Nano and bulk ZnO trigger diverse Zn-transport-related gene transcription in distinct regions of the small intestine in mice after oral exposure

Achieving the Optimal AgO Concentrations to Modulate the Anti-Trypanosoma cruzi Activity of Ag-ZnO/AgO Nanocomposites: In Vivo Investigations

Background/Objectives: For the development of new treatments, the acute phase of Chagas disease (CD) in experimental models acts as a filter to screen out potentially effective interventions. Therefore, the aim of this study was to evaluate ZnO nanocrystals and Ag-ZnO/AgO nanocomposites containing different proportions of silver (ZnO:5Ag, ZnO:9Ag and ZnO:11Ag) in an experimental model of the acute phase of CD. Methods: C57Bl/6 mice were infected with 1000 forms of the Colombian strain of T. cruzi. The treatment was carried out by gavage with 5 mg/kg/d for 7 consecutive days from the first detection of parasitemia. Weight, parasitemia and survival were assessed during treatment and up to the day of euthanasia. After euthanasia, the cardiac and intestinal parasitism, inflammatory infiltrate, collagen deposition and cytokine dosages were analyzed. Results: It was observed that the nanocomposites ZnO:9Ag and ZnO:11Ag were the most effective in reducing parasitemia and increasing the survival of the infected animals. However, pure ZnO induced the maintenance of parasitemia and reduced their survival. The ZnO:9Ag and ZnO:11Ag nanocomposites were able to reduce the number of cardiac amastigote nests. In addition, they were responsible for reducing TNF-α and IL-6 in situ. ZnO:9Ag and ZnO:11Ag induced a reduction in the intestinal inflammatory infiltrate and neuronal protection in the myenteric plexus, as well as reducing TNF-α in situ. Conclusions: Based on these results, it is suggested that there is an ideal concentration in terms of the proportion of Ag/AgO and ZnO in nanocomposites for use against CD. Thus, ZnO:9Ag or ZnO:11Ag nanomaterials are potential candidates for the development of new biotechnological products for the therapy of CD.

Alterations of Gut-Derived Melatonin in Neurobehavioral Impairments Caused by Zinc Oxide Nanoparticles

Purpose

The widespread use of zinc oxide nanoparticles (ZnONPs) has raised concerns about its potential toxicity. Melatonin is a neurohormone with tremendous anti-toxic effects. The enterochromaffin cells are an essential source of melatonin in vivo. However, studies on the effects of ZnONPs on endogenous melatonin are minimal. In the present study, we aimed to investigate the effects of ZnONPs exposure on gut-derived melatonin.

Methods

In the present study, 64 adult male mice were randomly and equally divided into four groups, and each group was exposed to ZnONPs (0, 6.5, 13, 26 mg/kg/day) for 30 days. Subsequently, the neurobehavioral changes were observed. The effects of ZnONPs on the expression of melatonin-related genes arylalkylamine N-acetyltransferase (Aanat), melatonin receptor1A (Mt1/Mtnr1a), melatonin receptor1B (Mt2/Mtnr1b), and neuropeptide Y (Npy) on melatonin synthesis and secretion in duodenum, jejunum, ileum and colon during day and night were also assessed.

Results

The results revealed that oral exposure to ZnONPs induced impairments of locomotor activity and anxiety-like behavior in adult mice during the day. The transcriptional analysis of brain tissues revealed that exposure to ZnONPs caused profound effects on genes and transcriptional signaling pathways associated with melatonin synthesis and metabolic processes during the day and night. We also observed that, in the duodenum, jejunum, ileum and colon sites, ZnONPs resulted in a significant reduction in the expression of the gut-derived melatonin rate-limiting enzyme Aanat, the membrane receptors Mt1 and Mt2 and Npy during the day and night.

Conclusion

Taken together, this is the first study shows that oral exposure to ZnONPs interferes with melatonin synthesis and secretion in different intestinal segments of adult mice. These findings will provide novelty insights into the neurotoxic mechanisms of ZnONPs and suggest an alternative strategy for the prevention of ZnONP neurotoxicity.

Zinc Oxide Particles Can Cause Ovarian Toxicity by Oxidative Stress in Female Mice Model

Introduction

Zinc oxide nanoparticles (ZnO NPs) participate in all aspects of our lives, but with their wide application, more and more disadvantages are exposed. The goal of this study was to investigate the toxicity of ZnO NPs in female mice ovaries and explore its potential mechanism.

Methods

In this study, adult female mice were orally exposed to 0, 100, 200, and 400 mg/kg ZnO NPs for 7 days. We explored the underlying mechanisms via the intraperitoneal injection of N-acetyl-cysteine (NAC), an inhibitor of oxidative stress, and salubrinal (Sal), an inhibitor of endoplasmic reticulum (ER) stress.

Results

The results indicated that serum estradiol and progesterone levels declined greatly with increasing ZnO NPs dosage. Hematoxylin and eosin (HE) staining revealed increased atretic follicles and exfoliated follicular granulosa cells. Moreover, at the transcriptional level, antioxidant-related genes such as Keap1 and Nrf2, and ER stress-related genes PERK, eIF2α, and ATF4 were markedly upregulated. In addition, the expression of Caspase12, Caspase9, and Caspase3, which are genes related to apoptosis, was also upregulated in all ZnO NPs treatment groups. Serum malondialdehyde (MDA) content was remarkably up-regulated, whereas superoxide dismutase (SOD) activity was down-regulated. The 400 mg/kg ZnO NPs treatment group suffered the most substantial harm. However, ovarian damage was repaired when NAC and Sal were added to this group.

Conclusion

ZnO NPs had toxic effects on the ovary of female mice, which were due to oxidative stress, ER stress, and the eventual activation of apoptosis.

The effect of reproductive toxicity induced by ZnO NPs in mice during early pregnancy through mitochondrial apoptotic pathway

The potential toxicity of Zinc oxide nanoparticles (ZnO NPs) to human beings has become a widespread concern. This study explored the reproductive toxicity and the mechanism of toxicity of ZnO NPs in early pregnant mice. The results showed that abnormal weight changes, induced inflammation, reduced level of serum sex hormones, damaged uterus, increased abortion, and abnormal development of fetus. In the uterus, the transcription levels of ZnT-1, HO-1, Bax, Bax/Bcl-2, JNK, and Caspase-3 were significantly up-regulated while Bcl-2, ER-1 and PR were significantly down-regulated. The TUNEL-positive cells increased that were exposed to high levels of ZnO NPs. In summary, those results indicated that Zn from high levels of exposure to ZnO NPs accumulated in the uterus that could have caused the formation of ROS that led to oxidative stress, which might have activated the mitochondrial apoptotic pathway that could have caused the uterine injury which induced the observed reproductive toxicity.

In Vitro and In Vivo Models for Evaluating the Oral Toxicity of Nanomedicines

Toxicity studies for conventional oral drug formulations are standardized and well documented, as required by the guidelines of administrative agencies such as the US Food & Drug Administration (FDA), the European Medicines Agency (EMA) or European Medicines Evaluation Agency (EMEA), and the Japanese Pharmaceuticals and Medical Devices Agency (PMDA). Researchers tend to extrapolate these standardized protocols to evaluate nanoformulations (NFs) because standard nanotoxicity protocols are still lacking in nonclinical studies for testing orally delivered NFs. However, such strategies have generated many inconsistent results because they do not account for the specific physicochemical properties of nanomedicines. Due to their tiny size, accumulated surface charge and tension, sizeable surface-area-to-volume ratio, and high chemical/structural complexity, orally delivered NFs may generate severe topical toxicities to the gastrointestinal tract and metabolic organs, including the liver and kidney. Such toxicities involve immune responses that reflect different mechanisms than those triggered by conventional formulations. Herein, we briefly analyze the potential oral toxicity mechanisms of NFs and describe recently reported in vitro and in vivo models that attempt to address the specific oral toxicity of nanomedicines. We also discuss approaches that may be used to develop nontoxic NFs for oral drug delivery.

Protective effect of the NAC and Sal on zinc oxide nanoparticles-induced reproductive and development toxicity in pregnant mice

The growing use of zinc oxide nanoparticles (ZnO NPs) in various applications has raised many concerns about the potential risks to human health. In this research, the protective effects of cellular oxidative stress inhibitor N-Acetyl-cysteine (NAC) and endoplasmic reticulum (ER) stress inhibitor Salubrinal (Sal) on reproductive toxicity induced by ZnO NPs were investigated. The results showed that application of these two kinds of cell stress inhibitors after oral ingestion of ZnO NPs could prevent the weight loss of pregnant mice; reduce zinc content in the uterus, placenta and fetus; reduce abnormal development of the offspring; and decrease fetal abortion. Furthermore, RT-qPCR, Western blot and immunofluorescence assay results indicated that NAC restored the expression of Gclc, reduced the expression of ATF4, JNK and Caspase-12, and decreased the expression of eNOS and IGF-1, in the placenta. Sal decreased the expression of ATF4, JNK and Caspase-12, and increased the expression of eNOS and IGF-1caused by the oral ingestion of ZnO NPs. These results indicated that treatment with NAC and Sal after oral exposure could reduce reproductive and development toxicity caused by ZnO NPs which induced reproductive and development toxicity that was probably caused by the activation of oxide stress and ER stress.

Nano Zinc Oxide Induced Fetal Mice Growth Restriction, Based on Oxide Stress and Endoplasmic Reticulum Stress

ZnO NPs have been assessed to show adverse effects on reproductive organs, but the molecular mechanisms of reproductive toxicity have not been sufficiently studied. In this research, the dosage effects from the oral exposure of ZnO NPs (30 nm) to pregnant mice in gestation day 10.5 to 17.5 was analyzed. Pregnant mice exposed to ZnO NPs induced dam injury, mice fetal growth restriction, and the fetus number decreased. The pathological evaluation showed that ZnO NPs exposure caused placental spongiotrophoblast area decease and structural damage. The RT-qPCR and immunocytochemistry data indicated that ZnO NPs could induce placenta oxide stress, endoplasmic reticulum stress responses, apoptosis, and altered placental function. These findings indicated that ZnO NPs could induce dam injury and fetal growth restriction. Reproductive toxicity of ZnO NPs may be due to placental injury and function alteration caused by apoptosis, oxide stress, and endoplasmic reticulum stress after ZnO NPs exposure.

The current and future perspectives of zinc oxide nanoparticles in the treatment of diabetes mellitus

Diabetes mellitus (DM) is a multifaceted and costly disease, which requires serious attention. Finding a cheaper anti-diabetic alternative that can act on multiple disease-related targets and pathways is the ultimate treatment goal for DM. Nanotechnology has offered some exciting possibilities in biomedical and drug delivery applications. Zinc oxide nanoparticles (ZnO-NPs), a novel agent to deliver zinc, have great implications in many disease therapies including DM. This review summarizes the pharmacological mechanisms by which ZnO-NPs alleviate DM and diabetic complications. Research implications and future perspectives were also discussed.

Protein and lipid homeostasis altered in rat macrophages after exposure to metallic oxide nanoparticles

Metal oxide nanoparticles (NPs), such as ZnO, ZnFe₂O₄, and Fe₂O₃, are widely used in industry. However, little is known about the cellular pathways involved in their potential toxicity. Here, we particularly investigated the key molecular pathways that are switched on after exposure to sub-toxic doses of ZnO, ZnFe₂O₄, and Fe₂O₃ in the in vitro rat alveolar macrophages (NR8383). As in our model, the calculated IC₅₀ were respectively 16, 68, and more than 200 μg/mL for ZnO, ZnFe₂O₄, and Fe₂O₃; global gene and protein expression profiles were only analyzed after exposure to ZnO and ZnFe₂O₄ NPs. Using a rat genome microarray technology, we found that 985 and 1209 genes were significantly differentially expressed in NR8383 upon 4 h exposure to ¼ IC₅₀ of ZnO and ZnFe₂O₄ NPs, respectively. It is noteworthy that metallothioneins were overexpressed genes following exposure to both NPs. Moreover, Ingenuity Pathway Analysis revealed that the top canonical pathway disturbed in NR8383 exposed to ZnO and ZnFe₂O₄ NPs was eIF2 signaling involved in protein homeostasis. Quantitative mass spectrometry approach performed from both NR8383 cell extracts and culture supernatant indicated that 348 and 795 proteins were differentially expressed upon 24 h exposure to ¼ IC₅₀ of ZnO and ZnFe₂O₄ NPs, respectively. Bioinformatics analysis revealed that the top canonical pathways disturbed in NR8383 were involved in protein homeostasis and cholesterol biosynthesis for both exposure conditions. While VEGF signaling was specific to ZnO exposure, iron homeostasis signaling pathway was specific to ZnFe₂O₄ NPs. Overall, the study provides resource of transcriptional and proteomic markers of response to ZnO and ZnFe₂O₄ NP-induced toxicity through combined transcriptomics, proteomics, and bioinformatics approaches.