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Precise oral dosing in rodents is usually achieved by intragastric gavage. If performed incorrectly due to technical difficulties, inexperience, or animal resistance, oral gavage may have animal welfare implications such as esophageal and gastric rupture and aspiration. The stress that is induced by this procedure can also lead to confounding results. In several animal models, drug vehicles must be sugar-free, deliver drugs in a specific formulation, and sometimes supply water. Gelatin has all of these properties. The current study aimed to evaluate the use of gelatin vehicles with different sensory features as an alternative to oral gavage. We investigated the time taken by 2 different inbred mouse strains, FVB/N and C57BL/6J, to ingest sugar-free gelatin pellets of varying flavors. Results showed that FVB/N mice took more time to eat the unflavored, strawberry and diet-flavored gelatin pellets than did C57BL/6J mice. Both strains showed low preference for lemon flavor, with the same ingestion times after the second day. This study showed that the C57BL/6J mice are more likely to eat gelatin than are FVB/N mice, and that the 2 strains of mice show a lower preference for lemon flavoring as compared with other flavors. This method of voluntarily oral administration offers an alternative to gavage for studies that use oral dosing studies.

The aim of our study was to assess the nest-building behaviour of two mouse (Mus musculus) strains using different nesting materials and examine possible sex- and housing-specific effects. Adult mice of two strains (C57BL/6J; n = 64 and BALB/cAnNCrl; n = 99) were randomly allocated to the following housing groups: single-housed male, single-housed female, pair-housed male and pair-housed female. One of the following nest-building materials was placed in each home-cage in a random order: nestlets (Plexx BV, The Netherlands), cocoons (Carfil, Belgium), wooden wool, crinklets and compact (all three, Safe, Germany). The following day, nests were rated applying a nest-scoring scale ranging from 0 to 10, the nests were removed, and a different nest-building material provided. In both tested strains, nestlets achieved the highest nest-building scores when compared to the other four nest-building materials. All nest-building materials scored higher in BALB/c mice compared to C57BL/6J animals reaching statistical significance in crinklets only. Sex comparison revealed that female C57BL/6J mice only scored significantly higher using crinklets than males and BALB/c female mice were rated significantly higher using wooden wool, cocoons and compact than their male counterparts. While pair-housed C57BL/6J animals built higher-rated nests than single-housed mice in the C57BL/6J strain in all five materials tested, the scores were not significantly different in the BALB/c strain. Results of the present study reveal significant strain-, sex- and housing-related influences on the complexity of nests using different standardised building materials. Such observations need to be taken into account when planning the optimal enrichment programme for laboratory animals.

Excessive long-term consumption of dietary carbohydrates, including glucose, sucrose, or fructose, has been shown to have significant impact on genome-wide gene expression, which likely results from changes in metabolic substrate flux. However, there has been no comprehensive study on the acute effects of individual sugars on the genome-wide gene expression that may reveal the genetic changes altering signaling pathways, subsequent metabolic processes, and ultimately physiological/pathological responses. Considering that gene expressions in response to acute carbohydrate ingestion might be different in nutrient sensitive and insensitive mammals, we conducted comparative studies of genome-wide gene expression by deep mRNA sequencing of the liver in nutrient sensitive C57BL/6J and nutrient insensitive BALB/cJ mice. Furthermore, to determine the temporal responses, we compared livers from mice in the fasted state and following ingestion of standard laboratory mouse chow supplemented with plain drinking water or water containing 20% glucose, sucrose, or fructose. Supplementation with these carbohydrates induced unique extents and temporal changes in gene expressions in a strain specific manner. Fructose and sucrose stimulated gene changes peaked at 3 h postprandial, whereas glucose effects peaked at 12 h and 6 h postprandial in C57BL/6J and BABL/cJ mice, respectively. Network analyses revealed that fructose changed genes were primarily involved in lipid metabolism and were more complex in C57BL/6J than in BALB/cJ mice. These data demonstrate that there are qualitative and antitative differences in the normal physiological responses of the liver between these two strains of mice and C57BL/6J is more sensitive to sugar intake than BALB/cJ.

The effects of 3,5,3',4'-tetrahydroxystilbene (piceatannol) on azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colon cancer growth and changes in IL-1β, IL-6, tumor necrosis factor-α (cytokines), MCP-1, vascular endothelial growth factor, and PD-1 colon levels were investigated herein.AOM (10 mg/kg,In mice administered piceatannol (12.5 mg/kg), the tumor number, tumor area, and Ki-67-positive cell numbers decreased by 30.1%, 57.2%, and 89.1%, respectively, colon MCP-1 and PD-1 levels showed reductions of 43.8% and 70.9%, respectively, and COX-2-positive cell numbers declined by 60.2%.The inhibitory effects of piceatannol on AOM/DSS-induced colon tumor growth

The electroencephalogram (EEG) provides an objective, neural correlate of consciousness. Opioid receptors modulate mammalian neuronal excitability, and this fact was used to characterize how opioids administered to mice alter EEG power and states of consciousness. The present study tested the hypothesis that antinociceptive doses of fentanyl, morphine, or buprenorphine differentially alter the EEG and states of sleep and wakefulness in adult, male C57BL/6J mice. Mice were anesthetized and implanted with telemeters that enabled wireless recordings of cortical EEG and electromyogram (EMG). After surgical recovery, EEG and EMG were used to objectively score states of consciousness as wakefulness, rapid eye movement (REM) sleep, or non-REM (NREM) sleep. Measures of EEG power (dB) were quantified as δ (0.5-4 Hz), θ (4-8 Hz), α (8-13 Hz), σ (12-15 Hz), β (13-30 Hz), and γ (30-60 Hz). Compared with saline (control), fentanyl and morphine decreased NREM sleep, morphine eliminated REM sleep, and buprenorphine eliminated NREM sleep and REM sleep. Opioids significantly and differentially disrupted the temporal organization of sleep/wake states, altered specific EEG frequency bands, and caused dissociated states of consciousness. The results are discussed relative to the fact that opioids, pain, and sleep modulate interacting states of consciousness.

Bovine milk exosomes (BMEs) are being explored in drug delivery despite their rapid elimination by macrophages. We aimed at identifying the BME transporter in murine bone marrow-derived macrophages (BMDMs). Fluorophore-labeled BMEs were used in transport studies in BMDMs from C57BL/6J and class A scavenger receptor type 1/2 (CASR-1/2) knockout mice and tissue accumulation in macrophage-depleted C57BL/6J mice. Parametric and nonparametric statistics tests for pairwise and multiple comparisons were used. Chemical inhibitors of phagocytosis by cytochalasin D led to a 69 ± 18% decrease in BME uptake compared with controls ( P < 0.05), whereas inhibitors of endocytic pathways other than phagocytosis had a modest effect on uptake ( P > 0.05). Inhibitors of class A scavenger receptors (CASRs) including CASR-1/2 caused a 70% decrease in BME uptake ( P < 0.05). The uptake of BMEs by BMDMs from CASR-1/2 knockout mice was smaller by 58 ± 23% compared with wild-type controls ( P < 0.05). Macrophage depletion by clodronate caused a more than 44% decrease in BME uptake in the spleen and lungs ( P < 0.05), whereas the decrease observed in liver was not statistically significant. In conclusion, CASR-1/2 facilitates the uptake of BMEs in BMDMs and C57BL/6J mice.

The development of morphine tolerance in C57BL/6j mice was estimated by the analgesic effect in tail-flick and hot plate tests. Morphine hydrochloride (10 mg/kg body weight) was administered to animals twice for 5 days and once on the sixth day, saline or myelopeptides were injected 15 min before morphine administration (2 μg/kg body weight). In the tail-flick test, all studied myelopeptides suppressed the development of tolerance to morphine and did not show their own analgesic activity. In the hot plate test, only three myelopeptides (MP2, MP5, and MP6) were found to reduce the formation of morphine tolerance. MP1 significantly reduced the analgesic effect of morphine on days 1-3 of administration, but contributed to the preservation of the analgesic effect during the period of tolerance development.

Konjac glucomannan polysaccharide (KGM), inulin oligosaccharide (inulin) and their mixture has been shown to modulate the gut-associated lymphoid tissue immunity.The present study was mainly to determine effects of a low-level (2% w/w) KGM and inulin and their combination on dextran sodium sulfate (DSS)-induced colitis. We also determine the potential mechanisms mediating these effects of dietary fibers.C57BL/6J mice (6 weeks of age, eight per group) were randomly assigned to consume one of the following diets: control (DSS group) or control diet supplemented with 2% (w/w) of KGM (KGM group), 2% (w/w) of inulin oligosaccharide (inulin group) or KGM+Inulin (1%, w/w each (K+I group)) for 29 days, combined with the DSS drinking water (2% w/v) treatment on days 21-26. Another group served as vehicle was fed the control diet and given regular drinking water throughout the study. Fresh feces were collected on days 26-29. Mice were killed on day 30 after fasting. Segments of distal colon were processed for histological procedure. The remaining colonic tissues were processed to determine the colonic gene expressions of cytokines, tight junction proteins and antioxidant enzymes.The present study indicated that DSS resulted in colonic dysplasia, severe leukocyte infiltration and enhanced gene expressions of pro-inflammatory cytokines. All fiber treatments ameliorated these indices of colitis. DSS treatment reduced the colonic gene expressions of tight junction proteins and antioxidant enzymes, which were ameliorated or normalized with fiber supplementation. In addition, all fiber treatments prevented the DSS-induced alterations in the fecal microbiota and short-chain acid levels.Supplementation of low-level, 2% (w/w), of KGM polysaccharide, inulin oligosaccharide and K + I reduced the DSS-induced colitis and mucosal barrier dysfunction, which was likely to be mediated by the prebiotic effects.

Time-restricted feeding is used to study the food-entrainable oscillator in mammals, yet there is considerable inconsistency in procedures for imposing restrictions. Additionally, the majority of r...

The immature platelet fraction (IPF) is a measure of newly released platelets, which has been used as a marker of platelet production in multiple human studies but is not widely available in multispecies analyzers. We developed gates to measure the IPF in diluted and undiluted murine blood samples on the Sysmex XN-1000V multispecies hematology analyzer. IPF gates were created using undiluted and diluted (1/10) blood samples obtained from adult and newborn (postnatal day 10, P10) C57BL/6J wild-type (WT) mice, and from 3 murine models of thrombocytopenia: c-MPL−/− mice, which lack the thrombopoietin receptor (hyporegenerative); antibody-mediated thrombocytopenia; and acute inflammation-induced thrombocytopenia. P10 mice were chosen because, at their size, we could consistently obtain (by terminal phlebotomy) the blood volume needed to run an undiluted sample. The undiluted blood IPF gate successfully differentiated between mechanisms of thrombocytopenia in both adult and P10 mice. For diluted samples, 2 IPF gates were generated: a thrombocytopenic (T) gate, which performed well in samples with platelet counts (PCs) 9/L in adult mice and 9/L in newborn mice, and a non-thrombocytopenic (NT) gate, which performed well in samples with PCs above these thresholds. PCs and IPFs measured in diluted blood using these gates agreed well with those measured in undiluted blood and had good reproducibility. These diluted gates allow for the accurate measurement of PCs and IPFs in small (10 µL) blood volumes, which can be obtained easily from adult and newborn mice as small as P1 to assess platelet production serially.

BackgroundColorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and thus mouse models of CRC are of significant value to study the pathogenesis. The Azoxymethane/Dextran sulfate sodium (AOM/DSS) model is a widely used, robust initiation-promotion model for chemical induction of colitis-associated CRC in rodents. However, the dosage of chemicals, treatment regimens and outcome measures vary greatly among studies employing this model. Thus, the aim of this study was to examine an AOM/DSS model involving a reduced (1%) dose of DSS for induction of carcinogenesis in A/J and C57BL/6J (B6) mice.ResultsWe show that colonic preneoplastic lesions can be reliably detected in A/J and B6 mice by use of a AOM/DSS model involving a single injection of 10 mg/kg AOM followed by three 7-day cycles of a low-dose (1%) DSS administration. Supporting existing evidence of A/J mice exhibiting higher susceptibility to AOM than B6 mice, our AOM/DSS-treated A/J mice developed the highest number of large colonic lesions. Clinical symptoms in both strains subjected to the AOM/DSS treatment did not persist in-between treatment cycles, demonstrating that the animals tolerated the treatment well.ConclusionsOur findings suggest that a reduced dose of DSS in the AOM/DSS model can be considered in future studies of early phase colorectal carcinogenesis in the A/J and B6 mouse strains using preneoplastic lesions as an outcome measure, and that such regimen may reduce the risk of early trial terminations to accommodate human endpoints. Overall, our data emphasize the importance of devoting attention towards choice of protocol, outcome measures and mouse strain in studies of CRC in mice according to the study purpose.

Genetic and environmental factors interact with each other to influence the risk of various psychiatric diseases; however, the intensity and nature of their interactions remain to be elucidated. We established a maternal infection model using polyinosinic‐polycytidylic acid (Poly(I:C)) to determine the relationship between the maternal breeding environment and behavioral changes in the offspring. We purchased pregnant C57BL/6J mice from three breeders and administered Poly(I:C) (2 mg/kg) intravenously in their tail vein on gestation day 15. The offspring were raised to 8‐12 weeks old and subjected to the acoustic startle tests to compare their startle response intensity, prepulse inhibition levels, and degree of the adaptation of the startle response. No statistical interaction between Poly(I:C) administration and sex was observed for prepulse inhibition; thus, male and female mice were analyzed together. There was a statistical interaction between the breeder origin of offspring and prepulse inhibition; the Poly(I:C) challenge significantly decreased prepulse inhibition levels of the offspring born to the pregnant dams from Breeder A but not those from the other breeders. However, we failed to detect significant inter‐breeder differences in Poly(I:C) effects on startle response and on startle adaptation with the given number of mice examined. The rearing environment of mouse dams has a prominent effect on the Poly(I:C)‐induced prepulse inhibition deficits in this maternal immune activation model., The maternal immune activation (MIA) model using polyinosinic‐polycytidylic acid [Poly(I:C)] is often employed for animal modeling for schizophrenia and/or autism. Here we found a marked inter‐breeder difference in prepulse inhibition of the offspring mice C57BL/6J.

Objectives An enriched environment (EE) has been known to promote structural changes in the brain and enhance learning and emotional performance. However, little is known about the effect of an EE on brain stem functions, such as the micturition function. In this study, we examined whether an EE affects micturition activity in mice. Methods Male C57BL/6J mice were used. We assessed the micturition activity of freely moving mice using a novel system developed in-house. Results During the dark period, but not light, the EE significantly increased voiding frequency, total voided volume, mean voided volume, voiding duration, mean flow rate, and maximum flow rate compared with the control environment. This EE effect on micturition function was associated with habituation to novel environments in the open-field test, but not with amelioration of motor coordination in the rotarod test. Interestingly, even after the mice were withdrawn from the EE, the improvements in micturition function persisted, while other behavioral changes were abolished. The relative value of voiding frequency and total voided volume during the light period, expressed as a percentage of 24 hours, increased with age when mice were reared in a standard environment. However, this age-related change was not observed in mice reared in an EE. Conclusions These results suggest that an EE may promote micturition activity during the active phase of C57BL/6J mice, and its effects persist even after withdrawal from the EE. Furthermore, an EE may mitigate dysfunctions in micturition activity, such as polyuria, during the resting phase in aged mice.

Background Current models of compulsive-like quinine-adulterated alcohol (QuA) drinking in mice, if improved, could be more useful for uncovering the neural mechanisms of compulsive-like alcohol drinking. The purpose of these experiments was to further characterize and improve the validity of a model of compulsive-like QuA drinking in C57BL/6J mice. We sought to determine whether compulsive-like alcohol drinking could be achieved following 2 or 3 weeks of Drinking-in-the-Dark (DID), whether it provides evidence for a robust model of compulsive-like alcohol drinking by inclusion of a water control group and use of a highly concentrated QuA solution, whether repeated QuA exposures alter compulsive-like drinking, and whether there are sex differences in compulsive-like alcohol drinking. Methods Male and Female C57BL/6J mice were allowed free access to either 20% alcohol or tap water for 2 hours each day for approximately 3 weeks. After 2 or 3 weeks, the mice were given QuA (500 μM) and the effect of repeated QuA drinking sessions on compulsive-like alcohol drinking was assessed. 3-minute front-loading, 2 hour binge-drinking, and blood alcohol concentrations were determined. Results Compulsive-like QuA drinking was achieved after 3 weeks, but not 2 weeks, of daily alcohol access as determined by alcohol history mice consuming significantly more QuA than water history mice and drinking statistically nondifferent amounts of QuA than nonadulterated alcohol at baseline. Thirty-minute front-loading of QuA revealed that alcohol history mice front-loaded significantly more QuA than water history mice, but still found the QuA solution aversive. Repeated QuA exposures did not alter these patterns, compulsive-like drinking did not differ by sex, and BACs for QuA drinking were at the level of a binge. Conclusions These data suggest that compulsive-like QuA drinking can be robustly achieved following 3 weeks of DID and male and female C57BL/6J mice do not differ in compulsive-like alcohol drinking.

High-fat diet (HFD)-induced obesity is related to cognitive and memory dysfunction. Much attention was focused on functional foods as a therapeutic strategy to treat cognitive decline by obesity. I...

We recently showed that the treatment with Resveratrol (RES) contrasts the effects of ageing on the skeletal muscle (SKM), reduces the appearance of tubular aggregates (TAs), and improves the fatigue resistance. Since fatigue resistance depends on the SKM capillary network, and RES has been described to improve vascularisation, we analysed the SKM capillarization in naturally age- ing C57BL/6J male mice, fed with 0.04% RES in the diet for 6months, which showed a better fatigue resistance in a previous work. Our data show an inverse correlation between the number of capillaries per fibre (CAF) and TAs in both control and treated type IIB fibres, and an increase of CAF in ageing SKM upon RES-treatment. The present work suggests that capillarization is one of the determinants of the development of TAs and fatigue resistance, and that RES can be con- sidered a good candidate to counteract capillary rarefaction in the SKM tissue.

The chronic unpredictable mild stress (CUMS) model of depression in mice is a model commonly used to investigate stress-induced depressive-like behaviours. The duration of the stress-inducing procedure is variable, thus making it difficult to compare results and draw general conclusions from different protocols. Here, we decided to investigate how the duration of the CUMS procedure affects behavioural changes, body weight as well as the level of plasma corticosterone in stressed and nonstressed C57BL/6J mice subjected to CUMS for 18 or 36 days. We found that 18 days of CUMS induced a robust decrease in grooming time in the splash test and a significant increase in the immobility time in the tail suspension test (TST) and the forced swim test (FST). All of these stress-induced depression-related behavioural effects diminished or even disappeared after 36 days of CUMS. Plasma corticosterone levels were increased in the CUMS mice compared to those in the nonstressed mice. However, this effect was more pronounced in mice stressed for 18 days. On the other hand, a gradual decline in weight loss in the stressed animals was observed as the duration of the CUMS procedure increased. Altogether, the results indicate that 18 days of CUMS did not affect body weight but caused significant behavioural effects as well as a robust increase in corticosterone levels, while 36 days of CUMS induced significant reduction in weight gain but only slight or even non-significant behavioural effects. These results may indicate the presence of adaptive changes to the long-term CUMS procedure in C57BL/6J mice.

The chemopreventive effects of various mixed cereal grain (MCG) samples on azoxymethane (AOM, 10 mg/kg) and dextran sulfate sodium (DSS, 2% w/v)-induced colorectal cancer (CRC) in C57BL/6J mice were studied. The main MCG preparation consisted of fermented brown rice (FBR), glutinous brown rice, glutinous Sorghum bicolor, glutinous Panicum miliaceum, Coix lacryma-jobi and black soybean at an appropriate mixing ratio. Other MCG preparations contained rice coated with 5% Phellinus linteus and 5% Curcuma longa (MGR-PC), or 10% Phellinus linteus (MCG-P), or 10% Curcuma longa (MCG-C). Consumption of dietary MCG-PC by CRC mice significantly increased colon length, decreased the ratio of colon weight to length, and reduced the number of colon tumors. Similar effects, although to a lower extent, were observed in CRC mice fed with MCG-P, followed by those fed with MCG-C, MCG, FBR or white rice (WR). MCG-PC significantly suppressed colonic neoplasia, and decreased the levels of various cytokines (tumor necrosis factor: Tnf, interleukin 1 beta: Il1b, interleukin 6: Il6, and interferon gamma: Ifng) in serum and colon tissue of the CRC mice. In addition, MCG-PC increased the mRNA expressions of tumor protein p53(Tp53) and cyclin-dependent kinase inhibitor 1A(Cdkn1a), activated pro-apoptotic caspase 3(Casp3), and reduced expression of both mRNA and protein of inducible inducible nitric oxide synthase 2 (Nos2), prostaglandin-endoperoxide synthase 2 (Ptgs2), and cyclin D1(Ccnd1) in colon tissue. These findings suggest that than compared with other cereal grain preparations, MCG-PC had a greater activity against AOM/DSS-induced CRC by reducing intestinal inflammation, and modulating the expression of certain carcinogenesis related factors (Nos2, Ptgs2, Tp53, Cdkn1a, Ccnd1 and Casp3) in colon tissue of CRC mice.

Aim: The measurement of glomerular filtration rate (GFR) in experimental rodents is pivotal to understanding the progression of kidney disease and benefits of treatment strategies. A non‐invasive clearance device has been developed, which measures transcutaneous decay of injected FITC‐sinistrin in conscious rodents. The technique was validated against the well‐established plasma clearance method in the same mice, but on consecutive days, using only models of uninephrectomy and polycystic kidney disease. We aimed to validate this widely used technique in the same lean or obese mice, at the same time. Methods: Five‐week‐old male C57BL/6J mice were randomised to a high fat diet (n = 12) or normal diet (n = 11) for 10 weeks. Transcutaneous and plasma clearance of FITC‐sinistrin were measured simultaneously in each mouse. Results: In lean mice, there was a positive correlation between transcutaneous and plasma derived GFR (P

Objectively recognizing postoperative pain in mice is challenging, making it difficult to determine an appropriate postoperative analgesic regimen. Adult male mice produce ultrasonic vocalizations after exposure to adult female urine (FiUSV). To determine if FiUSV can be used as a indicator of postoperative pain, FiUSV produced by male C57BL/6J mice were assessed for 5 d before and after vasectomy or sham surgery with or without sustained-release buprenorphine. Postoperative pain was assessed by monitoring vocalization using an ultrasonic microphone and by evaluating orbital tightness, posture, and piloerection at postoperative time points. Before vasectomy or sham surgery, 25 of 38 male mice produced FiUSV on 4 of 5 d (143 ± 93 FiUSV). Vasectomized mice without postoperative analgesia produced significantly fewer FiUSV (59 ± 26 FiUSV) compared with baseline (212 ± 102 FiUSV) at 4 h postoperatively, but returned to baseline by 28 h. Vasectomized mice treated with buprenorphine and sham-surgery mice had no change in FiUSV from baseline at any time point after surgery. Activity was decreased compared with baseline in vasectomized mice, regardless of receiving postoperative analgesia or not, but only at the 4-h time point. There were no differences in behavior scores between vasectomized mice and sham-surgery mice at any time point. These results show that FiUSV can be used to detect postoperative pain in male C57BL/6J mice after vasectomy.

Persons suffering from opioid use disorder (OUD) experience long-lasting dysphoric symptoms well into extended periods of withdrawal. This protracted withdrawal syndrome is notably characterized by heightened anxiety and hyperkatifeia. Here we investigated if an exacerbated withdrawal model of acute morphine dependence results in lasting behavioral adaptation 6 weeks into forced abstinence in C57BL/6J mice. We found that our exacerbated morphine withdrawal paradigm produced distinct alterations in behavior in elevated-plus maze (EPM), open field, and social interaction tests in male and female mice. Following protracted withdrawal male mice showed enhanced exploration of the open arms of the EPM, reduced latency to enter the corner of the OF, and a social interaction deficit. In contrast, female mice showed enhanced thigmotaxis in the OF. Both sexes showed that protracted withdrawal enhanced locomotor behavior in response to subsequent morphine challenge, albeit at different doses. These findings will be relevant for future investigation examining the neural mechanisms underlying these behaviors, and will aid in uncovering physiological sex differences in response to opioid withdrawal.

Oil enrichment with trace amounts of components has significant effects on animal nutrition and health. In this work, the potential impact of sinapine, a trace amount of polyphenol naturally present in rapeseeds, was investigated in high-fat diet (HF)-fed C57BL/6J mice. The mice were fed with different diets including chow diet (LF), HF diet, rapeseed oil-containing HF diet (RO), and rapeseed oils enriched with sinapine (500 mg kg−1 oil, high-fat diet, RP) for 12 weeks. Here, it was demonstrated that sinapine supplementation significantly reduced (P < 0.05) body weight increase, fat accumulation, and fatty liver formation in mice when compared with those fed with a high-fat diet. The TG, LDL-C, ALT and AST levels in the RP group were significantly reduced (P < 0.05) by 15.67%, 73.62%, 20.67%, and 31.58%, respectively, compared with that in the HF group. Besides, the addition of sinapine prevented the degeneration of mouse adipocytes and lipid accumulation in the liver. Moreover, this change was achieved by downregulating SREBP-1c and FAS and upregulating PPAR-α and ACOX1 gene expression levels. Our results indicate that sinapine can be used as a prebiotic to enhance the nutritional function of vegetable oils to prevent obesity-related chronic diseases such as NAFLD.

Superovulation is used to stimulate the production and release of large amounts of oocytes in mice by using two hormones that mimic FSH (PMSG) and LH (hCG) effects. Since superovulation can have a negative impact on oocyte and embryo development, this investigation aimed to compare two alternatives for 2-cells embryo collection in order to reduce the number of females and to benefit from the superovulation process. Data from mouse embryo collection from our facility was analyzed to compare the number of 2-cells embryos collected at 1.5 dpc and the number of 2-cells embryos obtained after overnight incubation of 1-cell embryos, collected at 0.5 dpc. Genetically modified mouse strains with a similar background (C57BL/6J, B6*129 and FVB/NJ) were analyzed and for strains at a C57BL/6J and B6*129 background, the number of 2-cells embryos obtained after incubation was significantly higher when compared to the number of 2-cells embryos collected at 1.5 dpc (1.4-fold and 1.7-fold, respectively). C57BL/6J wild type mice had similar results with a higher number of 2-cells embryos when collection was performed at 0.5 dpc followed by incubation (1.4-fold). These results can help the planning of 2-cells embryo harvesting by reducing the number of females needed for this procedure.

Purpose: Analgesic treatment with diclofenac deteriorates bone structure and decreases biomechanical properties. This bone loss has been though to be reversed by training. The impact of exercise on bone treated with diclofenac (DF) has reminded elusive. In the present study, we assayed the combined impact of exercises and DF on mouse femur. Methods: The femur samples we obtained from 30 days treated C57BL/6J female mice. The training group ran on a horizontal treadmill at 12 m/min by 30 min a day (5% grade/slope). The group of ten mice treated with DF received the drug subcutaneously every day (5 mg/kg of body weight/day). The combined group ran on the treadmill and obtained DF. After 30 days, we sacrificed mice and studied their femurs using microcomputed tomography (µCT), dynamic mechanical analysis (DMA) and nanoindentation. Results: We observed that treadmill running and DF decreased trabecular bone volume and mineral density. Combined effect of training and DF was not additive. A significant interaction of both parameters suggested protective effect of training on bone loss provoked by DF. The femur cortical bone shell remained untouched by the training and treatment. The training and the DF treatment did not alter the storage modulus E' significantly. The unchanged storage modulus would be suggesting on the unaltered bone strength. Conclusions: We concluded that even relatively short time of training with concomitant DF treatment could be protective on trabecular bone. Although viscoelastic properties of the entire femur were not modulated, femur trabecular tissue was thinned by treatment with DF and protected by training.

Sex differences in running behaviors between female and male mice occur naturally in the wild. Recent experiments using head‐fixed mice on a voluntary running wheel have exploited analogous locomotor activity to gain insight into the neural underpinnings of a number of behaviors ranging from spatial navigation to decision‐making. It is however largely unknown if sex differences exist between females and males in a head‐fixed experimental paradigm. To address this, we characterized locomotor activity in head‐fixed female and male C57BL/6J mice on a voluntary running wheel. First, we found that over the initial 7‐day period, on average, animals increased both the velocity and the time spent running. Furthermore, we found that female mice habituated to running forward over the initial 2 days of encountering the wheel, while male mice took up to 4 days to habituate to running forward. Taken together, we characterized features of a sexually divergent behavior in head‐fixed running that should be considered in experiments employing female and male mice., Over a 7‐day period of exposure to a voluntary running wheel, head‐fixed animals significantly increased the velocity and the amount of time with which they ran. During this period, a difference was found in the time female mice run forward as compared to males. The sex‐specific differences were abolished by day 5, at which point both males and females consistently ran in the forward direction. These data suggest sexually dimorphic behaviors occur during early exposure to head‐fixed running.

The exploration of thrombotic mechanisms relies on the application of blood collection methods from laboratory mice with a minimal pre-activation of platelets and the clotting system. So far, very little is known on how the blood collection method and the anticoagulant used influence pre-activation of mouse platelets and coagulation. To determine the most suitable blood collection method, we systematically compared blood collection by heart puncture

Background: Binge alcohol drinking has been characterized as a key feature of alcoholism. The drinking‐in‐the‐dark (DID) preclinical model, a procedure that promotes high levels of ethanol (EtOH) intake in short periods of time, has been extensively used to investigate neuropharmacological and genetic determinants of binge‐like EtOH consumption. Using DID methodology, alcohol‐preferring strains of mice such as C57BL/6J (B6) mice consume enough EtOH to achieve blood concentrations (≥1.0 mg/ml) associated with behavioral intoxication (i.e., motor incoordination). DID procedures typically involve the use of socially isolated animals (single‐housed prior to and during the experiment). Previous research indicates that stress associated with social isolation can induce anxiety‐like behavior and promote increases in EtOH intake. The present study investigates the role of housing conditions in anxiety‐like behavior and binge‐like EtOH intake using a DID procedure. Methods: Male and female B6 mice were isolated or pair‐housed for a period of 6 weeks prior to evaluation of anxiety‐like (elevated plus maze, light and dark box, open field) and drinking (water, 10% sucrose, 10 to 30% EtOH) behavior. In order to measure intake, a variation of the standard DID procedure using a removable, transparent, and perforated plastic barrier strip (designed to temporarily divide the cage in 2) was introduced. This allowed for individual intake records (2‐hour test) of isolated and socially housed animals. Results: Increased anxiety‐like behavior and reduced sucrose consumption were found in isolated mice. The effects of housing conditions on EtOH intake were sex‐ and concentration‐dependent. In male mice, isolation increased 20 and 30% EtOH intake. In females, however, an increased intake of EtOH (30%) was found in socialized animals. No effects of housing or sex were found at EtOH 10%. Conclusions: Together with previous literature, the present study suggests that social isolation can promote anxiety‐associated behavior and produce sex‐dependent changes in binge‐like EtOH consumption.

The research on strain-, sex-, and stress-specific differences in structural and functional connectivity of the brain is important for elucidating various behavioral features and etiologies of psychiatric disorders. Socially impaired BTBR mice are considered a model of autism spectrum disorders. Here we present high-resolution magnetic resonance imaging data from the brain of 89 adolescent mice (C57BL/6J and BTBR) in axial, sagittal, and coronal views. The study [1] includes both females and males differed in early-life experience (normally reared or subjected to prolonged maternal separation: 3 h daily from postnatal day 2 to 15). The MRI data were obtained on a horizontal tomograph Biospec 117/16 instrument with a magnetic field strength of 11.7 T. Thus, multislice Turbo RARE T2-weighted images of the brain were captured in eight groups of mice. Altogether, these data allow to evaluate strain-, sex-, and stress-specific alterations in the volumes of various brain structures and to better understand the relation between brain structural differences and behavioral abnormalities.

International audience; Melatonin, a major signal of the circadian system, is also involved in brain functions such as learning and memory. Chronic melatonin treatment is known to improve memory performances, but the respective contribution of its central receptors, MT1 and MT2, is still unclear. Here, we used new single receptor deficient MT1-/and MT2-/mice to investigate the contribution of each receptor in the positive effect of chronic melatonin treatment on long-term recognition memory. The lack of MT2 receptor precluded memory-enhancing effect of melatonin in the object recognition task and to a lesser extent in the object location task, whereas the lack of MT1 receptor mitigated its effect in the object location task only. Our findings support a key role of MT2 in mediating melatonin's beneficial action on long-term object recognition memory, whereas MT1 may contribute to the effect on object location memory.

Studying aging is important to further understand the molecular mechanisms underlying this physiological process and, ideally, to identify a panel of aging biomarkers. Animals, in particular mice, are often used in aging studies, since they mimic important features of human aging, age quickly, and are easy to manipulate. The present work describes the use of Fourier Transform Infrared (FTIR) spectroscopy to identify an age-related spectroscopic profile of the cardiac and skeletal muscle tissues of C57BL/6J female mice. We acquired ATR-FTIR spectra of cardiac and skeletal muscle at four different ages: 6, 12, 17 and 24 months (10 samples at each age) and analyzed the data using multivariate statistical tools (PCA and PLS) and peak intensity analyses. The results suggest deep changes in protein secondary structure in 24-month-old mice compared to both tissues in 6-month-old mice. Oligomeric structures decreased with age in both tissues, while intermolecular β-sheet structures increased with aging in cardiac muscle but not in skeletal muscle. Despite FTIR spectroscopy being unable to identify the proteins responsible for these conformational changes, this study gives insights into the potential of FTIR to monitor the aging process and identify an age-specific spectroscopic signature.

During the last decades, most of the preclinical neurodegenerative research was performed in mouse models of amyloidosis, tauopathies or alpha-synucleinopathies preferentially maintained on a C57BL/6J background. However, comprehensive neurobehavioural data from C57BL/6J mice outlining the critical point of spontaneous cognitive decline are incomplete. In this study, we aimed for the neurobehavioural phenotyping of hippocampusdependent spatial learning and memory of aging C57BL/6J mice. Neurobehavioural phenotyping was performed by means of a Morris Water Maze (MWM) and a Novel Object Recognition (NOR) test. MWM measurements revealed signs of age-related memory loss in C57BL/6J animals from the age of 6 months onward. The NOR assessment strengthened latter finding by decreasing discrimination indexes (DI) and recognition indexes (RI) starting from the age of 6 months. Taken together, these findings contribute to the current knowledge of spontaneous cognitive behaviours of this perhaps most widely used mouse strain and serve as a benchmark for dementia mouse models to distinguish spontaneous from pathological neurodegenerative behaviour.

Aging is characterized generally by progressive and overall physiological decline of functions and is observed in all animals. A long line of evidence has established the laboratory mouse as the prime model of human aging. However, relatively little is known about the detailed behavioral and functional changes that occur across their lifespan, and how this maps onto the phenotype of human aging. To better understand age-related changes across the life-span, we characterized functional aging in male C57BL/6J mice of five different ages (3, 6, 12, 18, and 22 months of age) using a multi-domain behavioral test battery. Spatial memory and physical activities, including locomotor activity, gait velocity, and grip strength progressively declined with increasing age, although at different rates; anxiety-like behaviors increased with aging. Estimated age-related patterns showed that these functional alterations across ages are non-linear, and the patterns are unique for each behavioral trait. Physical function progressively declines, starting as early as 6 months of age in mice, while cognitive function begins to decline later, with considerable impairment present at 22 months of age. Importantly, functional aging of male C57BL/6J mouse starts at younger relative ages compared to when it starts in humans. Our study suggests that human-equivalent ages of mouse might be better determined on the basis of its functional capabilities.

Introduction: The mechanisms underlying obesity are not fully understood, necessitating the creation of novel animal models for the investigation of metabolic disorders. We have previously found that neurosecretory protein GL (NPGL), a newly identified hypothalamic neuropeptide, is involved in feeding behavior and fat accumulation in rats. However, the impact of NPGL on obesity remains unclear in any animal model. The present investigation sought to elucidate whether NPGL causes obesity in the obesity-prone mouse strain C57BL/6J. Methods: We overexpressed the NPGL-precursor gene (Npgl) in the hypothalamus using adeno-associated virus in male C57BL/6J mice fed normal chow (NC) or a high-calorie diet (HCD). After 9 weeks of Npgl overexpression, we measured adipose tissues, muscle, and several organ masses in addition to food intake and body mass. To assess the effects of Npgl overexpression on peripheral tissues, we analyzed mRNA expression of lipid metabolism-related genes by quantitative RT-PCR. Whole body energy consumption was assessed using an O2/CO2 metabolism measurement before an apparent increase in body mass. Results: Npgl overexpression increased food intake, body mass, adipose tissues and liver masses, and food efficiency under both NC and HCD, resulting in obesity observable within 8 weeks. Furthermore, we observed fat accumulation in adipose tissues and liver. Additionally, mRNA expression of lipid metabolism-related factors was increased in white adipose tissue and the liver after Npgl overexpression. Npgl overexpression inhibited energy expenditure during a dark period. Conclusion: Taken together, the present study suggests that NPGL can act as an obesogenic factor that acts within a short period of time in mice. As a result, this Npgl overexpression-induced obesity can be widely applied to study the etiology of obesity from genes to behavior.

Male C57Bl/6J mice were exposed to daily 24-h illumination over 14 days and daily intragastrically received melatonin (1 mg/kg) or water (placebo). Controls were kept under standard day/night (14/10 h) conditions. Melatonin prevented the development of anemia in mice exposed to continuous illumination, which was proven by higher blood hemoglobin levels by the end of the experiment in melatonin-treated animals in comparison with the placebo group. Studies by the low-field NMR spectrometry detected lower lean body mass, total body water, and especially, fat content (by ~13%) in animals receiving placebo. Melatonin treatment led to an increase in the lean body mass and total body water on day 7 (in comparison with the placebo group) without affecting fat mass. On day 14 of continuous illumination, lean body mass increased in comparison with the corresponding parameter in the control and placebo groups. Melatonin had no effect on the physical endurance of mice exposed to continuous illumination (assessed by the grid hanging test).

Isogenic laboratory mouse strains are used to enhance reproducibility as individuals within a strain are essentially genetically identical. For the most widely used isogenic strain, C57BL/6, there is also a wealth of genetic, phenotypic, and genomic data, including one of the highest quality reference genomes (GRCm38.p6). However, laboratory mouse strains are living reagents and hence genetic drift occurs and is an unavoidable source of accumulating genetic variability that can have an impact on reproducibility over time. Nearly 20 years after the first release of the mouse reference genome, individuals from the strain it represents (C57BL/6J) are at least 26 inbreeding generations removed from the individuals used to generate the mouse reference genome. Moreover, C57BL/6J is now maintained through the periodic reintroduction of mice from cryopreserved embryo stocks that are derived from a single breeder pair, aptly named C57BL/6J Adam and Eve. To more accurately represent the genome of today’s C57BL/6J mice, we have generated ade novoassembly of the C57BL/6J Eve genome (B6Eve) using high coverage, long-read sequencing, optical mapping, and short-read data. Using these data, we addressed recurring variants observed in previous mouse studies. We have also identified structural variations that impact coding sequences, closed gaps in the mouse reference assembly, some of which are in genes, and we have identified previously unannotated coding sequences through long read sequencing of cDNAs. This B6Eve assembly explains discrepant observations that have been associated with GRCm38-based analyses, and has provided data towards a reference genome that is more representative of the C57BL/6J mice that are in use today.

Wheel-running in rodents can mitigate addiction-related effects of drugs of abuse like cocaine. However, conditioned place preference (CPP) experiments have reported conflicting results, a situation warranting further studies. Our purpose was to test whether wheel-running exercise during adolescence could impact the formation and long-term retention of CPP to cocaine in mice. Male C57BL/6 J mice were individually housed either with (n = 32) or without (n = 32) a running wheel from the age of 35 days. Behavioral testing began 3 weeks after such housing, mice underwent a baseline session followed by 10 once-daily conditioning sessions receiving peritoneal injections of 10 mg/kg cocaine and saline on alternate days (n = 16), control mice receiving saline every day (n = 16). One and 21 days after the last conditioning session, they were tested for CPP. Both groups exhibited comparable well-marked cocaine-induced CPP in both post-conditioning tests resulting in a negligible interaction between housing and the pharmacological treatment (η²p < 0.01). These results, along with the discrepancy found in the literature, question the nature (and the robustness) of the effects that exercise induces on CPP to cocaine.

There is increasing evidence that seizures during early development can impact ultrasonic vocalizations (USVs) emitted from neonatal mice. However, most of the effects of early-life seizures have been reported using chemoconvulsants that produce continuous seizures (status epilepticus). In the present study, we evaluated the impact of different seizure frequency loads during early-life vocalization development in C57BL/6J male and female mice. For the high seizure load (HSL) paradigm, we administered 3 flurothyl seizures to mice on postnatal day (PD) 7 through PD11, and recorded USVs on PD12. We found that the induction of seizures across PD7-11 resulted in increased average duration (P 0.05) and cumulative duration (P 0.05) of USVs across both sexes. Call-type analyses indicated several call-type changes, including reduced production of complex call-types from males' HSL condition. For the low seizure load (LSL) paradigm, we induced 3 flurothyl seizures only on PD10 and recorded USVs on PD12. We found no change in any spectral or temporal features of USVs. However, call-type production analyses indicated that both male and female animals from the LSL paradigm also produced changes in call-types. This study provides evidence that the magnitude of communication impairment following seizures is significantly impacted by seizure frequency load early in development.

It is well-documented that melatonin deficiency has been linked to the etiopathogenesis of adolescent idiopathic scoliosis. In this study, we intended to apply melatonin in melatonin-deficient mice to ascertain whether melatonin could reduce the incidence/severity of scoliosis, and investigate the role of melatonin on bone mineral density in scoliosis. A total of 80 mice were divided into 4 groups: 20 quadrupedal mice and 20 bipedal mice served as controls; 20 quadrupedal and 20 bipedal mice received oral melatonin (8 mg/kg BW) daily. After 5th, 10th, 15th and 20th weeks of treatment, radiographs and in vivo micro-CT were used to determine the incidence of scoliosis and bone qualities, respectively. Upon sacrifice, the levels of melatonin were measured in each group. At 20th week, the occurrence of scoliosis was 80%, 30%, 22% and 5% in bipedal, quadrupedal, bipedal + melatonin and quadrupedal + melatonin group, respectively. The trabecular bone quality of the vertebral body was significantly ameliorated in the melatonin-treated bipedal models. Likewise, the number of osteoclasts was significantly less in those treated with melatonin. Our results indicated that melatonin deficiency may be crucial for scoliotic development, and restoration of melatonin levels can prevent scoliotic development with the improvement in bone density.

RATIONALE: Stressful life experiences can persistently increase the motivation for, and consumption of, intensely rewarding stimuli, like cocaine over time. In rodents, intermittent versus continuous exposure to social stress engender opposing changes to reward-related behavior, as measured by consumption of sucrose and cocaine. OBJECTIVE: The present study examines if the effects of intermittent versus continuous social stress on cocaine self-administration in mice parallel those seen in rats. METHODS: Both forms of social stress involve a brief daily physical confrontation with an aggressive resident for 10 consecutive days. Continuous social stress involves constant visual and olfactory exposure to an aggressive resident via habitation in a protected portion of the resident’s home cage, while exposure to an aggressive resident during intermittent social stress is limited to a single, physical encounter per day. Implementing a femoral vein catheterization method for the first time in mice, we determined divergent changes to intravenous cocaine self- administration. RESULTS: Modestly increased cocaine self-administration after intermittent social stress was confirmed. In a subset of animals, continuous social stress in mice substantially increased cocaine self-administration and sucrose intake. By stark contrast, another subpopulation had substantial attenuation of cocaine self-administration and sucrose intake after continuous social stress. CONCLUSIONS: Bimodal divergence in responding for rewarding stimuli including cocaine after social stress experience likely reflects two opposing forms of coping to continuous social stress that promote either a sensitization or attenuation of reward seeking.

This study examined a new redox nanoparticle (RNPN) for its ability to protect mice from the life-shortening effect of radiation. A single dose of RNPN was injected subcutaneously into mice 3 or 24 h before whole-body irradiation. Kaplan–Meier survival analysis showed that RNPN given 24 h before whole-body irradiation protected mice against radiation-induced mortality. Histological evaluation of the bone marrow showed that the probable cause of sporadic deaths was bone marrow aplasia. Furthermore, analysis of blood biomarkers revealed abnormalities in the irradiated control group. Such symptoms/indicators of poor health were reduced in RNPN-treated mice.