Components of silk including silk fibroin have long been used as anti-diabetic remedies in oriental medicine. However, detailed mechanisms underlying these anti-diabetic effects remain unclear. In this study, we examined the anti-diabetic activity of silk fibroin hydrolysate (SFH) in C57BL/KsJ-db/db (db/db) mice, a well-known animal model of non-insulin dependent diabetes mellitus. When the db/db mice were administered SFH in drinking water for 6 weeks, hyperglycemia in the animals gradually disappeared and the level of glycosylated hemoglobin decreased, indicating that SFH plays important role in reducing the symptoms of diabetes. In addition, SFH-treated db/db mice exhibited improved glucose tolerance with increased plasma insulin levels. Immunohistochemical and morphological analyses showed that SFH up-regulated insulin production by increasing pancreatic β cell mass in the mice. In summary, our results suggest that SFH exerts anti-diabetic effects by increasing pancreatic β cell mass in a non-insulin dependent diabetes mellitus mouse model.

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Considering that sex differences in glucose metabolism are observed in mice, researchers unconsciously use male mice to reduce variations by an estrogen cycle in female mice. In this study, we investigated the sex differences in glucose homeostasis in streptozotocin (STZ)-induced diabetes inbred mice (C57BL/6J). The C57BL/6J male and female mice were injected with or without STZ (40 mg/kg) for 5 consecutive days. Levels of fasting blood glucose (FBG), glycosylated hemoglobin (HbA1C), lipid profiles, oral glucose tolerance, and insulin resistance were measured at 3 and 6 weeks after STZ treatment. The FBG level in the STZ-induced male (M-STZ) group was significantly higher than that in the STZ-induced female (F-STZ) group during the entire experimental period. Furthermore, HbA1C and glucose tolerance levels in the M-STZ group were significantly higher than those in the F-STZ group at 3 and 6 weeks after STZ treatment. The glucagon/insulin ratio in the M-STZ group was significantly higher than that in the F-STZ group. Values of the homeostatic model assessment-insulin resistance, an indicator of β-cell function and insulin resistance, significantly increased in both the M-STZ and F-STZ groups at 3 weeks after STZ treatment. However, insulin resistance was observed in the M-STZ group, but not in the F-STZ group, at 6 weeks after STZ treatment. Taken together, our results indicate that glucose metabolism in the M-STZ group was worse than that in the F-STZ group, indicating that estrogen may have an important role in glucose metabolism by STZ treatment.

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As the mechanism of aged black garlic (ABG) extract affecting lipid metabolism in adipocytes remains unclear, this study evaluated the effect of ABG extract on lipid metabolism and the expression of related proteins in mature 3T3-L1 adipocytes. ABG extract treatments at 0, 0.625, 1.25, and 2.5, and 5 mg/mL had no effect on cell morphology or viability in adipocytes. ABG extract suppressed lipogenesis and induced lipolysis in a dose-dependent manner compared to control. Furthermore, ABG extract at 2.5 and 5 mg/mL significantly reduced protein expression of proliferator activated receptor γ (PPARγ) and perilipin in mature 3T3-L1 adipocytes. The hormone-sensitive lipase (HSL) and Ser-pHSL levels were also significantly reduced by treatment with 5 mg/mL of ABG extract. Taken together, these results suggest that ABG extract has anti-lipogenic and lipolytic effects in mature 3T3-L1 adipocytes, indicating a potential in anti-obesity therapies.

The C57BLKS/J-Leprdb mouse has a point mutation in the leptin receptor gene and is one of the most useful animal model for non-insulin dependent diabetes mellitus in human. Since the homozygote of C57BLKS/J-Leprdb mouse is infertile, detection of point mutation in the leptin receptor gene is important for efficient maintaining strains as well as mass production of homozygotes. To develop a rapid and efficient genotyping method for C57BLKS/J-Leprdb mouse, the tetra-primer amplification-refractory mutation system polymerase chain reaction (ARMS-PCR) was used. The 407 and 199 bp PCR products were amplified from normal (+/+) mice; while the 407 and 268 bp PCR products were amplified from homozygotes (db/db) mice; and the 407, 268, and 199 bp PCR products were amplified from heterozygotes (db/+) mice. This result showed that the tetra-primer ARMS-PCR analysis by us is suitable to detect point mutation of the leptin receptor gene. Taken together, our method will dramatically reduce animal use for maintenance of strains as well as production of homozygote in the C57BLKS/J-Leprdb strains.

Campylobacter, the most common etiologic agent of zoonotic gastroenteritis in humans, is present in many reservoirs including livestock animals, wildlife, soil, and water. Previously, we reported a novel Campylobacter jejuni strain SCJK02 (MLST ST-8388) from the gut of wild mice (Micromys minutus) using culture-dependent methods. However, due to fastidious growth conditions and the presence of viable but non-culturable Campylobacter spp., it is unclear whether M. minutus is a Campylobacter reservoir. This study aimed to: 1) determine the distribution and proportion of Campylobacter spp. in the gut microbiota of wild mice using culture-independent methods and 2) investigate the gut microbiota of wild mice and the relationship of Campylobacter spp. with other gut microbes. The gut microbiota of 38 wild mice captured from perilla fields in Korea and without any clinical symptoms (18 M. minutus and 20 Mus musculus) were analyzed. Metagenomic analysis showed that 77.8% (14 of 18) of the captured M. minutus harbored Campylobacter spp. (0.24–32.92%) in the gut metagenome, whereas none of the captured M. musculus carried Campylobacter spp. in their guts. Notably, 75% (6 of 8) of M. minutus determined to be Campylobacter-negative using culture-dependent methods showed a high proportion of Campylobacter through metagenome analysis. The results of metagenome analysis and the absence of clinical symptoms suggest that Campylobacter may be a component of the normal gut flora of wild M. minutus. Furthermore, linear discriminant analysis (LDA) showed that Campylobacter was the most enriched genus in the gut microbiota of M. minutus (LDA score, 5.37), whereas Lactobacillus was the most enriched genus in M. musculus (LDA score, −5.96). The differences in the presence of Campylobacter between the two species of wild mice may be attributed to the differential abundance of Campylobacter and Lactobacillus in their respective gut microbiota. In conclusion, the results indicate that wild M. minutus may serve as a potential Campylobacter reservoir. This study presents the first metagenomics analysis of the M. minutus gut microbiota to explore its possible role as an environmental Campylobacter reservoir and provides a basis for future studies using culture-independent methods to determine the role of environmental reservoirs in Campylobacter transmission.

Laboratory inbred mice are used widely and commonly in biomedical research, but inbred mice do not have a big enough gene pool for the research. In this study, genetic and morphometric analyses were performed to obtain data on the characteristics of a newly developing inbred strain (KWM/Hym) captured from Chuncheon, Korea. All of five Korean wild male mice have the zinc-finger Y ( ZfY ) gene. Also, all of 19 Korean wild mice used in this analysis have the AKV-type murine leukemia virus gene, indicating that Korean wild mice might be Mus musculus musculus . To identify the genetic polymorphism in KWM/Hym, SNP analysis was performed. In a comparison with 28 SNP markers, there was a considerable difference between KWM/Hym and several inbred strains. The homogeneity between KWM/Hym and the inbred strains was as follows: C57BL/6J (39.3%), BALB/c AJic (42.9%), and DBA/2J (50%). KWM/Hym is most similar to the PWK/PhJ inbred strain (96.4%) derived from wild mice (Czech Republic). To identify the morphometric characteristics of KWM/Hym, the external morphology was measured. The tail ratio of male and female was 79.60±3.09 and 73.55±6.14%, respectively. KWM/Hym has short and agouti-colored hairs and its belly is white with golden hair. Taking these results together, KWM/Hym, a newly developing inbred mouse originated from wild mouse, might be use as new genetic resources to overcome the limitations of the current laboratory mice.