A model animal showing spontaneous onset is a useful tool for investigating the mechanism of disease. Here, I would like to introduce two aging model animals expected to be useful for neuroscience research: the senescence-accelerated mouse (SAM) and the klotho mouse. The SAM was developed as a mouse showing a senescence-related phenotype such as a short lifespan or rapid advancement of senescence. In particular, SAMP8 and SAMP10 show age-related impairment of learning and memory. SAMP8 has spontaneous spongy degeneration in the brain stem and spinal cord with aging, and immunohistochemical studies reveal excess protein expression of amyloid precursor protein and amyloid β in the brain, indicating that SAMP8 is a model for Alzheimer’s disease. SAMP10 also shows age-related impairment of learning and memory, but it does not seem to correspond to Alzheimer’s disease because senile plaques primarily composed of amyloid β or neurofibrillary tangles primarily composed of phosphorylated tau were not observed. However, severe atrophy in the frontal cortex, entorhinal cortex, amygdala, and nucleus accumbens can be seen in this strain in an age-dependent manner, indicating that SAMP10 is a model for normal aging. The klotho mouse shows a phenotype, regulated by only one gene named α-klotho, similar to human progeria. The α-klotho gene is mainly expressed in the kidney and brain, and oxidative stress is involved in the deterioration of cognitive function of the klotho mouse. These animal models are potentially useful for neuroscience research now and in the near future.
Tuberculosis (TB) in nonhuman primates is a serious menace to the welfare of the animals and human who come into contact with them, while the rapid, accurate, and robust diagnosis is challenging. In this study, we first sought to establish an appropriate primate TB model resembling natural TB in nonhuman primates. Four rhesus monkeys (Macaca mulatta) of Chinese origin were infected intratracheally with two low doses of M. tuberculosis H37Rv. Regardless of the infectious doses, all monkeys were demonstrated to be successfully infected by clinical assessments, tuberculin skin test conversions, peripheral immune responses, gross observations, histopathology analysis, and M. tuberculosis burdens. Furthermore, we extended the usefulness of this model for assessing the following immunodiagnostic antigens: CFP10, ESAT-6, CFP10-ESAT-6, and an antigen cocktail of CFP10 and ESAT-6. The data showed that CFP10 was an M. tuberculosis-specific, “early” antigen used for serodiagnosis of TB in nonhuman primates. In conclusion, we established a useful primate TB model depending on low doses of M .tuberculosis and affording new opportunities for studies of M. tuberculosis disease and diagnostics.
The Cre/loxP system is a strategy for controlling temporal and/or spatial gene expression through genome alteration in mice. As successful Cre/loxP genome alteration depends on Cre-driver mice, Cre-reporter mice are essential for validation of Cre gene expression in vivo. In most Cre-reporter mouse strains, although the presence of reporter product indicates the expression of Cre recombinase, it has remained unclear whether a lack of reporter signal indicates either no Cre recombinase expression or insufficient reporter gene promoter activity. We produced a novel ROSA26 knock-in Cre-reporter C57BL/6N strain exhibiting green emission before and red after Cre-mediated recombination, designated as strain R26GRR. Ubiquitous green fluorescence and no red fluorescence were observed in R26GRR mice. To investigate the activation of tdsRed, EGFP-excised R26GRR, R26RR, mice were produced through the crossing of C57BL/6N mice with R26GRR/Ayu1-Cre F1 mice. R26RR mice showed extraordinarily strong red fluorescence in almost all tissues examined, suggesting ubiquitous activation of the second reporter in all tissues after Cre/loxP recombination. Moreover, endothelial cell lineage and pancreatic islet-specific expression of red fluorescence were detected in R26GRR/Tie2-Cre F1 mice and R26GRR /Ins1-Cre F1 mice, respectively. These results indicated that R26GRR mice are a useful novel Cre-reporter mouse strain. In addition, R26GRR mice with a pure C57BL/6N background represent a valuable source of green-to-red photoconvertible cells following Cre/loxP recombination for application in transplantation studies. The R26GRR mouse strain will be available from RIKEN BioResource Center (http://www.brc.riken.jp/lab/animal/en/).
Daily consumption of garlic is known to lower the risk of hypertension and ischemic heart disease. In this study, we examined whether aged garlic extract (AGE) prevents hypertension and the progression of compensated left ventricular (LV) hypertrophy in Dahl salt-sensitive (DS) rats. DS rats were randomly divided into three groups: those fed an 8% NaCl diet until 18 weeks of age (8% NaCl group), those additionally treated with AGE (8% NaCl + AGE group), and control rats maintained on a diet containing 0.3% NaCl until 18 weeks of age (0.3% NaCl group). AGE was administered orally by gastric gavage once a day until 18 weeks of age. LV mass was significantly higher in the 8% NaCl + AGE group than in the 0.3% NaCl group at 18 weeks of age, but significantly lower in the 8% NaCl + AGE group than in the 8% NaCl group. No significant differences were observed in systolic blood pressure (SBP) between the 8% NaCl and 8% NaCl + AGE groups at 12 and 18 weeks of age. LV end-diastolic pressure and pressure half-time at 12 and 18 weeks of age were significantly lower in the 8% NaCl + AGE group compared with the 8% NaCl group. AGE significantly reduced LV interstitial fibrosis at 12 and 18 weeks of age. Chronic AGE intake attenuated LV diastolic dysfunction and fibrosis without significantly decreasing SBP in hypertensive DS rats.
Cationic amino acid transport activity in a canine lens epithelial cells (LEC) line was investigated. The transporter activity of arginine was 0.424 ± 0.047 nmol/mg protein min, while the presence of N-ethylmaleimide, an inhibitor of the canine cationic amino acid transporter (CAT), reduced transport activity by 30%. A full-length cDNA sequence of canine CAT1 was 2558 bp long and was predicted to encode the 629 amino acid polypeptides. The deduced amino acid sequence of canine CAT1 showed similarities of 92.1% and 88.6% to those of the human and mouse, respectively. Western blot analysis detected a band at 70 kDa in a membrane protein sample of LEC. RT-PCR analysis confirmed that CAT1 was ubiquitously detected in all tissues examined.
Adipose tissues are closely connected with the immune system. It has been suggested that metabolic syndromes such as type 2 diabetes, arteriosclerosis and liver steatosis can be attributed to adipose tissue inflammation characterized by macrophage infiltration. To understand a physiological and pathological role of natural killer T (NKT) cells on inflammation in adipose tissue, we characterized a subset of NKT cells in abdominal and subcutaneous adipose tissues in C57BL/6J mice fed normal or high-fat diets. NKT cells comprised a larger portion of lymphocytes in adipose tissues compared with the spleen and peripheral blood, with epididymal adipose tissue having the highest number of NKT cells. Furthermore, some NKT cells in adipose tissues expressed higher levels of CD69 and intracellular interferon-γ, whereas the Vβ repertoires of NKT cells in adipose tissues were similar to other cells. In obese mice fed a high-fat diet, adipose tissue inflammation had little effect on the Vβ repertoire of NKT cells in epididymal adipose tissues. We speculate that the NKT cells in adipose tissues may form an equivalent subset in other tissues and that these subsets are likely to participate in adipose tissue inflammation. Additionally, the high expression level of CD69 and intracellular IFN-γ raises the possibility that NKT cells in adipose tissue may be stimulated by some physiological mechanism.
Here, to determine the effects of transport stress on blood parameters in dogs, we investigated the changes in hematologic and serum chemical parameters in healthy beagle dogs transported from Beijing, China, to Osaka, Japan, to obtain the background data. Only the activity of serum alkaline phosphatase increased clearly upon arrival, a change attributed to transport stress, but the activity gradually reduced afterward. No marked changes in levels of other blood parameters were noted. Our findings here suggest that alkaline phosphatase is a useful tool for studying transport stress.
The waltzer (v) mouse mutant harbors a mutation in Cadherin 23 (Cdh23) and is a model for Usher syndrome type 1D, which is characterized by congenital deafness, vestibular dysfunction, and prepubertal onset of progressive retinitis pigmentosa. In mice, functionally null Cdh23 mutations affect stereociliary morphogenesis and the polarity of both cochlear and vestibular hair cells. In contrast, the murine Cdh23ahl allele, which harbors a hypomorphic mutation, causes an increase in susceptibility to age-related hearing loss in many inbred strains. We produced congenic mice by crossing mice carrying the v niigata (Cdh23v-ngt) null allele with mice carrying the hypomorphic Cdh23ahl allele on the C57BL/6J background, and we then analyzed the animals’ balance and hearing phenotypes. Although the Cdh23v-ngt/ahl compound heterozygous mice exhibited normal vestibular function, their hearing ability was abnormal: the mice exhibited higher thresholds of auditory brainstem response (ABR) and rapid age-dependent elevation of ABR thresholds compared with Cdh23ahl/ahl homozygous mice. We found that the stereocilia developed normally but were progressively disrupted in Cdh23v-ngt/ahl mice. In hair cells, CDH23 localizes to the tip links of stereocilia, which are thought to gate the mechanoelectrical transduction channels in hair cells. We hypothesize that the reduction of Cdh23 gene dosage in Cdh23v-ngt/ahl mice leads to the degeneration of stereocilia, which consequently reduces tip link tension. These findings indicate that CDH23 plays an important role in the maintenance of tip links during the aging process.
Adiponectin and its receptors have been demonstrated to play important roles in regulating glucose and lipid metabolism in mice. Obesity, type II diabetes and cardiovascular disease are highly correlated with down-regulated adiponectin signaling. In this study, we generated mice overexpressing the porcine Adipor1 transgene (pAdipor1) to study its beneficial effects in metabolic syndromes as expressed in diet-induced obesity, hepatosteatosis and insulin resistance. Wild-type (WT) and pAdipor1 transgenic mice were fed ad libitum with a standard chow diet (Chow) or a high-fat/sucrose diet (HFSD) for 24 weeks, beginning at 6 to 7 weeks of age. There were 12 mice per genetic/diet/sex group. When challenged with HFSD to induce obesity, the pAdipor1 transgenic mice resisted development of weight gain, hepatosteatosis and insulin resistance. These mice had lowered plasma adiponectin, triglyceride and glycerol concentrations compared to WT mice. Moreover, we found that (indicated by mRNA levels) fatty acid oxidation was enhanced in skeletal muscle and adipose tissue, and liver lipogenesis was inhibited. The pAdipor1 transgene also restored HFSD-reduced phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose transporter 4 mRNA in the adipose tissues, implying that the increased Pck1 may promote glyceroneogenesis to reduce glucose intolerance and thus activate the flux of glyceride-glycerol to resist diet-induced weight gain in the adipose tissues. Taken together, we demonstrated that pAdipor1 can prevent diet-induced weight gain and insulin resistance. Our findings may provide potential therapeutic strategies for treating metabolic syndromes and obesity, such as treatment with an ADIPOR1 agonist or activation of Adipor1 downstream targets.