Like humans, songbirds are one of the few animal groups that learn vocalization. Vocal learning requires coordination of auditory input and vocal output using auditory feedback to guide one’s own vocalizations during a specific developmental stage known as the critical period. Songbirds are good animal models for understand the neural basis of vocal learning, a complex form of imitation, because they have many parallels to humans with regard to the features of vocal behavior and neural circuits dedicated to vocal learning. In this review, we will summarize the behavioral, neural, and genetic traits of birdsong. We will also discuss how studies of birdsong can help us understand how the development of neural circuits for vocal learning and production is driven by sensory input (auditory information) and motor output (vocalization).

View full abstract

Exon II of glucokinase (Gk) was deleted to produce a systemic heterozygous Gk knockout (Gk^+/−) mouse. The relative expression levels of Gk in the heart, lung, liver, stomach, and pancreas in Gk^+/− mice ranged from 0.41–0.68 versus that in wild (Gk^+/+) mice. On the other hand, its expression levels in the brain, adipose tissue, and muscle ranged from 0.95–1.03, and its expression levels in the spleen and kidney were nearly zero. Gk knockout caused no remarkable off-target effect on the expression of 7 diabetes causing genes (Shp, Hnf1a, Hnf1b, Irs1, Irs2, Kir6.2, and Pdx1) in 10 organs. The glucose tolerance test was conducted to determine the blood glucose concentrations just after fasting for 24 h (FBG) and at 2 h after high-glucose application (GTT2h). The FBG-GTT2h plots obtained with the wild strain fed the control diet (CD), Gk^+/− strain fed the CD, and Gk^+/− strain fed the HFD were distributed in separate areas in the FBG-GTT2h diagram. The respective areas could be defined as the normal state, prediabetes state, and diabetes state, respectively. Based on the results, the criteria for prediabetes could be defined for the Gk^+/− strain developed in this study.

View full abstract

The DBA/2J strain is a model for early-onset, progressive hearing loss in humans, as confirmed in the present study. DBA/2J mice showed progression of hearing loss to low-frequency sounds from ultrasonic-frequency sounds and profound hearing loss at all frequencies before 7 months of age. It is known that the early-onset hearing loss of DBA/2J mice is caused by affects in the ahl (Cdh23^ahl) and ahl8 (Fscn2^ahl8) alleles of the cadherin 23 and fascin 2 genes, respectively. Although the strong contributions of the Fscn2^ahl8 allele were detected in hearing loss at 8- and 16-kHz stimuli with LOD scores of 5.02 at 8 kHz and 8.84 at 16 kHz, hearing loss effects were also demonstrated for three new quantitative trait loci (QTLs) for the intervals of 50.3–54.5, 64.6–119.9, and 119.9–137.0 Mb, respectively, on chromosome 5, with significant LOD scores of 2.80–3.91 for specific high-frequency hearing loss at 16 kHz by quantitative trait loci linkage mapping using a (DBA/2J × C57BL/6J) F₁ × DBA/2J backcross mice. Moreover, we showed that the contribution of Fscn2^ahl8 to early-onset hearing loss with 32-kHz stimuli is extremely low and raised the possibility of effects from the Cdh23^ahl allele and another dominant quantitative trait locus (loci) for hearing loss at this ultrasonic frequency. Therefore, our results suggested that frequency-specific QTLs control early-onset hearing loss in DBA/2J mice.

View full abstract

The main objective of this study was to compare the effects of ketamine and xylazine in aging rats when coadministered intraperitoneally at high anesthetic doses. Three groups (n=6 rats/group) consisting of rats at 3, 6 and 12 months of age were used. During anesthesia, animals were monitored for heart rate, respiratory frequency, blood oxygen saturation, and rectal temperature. The corneal and paw withdrawal reflex were also examined during anesthesia. During anesthesia, withdrawal and corneal reflexes were absent for progressively longer durations with increasing age. Significant decreases in cardiac and respiratory frequency and, blood oxygen saturation occurred for the 6- and 12-month-old animals. Respiratory frequency and blood oxygen saturation returned to normal at the end of the anesthesia; however, the significant decrease in cardiac frequency persisted in the 6- and 12-month-old animals. Rectal temperature was decreased significantly only in the 3-month-old animals. Pulmonary edema and effusion occurred in 50% of the 12-month-old animals. In conclusion, if ketamine-xylazine are used for anesthesia, the doses should be optimized for the age of the subjects prior to initiation of the research project.

View full abstract

The fifth component of complement (C5) is considered to be the center of complement activation and function. However, there are no genetically engineered knockout mice for this gene, and the only commercially available inherited C5-deficient mice, in which a “TA” nucleotide deletion in the coding frame was previously identified, are in theC57BL/10Sn genetic background rather than the commonly used backgrounds C57BL/6 and BALB/c. Therefore, these mice must be backcrossed into the desired genetic background. Here, we developed an ARMS (amplification refractory mutation system) PCR method using a specific primer pair that was able to discriminate between the genotypes when the resulting product was analyzed by agarose gel electrophoresis. These results were supported by quantitative RT-PCR and semi-quantitative PCR and were consistent with the results from sequencing each backcrossed generation. Using ARMS-PCR method, we generated C5-deficient mice in the C57BL/6 background over 9 backcrossed generations and further verified the phenotype using complement-mediated hemolytic assays. In this study, we describe a simple, rapid and reliable PCR-based method for genotyping inherited C5-deficient mice that may be used to backcross C57BL/10Sn mice into other genetic backgrounds.

View full abstract

This study was conducted to examine any changes caused by feed restriction in dogs to contribute to safety evaluation in toxicity studies. Two male 7-month-old beagle dogs/group were fed 300 (control), 150 (50% of control), or 70 g/animal of diet daily (23% of control) for 4 weeks. Effects of feed restriction, except for clinical signs, were noted depending on the feed dosage in almost all examinations. The principal outcomes were: decreased body weight and water consumption, ECG changes (decreased heart rate and prolonged QTc), and hematopoietic and lymphopoietic suppression (decreased reticulocyte ratio or white blood cell count in hematology, decreased nucleated cell count in bone marrow, decreased erythroid parameters in myelography, and hypocellularity of bone marrow and thymic atrophy in histopathology). In addition, some changes were noted in urinalysis (decreased urine volume and sodium and potassium excretion), blood chemistry (decreased ALP and inorganic phosphorus and increased creatinine), organ weights, and gastric histopathology. These results provide important reference data for distinguishing the primary effects of test compounds from secondary effects of decreased food consumption in toxicity studies in beagle dogs.

View full abstract

Animal welfare depends on the possibility to express species-specific behaviours and can be strongly compromised in socially and environmentally deprived conditions. Nesting materials and refuges are very important resources to express these behaviours and should be considered as housing supplementation items. We evaluated the effects of one item of housing supplementation in standard settings in laboratory mice. C57BL/6JOlaHsd (B6) and BALB/cOlaHsd (BALB) young male and female mice, upon arrival, were housed in groups of four in standard laboratory cages and after 10 days of acclimatization, a red transparent plastic triangular-shaped Mouse House™ was introduced into half of the home cages. Animals with or without a mouse house were observed in various contexts for more than one month. Body weight gain and food intake, home cage behaviours, emotionality and response to standard cage changing procedures were evaluated. The presence of a mouse house in the home cage did not interfere with main developmental and behavioural parameters or emotionality of BALB and B6 male and female mice compared with controls. Both strains habituated to the mouse house in about a week, but made use of it differently, with BALB mice using the house more than the B6 strain. Our results suggest that mice habituated to the mouse house rather quickly without disrupting their home cage activities. Scientists can thus be encouraged to use mouse houses, also in view of the implementation of the EU Directive (2010/63/EU).

View full abstract

Primary dysmenorrhea (PD) is a common gynecological disorder. Hitherto, animal models which recapitulate clinical features of PD have not been fully established. We aimed to examine whether a pain model in mice could mimic the clinic features of PD. After pretreated with estradiol benzoate (1 mg/kg/day) intraperitoneally (i.p.) for 3 consecutive days, non-pregnant female Imprinting Control Region mice (6–8 weeks old) was injected with 0.4 U of oxytocin to induce the stretching or writhing response which was recorded for a time period of 30 min. During the writhing period, the uterine artery blood flow alterations were examined by Doppler ultrasound detection. After writhing test, the uterine morphological changes were observed by hematoxylin and eosin (H&E) staining histopathology. In addition, enzyme-linked immunosorbent assay kit was used to measure the levels of prostaglandins F_2α/prostaglandins E₂ (PGF_2α/PGE₂) and TXB₂ (a metabolite of TXA₂)/6-keto-PGF_1α (a metabolite of PGI₂) in the uterine tissue homogenates and plasma, respectively. Western blot analyses were performed to determine the expressions of oxytocin receptor (OTR), beta2-adrenergic receptor (beta2-AR), and cyclooxygenase-2 (COX-2) in uterine, which are responsible for the uterine contraction. The writhing response only occurred in the estrogen pretreated female mice. The area of uterine myometrium significantly decreased along with the increased thickness in the oxytocin-induced estrogen pretreated mice model. The uterine artery blood flow velocity dropped, while the pulsatility index and resistance index slightly increased after the injection of oxytocin. The PGF_2α/PGE₂ level significantly increased and the plasma TXB₂/6-keto-PGF_1α level significantly enhanced. Compared with the control group, the uterine histopathology demonstrated moderate to severe edema of endometrium lamina propria. In consistent with the uterine morphological changes, a significant reduction of beta2-AR and a significant increase of OTR and COX-2 in the uterine tissue were observed. The writhing response was caused by the abnormal contraction of uterus. The uterine spasm and ischemia changes of oxytocin-induced estrogen pretreated female mice model were similar to the pathology of human PD. We reported an in vivo mice model, which can be used to study PD and for clinical therapeutic evaluations.

View full abstract

The members of the MAF family of transcription factors are homologs of v-Maf –the oncogenic component of the avian retrovirus AS42. The MAF family is subdivided into 2 groups, small and large MAFs. To elucidate the role of the large MAF transcription factors in the endocrine pancreas, we analyzed large MAF gene knockout mice. It has been shown that Mafa^−/− mice develop phenotypes including abnormal islet structure soon after birth. This study revealed that Ins1 and Ins2 transcripts and the protein contents were significantly reduced in Mafa^−/− mice at embryonic day 18.5. In addition, Mafa^−/−;Mafb^−/− mice contained less than 10% of the insulin transcript and protein of those of wild-type mice, suggesting that Mafa and Mafb cooperate to maintain insulin levels at the embryonic stage. On the other hand, the number of insulin-positive cells in Mafa^−/− mice was comparable to that of wild-type mice, and even under a Mafb-deficient background the number of insulin-positive cells was not decreased, suggesting that Mafb plays a dominant role in embryonic β-cell development. We also found that at 20 weeks of age Mafa^−/−;Mafb^+/− mice showed a higher fasting blood glucose level than single Mafa^−/− mice. In summary, our results indicate that Mafa is necessary for the maintenance of normal insulin levels even in embryos and that Mafb is important for the maintenance of fasting blood glucose levels in the Mafa-deficient background in adults.

View full abstract

Nephropathy frequently co-occurs with metabolic syndrome in humans. Metabolic syndrome is a cluster of metabolic diseases including obesity, diabetes, hypertension, and dyslipidemia, and some previous studies revealed that dyslipidemia contributes to the progression of kidney dysfunction. To establish a new nephropathy model with metabolic syndrome, we produced human apolipoprotein B (apoB) transgenic (Tg.) SHR/NDmcr-cp (SHR-cp/cp) rats, in which dyslipidemia is exacerbated more than in an established metabolic syndrome model, SHR-cp/cp rats. Human apoB Tg. SHR-cp/cp rats showed obesity, hyperinsulinemia, hypertension, and severe hyperlipidemia. They also exhibited exacerbated early-onset proteinuria, accompanied by increased kidney injury and increased oxidative and inflammatory markers. Histological analyses revealed the characteristic features of human apoB Tg. SHR-cp/cp rats including prominent glomerulosclerosis with lipid accumulation. Our newly established human apoB Tg. SHR-cp/cp rat could be a useful model for the nephropathy in metabolic syndrome and for understanding the interaction between dyslipidemia and renal dysfunction in metabolic syndrome.

View full abstract