Single-day and multi-day exposure to orogastric gavages does not affect intestinal barrier function in mice.

Animals involved in common laboratory procedures experience minor levels of stress. The direct effect of limited amounts of stress on gastrointestinal function has not been reported yet. Therefore, this study aimed to assess the effect of single-day and multi-day orogastric gavages on gut physiology in mice. To this end, 12-wk-old female C57Bl6/J mice were randomized to receive treatment with sterile water (200 µL) delivered by orogastric gavages twice daily for a total of 1 or 10 day(s). Control animals did not receive any treatment. Subsequently, gastrointestinal function was assessed by measuring fecal pellet production. Furthermore, ex vivo intestinal barrier and secretory function of the distal colon, proximal colon, and terminal ileum were quantified in Ussing chambers. In mice, single-day gavages did neither influence corticosterone levels nor gastrointestinal function. In mice exposed to multi-day gavages, corticosterone levels were slightly but significantly increased compared with controls after 10 days of treatment. Gastrointestinal motor function was altered, as evidenced by increased fecal pellet counts and a small increase in fecal water content. However, exposure to repeated gavages did not lead to detectable alterations in gastrointestinal barrier function as quantified by the paracellular flux of the probe 4 kDa FITC-dextran as well as transepithelial resistance measurements. Thus, the administration of drugs via single-day or multi-day orogastric gavages leads to no or minor stress in mice, respectively. In both cases, it does not hamper the study of the intestinal barrier function and therefore remains a valuable administration route in preclinical pharmacological research.NEW & NOTEWORTHY Exposure of mice to serial orogastric gavages over the course of 10 days leads to a small but significant increase in plasma corticosterone levels, indicating the presence of a limited amount of stress that is absent after a single-day treatment. This minor stress after multi-day gavages results in increased fecal pellet production and fecal water content in exposed compared with nontreated mice but does not affect the intestinal barrier function in the distal colon, proximal colon, or terminal ileum.

Exacerbating effects of single-dose acute ethanol exposure on neuroinflammation and amelioration by GPR110 (ADGRF1) activation.

BACKGROUND: Neuroinflammation is a widely studied phenomenon underlying various neurodegenerative diseases. Earlier study demonstrated that pharmacological activation of GPR110 in both central and peripheral immune cells cooperatively ameliorates neuroinflammation caused by systemic lipopolysaccharide (LPS) administration. Ethanol consumption has been associated with exacerbation of neurodegenerative and systemic inflammatory conditions. The goal of this study is to determine the effects of single-dose acute ethanol exposure and GPR110 activation on the neuro-inflammation mechanisms. METHODS: For in vivo studies, GPR110 wild type (WT) and knockout (KO) mice at 10-12 weeks of age were given an oral gavage of ethanol (3 g/kg) or maltose (5.4 g/kg) at 1-4 h prior to the injection of LPS (1 mg/kg, i.p.) followed by the GPR110 ligand, synaptamide (5 mg/kg). After 2-24 h, brains were collected for the analysis of gene expression by RT-PCR or protein expression by western blotting and enzyme-linked immunosorbent assay (ELISA). Microglial activation was assessed by western blotting and immunohistochemistry. For in vitro studies, microglia and peritoneal macrophages were isolated from adult WT mice and treated with 25 mM ethanol for 4 h and then with LPS (100 ng/ml) followed by 10 nM synaptamide for 2 h for gene expression and 12 h for protein analysis. RESULTS: Single-dose exposure to ethanol by gavage before LPS injection upregulated pro-inflammatory cytokine expression in the brain and plasma. The LPS-induced Iba-1 expression in the brain was significantly higher after ethanol pretreatment in both WT and GPR110KO mice. GPR110 ligand decreased the mRNA and/or protein expression of these cytokines and Iba-1 in the WT but not in GPR110KO mice. In the isolated microglia and peritoneal macrophages, ethanol also exacerbated the LPS-induced expression of pro-inflammatory cytokines which was mitigated at least partially by synaptamide. The expression of an inflammasome marker NLRP3 upregulated by LPS was further elevated with prior exposure to ethanol, especially in the brains of GPR110KO mice. Both ethanol and LPS reduced adenylate cyclase 8 mRNA expression which was reversed by the activation of GPR110. PDE4B expression at both mRNA and protein level in the brain increased after ethanol and LPS treatment while synaptamide suppressed its expression in a GPR110-dependent manner. CONCLUSION: Single-dose ethanol exposure exacerbated LPS-induced inflammatory responses. The GPR110 ligand synaptamide ameliorated this effect of ethanol by counteracting on the cAMP system, the common target for synaptamide and ethanol, and by regulating NLRP3 inflammasome.

Subchronic toxicity study of ferric oxide nanoparticles through intragastric administration: A 94-d, repeated dose study in Sprague Dawley rats.

In this study, the toxicity of ferric oxide nanoparticles (Fe2O3 NPs) administered through gavage to Sprague Dawley (SD) rats for 94 d, consecutively and the recovery after Fe2O3 NPs withdrawal for 30 d were evaluated. The vehicle control group, low-, medium-, and high-dose groups were administered with the vehicle (0.5% sodium carboxymethyl cellulose [CMC-Na]), 125, 250, and 500 mg/kg of Fe2O3 NPs, respectively, administered every morning for 94 d. There was no significant difference in the body weight, food intake, hematological, blood biochemical, and urine indices of SD rats in each administration group and the control group (P > 0.05). There was no significant difference in organ weight, organ indices, and the coefficient of the visceral brain between the SD rats in the different dosage groups and the SD rats in the vehicle control group (P > 0.05). Histopathological observations showed that there was no correlation between the pathological lesions of the organs observed in this study and the dose of Fe2O3 NPs (P > 0.05). The no-observed-adverse-effect level (NOAEL) dose of Fe2O3 NPs was initially determined to be 500 mg/kg administered to SD rats through oral gavage for 94 d, consecutively, followed by recovery after Fe2O3 NPs withdrawal for 30 d.

Acute Effects of Brevetoxin-3 Administered via Oral Gavage to Mice.

Brevetoxins (BTXs) constitute a family of lipid-soluble toxic cyclic polyethers mainly produced by Karenia brevis, which is the main vector for a foodborne syndrome known as neurotoxic shellfish poisoning (NSP) in humans. To prevent health risks associated with the consumption of contaminated shellfish in France, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) recommended assessing the effects of BTXs via an acute oral toxicity study in rodents. Here, we investigated the effect of a single oral administration in both male and female mice with several doses of BTX-3 (100 to 1,500 µg kg-1 bw) during a 48 h observation period in order to provide toxicity data to be used as a starting point for establishing an acute oral reference dose (ARfD). We monitored biological parameters and observed symptomatology, revealing different effects of this toxin depending on the sex. Females were more sensitive than males to the impact of BTX-3 at the lowest doses on weight loss. For both males and females, BTX-3 induced a rapid, transient and dose-dependent decrease in body temperature, and a transient dose-dependent reduced muscle activity. Males were more sensitive to BTX-3 than females with more frequent observations of failures in the grip test, convulsive jaw movements, and tremors. BTX-3's impacts on symptomatology were rapid, appearing during the 2 h after administration, and were transient, disappearing 24 h after administration. The highest dose of BTX-3 administered in this study, 1,500 µg kg-1 bw, was more toxic to males, leading to the euthanasia of three out of five males only 4 h after administration. BTX-3 had no effect on water intake, and affected neither the plasma chemistry parameters nor the organs' weight. We identified potential points of departure that could be used to establish an ARfD (decrease in body weight, body temperature, and muscle activity).

Effect of different ways of ingesting orange essential oil on blood immune index and intestinal microflora in mice.

BACKGROUND: Studies have found that the addition of plant essential oils to feed had a positive effect on intestinal microflora and immunity in mice. However, the effect of different ways of ingestion of orange essential oil on mice has seldom been reported. In the present study, we investigated the effects of ingestion of orange essential oil by gavage, sniffing and feeding on intestinal microflora and immunity in mice. RESULTS: The results obtained showed that a low concentration of essential oil feeding significantly increased the spleen index of mice (P < 0.05). The effect of different ways of ingestion on the thymus index, immunoglobulin G and immunoglobulin M of mice was not significant (P > 0.05). High and medium concentrations of essential oil feeding increased the level of interleukin-2 in mice (P < 0.05). H+ K+ -ATPase activity was significantly increased in mice fed with gavage and different concentrations of essential oil feed compared to the control group (P < 0.05). The analysis of the results of the microflora in the cecum and colon of mice indicated that the medium concentration of essential oil feeding group and the sniffing group significantly changed the structure of the flora and increased the diversity of the intestinal microflora. All three essential oil ingestion methods increased the abundance of Bacteroidetes and Lactobacillus in the intestine of mice. CONCLUSION: Compared with gavage and feeding, sniffing had a significant effect on immunoglobulins in mice. All the three ingestion methods could affect the intestinal microflora of mice and increase the abundance of Lactobacillus. © 2022 Society of Chemical Industry.

Comparing the Efficacy of a New Clinical Skills Model with a Traditional Method to Teach Tube Feeding of an Avian Patient.

Interactive clinical skills models have been demonstrated to be useful for teaching medical and veterinary clinical skills, yet to date, very few exist for teaching skills relevant to zoological companion animals and wildlife species including birds. This two-part study aimed to create, develop, and validate a model. Interviews and a survey were conducted using veterinary and wildlife professionals to select an avian clinical skill that is challenging and performed frequently. Tube/gavage feeding, or "crop tubing" satisfied both criteria; on average it was performed 71 times a year by surveyed respondents was rated 3.4/9 for difficulty of teaching and 3.5/9 for difficulty of learning. Therefore, a new model of a bird, made from a soft toy, silicone, and 3D printed parts, was designed to train students to perform this technique. Forty-two participants were recruited and divided into two groups; one used the model the other watched an instructional video on crop tubing. The students completed a self-evaluated confidence questionnaire, before and after, using either resource. They then performed the technique on a dead bird and their proficiency at 10 different actions that comprised the technique was evaluated by two assessors. The model group performed significantly better than the video group on all evaluated actions (U ≤ 143.5, p ≤ .0031), and reported significantly higher confidence (U = 129.5, p = 0.018). In conclusion, the newly developed model in combination with an instruction booklet offers an effective and inexpensive alternative way to teach crop tubing in a teaching environment, without compromising animal welfare.

Delivery method matters: omega-3 supplementation by restricted feeding period and oral gavage has a distinct impact on corticosterone secretion and anxious behavior in adolescent rats.

Objectives: Oral gavage and time-restricted feeding are common delivery methods for dietary supplementation to rodents. However, the stress associated with selected feeding regimens could represent a confounding variable. In rodents, the adolescence period is particularly vulnerable to stressful events, in part related to ongoing maturation of the brain. In this context, omega-3 dietary supplementation has shown beneficial effects on neuronal growth, cognitive performance and stress regulation, while high-fat diet (HVF) has been associated with enhanced stress and anxiety. Therefore, this study has two aims: (1) evaluate the influence of 21-day supplementation with soybean oil (control group; CSO), fish oil (FO) or hydrogenated vegetable fat (HVF) fatty acids (FA) during the adolescence period on corticosterone secretion and anxiety-like behavior and, (2) compare the impact of dietary supplementation using oral gavage or time-limited feeding on these measures.Methods: Oral gavage or restricted feeding were used to daily feed adolescent rats (PND28-47; n = 49). On supplementation days 1, 7, 14 and 21, droplets of blood were collected for corticosterone (CORT) assessments. The Open Field (OFT) and the Elevated-Plus Maze (EPM) tests served to assess anxiety-like behavior on PND50.Results: Our findings indicate increased CORT secretion in restricted-(R) compared to gavage-fed animals on DAY7 and DAY14, suggesting heightened HPA-axis reactivity. Notably, CORT secretion diminished in FO-R-rats (DAY21), suggesting improved coping/adjustment. Consistent with CORT assessments, findings in the OFT and EPM supported attenuated anxiety in gavage versus restricted groups. FO and CSO supplementation reduced anxiety compared to HVF intake.Conclusions: Our findings uncover a significant impact of feeding methods on anxiety-like behavior and physiological stress response in rodents, supporting oral gavage as a less stressful option during the adolescent developmental stage. Supplement-specific effects on CORT secretion further indicated an influence of fish oil in regulating the stress response.

Toxicokinetic study following intratracheal instillation or oral gavage of two [7Be]-tagged carbon black samples.

BACKGROUND: The toxicokinetic behaviour of nanostructured particles following pulmonary or oral deposition is of great scientific interest. In this toxicokinetic study, following the general principles of OECD TG 417, the systemic availability of carbon black, a nanostructured material consisting of agglomerated aggregates was characterised. METHODS: Each of two grades of beryllium-7 labelled carbon black (Monarch® 1000, oxidized and Printex® 90; untreated) was administered either intratracheally or orally to adult rats. Independent of route, rats received a single dose of approximately 0.3 mg radiolabelled carbon black. A total of 12 rats were treated per grade and per exposure route: 4 females each for feces/urine/organs and serial blood kinetics; 4 males for organs. At necropsy, the complete suite of organs was analysed for females, but only the lungs, liver, kidney, reproductive organs for males. RESULTS: In the pulmonarily exposed animals, 7Be-Monarch® 1000 and 7Be-Printex® 90 was detected in feces in the first 3 days after treatment at significant levels, i.e. 17.6% and 8.2%, respectively. In urine, small percentages of 6.7% and 0.4% were observed, respectively. In blood, radioactivity, representative of carbon black was within the background noise of the measurement method. At necropsy, 20 days post-instillation, both test items were practically exclusively found in lungs (75.1% and 91.0%, respectively) and in very small amounts (approximately 0.5%) in the lung-associated lymph nodes (LALN). In the other organs/tissues the test item was not detectable. BAL analyses indicated that carbon black particles were completely engulfed by alveolar macrophages. In orally exposed animals, 98% (7Be-Monarch® 1000) and 99% (7Be-Printex® 90) of the measured radioactivity was detected in feces. Excretion was complete within the first 3 days following treatment. 1.3% and 0.5% of measured activity was attributable to urine in animals that received 7Be-Monarch® 1000 and 7Be-Printex® 90, respectively. Radioactivity was absent in blood and other organs and tissues. CONCLUSION: Radioactivity, representative of carbon black, was not detected beyond the experimentally defined limit of quantitation systemically after deposition in lungs or stomach in rats. Under these experimental conditions, the two CB samples were not shown to translocate beyond the lung or the GI tract into the blood compartment.

Postoperative feeding in neonatal duodenal obstruction.

BACKGROUND: Findings from manometry studies and contrast imaging reveal functioning gastric physiology in newborns with duodenal atresia and stenosis. Stomach reservoir function should therefore be valuable in aiding the postoperative phase of gastric feeding. The aim of this study was therefore to compare the feasibility of initiating oral or large volume(s) gavage feeds vs small volume bolus feeds following operation for congenital duodenal anomalies. METHODS: Single-center electronic medical records of all babies with duodenal atresia and stenosis admitted to a university surgical center during January 1997-September 2021 were analyzed. A fast-fed group (FF) included newborns fed with oral or gavage feeds advanced at a rate of at least 2.5 ml/kg and then progressed more than once a day vs slow-fed group (SF) fed with gavage feeds at incremental rate less than 2.5 ml/kg/day for each time period of oral tolerance or by drip feeds. Total feed volume was limited to 120-150 ml/kg/day in the respective study cohort populations. RESULTS: Fifty-one eligible patients were recruited in the study - twenty-six in FF group and twenty-five in SF group. Statistically significant differences were observed in the (i) date of first oral feeds (POD 7.7 ± 3.2 vs 16.1 ± 7.7: p < 0.001), and (ii) first full feeds (POD 12.5 ± 5.3 vs 18.8 ± 9.7: p < 0.01) in FF vs SF study groups. CONCLUSION: Initial feeding schedules with oral or incremental gavage-fed rates of at least 2.5 ml/kg in stepwise increments and multi-steps per day is wholly feasible in the postoperative feeding regimens of neonates with congenital duodenal disorders. Significant health benefits are thus achievable in these infants allowing an earlier time to acquiring full enteral feeding and their hospital discharge.

Pathway of Diatoms Enter Experimental Rabbits through the Lymphatic System of the Digestive Tract.

OBJECTIVES: To study whether diatoms can enter the body through the lymphatic system of the digestive tract. METHODS: Twenty experimental rabbits were divided into the test group and the control group randomly, and intragastric administration was performed with 20 mL water sample from the Pearl River and 20 mL ultrapure water, respectively. After 30 min, lymph, lungs, livers and kidneys were extracted for the diatom test. The concentration, size and type of diatoms were recorded. RESULTS: The concentration of diatoms of the test group was higher than that of the control group (P<0.05). In the test group, Stephanodiscus, Coscinodiscus, Cyclotella, Melosira, Nitzschia, Synedra, Cymbella, and Navicula were detected; in the control group, Stephanodiscus, Coscinodiscus and Cyclotella were detected. The long diameter and the short diameter of diatoms of the test group were higher than those of the control group (P<0.05). In the test group, 1-2 diatoms were detected in 3 lung samples and 2 liver samples, which were Stephanodiscus or Cyclotella, and no diatoms were detected in the kidney samples; in the control group, 1-2 diatoms were detected in 2 lung samples and 3 liver samples, which were Stephanodiscus or Coscinodiscus, and no diatoms were detected in the kidney samples. CONCLUSIONS: Diatoms can enter the body through the lymphatic fluid, which is one of the reasons for the presence of diatoms in tissues and organs of non-drowning cadavers.

Effects of 0.5% and 2.0% Sodium Lauryl Sulfate in Male CD-1 Mice From a 3-Month Oral Gavage Toxicity Study.

The tolerability of single daily gavage doses of 0.5% or 2.0% (wt/vol) sodium lauryl sulfate (SLS) in 11- to 12-week-old male CD-1 mice was evaluated in a study of 3 months in duration. Live-phase, gross necropsy, and histopathologic parameters were evaluated. Mortality of 14% occurred in mice administered formulations containing SLS. Clinical observations in mice administered SLS included abnormal respiration (audible, irregular, and/or labored), swollen abdomen, rough haircoat, hunched appearance, and hypoactivity. Necropsy findings in mice administered SLS consisted of enlarged intestines containing abnormal contents with gas. There were no instances of mechanical gavage-related injury. Histologic evaluation of the respiratory tract revealed injury to the nasal passages and nasopharynx, including, but not limited to, inflammation, exudate, apoptosis/necrosis of epithelium, and atrophy of epithelium or olfactory nerves. Collectively, the data indicated that under the experimental conditions of our 3-month study in male CD-1 mice, once-daily gavage administration of vehicle formulations containing SLS at 0.5% or 2.0% resulted in nasal injury and 14% mortality supportive of gastroesophageal reflux. Sponsors utilizing formulations containing SLS in toxicity studies in CD-1 mice should exclude gastroesophageal reflux as a confounding factor in studies with morbidity or mortality associated with respiratory distress or evidence of aerophagia.

Preclinical validation of the micropipette-guided drug administration (MDA) method in the maternal immune activation model of neurodevelopmental disorders.

Pharmacological treatments in laboratory rodents remain a cornerstone of preclinical psychopharmacological research and drug development. There are numerous ways in which acute or chronic pharmacological treatments can be implemented, with each method having certain advantages and drawbacks. Here, we describe and validate a novel treatment method in mice, which we refer to as the micropipette-guided drug administration (MDA) procedure. This administration method is based on a sweetened condensed milk solution as a vehicle for pharmacological substances, which motivates the animals to consume vehicle and/or drug solutions voluntarily in the presence of the experimenter. In a proof-of-concept study, we show that the pharmacokinetic profiles of the atypical antipsychotic drug, risperidone, were similar whether administered via the MDA procedure or via the conventional oral gavage method. Unlike the latter, however, MDA did not induce the stress hormone, corticosterone. Furthermore, we assessed the suitability and validity of the MDA method in a mouse model of maternal immune activation, which is frequently used as a model of immune-mediated neurodevelopmental disorders. Using this model, we found that chronic treatment (>4 weeks, once per day) with risperidone via MDA led to a dose-dependent mitigation of MIA-induced social interaction deficits and amphetamine hypersensitivity. Taken together, the MDA procedure described herein represents a novel pharmacological administration method for per os treatments in mice that is easy to implement, cost effective, non-invasive, and less stressful for the animals than conventional oral gavage methods.

Nanostructured recombinant protein particles raise specific antibodies against the nodavirus NNV coat protein in sole.

Nervous necrosis virus (NNV) reassortant strains RGNNV/SJNNV have emerged as a potent threat to the Mediterranean marine aquaculture industry, causing viral encephalopathy and retinopathy (VER) in Senegalese sole (Solea senegalensis). In this study, a cheap and practical vaccine strategy using bacterial inclusion bodies made of the coat protein of a virulent reassortant strain of this betanodavirus was devised. The nanostructured recombinant protein nanoparticles, VNNV-CNP, were administered without adjuvant to two groups of juvenile sole, one by intraperitoneal injection and the other by oral intubation. Specific antibodies were raised in vivo against the NNV coat protein via both routes, with a substantial specific antibody expansion in the injected group 30 days post homologous prime boost. Expression levels of five adaptive immune-related genes, cd8a, cd4, igm, igt and arg2, were also quantified in intestine, spleen and head kidney. Results showed cd4 and igm were upregulated in the head kidney of injected fish, indicating activation of an adaptive systemic response, while intubated fish exhibited a mucosal response in the intestine. Neither route showed significant differential expression of cd8a. The specific antibody response elicited in vivo and the lack of any signs of toxicity over the 6-week study period in young fish (n = 100), evidences the potential of the nanoparticle as a vaccine candidate.

A comparative study of Enterocytozoon hepatopenaei (EHP) challenge methods in Penaeus vannamei.

The microsporidium Enterocytozoon hepatopenaei (EHP) is considered as an emerging pathogen threating the shrimp industry worldwide. It is an intracellular parasite that has been associated with retarded growth syndrome and white feces syndrome in shrimp. Although the impact of EHP to the shrimp industry is well known, many aspects of host-pathogen interactions are not well understood. A major limitation in the study of EHP is the lack of a reliable method to produce large quantities of inoculum rapidly and reproducibly. The present study was designed to compare different challenge methods including intramuscular injection, oral administration, co-habitation, hepatopancreas (HP) injection and reverse gavage. The results showed that the HP injection and the reverse gavage are two promising methods to infect shrimp rapidly and generate inoculum in a reproducible manner starting with a limited amount of inoculum. Therefore, the HP injection and reverse gavage were chosen for a scale-up study. Histopathology results showed that EHP proliferated in the epithelial cells of the HP in shrimp challenged via direct injection of inoculum into HP and reverse gavage treatments. In accordance with the histopathology results, the qPCR data showed that EHP loads in the challenged shrimp increased significantly with the HP injection and reverse gavage methods. Furthermore, the histopathological and quantification results indicate that HP injection and reverse gavage are two novel methods that can be used in EHP-challenge studies and for rapidly generating viable EHP inoculum.

Spatiotemporal distribution of Streptococcus agalactiae attenuated vaccine strain YM001 in the intestinal tract of tilapia and its effect on mucosal associated immune cells.

In this study, the tilapia was orally vaccinated by the attenuated Streptococcus agalactiae(S. agalactiae) strain YM001, and the distribution and the pathological effect of strain YM001 in different intestinal segments of tilapia were evaluated by real-time PCR(qPCR), immunohistochemistry(IHC) and histomorphology. The qPCR results showed that the number of bacteria was the highest in the intestinal tracts at 12 h post oral gavage in the YM001 group, then began to decrease sharply and eliminated at 7 d. And the number of bacteria was highest in the foregut, hindgut, and rectum at 12 h, 24 h, and 3 d, respectively. IHC indicated that bacteria mainly distributed in the margin epithelium and the goblet cells at 12 h - 24 h, and in the submucosa and muscle layer in the YM001 group in 3 d post gavage, then almost disappeared at 7 d. Histological examination of intestines post gavage displayed that an inflammation was observed at 7 d in the YM001 group and the intestinal structure was fully recovered at 15 d. and the intestinal structure was fully recovered at 15 d. Conclusion: The attenuated S. agalactiae vaccine strain YM001 could enter the intestinal tissue after oral gavage and had a strong spatial and temporal selectivity in the intestinal tract, which could cause obvious mucosal immune response and mild pathological reaction, but the pathological change could be gradually repaired with the extinction of bacteria in the body.

The Endothelin-A Receptor Antagonist Zibotentan Induces Damage to the Nasal Olfactory Epithelium Possibly Mediated in Part through Type 2 Innate Lymphoid Cells.

Zibotentan, an endothelin-A receptor antagonist, has been used in the treatment of various cardiovascular disorders and neoplasia. Castrated athymic nude mice receiving zibotentan for a preclinical xenograft efficacy study experienced weight loss, gastrointestinal bloat, and the presence of an audible respiratory click. Human side effects have been reported in the nasal cavity, so we hypothesized that the nasal cavity is a target for toxicity in mice receiving zibotentan. Lesions in the nasal cavity predominantly targeted olfactory epithelium in treated mice and were more pronounced in castrated animals. Minimal lesions were present in vehicle control animals, which suggested possible gavage-related reflux injury. The incidence, distribution, and morphology of lesions suggested direct exposure to the nasal mucosa and a possible systemic effect targeting the olfactory epithelium, driven by a type 2 immune response, with group 2 innate lymphoid cell involvement. Severe nasal lesions may have resulted in recurrent upper airway obstruction, leading to aerophagia and associated clinical morbidity. These data show the nasal cavity is a target of zibotentan when given by gavage in athymic nude mice, and such unanticipated and off-target effects could impact interpretation of research results and animal health in preclinical studies.

Indomethacin-induced gut damage in a surrogate insect model, Galleria mellonella.

Indomethacin is a non-steroidal anti-inflammatory drug that causes gastric ulceration and increased 'leakiness' in rat models, and is used routinely as a toxicology assay to screen novel compounds for repair and restitution properties. We set out to establish conditions for indomethacin-induced gut damage in wax-moth (Galleria mellonella) larvae with a view to reducing the need for rodents in such experimentation. We administered indomethacin (0.5-7.5 µg/larva; 2-30 mg/kg) to G. mellonella via intrahaemocoelic injection and gavage (force-feeding) and monitored survival and development, blood cell (haemocyte) numbers, and changes in gut permeability. Increased levels of gut leakiness were observed within the first 4- to 24 h by tracking fluorescent microspheres in the faeces and haemolymph (blood equivalent). Additionally, we recorded varying levels of tissue damage in histological sections of the insect midgut, including epithelial sloughing and cell necrosis. Degeneration of the midgut was accompanied by significant increases in detoxification-associated activities (superoxide dismutase and glutathione-S-transferase). Herein, we present the first evidence that G. mellonella larvae force-fed indomethacin display broad symptoms of gastric damage similar to their rodent counterparts.

Enhanced the Bioavailability of Sterile 20(S)-Protopanaxadiol Nanocrystalline Suspension Coated by Bovine Serum Albumin for Intramuscular Injection: In Vitro and In Vivo Evaluation.

The aim of this study was to prepare a 20(S)-protopanaxadiol nanocrystalline suspension and enhance the bioavailability of 20(S)-protopanaxadiol by intramuscular injection. 20(S)-Protopanaxadiol nanocrystalline suspension was prepared using an anti-solvent combined with ultrasonic approach, in which meglumine and bovine serum albumin were screened as the optimized stabilizer and the coating agent during spray drying process, respectively. The optimal nanocrystallines were nearly spherical with a uniform particle size distribution, the mean particle size, polydispersity index, and drug loading of which were 151.20 ± 2.54 nm, 0.11 ± 0.01, and 47.15% (w/w), respectively. Sterile 20(S)-protopanaxadiol nanocrystalline suspension was obtained by passing through a 0.22-µm membrane, and the average filtration efficiency (FE%) was 99.96%. The cumulative release percentage of 20(S)-protopanaxadiol nanocrystalline suspension was 92.36% 20(S)-protopanaxadiol within 60 min in vitro, which was relatively rapid compared with that of the physical mixture for 12.51% and the 20(S)-protopanaxadiol bulk powder for 9.71% during the same time interval. The sterile 20(S)-protopanaxadiol nanocrystalline suspension caused minimal irritation responses by histological examination, indicating a good biocompatibility between the 20(S)-protopanaxadiol nanocrystalline suspension and muscle tissues. In pharmacokinetic study, the absolute bioavailability of 20(S)-protopanaxadiol nanocrystalline suspension for intramuscular injection and for oral gavage was 5.99 and 0.03, respectively. In summary, the 20(S)-protopanaxadiol nanocrystalline via intramuscular injection is an efficient drug delivery system to improve its bioavailability.

Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

BACKGROUND: Little is known about the mechanism underlying the genotoxicity observed in the liver following pulmonary exposure to carbon black (CB) nanoparticles (NPs). The genotoxicity could be caused by the presence of translocated particles or by circulating inflammatory mediators released during pulmonary inflammation and acute-phase response. To address this, we evaluated induction of pulmonary inflammation, pulmonary and hepatic acute-phase response and genotoxicity following exposure to titanium dioxide (TiO2), cerium oxide (CeO2) or CB NPs. Female C57BL/6 mice were exposed by intratracheal instillation, intravenous injection or oral gavage to a single dose of 162 µg NPs/mouse and terminated 1, 28 or 180 days post-exposure alongside vehicle control. RESULTS: Liver DNA damage assessed by the Comet Assay was observed after intravenous injection and intratracheal instillation of CB NPs but not after exposure to TiO2 or CeO2. Intratracheal exposure to NPs resulted in pulmonary inflammation in terms of increased neutrophils influx for all NPs 1 and 28 days post-exposure. Persistent pulmonary acute phase response was detected for all NPs at all three time points while only a transient induction of hepatic acute phase response was observed. All 3 materials were detected in the liver by enhanced darkfield microscopy up to 180 days post-exposure. In contrast to TiO2 and CeO2 NPs, CB NPs generated ROS in an acellular assay. CONCLUSIONS: Our results suggest that the observed hepatic DNA damage following intravenous and intratracheal dosing with CB NPs was caused by the presence of translocated, ROS-generating, particles detected in the liver rather than by the secondary effects of pulmonary inflammation or hepatic acute phase response.

Initial hazard assessment of 4-benzylphenol, a structural analog of bisphenol F: Genotoxicity tests in vitro and a 28-day repeated-dose toxicity study in rats.

4-Benzylphenol (CAS No. 101-53-1), a structural analog of bisphenol F, has estrogenic activity in vitro and in vivo, as is the case with bisphenol F. 4-Benzylphenol is used in plastics and during organic synthesis. Since its safety is largely unknown, we conducted toxicity tests as part of screening risk assessment in an existing chemical safety survey program. Based on results of the Ames test and the chromosomal aberration test using Chinese hamster lung cells (OECD TG 471 and 473), 4-benzylphenol was determined to be non-genotoxic in vitro. In a 28-day repeated-dose toxicity study, Crl:CD (SD) rats were administrated 4-benzylphenol by gavage at 0, 30, 150, or 750 mg/kg/day (OECD TG 407). Consequently, body weight was lower in males at 750 mg/kg/day. In the liver, relative organ weights were increased in both sexes at 750 mg/kg/day, and centrilobular hepatocellular hypertrophy was observed in males at 150 and 750 mg/kg/day. In the forestomach, hyperkeratosis and hyperplasia of squamous cells were observed in males at 150 and 750 mg/kg/day, and in females at 750 mg/kg/day. Based on these results, we identified the NOAEL for 4-benzylphenol as 30 mg/kg/day, with a hazard assessment value (D-value) of 0.05 mg/kg/day corresponding to hazard class 3.