehyde levels) and antioxidant enzymes such as CAT and GST in intestine and liver tissues of gold fish, Carassius auratus.…”

Underlying Mechanisms of Memory Deficits Induced by Etomidate Anesthesia in Aged Rat Model

“…[ 23 ] Therefore, the lack of change in the oxidative stress parameters observed here was reasonable and consistent with a previous study. [ 24 ]…”

Application Of Nanotechnology In Agriculture And Food Industry, Its Prospects And Risks

“…Pre-treatment by TiO 2 NPs increased antioxidant capacity and acetylcholinesterase (AChE) activity in intoxicated silkworm and improved B. mori larval survival under phoxim-induced toxicity [199]. TiO 2 NPs pre-treatment also reduced the phoxim-induced brain damage of the 5th larval instar of B. mori; under phoxim exposure they relieved severe brain damage and oxidative stress in the brain and inhibited the down-regulated expression of H + -transporting ATP synthase and vacuolar ATP synthase that are involved in ion transport and energy metabolism [200]. Moreover, TiO 2 NPs significantly decreased reduction of protein, glucose and pyruvate contents, lactate dehydrogenase, succinate dehydrogenase and malate dehydrogenase activities and attenuated increases of free amino acids, urea, uric acid and lactate levels, activities of protease, alanine aminotransferase and aspartate aminotransferase in the hemolymph of silkworms caused by phoxim exposure [201].…”