Molecular mechanisms of silk gland damage caused by phoxim exposure and protection of phoxim-induced damage by cerium chloride in Bombyx mori.

It is known that exposure to organophosphorus pesticides (OP) including phoxim can produce oxidative stress, neurotoxicity, and greatly attenuate cocooning rate in the silkworm, Bombyx mori. Cerium treatment has been demonstrated to relieve phoxim-induced toxicity in B. mori; however, very little is known about the molecular mechanisms of silk gland injury due to OP exposure and protection of gland damage due to cerium pretreatment. The aim of this study was to evaluate silk gland damage and its molecular mechanisms in phoxim-induced silkworm toxicity and the protective mechanisms of cerium following exposure to phoxim. The results showed that phoxim exposure resulted in severe gland damage, reductions in protein synthesis and the cocooning rate of silkworms. Cerium (Ce) attenuated gland damage caused by phoxim, promoted protein synthesis, increased the antioxidant capacity of the gland and increased the cocooning rate of B. mori. Furthermore, digital gene expression data suggested that phoxim exposure led to significant up-regulation of 714 genes and down-regulation of 120 genes. Of these genes, 122 were related to protein metabolism, specifically, the down-regulated Ser2, Ser3, Fib-L, P25, and CYP450. Ce pretreatment resulted in up-regulation of 162 genes, and down-regulation of 141 genes, importantly, Ser2, Ser3, Fib-L, P25, and CYP333B8 were up-regulated. Treatment with CeCl3 + phoxim resulted in higher levels of Fib-L, P25, Ser2, Ser3, CAT, TPx, and CYP333B8 expression in the silk gland of silkworms. These findings indicated that Ce increased cocooning rate via the promotion of silk protein synthesis-related gene expression in the gland under phoxim-induced toxicity. These findings may expand the application of rare earths in sericulture.

Mechanisms of larval midgut damage following exposure to phoxim and repair of phoxim-induced damage by cerium in Bombyx mori.

Bombyx mori is an important economic animal for silk production. However, it is liable to be infected by organophosphorus pesticide that can contaminate its food and growing environment. It has been known that organophosphorus pesticide including phoxim exposure may damage the digestive systems, produce oxidative stress and neurotoxicity in silkworm B. mori, whereas cerium treatment has been demonstrated to relieve phoxim-induced toxicity in B. mori. However, very little is known about the molecular mechanisms of midgut injury due to phoxim exposure and B. mori protection after cerium pretreatment. The aim of this study was to evaluate the midgut damage and its molecular mechanisms, and the protective role of cerium in B. mori following exposure to phoxim. The results showed that phoxim exposure led to severe midgut damages and oxidative stress; whereas cerium relieved midgut damage and oxidative stress caused by phoxim in B. mori. Furthermore, digital gene expression suggested that phoxim exposure led to significant up-regulation of 94 genes and down-regulation of 52 genes. Of these genes, 52 genes were related with digestion and absorption, specifically, the significant alterations of esterase, lysozyme, amylase 48, and lipase expressions. Cerium pretreatment resulted in up-regulation of 116 genes, and down-regulation of 29 genes, importantly, esterase 48, lipase, lysozyme, and α-amylase were up-regulated. Treatment with Phoxim + CeCl3 resulted in 66 genes up-regulation and 39 genes down-regulation; specifically, levels of esterase 48, lipase, lysozyme, and α-amylase expression in the midgut of silkworms were significantly increased. Therefore, esterase 48, lipase, lysozyme, and α-amylase may be potential biomarkers of midgut toxicity caused by phoxim exposure. These findings may expand the application of rare earths in sericulture.

Molecular mechanism of oxidative damage of lung in mice following exposure to lanthanum chloride.

Exposure to lanthanoids (Ln) elicits an adverse response such as oxidative injury of lung in animals and human. The molecular targets of Ln remain unclear. In the present study, the function and signal pathway of nuclear factor erythroid 2 related factor 2 (Nrf2) in LaCl3 -induced oxidative stress in mouse lung were investigated. Mice were exposed to 2, 5, and 10 mg/kg body weight by nasal administration for 6 consecutive months. With increased doses, La was markedly accumulated and promoted the reactive oxygen species (ROS) production in the lung, which in turn resulted in peroxidation of lipids, proteins and DNA, and severe pulmonary damages. Furthermore, LaCl3 exposure could significantly increase levels of Nrf2, heme oxygenase 1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC) expressions in the LaCl3 -exposed lung. These findings imply that the induction of Nrf2 expression is an adaptive intracellular response to LaCl3 -induced oxidative stress in mouse lung, and that Nrf2 may regulate the LaCl3 -induced pulmonary damages.

Mechanisms of nanosized titanium dioxide-induced testicular oxidative stress and apoptosis in male mice.

BACKGROUND: Due to the increased application of titanium dioxide nanoparticles (TiO2 NPs) in the food industry and daily life, their potential toxic effects in humans and animals have been investigated. However, very few studies have focused on testicular oxidative stress and/or apoptosis. METHODS: In order to understand the possible molecular mechanisms of testicular lesions following exposure to TiO2 NPs, male mice were exposed to 2.5, 5, or 10 mg/kg body weight TiO2 NPs for 90 consecutive days. Testicular oxidative stress and apoptosis were then evaluated, and the testicular mRNA expression of several genes and their proteins involved in oxidative stress and/or apoptosis was investigated. RESULTS: TiO2 NPs entered Sertoli cells and caused severe testicular oxidative damage and/or apoptosis, accompanied by excessive production of reactive oxygen species and peroxidation of lipids, proteins and DNA as well as a significant reduction in antioxidant capacity. Furthermore, exposure to TiO2 NPs resulted in the up-regulation of caspase-3, Nrbp2, and cytochrome c expression, and caused down-regulation of SOD, CAT, GPx, GST, GR, Cyp1b1, Car3, Bcl-2, Acaa2, and Axud1 expression in mouse testis. CONCLUSIONS: TiO2 NPs entered Sertoli cells via the blood-testis barrier and were deposited in mouse seminiferous cord and/or Sertoli cells, causing oxidative damage and apoptosis.

Nano-sized titanium dioxide-induced splenic toxicity: a biological pathway explored using microarray technology.

Titanium dioxide nanoparticles (TiO2 NPs) have been widely used in various areas, and its potential toxicity has gained wide attention. However, the molecular mechanisms of multiple genes working together in the TiO2 NP-induced splenic injury are not well understood. In the present study, 2.5, 5, or 10mg/kg body weight TiO2 NPs were administered to the mice by intragastric administration for 90 consecutive days, their immune capacity in the spleen as well as the gene-expressed characteristics in the mouse damaged spleen were investigated using microarray assay. The findings showed that with increased dose, TiO2 NP exposure resulted in the increases of spleen indices, immune dysfunction, and severe macrophage infiltration as well as apoptosis in the spleen. Importantly, microarray data showed significant alterations in the expressions of 1041 genes involved in immune/inflammatory responses, apoptosis, oxidative stress, stress responses, metabolic processes, ion transport, signal transduction, cell proliferation/division, cytoskeleton and translation in the 10 mg/kg TiO2 NP-exposed spleen. Specifically, Cyp2e1, Sod3, Mt1, Mt2, Atf4, Chac1, H2-k1, Cxcl13, Ccl24, Cd14, Lbp, Cd80, Cd86, Cd28, Il7r, Il12a, Cfd, and Fcnb may be potential biomarkers of spleen toxicity following exposure to TiO2 NPs.

Pulmonary toxicity in mice following exposure to cerium chloride.

The widespread application of lanthanoids (Lns) in manufacturing industries has raised occupational and environmental health concerns about the possible increased health risks to humans exposed to Lns in their working and living environments. Numerous studies have shown that exposures to Ln cause pulmonary injury in animals, but very little is known about the molecular mechanisms of the pulmonary inflammation caused by cerium chloride (CeCl3) exposure. In this study, we evaluated the oxidative stress and molecular mechanism underlying with the pulmonary inflammation associated with chronic lung toxicity in mice treated with nasally instilled CeCl3 for 90 consecutive days. Our findings suggest that significant cerium accumulated in the lung, leading the obvious increase of the lung indices, significant increases in inflammatory cells and levels of lactate dehydrogenase, alkaline phosphate, and total protein, overproduction of reactive oxygen species and peroxidation of lipids, reduced antioxidant capacity, and pulmonary inflammation. CeCl3 exposure also activated nuclear factor κB, increased the expression of tumor necrosis factor α, cyclooxygenase-2, heme oxygenase 1, interleukin 2, interleukin 4, interleukin 6, interleukin 8, interleukin 10, interleukin 18, interleukin 1ß, and CYP1A1. However, CeCl3 reduced the expression of nuclear factor κB (NF-κB)-inhibiting factor and heat shock protein 70. These findings suggest that the pulmonary inflammation caused by CeCl3 in mice is closely associated with oxidative stress and inflammatory cytokine expression.

Kidney injury and alterations of inflammatory cytokine expressions in mice following long-term exposure to cerium chloride.

It has been demonstrated that the organic damages of animals can be caused by exposure to lanthanide oxides or compounds. However, the molecular mechanism of CeCl3 -induced kidney injury remains unclear. In this study, the mechanism of nephric damage in mice induced by an intragastric administration of CeCl3 was investigated. The results showed that Ce(3+) was accumulated in the kidney, which in turn led to oxidative stress, severe nephric inflammation, and dysfunction in mice. Furthermore, CeCl3 activated nucleic factor κB, which in turn increased the expression levels of tumor necrosis factor α, macrophage migration inhibitory factor, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-18, interleukin-1ß, cross-reaction protein, transforming growth factor-ß, interferon-γ, and CYP1A1, while suppressed heat shock protein 70 expression. These findings implied that Ce(3+) -induced kidney injury of mice might be associated with oxidative stress, alteration of inflammatory cytokine expression, and reduction of detoxification of CeCl3 .

Neurotoxicity and gene-expressed profile in brain-injured mice caused by exposure to titanium dioxide nanoparticles.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in toothpastes, sunscreens, and products for cosmetic purpose that the human use daily. Although the neurotoxicity induced by TiO2 NPs has been demonstrated, very little is known about the molecular mechanisms underlying the brain cognition and behavioral injury. In this study, mice were exposed to 2.5, 5, and 10 mg/kg body weight (BW) TiO2 NPs by nasal administration for 90 consecutive days, respectively, and their brains' injuries and brain gene-expressed profile were investigated. Our findings showed that TiO2 NPs could be translocated and accumulated in brain, led to oxidative stress, overproliferation of all glial cells, tissue necrosis as well as hippocampal cell apoptosis. Furthermore, microarray data showed significant alterations in the expression of 249 known function genes, including 113 genes upregulation and 136 genes downregulation following exposure to 10 mg/kg BW TiO2 NPs, which were associated with oxidative stress, immune response, apoptosis, memory and learning, brain development, signal transduction, metabolic process, DNA repair, response to stimulus, and cellular process. Especially, significant increases in Col1a1, serine/threonine-protein kinase 1, Ctnnb1, cysteine-serine-rich nuclear protein-1, Ddit4, Cyp2e1, and Krev interaction trapped protein 1 (Krit1) expressions and great decreases in DA receptor D2, Neu1, Fc receptor-like molecules, and Dhcr7 expressions following long-term exposure to TiO2 NPs resulted in neurogenic disease states in mice. Therefore, these genes may be potential biomarkers of brain toxicity caused by TiO2 NPs exposure, and the application of TiO2 NPs should be carried out cautiously.

Phoxim-induced damages of Bombyx mori larval midgut and titanium dioxide nanoparticles protective role under phoxim-induced toxicity.

Phoxim (O,O-diethyl O-(alpha-cyanobenzylideneamino) phosphorothioate) is a powerful organophosphorus pesticide with high potential for Bombyx mori larvae of silkworm exposure. However, it is possible that during the phoxim metabolism, there is generation of reactive oxygen species (ROS) and phoxim may produce oxidative stress and neurotoxicity in an intoxicated silkworm. Titanium dioxide nanoparticles (TiO2 NPs) pretreatment has been demonstrated to increase antioxidant capacity and acetylcholinesterase (AChE) activity in organisms. This study was, therefore, undertaken to determine phoxim-induced oxidative stress and neurotoxicity to determine whether phoxim intoxication alters the antioxidant system and AChE activity in the B. mori larval midgut, and to determine whether TiO2 NPs pretreatment attenuates phoxim-induced toxicity. The findings suggested that phoxim exposure decreased survival of B. mori larvae, increased malondialdehyde (MDA), carbonyl and 8-OHdG levels, and ROS accumulation in the midgut. Furthermore, phoxim significantly decreased the activities of AChE, superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione-S-transferase (GST), and levels of ascorbic acid (AsA), reduced glutathione (GSH), and thiol in the midgut. TiO2 pretreatment, however, could increase AChE activity, and remove ROS via activating SOD, CAT, APX, GR, and GST, and accelerating AsA-GSH cycle, thus attenuated lipid, protein, and DNA peroxidation and improve B. mori larval survival under phoxim-induced toxicity. Moreover, this experimental system would help nanomaterials to be applied in the sericulture.

Molecular mechanisms of phoxim-induced silk gland damage and TiO2 nanoparticle-attenuated damage in Bombyx mori.

Phoxim is a useful organophosphate (OP) pesticide used in agriculture in China, however, exposure to this pesticide can result in a significant reduction in cocooning in Bombyx mori (B. mori). Titanium dioxide nanoparticles (TiO2 NPs) have been shown to decrease phoxim-induced toxicity in B. mori; however, very little is known about the molecular mechanisms of silk gland damage due to OP exposure and repair of gland damage by TiO2 NP pretreatment. In the present study, exposure to phoxim resulted in a significant reduction in cocooning rate in addition to silk gland damage, whereas TiO2 NP attenuated phoxim-induced gland damage, increased the antioxidant capacity of the gland, and increased cocooning rate in B. mori. Furthermore, digital gene expression data suggested that phoxim exposure led to significant alterations in the expression of 833 genes. In particular, phoxim exposure caused significant down-regulation of Fib-L, Ser2, Ser3, and P25 genes involved in silk protein synthesis, and up-regulation of SFGH, UCH3, and Salhh genes involved in silk protein hydrolysis. A combination of both phoxim and TiO2 NP treatment resulted in marked changes in the expression of 754 genes, while treatment with TiO2 NPs led to significant alterations in the expression of 308 genes. Importantly, pretreatment with TiO2 NPs increased Fib-L, Ser2, Ser3, and P25 expression, and decreased SFGH, UCH3, and Salhh expression in silk protein in the silk gland under phoxim stress. Therefore, Fib-L, Ser2, Ser3, P25, SFGH, UCH3, and Salhh may be potential biomarkers of silk gland toxicity in B. mori caused by phoxim exposure.

Immunomodulatory effects in the spleen-injured mice following exposure to titanium dioxide nanoparticles.

Immune injuries following the exposure of titanium dioxide nanoparticles (TiO2 NPs) have been greatly concerned along with the TiO2 NPs are widely used in pharmacology and daily life. However, very little is known about the immunomodulatory mechanisms in the spleen-injured mice due to TiO2 NPs exposure. In this study, mice were continuously exposed to 2.5, 5, or 10 TiO2 NPs mg kg(-1) body weight for 90 days with intragastric administration to investigate the immunomodulatory mechanisms in the spleen. The findings showed that TiO2 NPs exposure resulted in significant increases in spleen and thymus indices, and titanium accumulation, in turn led to histopathological changes and splenocyte apoptosis. Furthermore, the exposure of TiO2 NPs could significantly increase the levels of macrophage inflammatory protein (MIP)-1α, MIP-2, Eotaxin, monocyte chemotactic protein-1, interferon-γ, vascular cell adhesion molecule-1, interleukin-13, interferon-γ-inducible protein-10, migration inhibitory factor, CD69, major histocompatibility complex, protein tyrosine phosphatase, protein tyrosine kinase 1, basic fibroblast growth factor, Fasl, and GzmB expression, whereas markedly decrease the levels of NKG2D, NKp46, 2B4 expression involved in immune responses, lymphocyte healing and apoptosis. These findings would better understand toxicological effects induced by TiO2 NPs exposure.

Gene expression profile in chronic mouse liver injury caused by long-term exposure to CeCl3.

Numerous studies have demonstrated lanthanide (Ln) accumulation in the liver, and the corresponding damage; however, very little work has been done to evaluate the relationship between Ln-induced liver injury and its gene expression profile in mice. In this study, liver injury and gene-expressed profiles in male mice induced by oral administration of CeCl3 (2 mg/kg) via gavage for 90 consecutive days were investigated. The results showed that cerium accumulation, liver inflammation, and hepatocyte necrosis were observed. CeCl3 exposure significantly decreased the counts of white blood cells, lymphocyte, and platelet, the reticulocyte count (Ret) and neutrophilic granulocyte percentages as well as A/G ratio, whereas markedly increased the activities of alkaline phosphatase, lactate dehydrogenase, and cholinesterase, and the concentrations of triglycerides and total cholesterol. Furthermore, microarray results of liver showed that the differential expression of 675 known function genes involved in immune/inflammation response, apoptosis, metabolic process, cell cycle, cell proliferation, cytoskeleton, oxidative stress, signal transduction, transcription, translation, and transportation in CeCl3 exposed livers, respectively. Specifically, the significant downregulation of Nt5e led to inflammation, overexpressed Cyp4a12a and great suppression of Cdkn1a resulted in hepatocyte apoptosis, marked elevation of Cel, and Cyp7b1 expression caused the metabolic disorders in mouse liver after long-term CeCl3 exposure. Therefore, these genes may be in great relation to liver damages induced by exposure to CeCl3 .

Immune dysfunction and liver damage of mice following exposure to lanthanoids.

In an effort to investigate the effects of exposure to lanthanoids (Ln) on the immune response and liver function, mice were orally exposed to LaCl3 , CeCl3 , and NdCl3 at 2, 10, and 20 mg/kg doses for 30 days, respectively; lymphocyte counts, serum IgM level, hematological indices, biochemical parameters of liver functions, and histopathological changes in Ln(3+) -treated mice were assessed. Indeed, 20 mg/kg Ln(3+) significantly inhibited mice growth and reduced the counts of white blood cells, platelets, and reticulocyte in mice blood. Specifically, in these Ln(3+) -treated mice, CD3+, CD4+, CD8+, CD19+ and NK cells, and CD4+/CD8+ ratio as well as serum IgM level were decreased. Furthermore, liver function was disrupted, as evidenced by the increased alanine aminotransferase, total bilirubin, total bile acid and triglycerides, and the decreased glucose and ratio of albumin to globulin. The cytoarchitecture damage and fatty degeneration in liver caused by Ln(3+) at 20 mg/kg dose were also observed. Our findings showed that exposure to Ln affected the cell and humoral immunity and disturbed liver function in mice. In addition, Ce(3+) was found to exhibit higher toxicity than La(3+) and Nd(3+).

Neurotoxic characteristics of spatial recognition damage of the hippocampus in mice following subchronic peroral exposure to TiO2 nanoparticles.

Due to the increased application of titanium dioxide nanoparticles (TiO2 NPs) in various areas, numerous studies have been conducted which have confirmed that exposure to TiO2 NPs may result in neurological damage in both mice and rats. However, very few studies have focused on the molecular mechanisms of spatial recognition injury. In the present study, to understand the possible neurobiological responses of the mouse hippocampus following subchronic peroral exposure to low level TiO2 NPs, mice were exposed to 2.5, 5, and 10mg/kg body weight TiO2 NPs for 90 consecutive days. Hippocampal pathology and neuron ultrastructure, and long-term potentiation (LTP) were then evaluated, and the hippocampal mRNA-expression of several genes and their proteins involved in homeostasis of neuronal synaptic plasticity were investigated using a quantitative real-time PCR and ELISA method. We observed that subchronic peroral exposure to TiO2 NPs caused severe pathological changes, spatial recognition impairment, and resulted in significant LTP reduction and down-regulation of N-methyl-D-aspartate (NMDA) receptor subunits (NR2A and NR2B) expression associated with the simultaneous inhibition of CaMKIV, cyclic-AMP responsive element binding proteins (CREB-1, CREB-2), and FosB/DFosB in mouse hippocampal tissues. Therefore, our findings suggest that the application of TiO2 NPs in the various areas should be paid more attention.

Titanium dioxide nanoparticles relieve silk gland damage and increase cocooning of Bombyx mori under phoxim-induced toxicity.

Organophosphate pesticides are applied widely in the world for agricultural purposes, and their exposures often resulted in non-cocooning of Bombyx mori in China. TiO2 nanoparticles have been demonstrated to increase pesticide resistance of Bombyx mori. While the toxicity of phoxim is well-documented, very limited information exists on the mechanisms of TiO2 nanoparticles improving the cocooning function of Bombyx mori following exposure to phoxim. The present study was, therefore, undertaken to determine whether TiO2 nanoparticles attenuate silk gland injury and elevate cocooning of B. mori following exposure to phoxim. The findings suggested that phoxim exposure resulted in severe damages of the silk gland structure and significantly decreased the cocooning in the silk gland of Bombyx mori. Furthermore, phoxim exposure significantly resulted in reductions of total protein concentrations and suppressed expressions of silk protein synthesis-related genes, including Fib-L, Fib-H, P25, Ser-2, and Ser-3, in the silk gland. TiO2 nanoparticle pretreatment, however, could significantly relieve silk gland injury of Bombyx mori. Importantly, TiO2 nanoparticles could remarkably elevate cocooning and total protein contents and promote expressions of Fib-L, Fib-H, P25, Ser-2, and Ser-3 in the silk gland following exposure to phoxim.

Renal injury and Nrf2 modulation in mouse kidney following chronic exposure to TiO2 nanoparticles.

TiO2 nanoparticles (NPs) are used in the food industry but have potential toxic effects in humans and animals. TiO2 NPs impair renal function and cause oxidative stress and renal inflammation in mice, associated with inhibition of nuclear factor erythroid-2-related factor 2 (Nrf2), which regulates genes encoding many antioxidants and detoxifying enzymes. This study determined whether TiO2 NPs activated the Nrf2 signaling pathway. Mice exhibited accumulation of reactive oxygen species and peroxidation of lipid, protein, and DNA in the kidney, coupled with renal dysfunction, glutathione depletion, inflammatory cell infiltration, fatty degeneration, and apoptosis. These were associated with increased expression of NOX4, cyclooxygenase-2, and nuclear factor-κB. Oxidative stress and inflammation were accompanied by decreased expression of Nrf2 and down-regulation of its target gene products including heme oxygenase 1, glutamate-cysteine ligase catalytic subunit, and glutathione S-transferase. Chronic TiO2 NP exposure is associated with suppression of Nrf2, which contributes to the pathogenesis of oxidative stress and inflammation.

Oxidative stress in the kidney injury of mice following exposure to lanthanides trichloride.

Environmental pollution from lanthanides (Ln) has been recognized as a major problem due to a grab exploitation of Ln mine in China. Exposure to Ln has been demonstrated to cause the nephrotoxicity, very little is known about the mechanism of oxidative damage to kidney in animals. In order to understand Ln-induced nephrotoxicity, various biochemical and chemical parameters were assayed in mouse kidney. Intragastric exposures of LaCl3, CeCl3, and NdCl3 at doses of 2, 5, and 10 mg kg(-1) BW for 90 consecutive days caused nephritis or epithelial cell necrosis and oxidative stress to kidney. An increase in coefficients of the kidney, La, Ce, and Nd accumulation and histopathological changes in the kidney could be observed, followed by increased reactive oxygen species production and peroxidation levels of lipid, protein and DNA, and decreased activities of superoxide dismutase, catalase, glutathione-S-transferase and glutathione reductase as well as antioxidants such as glutathione, ascorbic acid and thiol contents. Furthermore, La, Ce, and Nd significantly suppressed expression of genes and proteins of these antioxidative enzymes in mouse kidney. In addition, kidney functions were disrupted, including an increase of the creatinine, and reductions of uric acid, urea nitrogen, calcium and phosphonium. These findings suggest that nephritis generation or epithelial cell necrosis in mice following exposure to Ln is closely associated with oxidative stress. Of these damages, the most severe was in the Ce(3+)-exposed kidneys, next in the Nd(3+)-exposed kidneys, and the least in the La(3+)-exposed kidneys, which may be attributed to the 4f electron of Ln.

Titanium dioxide nanoparticle-induced testicular damage, spermatogenesis suppression, and gene expression alterations in male mice.

Although titanium dioxide nanoparticles (TiO2 NPs) have been demonstrated to accumulate in organs resulting in toxicity, there is currently only limited data regarding male reproductive toxicity by TiO2 NPs. In this study, testicular damage and alterations in gene expression profiles in male mice induced by intragastric administration of 2.5, 5, and 10mg/kg body weight of TiO2 NPs for 90 consecutive days were examined. Our findings showed that TiO2 NPs can cross the blood-testis barrier to reach the testis and accumulate therein, which, in turn, results in testicular lesions, sperm malformations, and alterations in serum sex hormone levels. Furthermore, microarray analysis showed that 70 genes with known functions were up-regulated, while 72 were down-regulated in TiO2 NPs-exposed testes. Of the altered gene expressions, Ly6e, Adam3, Tdrd6, Spata19, Tnp2, and Prm1 are involved in spermatogenesis, whereas Sc4mol, Psmc3ip, Mvd, Srd5a2, Lep, and Cyp2e1 are associated with steroid and hormone metabolism. Hence, the production and application of TiO2 NPs should be carried out cautiously, especially by humans of reproductive age.