Male Wistar Han Rats Research Articles

Assessing the severity of laparotomy and partial hepatectomy in male rats-A multimodal approach.

This study assessed the postoperative severity after three different visceral surgical interventions in rats by using objective parameters pertaining to various disciplines. The objective was to evaluate whether the degree of severity increases with the invasiveness of the intervention and whether this is in accordance with the EU Directive 2010/63. 136 adult male WistarHan rats were assigned to three groups: Sham-laparotomy (Sham) [7 days post-surgical survival time]; 50% partial hepatectomy (PH); 70% PH [PH groups with 1, 3, or 7 days post-surgical survival times]. Post-surgical severity assessment was performed via several multimodal assessment tools: I) model-specific score sheet focusing on body weight, general condition, spontaneous behavior, and the animals' willingness to move as well as on wound healing; II) Open Field tests evaluating the total distance and velocity an animal moved within 10 minutes and its rearing behavior during the test; III) telemetric data analyzing heart rate and blood pressure; and IV) analysis of blood (AST, ALT, and hemogram) and fecal samples (fecal corticosterone metabolites). Significant differences among the experimental groups and models were observed. We demonstrated that the Open Field test can detect significant changes in severity levels. Sham-laparotomy and removal of 50% of the liver mass were associated with comparable severity (mild-moderate); the severity parameters returned to baseline levels within seven days. Removal of 70% of the liver tissue seemed to be associated with a moderate severity grade and entailed a longer recovery period (>7 days) for complete regeneration. We recommend the use of Open Field tests as part of multimodal objective severity assessment.

Characterization of Urothelial Inclusions in Male Wistar Han Rats Treated Orally With the Novel α2A-Adrenoceptor Agonist Tasipimidine.

Intracellular inclusions were observed in urinary bladder epithelium of male Wistar rats, following oral treatment with high doses of the α2A-adrenoceptor agonist tasipimidine for 28 days. No cell death or inflammation was associated with the brightly eosinophilic inclusions. Electron microscopy (EM) studies showed that the inclusions represented intact or fragmented red blood cells (RBC) resulting from erythrophagocytosis, further supported by the presence of iron in urothelial cells. In addition, scattered iron-positive macrophages were observed in the submucosa and muscle layer, indicating microvascular leakage, as no major hemorrhage was evident. Despite the presence of inclusions, the urothelium showed normal uroplakin III distribution, normal cell turnover, and an absence of α-2u-globulin. It is, therefore, concluded that the inclusions were not associated with urothelial damage or increased renewal of the epithelium. This finding shows also that urothelial cells have the capability to phagocytize and break down RBCs originating from submucosal microvascular leakage. Similar changes were not observed in tasipimidine-treated beagle dogs (28 days), suggesting these findings were rat specific. The leakage of RBCs into the urothelium is suggested to be a consequence of exaggerated pharmacology leading to vasoconstriction of submucosal blood vessels in combination with transient increased bladder distension and pressure.

A pilot of the feasibility and usefulness of an aged obese model for use in stroke research

Background: Animal models of stroke have been criticised as having poor predictive validity, lacking risk factors prevalent in an aging population. This pilot study examined the development of comorbidities in a combined aged and high-fat diet model, and then examined the feasibility of modelling stroke in such rats. Methods: Twelve-month old male Wistar-Han rats (n=15) were fed a 60% fat diet for 8 months during which monthly serial blood samples were taken to assess the development of metabolic syndrome and pro-inflammatory markers. Following this, to pilot the suitability of these rats for undergoing surgical models of stroke, they underwent 30min of middle cerebral artery occlusion (MCAO) alongside younger controls fed a standard diet (n=10). Survival, weight and functional outcome were monitored, and blood vessels and tissues collected for analysis. Results: A high fat diet in aged rats led to substantial obesity. These rats did not develop type 2 diabetes or hypertension. There was thickening of the thoracic arterial wall and vacuole formation in the liver; but of the cytokines examined changes were not seen. MCAO surgery and behavioural assessment was possible in this model (with some caveats discussed in manuscript). Conclusions: This study shows MCAO is possible in aged, obese rats. However, this model is not ideal for recapitulating the complex comorbidities commonly seen in stroke patients.

Репродуктивна токсичність тріазолових фунгіцидів ципроконазолу і епоксиконазолу при дії на самців і самиць щурів wistar у період гаметогенезу

Aim. Studying the effect of generic pesticides cyproconazole (98 %) and two samples of epoxiconazole (epoxiconazole 1 — 95,75 % and epoxiconazole 2 — 98,7 %) on the reproductive system of male and female Wistar Han rats at the level of the organism when exposed during gametogenesis, identification and characterization of their hazard, as well as assessment of the risk of reproductive toxicity of these compounds. Materials and Methods. The test samples were administered daily (5 days a week) by oral gavage at doses of 0.2 and 2.0 mg/kg for cyproconazole and 0.5 and 2.0 mg/kg for epoxiconazoles during 11 weeks for males, and 10 weeks for females. Also, there were kept intact males and females, intended for crossover mating with experimental animals. After the end of the exposure, functional indicators of the state of the gonads and the ability of animals to reproduce offspring were studied. The duration and the frequency of each stage of the estrous cycle in female rats and the number of motile sperm, the total amount of sperm and the number of abnormal forms of germ cells of the male rats were studied. The reproductive function state in females was evaluated on day 20th of pregnancy. Thereby the number of corpora lutea in the ovaries, number of alive, dead and resorbed foetuses and embryos, the foetus weight, total weight of litters were registered. The studies were carried out in accordance with the recommendations of the Bioethics Commission and the Centre’s standard operating procedures, developed in accordance with the recommendations and requirements of Good Laboratory Practice (GLP). Conclusions. Test substances at a maximum dose of 2.0 mg/kg of body weight have reproductive toxicity and endocrine-disruptive effect, exerting a significant antiandrogenic effect on males and antiestrogenic effect on female rats. No-observed-adverse-effect-level (NOАEL) for gonadal and reproductive toxicity for male and female Wistar Han rats were established. They are 0.2 mg/kg body weight for cyproconazole and 0.5 mg/kg body weight for epoxiconazole. Key Words: azole fungicides, cyproconazole, epoxiconazole, reproductive toxicity, antiandrogenic and antiestrogenic effects, Wistar Han rats.

A pilot of the feasibility and usefulness of an aged obese model for use in stroke research.

Background: Animal models of stroke have been criticised as having poor predictive validity, lacking risk factors prevalent in an aging population. This pilot study examined the development of comorbidities in a combined aged and high-fat diet model, and then examined the feasibility of modelling stroke in such rats. Methods: Twelve-month old male Wistar-Han rats (n=15) were fed a 60% fat diet for 8 months during which monthly serial blood samples were taken to assess the development of metabolic syndrome and pro-inflammatory markers. Following this, to pilot the suitability of these rats for undergoing surgical models of stroke, they underwent 30min of middle cerebral artery occlusion (MCAO) alongside younger controls fed a standard diet (n=10). Survival, weight and functional outcome were monitored, and blood vessels and tissues collected for analysis. Results: A high fat diet in aged rats led to substantial obesity. These rats did not develop type 2 diabetes or hypertension. There was thickening of the thoracic arterial wall and vacuole formation in the liver; but of the cytokines examined changes were not seen. MCAO surgery and behavioural assessment was possible in this model (with some caveats discussed in manuscript). Conclusions: This study shows MCAO is possible in aged, obese rats. However, this model is not ideal for recapitulating the complex comorbidities commonly seen in stroke patients.

Mesenchymal stem cell derived extracellular vesicles as treatment for osteoarthritis in a rat high fat diet groove model

Purpose: Mesenchymal stromal/stem cells (MSC) hold a great promise to control the imbalance between anabolic and catabolic processes in an OA joint due to their immunomodulatory and regenerative capacities. Recently, intra-articular injections with human MSC entered the clinical trials as a novel, low invasive and relatively cheap therapy for OA. Although, the results of this novel treatment are promising, it remains unclear how MSC exert their beneficial effects in inflammation and tissue (cartilage) repair. Increasing evidence suggests that the therapeutic efficacy of MSC depends on paracrine signaling. Recently we have shown that MSC-derived extracellular vesicles (MSC-EVs) are an important component of this signaling and have a major contribution to cartilage regeneration and inhibition of TNF-alpha stimulated inflammatory responses in chondrocytes in vitro. Extracellular vesicles (EVs) are secreted by all cell types and range in size from 40 - 100 nm (exosomes) and from 100 -1000 nm (microvesicles). They increasingly appear to play an important role in intercellular communication by transportation of important molecules (peptides, mRNA, miRNA, enzymes). MSC-derived EVs have a great potential to serve as a safer cell free therapy for OA. The purpose of this study was to investigate if MSC-derived EVs can inhibit inflammation and promote cartilage repair to a similar extent as MSCs in a rat high fat diet groove model of OA. Methods: 36 male Wistar-han (Crl:WI(Han) rats were fed a high fat diet for 24 weeks, starting at an age of 12 weeks old. In week 12 of the study the rats received unilateral surgery where local cartilage damage was induced at the right knee joint by making five longitudinal grooves on the femoral condyles. In week 13 the rats were randomized into 3 groups and given an intraarticular injection with either PBS, 2 million human bone marrow derived MSCs or EVs derived from 2 million MSCs. The extracellular vesicles group received 5 of these doses with 5 days interval. Before, during and after the injections pain behavior was monitored by dynamic weight bearing and via measuring the left and right hind paw withdrawal responses to the application of von Frey hairs. uCT scans were made at week 0 and week 24, and used to determine the number of osteophytes and cartilage mineralization in the tibia. Additionally, tibial subchondral plate thickness, trabecular bone thickness, and trabecular bone volume fraction (total volume/trabecular bone volume) were measured using ImageJ 1.47v. At endpoint animals were sacrificed and the knee joints were harvested. Joint tissue is currently under preparation for histological staining to determine the OARSI histopathological score for rats. Data is represented as mean +/- standard deviation (SD) and the difference between the means in the three groups was statistically tested using one way ANOVA. Results: Results from the von Frey tests showed a clear decrease in 50% withdrawal threshold in the right hind paw, which was expected as the right side was the grooved limb. However, no difference between the three treatment groups in either left or right paw was seen. The mean osteophyte number in the PBS group was 4.7 (+/- 0.65) versus 3.6 (+/-2.15) in the MSC group and 4.3 (+/-1.8) in the MSC-EV group (figure 1A). In the MSC and MSC-EV treatment groups the variation in osteophyte number and total osteophyte diameter between the animals was large compared to the PBS group. Cartilage mineralization were observed in 9 of 12 animals in the PBS and MSC group and in 5 of 12 animals in the MSC-EV group. Both the number and total diameter was lowest in the MSC-EV group, but there was no significant difference as compared with control groups (Figure 1B). Other parameters measured on uCT like bone volume fraction, subchondral plate and trabecular bone thickness were similar between the 3 groups. Results from the OARSI histopathological score for rats is currently under preparation. Conclusions: Preliminary results from this in vivo study show no significant differences between PBS, MSC or MSC-EV treatment on uCT data or von Frey test. However, we do observe a large spread in osteophyte score and total diameter in the MSC and MSC-EV treated groups, which could be a sign that individual animals are responding differently to the treatments. Data from the OARSI scoring will help us determine if the response really is variable for MSC and MSC-EV treatment groups. This would be in accordance with observations made in humans, as many clinical trials that test MSC-based therapies report a substantial nonresponder group. In summary, although osteophytes are one of the hallmarks of osteoarthritis, we feel a complete picture of the joint damage including cartilage and synovium is needed to draw conclusions on the effect of the treatments in this study.

Neurotoxic effects of nephrotoxic compound diethylene glycol

Context Diethylene glycol (DEG) is an organic compound found in household products but also as an adulterant in medicines by acting as a counterfeit solvent. DEG poisonings have been characterized predominately by acute kidney injury (AKI), but also by delayed neurological sequelae such as decreased reflexes or face and limb weakness. Objectives Characterizing the neurological symptoms of DEG poisoning in a subacute animal model would create a clearer picture of overall toxicity and possibly make mechanistic connections between kidney injury and neuropathy. Methods Male Wistar-Han rats were orally administered doses of 4 − 6 g/kg DEG every 12 or 24 h and monitored for 7 days. Urine was collected every 12 h and endpoint blood and cerebrospinal fluid (CSF) were collected for a renal plasma panel and total protein estimation, respectively. Motor function tests were conducted before and after treatment. Kidney and brain tissue was harvested for metabolic analysis. Results Of the 43 animals treated with DEG, 11 developed AKI as confirmed by increased BUN and creatinine levels. Renal and brain DGA accumulation was markedly increased in animals that developed AKI compared to animals without AKI. The total protein content in CSF in animals with kidney injury was markedly elevated compared to control and to treated animals without AKI. Significant decreases in forelimb grip strength and decreases in locomotor and rearing activity were observed in animals with AKI compared to control and to animals without AKI. Discussion Repeated dosing with DEG in an animal model produced nephrotoxic effects like those in studies with acute DEG administration. The decrease in motor function and increase in CSF protein were only present in animals that developed AKI. Conclusions These studies show development of neurotoxicity in this DEG animal model and suggest that neurological symptoms are observed only when DGA accumulation and kidney injury also occur.

Токсикодинаміка за сумісної дії хлорпірифосу та івіну при тривалому надходженні до організму

The combined action of pesticides is one of the problems of toxicology, because in comparison to individual active substances, their mixtures can increase toxicity and delayed action effects, which is a risk to human health. It is known that plant growth regulators (PGR) when applied together with pesticides help to reduce the quantitative rates of pesticides applied, the accumulation of pesticides and heavy metals in plants, reduce the acute toxicity of xenobiotics. The combined effect of the prolonged admission of PGRs and pesticides is an unexplored area, and it is an important issue in preventive toxicology. The Aim of the Research. Determination of the nature of toxic effects of Chlorpyrifos and “Ivin” combined action at subchronic oral admission. Materials and Methods. Chlorpyrifos and PGR “Ivin” (2.6-dimethyl-N-pyridine oxide) combined action was studied on male Wistar Han rats. Substances were administered orally, via a feeding tube for 13 weeks; Chlorpyrifos was administered in the form of an aqueous emulsion with an auxiliary material OP-10 at a dose of 5 mg/kg (1/15 LD50), “Ivin” — in the form of an aqueous solution at a dose of 13 mg/kg and 0.013 mg/kg (1/100 and 1/100000 LD50 respectively), the control group of rats was given water with an auxiliary material OP-10. Signs of intoxication were recorded, body weight was measured in 4, 9 and 13 weeks, biochemical indicators of blood serum were determined (the activity of ALT and AST enzymes and alkaline phosphatase; the content of crude protein, urea, cholesterol, triglycerides and glucose were determined using kits of reagents by BioSystems (Spain); cholinesterase (ChE) activity in serum, red blood cells and brain tissue was determined with the use of methodology by Hesrtin S. using a kit of reagents produced by LLC NPP Filisit-Diagnostics (Ukraine). Results. No clinical signs of intoxication were detected in the experimental groups of rats. Under the isolated use of Chlorpyrifos a significant decrease in body weight, ChE inhibition activity in all bio substrates, with the greatest effect in the brain (by 48.8%); increase (after 9 and 13 weeks) in the activity of ALT and AST by 26.7–32.6%, 12.5–12.0%; a slight but a significant increase in the level of urea and glucose in blood serum to 17.3% and 17.6 %, respectively was detected. Under the combined action of Chlorpyrifos and “Ivin” in specified doses the body weight of rats was at control level, decrease of ChE activity was observed in all biological substrates and was at nearly the same level with the isolated use of Chlorpyrifos. There was a tendency towards the decline in ChE inhibition activity in brain tissue, and under the combined action of Chlorpyrifos with “Ivin” at higher doses after 4 weeks this effect was a significant (22.15%, p < 0.05). Conclusions. Chlorpyrifos under the isolated oral admission for 13 weeks has a weak hepatotoxic effect, as evidenced by the increase in cytolysis enzymes and urea levels in serum and causes a moderate anticholinesterase effect. “Ivin” under combined with Chlorpyrifos admission to the organism eliminates the hepatotoxic effects of Chlorpyrifos and reduces its anticholinergic effects in brain, which contributes to a less severe intoxication. Key Words: Chlorpyrifos, Ivin, hepatotoxic effect, anticholinesterase effect.

Abstract 14740: Sympathetic Down-regulation With Zamicastat Reduces Arrhythmogenicity in Isolated Hearts From Rats With Pulmonary Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a disease often causing right ventricular failure and death. During disease progression, structural and electrical remodeling of the right ventricle creates proarrhythmic substrates and triggers for arrhythmias. Studies of PAH patients show a hyperstimulation of the sympathetic nervous system (SNS) indicating that PAH may be mediated by SNS hyperactivation. Zamicastat (ZAM) is a reversible dopamine β-hydroxylase inhibitor that modulates SNS by reducing the biosynthesis of norepinephrine in peripheral sympathetic nerves. ZAM improves survival in the monocrotaline (MCT) rat model of PAH. Hypothesis: To evaluate the effect of ZAM on electrophysiological parameters in isolated hearts from MCT-treated rats. Methods: Male Wistar Han rats were randomized in 3 groups, Sham (n=6), MCT (n=15) and MCT+ZAM (n=17). On day zero, MCT and MCT+ZAM groups received MCT (60 mg/kg, SC) and Sham group received saline. Starting on day 12, MCT+ZAM rats were daily administered ZAM (30 mg/kg, PO) while all other animals were given vehicle. On day 28, hearts were excised and mounted on a Langendorff system. A bipolar circuit of two electrodes was placed on the epicardium for ECG recording. Provoked arrhythmias were induced with a burst pacing protocol (50Hz, 1 second) and the recovery time was measured as the time needed to reach 3 consecutive stable R-R intervals. Results: MCT increased the proportion of hearts exhibiting bundle branch blocks, 3 rd degree atrioventricular (AV) blocks, atrial fibrillation (AF), ventricular fibrillation (VF) and premature ventricular contractions (PVCs) when compared to Sham group. ZAM treatment suppressed 3 rd degree AV blocks, AF and VF. In addition, PVCs were less frequent in hearts from MCT+ZAM animals as compared to MCT group. Isolated hearts naturally entered a pause following overpacing-induced VF. MCT hearts showed a non-significant 1.7-fold increase in recovery time compared to Sham group. Hearts from MCT+ZAM animals had a significant ≈50% reduction in post-fibrillation pause. Conclusions: These data suggest that treatment with Zamicastat yields a lower proarrhythmic cardiac tissue decreasing the incidence of cardiac arrhythmias.

The effect of cannabidiol on sevoflurane minimum alveolar concentration reduction produced by morphine in rats

ObjectiveTo investigate the effect of cannabidiol (CBD) on sevoflurane minimum alveolar concentration (MACSEV) reduction produced by morphine in rats. Study designRandomized, blinded trial. AnimalsA total of 75 male Wistar Han rats weighing 276 ± 23 g (mean and standard deviation), aged 3 months. MethodsCannabidiol (CBD) was prepared in an ethanol-solutol-saline vehicle. Animals were randomly divided into 15 groups and given an intraperitoneal bolus of 1, 3, 5, 6.5, 7.5 or 10 mg kg−1 of CBD alone (CBD1, CBD3, CBD5, CBD6.5, CBD7.5 and CBD10 respectively) or combined with 5 mg kg−1 of morphine (MOR+CBD1, MOR+CBD3, MOR+CBD5, MOR+CBD6.5, MOR+CBD7.5 and MOR+CBD10). While three controls groups: MOR+saline, MOR+vehicle and vehicle were given an intraperitoneal bolus of morphine with saline, morphine with vehicle or vehicle alone respectively. The MACSEV was determined from alveolar gas samples at the time of tail clamp application. The MACSEV reduction was analyzed using a one-way ANOVA followed by Tukey’s test. Additionally, Kruskal-Wallis test for non-normally-distributed data was performed. Data are presented as mean ± standard deviation. P < 0.05 ResultsThe mean MACSEV was not reduced by the action of CBD administered alone, but the addition of morphine to the different doses of CBD significantly reduced the MACSEV. That reduction was greatest in the MOR+CBD1, MOR+CBD7.5 and MOR+CBD10 groups (29 ± 5%, 32 ± 5% and 30 ± 6% respectively), less in MOR+CBD3 and MOR+CBD6.5 groups (24 ± 3% and 26 ± 4% respectively) and least in MOR+CBD5 group (17 ± 2%). However, only the MOR+CBD5 group was statistically significantly different from MOR+CBD1, MOR+CBD7.5 and MOR+CBD10 groups. Conclusions and clinical relevanceMACSEV in rat was unaltered by the action of CBD alone, the reduction in MACSEV produced by morphine was not enhanced by the addition of CBD at the doses studied.

Spatial evaluation of long-term metabolic changes induced by cisplatin nephrotoxicity

Cisplatin is a widely used chemotherapeutic agent. However, it is causing nephrotoxic side effects including a reduced glomerular filtration rate and acute kidney injury. Although kidneys can recover to an extent from the treatment, long-term damage is possible. While a lot of research is focusing on short-term effects, little is known about adverse metabolic effects in the process of recovery. In this study, male Han Wistar rats were dosed with a single intraperitoneal injection of 3 mg/kg cisplatin. Urine and kidney samples were harvested 3, 8 and 26 days after administration. Tubular injury was demonstrated through urinary biomarkers. Complementing this, mass spectrometry imaging gives insight on molecular alterations on a spatial level, thus making it well suited to analyze short- and long-term disturbances. Various metabolic pathways seem to be affected, as changes in a wide range of metabolites were observed between treated and control animals. Besides previously reported early changes in kidney metabolism, unprecedented long-term effects were detected including deviation in nucleotides, antioxidants, and phospholipids.

Assessment of the anti-allodynic efficacy of a glycine transporter 2 inhibitor relative to pregabalin and duloxetine in a rat model of prostate cancer-induced bone pain.

The pathobiology of prostate cancer-induced bone pain (PCIBP) is underpinned by both inflammatory and neuropathic components. Here, we used a rat model of PCIBP to assess the analgesic efficacy of a glycine transporter 2 (GlyT2) inhibitor (N-(6-((1,3-dihydroxypropan-2-yl)amino)-2-(dimethylamino)pyridin-3-yl)-3,5-dimethoxy-4-(4-(trifluoromethyl)phenoxy) benzamide) relative to two clinically available adjuvant drugs that are recommended for the relief of neuropathic pain, viz, pregabalin and duloxetine. PCIBP was induced in male Wistar Han rats following intra-tibial injection (ITI) of rat prostate cancer (AT3B) cells into the left tibia. Sham-rats received an ITI of heat-killed AT3B cells. PCIBP rats with fully developed mechanical allodynia in the ipsilateral hindpaws as assessed using von Frey filaments, received single oral (p.o.) bolus doses of the GlyT2 inhibitor (3-30mg/kg), pregabalin (3-100mg/kg), duloxetine (3-100mg/kg), or vehicle. Baseline paw withdrawal thresholds (PWTs) were determined in the ipsilateral (injured side) and contralateral hindpaws immediately prior to dosing and at scheduled times for 3h post dosing in individual animals. Single oral bolus doses of the GlyT2 inhibitor (3-30mg/kg) evoked partial pain relief at the doses tested in the ipsilateral hindpaws of PCIBP rats without any discernible behavioural side effects. By contrast, single oral bolus doses of pregabalin at 10-100mg/kg evoked dose-dependent and complete alleviation of mechanical allodynia. By comparison, single oral bolus doses of duloxetine at doses up to 100mg/kg lacked efficacy. Oral administration of this GlyT2 inhibitor evoked partial pain relief in PCIBP rats and did not evoke central nervous system side effects in contrast to GlyT2 inhibitors reported by others.

Toxicity studies of fullerene C60 (1 μm and 50 nm) administered by nose-only inhalation to Wistar Han [Crl:WI (Han)] rats and B6C3F1/N mice.

Fullerene C60 (C60), a primary allotrope of carbon, is used in a variety of consumer applications including microelectronics, photovoltaics, batteries and fuel cells, and water treatment methods. Human exposure to engineered C60 due to industrial applications may occur via inhalation, oral, dermal, or parenteral routes. In these toxicity and tissue burden studies, male and female Wistar Han rats and B6C3F1/N mice were exposed to fullerene C60 (at least 95% pure) via nose-only inhalation for 3 months. Two different C60 fullerene aggregate sizes, 1 µm diameter (micro-C60) and 50 nm diameter (nano-C60) were studied to assess the potential for differential effects based on particle size. (Abstract Abridged).

Development and Application of a Transcriptomic Signature of Bioactivation in an Advanced In Vitro Liver Model to Reduce Drug-induced Liver Injury Risk Early in the Pharmaceutical Pipeline.

Early risk assessment of drug-induced liver injury (DILI) potential for drug candidates remains a major challenge for pharmaceutical development. We have previously developed a set of rat liver transcriptional biomarkers in short-term toxicity studies to inform the potential of drug candidates to generate a high burden of chemically reactive metabolites that presents higher risk for human DILI. Here, we describe translation of those NRF1-/NRF2-mediated liver tissue biomarkers to an in vitro assay using an advanced micropatterned coculture system (HEPATOPAC) with primary hepatocytes from male Wistar Han rats. A 9-day, resource-sparing and higher throughput approach designed to identify new chemical entities with lower reactive metabolite-forming potential was qualified for internal decision making using 93 DILI-positive and -negative drugs. This assay provides 81% sensitivity and 90% specificity in detecting hepatotoxicants when a positive test outcome is defined as the bioactivation signature score of a test drug exceeding the threshold value at an in vitro test concentration that falls within 3-fold of the estimated maximum drug concentration at the human liver inlet following highest recommended clinical dose administrations. Using paired examples of compounds from distinct chemical series and close structural analogs, we demonstrate that this assay can differentiate drugs with lower DILI risk. The utility of this in vitro transcriptomic approach was also examined using human HEPATOPAC from a single donor, yielding 68% sensitivity and 86% specificity when the aforementioned criteria are applied to the same 93-drug test set. Routine use of the rat model has been adopted with deployment of the human model as warranted on a case-by-case basis. This in vitro transcriptomic signature-based strategy can be used early in drug discovery to derisk DILI potential from chemically reactive metabolites by guiding structure-activity relationship hypotheses and candidate selection.

The analysis of acetaminophen (paracetamol) and seven metabolites in rat, pig and human plasma by U(H)PLC-MS.

A U(H)PLC-MS/MS method is described for the analysis of acetaminophen and its sulphate, glucuronide, glutathione, cysteinyl and N-acetylcysteinyl metabolites in plasma using stable isotope-labeled internal standards. P-Aminophenol glucuronide and 3-methoxyacetaminophen were monitored and semi-quantified using external standards. The assay takes 7.5min/sample, requires only 5μl of plasma and involves minimal sample preparation. The method was validated for rat plasma and cross validated for human and pig plasma and mouse serum. LOQ in plasma for these analytes were 0.44μg/ml (APAP-C), 0.58μg/ml (APAP-SG), 0.84μg/ml (APAP-NAC), 2.75μg/ml (APAP-S), 3.00μg/ml (APAP-G) and 16μg/ml (APAP). Application of the method is illustrated by the analysis of plasma following oral administration of APAP to male Han Wistar rats.

Severity assessment using three common behavioral or locomotor tests after laparotomy in rats: a pilot study.

The aim of this pilot study was to evaluate whether behavioral or locomotor tests (Open Field (OF), rotarod (RR), and CatWalk (CW)) can help assess the severity of laparotomy in rats.The new EU Directive (2010/63/EU) mandates severity assessment in experiments involving animals. However, validated and objective methods are needed to relate trial-specific monitoring results to the degree of distress caused to individual animals. Therefore, we focused on non-invasive or minimally invasive, simple, and convenient severity assessment methods in a surgical model.To evaluate surgical severity in this model, we compared moving velocity among three commonly used behavioral test methods (OF, RR, and CW) after midline laparotomy within postoperative 7 days.In this study, 30 adult male Wistar Han rats (n = 10 per test) were trained in their assigned test method and subsequently subjected to surgery. Severity scoring was performed daily using a modified score sheet developed previously. In addition, blood and fecal samples were collected to analyze surgical and postoperative corticosterone metabolite levels. We found significant differences among the experimental groups in terms of the analyzed parameters. In this context, the OF test was found to be the most suitable method for severity assessment after laparotomy in rats.

MT-102 prevents tissue wasting and improves survival in a rat model of severe cancer cachexia.

BackgroundCachexia, a common manifestation of malignant cancer, is associated with wasting of skeletal muscle and fat tissue. In this study, we investigated the effects of a new first in class anabolic catabolic transforming agent on skeletal muscle in a rat model of cancer cachexia.MethodsYoung male Wistar Han rats were intraperitoneally inoculated with 108 Yoshida hepatoma AH‐130 cells and once daily treated with 0.3 mg kg−1, 3 mg kg−1 MT‐102, or placebo by gavage.ResultsThree mg kg−1d−1 MT‐102 not only prevented progressive loss of fat mass (−6 ± 2 g vs ‐12 ± 1 g; P < 0.001); lean mass (+1 ± 10 g vs. −37 ± 2 g; P < 0.001) and body weight (+1 ± 13 g vs. −60 ± 2 g; P < 0.001) were remained. Quality of life was also improved as indicated by a higher food intake 12.9 ± 3.1 g and 4.3 ± 0.5 g, 3 mg kg−1d−1 MT‐102 vs. placebo, respectively, P < 0.001) and a higher spontaneous activity (52 369 ± 6521 counts/24 h and 29 509 ± 1775 counts/24 h, 3 mg·kg‐1d‐1 MT‐102 vs. placebo, respectively, P < 0.01) on Day 11. Most importantly, survival was improved (HR = 0.29; 95% CI: 0.16–0.51, P < 0.001). The molecular mechanisms behind these effects involve reduction of overall protein degradation and activation of protein synthesis, assessed by measurement of proteasome and caspase‐6 activity or Western blot analysis, respectively.ConclusionsThe present study shows that 3 mg kg−1 MT‐102 reduces catabolism, while inducing anabolism in skeletal muscle leading to an improved survival.

Regulatory safety pharmacology evaluation of BIA 10-2474

The present paper describes the regulatory safety pharmacology studies that were carried out to support the clinical trial application for BIA 10–2474. Animal studies complied with worldwide regulatory guidelines (e.g. EEC Council Directive 75/318/EEC and subsequent amendments). Oral administration of BIA 10–2474 at doses of 30, 100 and 300 mg/kg to male Han Wistar rats did not cause any significant physiological or behavioral changes, affect the respiration rate or the tidal volume, the gastrointestinal transit, urinary output volume or pH, nor urinary sodium, potassium or chloride excretion. BIA 10–2474, at 30 μg/mL, slightly, but significantly, reduced the hERG outward tail currents by 10.62%, but had no effect at 1, 3 or 10 μg/mL. BIA 10–2474 (1.5, 4.5 and 15 μg/mL) had no substantial effects on resting membrane potential (RMP), maximal upstroke velocity (Vmax), action potential amplitude (APA), action potential duration at 30%, 60% and 90% or action potential triangulation over the 30-min superfusion period in the dog isolated Purkinje fiber. In conscious dogs monitored by telemetry, BIA 10–2474 (20, 50 and 100 mg/kg p.o.) did not significantly modify arterial blood pressure as compared with controls (inter-group comparison), although a tendency toward an increase in arterial blood pressure was observed at 100 mg/kg, with systolic blood pressure being the most affected parameter. In conclusion, BIA 10–2474 had no adverse effects on any of the major vital organ systems, and, unfortunately, the data shed no further light on the mechanism(s) responsible for the clinical trial accident with BIA 10–2474.

High trait impulsivity potentiates the effects of chronic pain on impulsive behavior

Preclinical studies on impulsive decision-making in chronic pain conditions are sparse and often contradictory. Outbred rat populations are heterogeneous regarding trait impulsivity manifestations and therefore we hypothesized that chronic pain-related alterations depend on individual traits. To test this hypothesis, we used male Wistar-Han rats in two independent experiments. Firstly, we tested the impact of spared nerve injury (SNI) in impulsive behavior evaluated by the variable delay-to-signal test (VDS). In the second experiment, SNI impact on impulsivity was again tested, but in groups previously categorized as high (HI) and low (LI) trait impulsivity in the VDS.Results showed that in an heterogenous population SNI-related impact on motor impulsivity and delay intolerance cannot be detected. However, when baseline impulsivity was considered, HI showed a significantly higher delay intolerance than the respective controls more prevalent in left-lesioned animals and appearing to result from a response correction on prematurity from VDS I to VDS II, which was present in Sham and right-lesioned animals.In conclusion, baseline differences should be more often considered when analyzing chronic pain impact. While this study pertained to impulsive behavior, other reports indicate that this can be generalized to other behavioral dimensions and that trait differences can influence not only the manifestation of comorbid behaviors but also pain itself in a complex and not totally understood manner.

2,4-Decadienal does not induce genotoxic effects in in vivo micronucleus studies

2,4-Decadienal (E,E-) occurs naturally in foods and is also used as a flavoring ingredient. In vivo micronucleus studies were used to evaluate the potential for 2,4-decadienal to cause genotoxic effects. Male Han Wistar rats were dosed either by intraperitoneal injection or by gavage in two independent studies. The animals (12/group) received 25, 50, or 100 mg/kg bw of 2,4-decadienal via intraperitoneal injection, or 350, 700, or 1400 mg/kg bw via gavage. Dose-dependent decreases in the percentages of peripheral blood reticulocytes were observed in both studies, indicating that the target tissue was exposed to toxic levels of 2,4-decadienal. No induction of micronuclei in the bone marrow polychromatic erythrocytes or the peripheral blood reticulocytes was observed in either study. These results, coupled with previous mutagenicity studies, support the overall conclusion that 2,4-decadienal does not present a concern for genotoxicity.