Respiratory Responses to Single Oral Administration of Taurine in Sprague-Dawley Rats.

Taurine is a nonessential amino acid that has been increasingly consumed due to its various beneficial biological effects. Excessive taurine intake has been linked to the positive regulation of inflammatory responses and endoplasmic reticulum stress through the modulation of intracellular calcium levels. However, research on the potential adverse effects of taurine consumption on the respiratory system is limited. To address this, we investigated the respiratory responses of 6-week-old male Sprague-Dawley rats to taurine administered orally at 0, 100, 200, and 400 mg/kg. Respiratory rate, tidal volume, and minute volume were monitored in accordance with the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) Harmonized Tripartite Guideline S7A for Safety Pharmacology Studies for Human Pharmaceuticals. We found that taurine administration did not significantly alter respiratory rate or tidal volume; however, a significant increase in minute volume was observed 6 h after administration of 200 mg/kg taurine.

Repeated-dose toxicity and toxicokinetic study of isobutylparaben in rats subcutaneously treated for 13 weeks.

Parabens have historically served as antimicrobial preservatives in a range of consumables such as food, beverages, medications, and personal care products due to their broad-spectrum antibacterial and antifungal properties. Traditionally, these compounds were believed to exhibit low toxicity, causing minimal irritation, and possessing limited sensitization potential. However, recent evidence suggests that parabens might function as endocrine-disrupting chemicals (EDCs). Consequently, extensive research is underway to elucidate potential human health implications arising from exposure to these substances. Among these parabens, particular concerns have been raised regarding the potential adverse effects of iso-butylparaben (IBP). Studies have specifically highlighted its potential for inducing hormonal disruption, significant ocular damage, and allergic skin reactions. This study aimed to evaluate the prolonged systemic toxicity, semen quality, and estrus cycle in relation to endocrine disruption endpoints, alongside assessing the toxicokinetic behavior of IBP in Sprague-Dawley rats following a 13-week repeated subcutaneous administration. The rats were administered either the vehicle (4% Tween 80) or IBP at dosage levels of 2, 10, and 50 mg/kg/day for 13 weeks. Blood collection for toxicokinetic study was conducted on three specified days: day 1 (1st), day 30 (2nd), and day 91 (3rd). Systemic toxicity assessment and potential endocrine effects were based on various parameters including mortality rates, clinical signs, body weights, food and water consumption, ophthalmological findings, urinalysis, hematological and clinical biochemistry tests, organ weights, necropsy and histopathological findings, estrus cycle regularity, semen quality, and toxicokinetic behavior. The findings revealed that IBP induced local irritation at the injection site in males at doses ≥ 10 mg/kg/day and in females at 50 mg/kg/day; however, systemic toxicity was not observed. Consequently, the no-observed-adverse-effect level (NOAEL) for IBP was determined to be 50 mg/kg/day in rats of both sexes, indicating no impact on the endocrine system. The toxicokinetics of IBP exhibited dose-dependent systemic exposure, reaching a maximum dose of 50 mg/kg/day, and repeated administration over 13 weeks showed no signs of accumulation.

The effects of Pycnogenol, a pine bark extract on pulmonary inflammation by Asian sand dust in mice.

Asian sand dust (ASD), also called China dust or yellow dust, mainly occurs in East Asia during spring and autumn. Because ASD enters the body mainly through the respiratory system, it can cause respiratory disorders or worsen underlying diseases. Because of this, it has become an important health concern that threatens the well-being of humans and animals. In this study, we investigated the effects of 15 and 30 mg/kg of Pycnogenol (PYC15 and 30 groups), a pine bark extract, on ASD-induced pulmonary inflammation in mice. We evaluated the inflammatory cell counts, inflammatory cytokines, and matrix-metalloproteinase (MMP)-9 expression in animal models. PYC administration significantly decreased inflammatory cell infiltration into lung tissue; this was accompanied by a reduction in the levels of proinflammatory mediators including interleukin (IL)-1ß (P < 0.01), IL-6 (P < 0.01) and tumour necrosis factor-α (P < 0.01) in bronchoalveolar lavage fluids of ASD-exposed mice (ASD group). Histological analysis revealed that PYC suppressed ASD-induced pulmonary inflammation. Moreover, PYC suppressed the levels of matrix-metalloproteinase (MMP)-9 in the lung tissue of ASD-exposed mice, indicating that PYC reduced ASD-induced pulmonary inflammation by suppressing MMP-9. Together, these results indicate that PYC as the potential to treat ASD-driven pulmonary inflammation.

Respiratory Safety Pharmacological Testing with Single Intravenous Administration of Caffeine in Sprague-Dawley Rats.

As caffeine consumption continues to increase, both positive and negative effects are becoming evident. Caffeine directly affects the cardiovascular system, including heart function and rate. Thus, understanding the current respiratory safety pharmacological responses is of utmost importance. To elucidate the respiratory safety pharmacological characteristics of caffeine, male Sprague-Dawley rats, aged 6 weeks, were intravenously administered doses of 0, 2, 6, and 20 mg/kg of caffeine. Respiratory rate, tidal volume, and minute volume were subsequently measured. In this study, we observed a significant increase in respiratory rate and minute volume, but a remarkable reduction in tidal volume following the intravenous administration of caffeine at doses exceeding 6 mg/kg. These changes were evident within the timeframe of 0.25 to 1.5 h. The data we have collected can serve as valuable foundational scientific information for future research on caffeine, encompassing absorption, distribution, metabolism, excretion, and pharmacological core-battery experiments.

Particulate matter-mediated oxidative stress induces airway inflammation and pulmonary dysfunction through TXNIP/NF-κB and modulation of the SIRT1-mediated p53 and TGF-ß/Smad3 pathways in mice.

Exposure to particulate matter is currently recognized as a serious aggravating factor of respiratory diseases. In this study, we investigated the effects of particulate matter (PM) on the respiratory system in BALB/c mice and NCI-H292 cells. PM (0, 2.5, 5 and 20 mg/kg) was administered to mice by intra-tracheal instillation for 7 days. After a 7 day-repeated treatment of PM, we evaluated inflammatory cytokines/cell counts in bronchoalveolar lavage fluid (BALF) and conducted pulmonary histology and functional test. We also investigated the role of TXNIP/NF-κB and SIRT1-mediated p53 and TGF-ß/Smad3 pathways in PM-induced airway inflammation and pulmonary dysfunction. PM caused a significant increase in pro-inflammatory cytokines, inflammatory cell counts in bronchoalveolar lavage fluid. PM-mediated oxidative stress down-regulated thioredoxin-1 and up-regulated thioredoxin-interacting protein and activation of nuclear factor-kappa B in the lung tissue and PM-treated NCI-H292 cells. PM suppressed sirtuin1 protein levels and increased p53 acetylation in PM-exposed mice and PM-treated NCI-H292 cells. In addition, PM caused inflammatory cell infiltration and the thickening of alveolar walls by exacerbating the inflammatory response in the lung tissue. PM increased levels of transforming growth factor-ß, phosphorylation of Smad3 and activation of α-smooth muscle actin, and collagen type1A2 in PM-exposed mice and PM-treated NCI-H292 cells. In pulmonary function tests, PM exposure impaired pulmonary function resembling pulmonary fibrosis, characterized by increased resistance and elastance of the respiratory system, and resistance, elastance, and damping of lung tissues, whereas decreased compliance of the respiratory system, forced expired volume and forced vital capacity. Overall, PM-mediated oxidative stress caused airway inflammation and pulmonary dysfunction with pulmonary fibrosis via TXNIP pathway/NF-κB activation and modulation of the SIRT1-mediated TGF-ß/Smad3 pathways. The results of this study can provide fundamental data on the potential adverse effects and underlying mechanism of pulmonary fibrosis caused by PM exposure as a public health concern. Due to the potential toxicity of PM, people with respiratory disease must be careful with PM exposure.

Toxicity of a 90-day repeated oral dose of a collagen peptide derived from skate (Raja kenojei) skin: a rat model study.

Collagen peptides are widely employed as therapeutic materials due to their numerous beneficial properties, including for the following uses: antiaging, antioxidant applications, antibacterial applications, wound healing, tissue engineering, medication delivery, and cosmetics. Although collagen peptides are useful in these applications, to our knowledge, few published studies have been undertaken on their repeated-dose toxicity. We evaluated the possible subchronic toxicity of a collagen peptide derived from skate (Raja kenojei) skin (CPSS) in Sprague-Dawley rats by administering repeated oral doses over 90 days. Rats of both sexes were assigned randomly to one of four experimental groups, respectively receiving 0, 500, 1000, or 2000 mg/kg/day of CPSS. At all doses tested, repeated oral CPSS administration had no treatment-related adverse effects in terms of clinical signs, body weight, food consumption, detailed clinical observation, sensory reactivity, functional assessment, urinalysis, ophthalmic examination, gross pathology, hematology, serum biochemistry, hormone analysis, organ weight, and histopathology. Even though there were some alterations in hematologic parameters, serum biochemistry parameters, organ weight, and histopathological findings, these did not follow a dose-response pattern and were within historical limits for control rats. The oral no-observed-adverse-effect level (NOAEL) of the CPSS was 2000 mg/kg/day for both male and female rats in the applied experimental circumstances, and no target organs were identified.

Effects of melamine and cyanuric acid on placental and fetal development in rats.

Melamine or cyanuric acid alone has low toxicity, but combined exposure to melamine and cyanuric acid was reported to cause unexpected toxicological effects. This study investigated the potential effects and toxic mechanism of combined exposure to melamine and cyanuric acid on placental and fetal development in rats. Exposure to melamine and cyanuric acid caused maternal toxicity manifested by increased abnormal symptoms and decreased body weight gain. Developmental toxic effects included a decrease in placental and fetal weights with increased fetal deaths and post-implantation loss. Melamine and cyanuric acid induced oxidative stress in the developing placenta and fetus. The placentas from rats treated with melamine and cyanuric acid showed shortening of the placental layers with histological changes, decreased cell proliferation, increased apoptotic changes, and decreased insulin-like growth factor (IGF)/IGF-binding proteins (IGFBPs) and placental lactogen (PL) expression levels. Fetuses from melamine- and cyanuric acid-treated dams showed increased apoptotic changes and suppressed cellular proliferation in their livers and vertebrae. Consequently, combined exposure to melamine and cyanuric acid resulted in high levels of oxidative stress and impaired placental development associated with impairment of the IGF/IGFBP and PL systems, resulting in increased apoptotic changes and reduced fetal cell proliferation.

Exposure to China dust exacerbates testicular toxicity induced by cyclophosphamide in mice.

This study investigated the potential effects of China dust (CD) exposure on cyclophosphamide (CP)-induced testicular toxicity in mice, focusing on spermatogenesis and oxidative damage. CP treatment reduced testicular and epididymal weight and sperm motility and enhanced sperm abnormality. Histopathological examination presented various morphological alterations in the testis, including increased exfoliation of spermatogenic cells, degeneration of early spermatogenic cells, vacuolation of Sertoli cells, a decreased number of spermatogonia/spermatocytes/spermatids, along with a high number of apoptotic cells. In addition, the testis exhibited reduced glutathione (GSH) levels and glutathione reductase (GR) activity and enhanced malondialdehyde (MDA) concentration. Meanwhile, CD exposure exacerbated testicular histopathological alterations induced by CP. CD exposure also aggravated oxidative damage by increasing the lipid peroxidative product MDA and decreasing GSH levels and antioxidant enzyme activities in the testis. These results suggest that CD exposure exacerbates CP-induced testicular toxicity in mice, which might be attributed to the induction of lipid peroxidation and reduced antioxidant activity.

Toll-like receptor 4 is a key regulator of asthma exacerbation caused by aluminum oxide nanoparticles via regulation of NF-κB phosphorylation.

Aluminum oxide nanoparticles (Al2O3 NPs) have recently been reported to cause an inflammatory response in the lungs, and studies are being conducted on their adverse effects, especially in patients with underlying lung diseases such as asthma. However, the underlying mechanism of asthma aggravation caused by Al2O3 NPs remains unclear. This study investigated whether Al2O3 NPs exacerbate ovalbumin (OVA)-induced asthma and focused on the correlation between toll-like receptor 4 (TLR4) signaling and Al2O3 NP-induced asthma exacerbation. Al2O3 NP exposure in asthmatic mice resulted in increased inflammatory cell counts in the lungs, airway hyperresponsiveness, and increased levels of inflammatory cytokines compared with only OVA-induced mice, and excessive secretion of mucus was observed in the airways. Moreover, Al2O3 NP exposure in OVA-induced mice increased the expression levels of TLR4, phospho-nuclear transcription factor-kappa B (p-NFκB), myeloid differentiation factor 88 (MyD88), and phospho-NF kappa B inhibitor alpha (p-IκBα). Furthermore, in the lungs of TLR4 knockout mice exposed to Al2O3 NPs and in a human airway epithelial cell line with down regulated TLR4, the expression levels of MyD88, p-NFκB, and p-IκBα were decreased, and asthma-related allergic responses were reduced. Therefore, we demonstrated that TLR4 is important for aggravation of asthma induced by Al2O3 NPs, and this study provides useful information regarding as yet undiscovered novel target signaling.

Changes in the Neuronal Architecture of the Hippocampus in a 6-Hydroxydopamine-Lesioned Rat Model of Parkinson Disease.

PURPOSE: Parkinson disease (PD) is a progressive neurodegenerative disorder in which dopaminergic (DAergic) systems are destroyed (particularly in the nigrostriatal system), causing both motor and nonmotor symptoms. Hippocampal neuroplasticity is altered in PD animal models, resulting in nonmotor dysfunctions. However, little is known about the precise mechanism underlying the hippocampal dysfunctions in PD. METHODS: Striatal 6-hydroxydopamine (6-OHDA) infusions were performed unilaterally in adult Sprague Dawley rats. Both motor and nonmotor symptoms alongside the expression of tyrosine hydroxylase (TH) in the substantia nigra and striatum were confirmed in 6-OHDA-lesioned rats. The neuronal architecture in the hippocampus was analyzed by Golgi staining. RESULTS: During the 7-8 weeks after infusion, the 6-OHDA-lesioned rats exhibited motor and nonmotor dysfunctions (especially anxiety/depression-like behaviors). Rats with unilateral 6-OHDA infusion displayed reduced TH+ immunoreactivity in the ipsilateral nigrostriatal pathway of the brain. Golgi staining revealed that striatal 6-OHDA infusion significantly decreased the dendritic complexity (i.e., number of crossing dendrites, total dendritic length, and branch points) in the ipsilateral hippocampal conus ammonis 1 (CA1) apical/basal and dentate gyrus (DG) subregions. Additionally, the dendritic spine density and morphology were significantly altered in the CA1 apical/basal and DG subregions following striatal 6-OHDA infusion. However, alteration of microglial and astrocytic distributions did not occur in the hippocampus following striatal 6-OHDA infusion. CONCLUSION: The present study provides anatomical evidence that the structural plasticity in the hippocampus is altered in the late phase following striatal 6-OHDA infusion in rats, possibly as a result of the prolonged suppression of the DAergic system, and independent of neuroinflammation.

Transcriptome Profiling in the Hippocampi of Mice with Experimental Autoimmune Encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), approximates the key histopathological, clinical, and immunological features of MS. Hippocampal dysfunction in MS and EAE causes varying degrees of cognitive and emotional impairments and synaptic abnormalities. However, the molecular alterations underlying hippocampal dysfunctions in MS and EAE are still under investigation. The purpose of this study was to identify differentially expressed genes (DEGs) in the hippocampus of mice with EAE in order to ascertain potential genes associated with hippocampal dysfunction. Gene expression in the hippocampus was analyzed by RNA-sequencing and validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Gene expression analysis revealed 1202 DEGs; 1023 were upregulated and 179 were downregulated in the hippocampus of mice with EAE (p-value < 0.05 and fold change >1.5). Gene ontology (GO) analysis showed that the upregulated genes in the hippocampi of mice with EAE were associated with immune system processes, defense responses, immune responses, and regulation of immune responses, whereas the downregulated genes were related to learning or memory, behavior, and nervous system processes in the GO biological process. The expressions of hub genes from the search tool for the retrieval of interacting genes/proteins (STRING) analysis were validated by RT-qPCR. Additionally, gene set enrichment analysis showed that the upregulated genes in the hippocampus were associated with inflammatory responses: interferon-γ responses, allograft rejection, interferon-α responses, IL6_JAK_STAT3 signaling, inflammatory responses, complement, IL2_STAT5 signaling, TNF-α signaling via NF-κB, and apoptosis, whereas the downregulated genes were related to synaptic plasticity, dendritic development, and development of dendritic spine. This study characterized the transcriptome pattern in the hippocampi of mice with EAE and signaling pathways underpinning hippocampal dysfunction. However, further investigation is needed to determine the applicability of these findings from this rodent model to patients with MS. Collectively, these results indicate directions for further research to understand the mechanisms behind hippocampal dysfunction in EAE.

Lectin histochemistry of the olfactory mucosa of Korean native cattle, Bos taurus coreanae.

BACKGROUND: The olfactory mucosa (OM) is crucial for odorant perception in the main olfactory system. The terminal carbohydrates of glycoconjugates influence chemoreception in the olfactory epithelium (OE). OBJECTIVES: The histological characteristics and glycoconjugate composition of the OM of Korean native cattle (Hanwoo, Bos taurus coreae) were examined to characterize their morphology and possible functions during postnatal development. METHODS: The OM of neonate and adult Korean native cattle was evaluated using histological, immunohistochemical, and lectin histochemical methods. RESULTS: Histologically, the OM in both neonates and adults consists of the olfactory epithelium and the lamina propria. Additionally, using periodic acid Schiff and Alcian blue (pH 2.5), the mucus specificity of the Bowman's gland duct and acini in the lamina propria was determined. Immunohistochemistry demonstrated that mature and immature olfactory sensory neurons of OEs express the olfactory marker protein and growth associated protein-43, respectively. Lectin histochemistry indicated that numerous glycoconjugates, including as N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, complex type N-glycan, and fucose groups, were expressed at varied levels in the different cell types in the OMs of neonates and adults at varying levels. According to our observations, the cattle possessed a well-developed olfactory system, and the expression patterns of glycoconjugates in neonatal and adult OMs varied considerably. CONCLUSIONS: This is the first study to describe the morphological assessment of the OM of Korean native cattle with a focus on lectin histochemistry. The findings suggest that glycoconjugates may play a role in olfactory chemoreception, and that their labeling properties may be closely related to OM development and maturity.

Evaluation of genotoxicity of SUNACTIVE Zn-P240 in vitro and in vivo.

We evaluated the potential genotoxic effects of the nutrient supplement SUNACTIVE Zn-P240 in vitro and in vivo. Genotoxicity tests were performed at the Korea Testing and Research Institute, a GLP certification institution. A bacterial reverse mutation test was performed using the pre-incubation method, while the in vitro chromosome aberration test was performed using a cultured Chinese hamster lung cell line in the presence or absence of metabolic activation. The in vivo micronucleus test was performed using ICR mice. The bacterial reverse mutation test revealed that SUNACTIVE Zn-P240 did not induce genetic mutations at the tested doses in Salmonella typhimurium (TA98, TA100, TA1535, and TA1537) and Escherichia coli (WP2uvrA) tester strains. Meanwhile, the results of the in vitro chromosomal aberration and in vivo micronucleus tests revealed that SUNACTIVE Zn-P240 did not induce chromosomal aberrations. These results suggest that SUNACTIVE Zn-P240 did not exhibit mutagenic or clastogenic properties in vitro and in vivo.

Diallyl disulfide prevents 1,3-dichloro-2-propanol-induced hepatotoxicity through mitogen-activated protein kinases signaling.

We investigated whether diallyl disulfide (DADS) has protective effects against 1,3-dichloro-2-propanol (1,3-DCP)-induced hepatotoxicity and oxidative damage in rats and HepG2 cells. DADS was administered to rats once daily for 7 days at doses of 30 and 60 mg/kg/day. One hour after the final DADS treatment, the rats were administered 90 mg/kg 1,3-DCP to induce acute hepatotoxicity. DADS treatment significantly suppressed the increase in serum aminotransferase levels induced by 1,3-DCP administration, and reduced histopathological alterations in the liver. DADS treatment reduced 1-3-DCP-induced apoptotic changes in the liver, as revealed by terminal deoxynucleotidyl transferase dUTP nick end labeling staining and immunohistochemistry for caspase-3. DADS treatment competitively inhibited or reduced cytochrome p450 2E1 (CYP2E1) expression, which is involved in the metabolic activation of 1,3-DCP, and enhanced antioxidant properties. Furthermore, DADS treatment inhibited phosphorylation of mitogen-activated protein kinases (MAPKs) and apoptotic signaling. In in vitro experiments, MAPKs inhibitors reduced the expression of Bax/Bcl-2/Caspase 3 signaling, which effects were more significant in co-treated cells with DADS and MAPKs inhibitors. In conclusion, the protective effect of DADS against 1,3-DCP-induced hepatotoxicity may be related to blocking the metabolic activation of 1,3-DCP by suppressing CYP2E1 expression, inducing antioxidant enzyme activity, and reducing apoptotic activity by inhibiting phosphorylation of MAPKs.

Anti-asthmatic effects of Phlomis umbrosa Turczaninow using ovalbumin induced asthma murine model and network pharmacology analysis.

BACKGROUND: Phlomis umbrosa Turczaninow has been used as a tradition herbal medicine for treating various inflammatory diseases. PURPOSE: In present study, we explored the effects of P. umbrosa on asthma induced by ovalbumin (OVA) and elucidated the mechanism via in vivo verification and network pharmacology prediction. METHODS: The animals were intraperitoneally injected OVA on day 1 and 14, followed by OVA inhalation on days 21, 22, and 23. The animals were daily treated P. umbrosa extract (PUE, 20 and 40 mg/kg) by oral gavage from day 18 to day 23. RESULTS: PUE significantly decreased airway hyperresponsiveness, eosinophilia, and the production of inflammatory cytokines and OVA specific immunoglobulin E in animals with asthma, along with a reduction in airway inflammation and mucus secretion in lung tissue. In network analysis, antiasthmatic effects of PUE were closely related with suppression of mitogen-activated protein kinases and matrix metalloproteinases (MMPs). Consistent with the results from network analysis, PUE suppressed the phosphorylation of ERK and p65, which was accompanied by a decline in MMP-9 expression. CONCLUSION: Administration of PUE effectively reduced allergic responses in asthmatic mice, which was associated with the suppressed phosphorylation of ERK and p65, and expression of MMP-9. These results indicate that PUE has therapeutic potential to treat allergic asthma.

Evaluation of 28-day repeated oral dose toxicity of aluminum chloride in rats.

The present study investigated the potential adverse effects of aluminum chloride (AlCl3) following a 4-week repeated oral administration in Sprague-Dawley rats. The test article was administered once daily by gavage to male and female rats at dose levels of 0, 100, 300, and 900 mg/kg/day for 4 weeks. After administration of AlCl3 at 900 mg/kg/day, treatment-related systemic toxicity manifested as significant increases in salivation incidence, neutrophil percentage, reticulocytes, serum triglyceride, adrenal gland and liver weights, and single-hepatocyte necrosis, as well as significant decreases in body weight gain, food intake, hemoglobin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration (MCHC), lymphocyte percentage, serum total protein and albumin, and thymus weight in male rats; and significant increases in salivation incidence, serum triglyceride, and liver weight, as well as a significant decrease in lymphocyte percentage in female rats. At 300 mg/kg/day, a significant decrease in MCHC was found in male rats, but not in female rats. However, this finding was not toxicologically significant because the reduction was minimal and was not accompanied by changes in any other parameters. No treatment-related effects were observed in the 100 mg/kg/day group of both genders. Under the experimental conditions of this study, the target organs of AlCl3 were determined to be the blood, liver, and thymus in rats. The no-observed-adverse-effect level was found to be 300 mg/kg/day in rats of both genders.

Genotoxicity evaluation of self-assembled-micelle inhibitory RNA-targeting amphiregulin (SAMiRNA-AREG), a novel siRNA nanoparticle for the treatment of fibrotic disease.

The self-assembled-micelle inhibitory RNA-targeting amphiregulin (SAMiRNA-AREG) is a novel small-interfering RNA (siRNA) nanoparticle that is used for treatment of pulmonary fibrosis. We investigated the potential genotoxicity of SAMiRNA-AREG based on the guidelines published by the Organization for Economic Cooperation and Development. In the bacterial reverse mutation assay (Ames test), SAMiRNA-AREG did not induce mutations in Salmonella typhimurium TA100, TA1535, TA98, and TA1537 and Escherichia coli WP2uvrA at concentrations of up to 3000 µg/plate with or without metabolic activation. The SAMiRNA-AREG (concentrations up to 500 µg/mL) did not induce chromosomal aberrations in cultured Chinese hamster lung cells with or without metabolic activation. In the in vivo mouse bone marrow micronucleus assay, the SAMiRNA-AREG (concentrations up to 300 mg/kg body weight) did not affect the proportions of polychromatic erythrocytes and total erythrocytes, nor did it increase the number of micronucleated polychromatic erythrocytes in ICR mice. Collectively, these results suggest that SAMiRNA-AREG is safe with regard to genotoxicity such as mutagenesis or clastogenesis under the present experimental conditions. These results might support the safety of SAMiRNA-AREG as a potential therapeutic agent for pharmaceutical development.

Subchronic Toxicity Evaluation of Aluminum Oxide Nanoparticles in Rats Following 28-Day Repeated Oral Administration.

Several studies on the potential adverse effects of aluminum oxide nanoparticles (Al2O3NPs) have reported conflicting results. The present study investigated the potential adverse effects of Al2O3NPs in Sprague-Dawley rats following 28-day repeated oral administration. In addition, we aimed to determine the target organ and no-observed-adverse-effect level (NOAEL) of Al2O3NPs. Al2O3NPs was administered once daily by gavage to male and female rats at dose levels of 0, 500, and 1000 mg/kg/day for 28 days. There were no treatment-related adverse effects as indicated by the clinical signs, body weight, food consumption, urinalysis, ophthalmology, hematology, serum biochemistry, gross pathology, organ weight, and histopathology at all the tested doses. Under the experimental conditions of the present study, 28-day repeated oral administration of Al2O3NPs at doses of up to 1000 mg/kg/day did not induce any treatment-related systemic toxicity in male and female rats. The NOAEL of Al2O3NPs was set at 1000 mg/kg/day in both male and female rats and no target organs were identified.

Melatonin Alleviates Silica Nanoparticle-Induced Lung Inflammation via Thioredoxin-Interacting Protein Downregulation.

Silica dioxide nanoparticles (SiONPs) have been increasingly used in various industries; however, this has raised concerns regarding their potential toxicity. SiONPs are also a major component in the Asian sand dust that causes pulmonary diseases among the general public. Melatonin exerts some inhibitory effects against lung inflammation. In this study, we explored the therapeutic properties of melatonin against lung inflammation using an SiONPs-induced lung inflammation murine model and SiONPs-stimulated H292 cells, human airway epithelial cell line, by focusing on the involvement of thioredoxin-interacting protein (TXNIP) in the modulation of the MAPKs/AP-1 axis. We induced an inflammatory response by exposing mouse lungs and the H292 cells to SiONPs and confirmed the anti-inflammatory effect of melatonin. Melatonin inhibited the expression of various inflammatory mediators, including TNF-α, IL-6, and IL-1ß, in SiONPs-exposed mice and SiONPs-stimulated H292 cells; this inhibition contributed to a decline in inflammatory cell accumulation in the lung tissues. Furthermore, melatonin treatment decreased the expression of MAPKs and AP-1 by downregulating TXNIP, eventually decreasing the production of SiONPs-induced inflammatory mediators. Overall, these data suggest that melatonin reduces SiONPs-induced lung inflammation by downregulating the TXNIP/MAPKs/AP-1 signalling pathway, thereby supporting the use of melatonin as an effective approach to control SiONPs-induced lung inflammation.

The Involvement of PDE4 in the Protective Effects of Melatonin on Cigarette-Smoke-Induced Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is a significant disease threatening human health. Currently, roflumilast, a phosphodiesterase (PDE)4 inhibitor, is recommended as a therapeutic agent for COPD. In this study, we investigated the therapeutic effects of melatonin against COPD, focusing on determining whether it is a PDE4 inhibitor via in vivo and in vitro experiment using cigarette smoke (CS) and cigarette smoke condensate (CSC), respectively. In the in vivo experiments, melatonin treatment reduced inflammatory responses, including inflammatory cell counts. Melatonin treatment also suppressed the CS-exposure-induced upregulation of cytokine and matrix metalloproteinase (MMP)-9, reduced the PDE4B expression, and elevated cAMP levels. In addition, these effects were synergistic, as melatonin and roflumilast cotreatment eventually ameliorated the CS-exposure-induced worsening of lung function. In the CSC-stimulated NCI-H292 cells, melatonin inhibited elevation in the levels of inflammatory cytokines, MMP-9, and PDE4, and elevated cAMP levels. Furthermore, melatonin and roflumilast cotreatment was more effective on inflammatory responses than only melatonin or roflumilast treatment. Our results indicate that melatonin relieves inflammatory response and loss of lung function in COPD, which is associated with decreased PDE4 expression. Therefore, we suggest that melatonin is a putative candidate for the treatment of COPD.