Experimental Animals最新文献

Royal jelly (RJ) is recognized due to its high nutritional value and potential health benefits. Previous research showed that RJ supplementation decreased fat accumulation, resulting in weight loss and improvements in hyperglycemia and insulin resistance in high-fat diet (HFD)-induced obese mice. To expand the weight-reducing properties of RJ, this study aimed to investigate the effects of RJ supplementation on HFD-induced obese mice with impaired sleep stabilization. Over a 20-week period, the C57BL/6J mice were divided into the following dietary groups: normal diet (ND), ND supplemented with 5% lyophilized RJ powder (ND+RJ), HFD, and HFD supplemented with 5% lyophilized RJ powder (HFD+RJ) groups. Compared with the HFD group, the HFD+RJ group exhibited a significant reduction in body weight via a decrease in fat mass. Moreover, much like the ND group, the HFD+RJ group demonstrated improvements in the fragmentation of non-rapid eye movement (NREM) sleep and wakefulness. These processes contributed to the reestablishment of sleep/wake continuity and restored the overall stability of sleep. In contrast, the ND+RJ and ND groups exhibited a similar sleep/wake architecture. Thus, RJ supplementation in the ND demonstrated no substantial effect on sleep/wake. According to these findings, dietary RJ improves the sleep/wake architecture and restores sleep stability. Hence, RJ is a promising dietary component for addressing obesity and restoring sleep stability.

Wistar-SD Hypercholesterolemia (WSHc) Rat is a novel hyperlipidemia-susceptible rat that we discovered and bred earlier, which can be used as an ideal animal model for the study of non-alcoholic fatty liver disease (NAFLD). However, its pathogenesis of hyperlipidemia and genetic and biological characteristics need to be further investigated. In the current study, WSHc rats were fed a high-fat diet (HFD) and standard chow (SC), with age-matched Wistar rats as the control group undergoing the same treatment, followed by serum lipid level measurement. It was found that HFD-fed WSHc rats developed dyslipidemia. Transcriptomic analysis was performed to detect genes associated with cholesterol metabolism in the liver, and 119 differentially expressed genes were discovered through bioinformatics analysis and molecular biology verification. Additionally, Srebf1 was identified as a HUB gene and Nr1d1 as an independent key gene using the protein-protein interaction network and one-cluster clustering analysis. The two genes had also been further validated in molecular biology experiments and were consistent with transcriptomic results. Serum lipid metabolomics analysis identified 7 lipid subclasses and 84 lipid molecules using UHPLC-Q-TOF/MS. There were 62 and 70 lipid molecules with significant differences in the metabolic profiles of serum lipid mediators in the WSHc+HFD group compared to the WSHc+SC and Wistar+HFD groups, respectively, and the differential metabolites were mainly produced via sphingolipid and glycerophospholipid metabolism. In sum, the hypercholesterolemia model can be established with WSHc rats after the HFD induction, and the pathogenesis involves the Srebf1 and Nr1d1 genes and the sphingolipid and glycerophospholipid metabolism pathways.

Aging is a complex biological process. Several animal models, including nematodes, Drosophila, and rodents, have been used in research on aging mechanisms and the extension of healthy life expectancy. The present study investigated the physiological and anatomical changes associated with aging in two sub-strains of aged C57BL/6 mice used in aging research: C57BL/6NCrSlc (B6N) and C57BL/6J (B6J). The survival rate before 24 months old (mo) was higher in B6J mice than in B6N mice; however, after 24 mo, it was markedly lower in the former than in the latter. Body weight increased in male C57BL/6 mice until 15-18 mo and in females until 21-24 mo and then began to decrease. Body temperature was lower in B6N mice than in B6J mice until 24 mo. Food and water intakes increased from 18 mo in both strains. The incidence of alopecia was higher in female C57BL/6J mice from 3 mo. Necropsy findings showed a high rate of spontaneous tumors in both sub-strains. The incidence of cutaneous ulcerative infections and hepatic pathologies was significantly higher in the B6N strain. A high incidence of renal lesions was also observed in B6J mice, particularly in males. These results provide insights into the characteristics of these sub-strains and the phenotypic changes associated with aging, which will facilitate the use of aged mice as a quality resource for geriatric and gerontological research.

An unconventional myosin, myosin VI gene (MYO6), contributes to recessive and dominant hearing loss in humans and mice. The Kumamoto shaker/waltzer (ksv) mouse is a model of deafness resulting from a splice-site mutation in Myo6. While ksv/ksv homozygous mice are deaf due to cochlear hair cell stereocilia fusion at the neonatal stage, the hearing phenotypes of ksv/+ heterozygous mice have been less clear. Due to this splicing error, most MYO6 protein expression is lost in ksv mice; however, MYO6 with a single amino acid mutation (p.E461K) remains expressed. In this study, we investigated the hearing phenotypes and effect of a p.E461K mutation in ksv/+ heterozygous mice. Hearing tests indicated that hearing loss in ksv/+ mice arises concurrently at both low and high frequencies. In the low-frequency region, stereocilia fusions were detected in the inner hair cells of ksv/+ mice. Expression analysis revealed abnormal MYO6 expression and localization, along with atypical expression of proteins in the basal region of the stereocilia, suggesting that these abnormalities may contribute to stereocilia fusion in ksv/+ mice. Conversely, although the expression patterns of MYO6 and stereociliary basal-region proteins appeared normal in the cochlear area corresponding to high-frequency sounds, stereocilia loss in the outer hair cells was observed in ksv/+ mice. These findings suggest that the ksv/+ mice exhibit distinct mechanisms underlying hearing loss across areas responsible for low- and high-frequency hearing, differing from those previously reported in heterozygous Myo6 mice with loss-of-function and missense mutant alleles.

Streptozotocin (STZ) is widely used as a pancreatic beta-cell toxin to induce experimental diabetes in rodents. Strain-dependent variations in STZ-induced diabetes susceptibility have been reported in mice. Differences in STZ-induced diabetes susceptibility are putatively related to pancreatic beta-cell fragility via DNA damage response. In this study, we identified two STZ-induced diabetes susceptibility regions in chromosome 11 (Chr11) of Nagoya-Shibata-Yasuda (NSY) mice via congenic mapping using the C3H-11^NSY consomic strains, in which the entire Chr11 of STZ-resistant C3H/He (C3H) mice was replaced with that of NSY mice, and named them STZ susceptibility region for NSY (Ssnsy)-1 and -2, respectively. Screening for variants in the Ssnsy1 region revealed that NSY mice exhibited a characteristic missense c.599G>T (p.G200V) variant in a highly conserved region within the DNA repair gene, RAD50 double-strand break repair protein (Rad50). Subsequently, we generated R2B1-Rad50 knock-in mice, in which c.599T in Rad50 of STZ-susceptible C3H.NSY-R2B1 subcongenic mice was replaced with c.599G via genome editing. Compared with C3H.NSY-R2B1 mice, and R2B1-Rad50 knock-in mice showed suppressed hyperglycemia, incidence of diabetes, and decrease in plasma insulin levels following single high-dose and multiple low-dose injections of STZ. Our results suggest Rad50 as a susceptibility gene for STZ-induced diabetes that is involved in pancreatic beta-cell fragility. Forward genetic approaches using inbred mouse strains with STZ susceptibility as a phenotypic indicator will further elucidate the molecular mechanisms of pancreatic beta-cell destruction via DNA damage response.

In humans, cerebral malaria is the most common cause of malaria-related mortality. Mouse C57BL/6 (B6) sub-strains are the major model system for experimental cerebral malaria (ECM) as they show similar pathophysiology to human cerebral malaria after infection with the rodent malaria parasite Plasmodium berghei ANKA. This model system has been used to analyze the molecular mechanisms of cerebral malaria. To develop new mouse models, we analyzed the ECM susceptibility of NOD/Shi (NOD) and NSY/Hos (NSY) strains established from the non-inbred ICR strain. Both NOD and NSY strains exhibited clinical symptoms and pathologies similar to ECM in C57BL/6J (B6J) mice and died within 11 days of infection. Thus, the NOD and NSY strains are susceptible to ECM and may be useful as new ECM models. The ECM susceptibility of both strains is suggested to be due to homozygosity for the cerebral malaria susceptibility allele of the ECM susceptible ICR strain. Although analyses using B6 sub-strains have proposed that complement component 5 (C5) plays an important role in ECM pathogenesis, we found that C5 was not essential as the ECM susceptible NOD strain is C5 deficient. Thus, results obtained from B6 sub-strains may not reflect the full picture of ECM in mice. Comparative analyses of multiple ECM models will contribute to a more accurate identification of the factors essential for ECM.

Experimental autoimmune encephalomyelitis (EAE) serves as a model for studying multiple sclerosis, with immunization strategies utilizing myelin oligodendrocyte glycoprotein (MOG)_35-55 peptide, emulsified in adjuvant enriched with Mycobacterium tuberculosis (Mtb). This study examined the effects of Bacillus Calmette-Guérin (BCG) as an adjuvant, alongside the impact of MOG_35-55 peptide doses and their residual counter ions on EAE development. We found that BCG can be effectively used to induce EAE with similar incidence and severity as heat-killed H37Ra, contingent upon the appropriate MOG_35-55 peptide dose. Different immunization doses of MOG_35-55 peptide significantly affect EAE development, with higher doses leading to a paradoxical reduction in disease activity, probably due to peripheral tolerance mechanisms. Furthermore, doses of MOG_35-55 peptides with acetate showed a more pronounced effect on disease development compared to those containing trifluoroacetic acid (TFA), suggesting the potential influence of residual counter ions on EAE activity. We highlighted the feasibility of applying BCG to the establishment of EAE for the first time. Our findings emphasized the importance of MOG_35-55 peptide dosage and composition in modulating EAE development, offering insights into the mechanisms of autoimmunity and tolerance. This could have implications for autoimmune disease research and the design of therapeutic strategies.

Physiological responses to inhaled anesthetics vary among species. Therefore, a precise anesthetic technique is important for each individual species. In this study, we focused on the degu (Octodon degus), a small herbivorous rodent. Degus have recently begun to be used as laboratory models for brain research because of certain human-like characteristics, such as spontaneous development of Alzheimer's disease. In this study, we evaluated appropriate induction and maintenance anesthesia conditions for isoflurane and sevoflurane in degus by a stimulation test, electroencephalography (EEG), minimum alveolar concentration (MAC), and vital signs. During induction, more rapid time to loss of the righting reflex and deeper anesthesia in degus were observed in isoflurane. The MAC value for degus were 1.75 ± 0.0% in isoflurane and 2.25 ± 0.27% in sevoflurane. Whereas some degus were awake during maintenance anesthesia using both anesthetics at concentrations of ≤2%, no rats were awake when using sevoflurane at a concentration of 2%. The duration of the total flat EEG, a measure of the depth of maintenance anesthesia, was longer for isoflurane than for sevoflurane. Furthermore, higher concentrations of both anesthetics suppressed the respiratory rate in degus. These new findings regarding inhalation anesthesia in degus will contribute to future developments in the fields of laboratory animals and veterinary medicine.

Laboratory rats, like mice, are a type of animal commonly used in scientific investigations as well as in basic aging and geriatric research. The selection of a rat strain is an important first step in the planning and design of an experiment due to physiological, anatomical, and ethological variations in each strain, which may significantly modify the expected results. In the present study, we characterized age-related changes, from 3 months old (mo) to 24 mo, in three male rat strains commonly used in medical research: RccHan^®️:WIST (RccHan:WIST), F344/NSlc (F344), and Slc:SD Rat (SD). The body weight, water/food consumption, and survival rate of each strain were physiologically evaluated. Hematological and biochemical values were analyzed every three months. Hematological results showed a decrease in lymphocytes and increases in other leukocytes from 12 mo in F344 and SD rats. The incidence of hematological disorder was 10-15% in F344 and SD rats from 18 mo. Increases in hepatic biochemical parameters (alanine transaminase (GPT/ALT) and aspartate transaminase (GOT/AST)) and cytopathological parameters (creatine phosphokinase (CPK)) were observed in male F344 rats at 12 mo. Triglycerides (TG) serum levels were significantly elevated in the 12 mo RccHan:WIST rats, while Lipase (LIP) levels were significantly reduced in 24 mo. The present results revealed significant variations in hematological and biochemical values in the different laboratory male rat strains due to genetic and nutritional-metabolic factors specific to each strain.

Secondary brain injury (SBI) is one of the main causes of high mortality and disability rates following intracerebral hemorrhage (ICH). Tumor necrosis factor receptor-associated factor 6 (TRAF6) plays a crucial role in the process of pyroptosis, and modulating its expression may present a novel therapeutic strategy for mitigating brain injury. This study aims to explore the mechanisms of TRAF6 in pyroptosis after ICH. C57BL/6J mice were used to establish the ICH model. Brain was collected at different time points for q-PCR and western blot to detect the level of TRAF6. After the C25-140 (the TRAF6 inhibitor) was administrated, the mice were divided into four groups. Then, the neurological deficit, brain water content, and blood-brain barrier (BBB) damage were detected. Immunofluorescence and western blot were used to detect the level of pyroptosis proteins, and ELISA and q-PCR were used to detect the levels of IL-18 and IL-1β. TRAF6 expression was upregulated after ICH and was mainly expressed in neurons. Inhibition of TRAF6 expression with C25-140 alleviated neurological deficits and reduced brain edema after ICH. In addition, inhibition of TRAF6 also reduced the expression of pyroptosis inflammasomes such as GSDMD, NLRP3, and ASC, as well as neurological damage caused by IL-18 and IL-1β after ICH. TRAF6 regulates neuronal pyroptosis in SBI after ICH. Inhibition of TRAF6 may be a potential target for alleviating inflammatory damage after ICH.