Enhancing Effects of Sericin on Corneal Wound Healing in Otsuka Long-Evans Tokushima Fatty Rats as a Model of Human Type 2 Diabetes

Nagai, Noriaki; Murao, Takatoshi; Ito, Yoshimasa; Okamoto, Norio; Sasaki, Michihito

doi:10.1248/bpb.32.1594

Cited by 50 publications

(35 citation statements)

References 41 publications

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“…Many studies regarding the health benefits of SP intake have been reported (8)(9)(10)(11). SP not only regulate blood glucose level and hyperlipidemia and but also decrease blood triglycerides and LDL cholesterol (12,13).…”

mentioning

confidence: 99%

Silk Peptide Intake Increases Fat Oxidation at Rest in Exercised Mice

Kim

Hwang

Yun

et al. 2013

J Nutr Sci Vitaminol

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250Obesity is associated with lifestyle habits such as inactivity, bad eating practices, stress and excessive net intake of calories (1). Among these, energy imbalance and inactivity are becoming serious problems. Total energy cost can be divided into three parts, including resting metabolic rate (RMR), diet-induced thermogenesis (DIT), and the amount of energy used for physical activity energy expenditure (AEE) (2). The greatest component of daily energy expenditure is RMR, constituting about 70% of the total energy expenditure (3, 4).Silk peptides (SP) have been ingested for a long time in Asian countries (5). In recent years, additional applications have been developed for silk, mainly in the field of biotechnology and biomedicine. The versatility of these new implementations arises from the singularity of the molecular structure of silk (6). Proteins such as fibroin and sericin are the main constituents of silk, with fibroin constituting 70 to 80% and sericin 20 to 30% of the total cocoon weight (6, 7).Many studies regarding the health benefits of SP intake have been reported (8-11). SP not only regulate blood glucose level and hyperlipidemia and but also decrease blood triglycerides and LDL cholesterol (12,13). In addition, a high dose (800 mg/kg) of SP was shown to exert stamina-enhancing activity in forced swimming mice by preventing tissue injuries and increasing anti-fatigue (14). Moreover, it is well known that increasing the concentration of leptin leads to an exothermic reaction and an increase in the amount of activity. Therefore, SP promotes fat oxidation and increases energy expenditure (15,16). Additionally, in several rat and mouse model studies, food intake and body weight were decreased in rodents fed ad libitum (5,14,16).However, measurements in those studies have been conducted for analysis of blood profiles and hormones in mice. Accordingly, we investigated the effects of SP administration using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for 24 h. Materials and MethodsAnimals. Seven-week-old male ICR-mouse (n518) were used. Mice were purchased from Orient Bio Inc. (Seongnam, Korea). All mice were housed in standard plastic cages under controlled conditions of humidity (50%) and temperature (2361˚C) with alternating 12 h cycles of light and dark. Mice were adapted to the laboratory housing conditions for 3 d. They were given free access to water and a non-purified commercial diet (5L79, Orient Bio Inc.) containing (g/kg diet): crude protein, 180; crude fat, 52; crude fiber, 52; minerals, 57; and carbohydrate, 368. The protein, fat, and carbohydrate ratio (%) based on calories was 21 : 14 : 65, and (Received January 11, 2013) Summary Silk peptides (SP) have been reported to decrease body weight and accumulate fat. We investigated the effects of SP administration by using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for the duration of 24 h. Seven-week-old male ICR-...

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Silk Peptide Intake Increases Fat Oxidation at Rest in Exercised Mice

Kim

Hwang

Yun

et al. 2013

J Nutr Sci Vitaminol

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“…The data for 38-week-old normal and OLETF rats have been reported in ref. 43; the data represent remeasurements made to compare blood test values for diabetes mellitus in 38-and 60-week-old normal and OLETF rats. The data are presented as means ± S.E.…”

Section: Rates Of Corneal Wound Healing In Normal Andmentioning

confidence: 99%

Kinetic Analysis of the Rate of Corneal Wound Healing in Otsuka Long-Evans Tokushima Fatty Rats, a Model of Type 2 Diabetes Mellitus

et al. 2010

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Diabetic keratopathy is a well-known ocular complication secondary to type 2 diabetes mellitus. In this study, we performed a kinetic analysis of corneal wound healing in Long-Evans rats (normal rat) and Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Corneal wound healing in 7-week-old normal rats was mostly complete 24 h after corneal epithelial abrasion, and the process of corneal wound healing took place according to an equation with a fi rst-order rate constant. The rate of corneal wound healing in normal rats decreased with aging. The process of corneal wound healing in 38-and 60-week-old normal and OLETF rats occurred in two phases with rate constants for the fi rst and second phases represented as α and β, respectively. The α and β values in 38-and 60-week-old OLETF rats were lower than those in normal rats of the corresponding age. Furthermore, a close relationship was observed between the corneal wound healing rate constant and plasma glucose levels in OLETF rats. The present studies suggest the sequence of events that occur following damage to the corneal surface in OLETF rats as a model animal for a human type 2 diabetes mellitus.

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“…In addition, Tsubouchi et al (2005) reported that sericin improves the attachment of cultured human skin fibroblasts. Nagai et al (2009) revealed that sericin can promote wound healing. Dash et al (2008) reported that tasar silk sericin inhibits ultraviolet-B-induced apoptosis in human skin keratinocytes.…”

Section: Introductionmentioning

confidence: 99%

Effect of centrifugation on the structure and properties of silk sericin

Park¹,

Um²

2016

International Journal of Industrial Entomology

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Recently, silk sericin has been studied extensively for biomedical and cosmetic applications because of its unique properties, including UV resistance and wound healing ability. For use in applications, sericin is fabricated in various forms including films and gels. However, the mechanical properties of sericin are too weak. In this basic study on improving the mechanical properties of sericin, a silk sericin aqueous solution was separated into two layers by centrifugation. The solution viscosity, molecular conformation, and mechanical properties of each separation layer of the sericin were examined. Sericin from the lower layer had a higher solution viscosity and film mechanical properties (strength and strain) than that from the upper layer, implying that sericin from the lower layer had a higher molecular weight than that from the upper layer. The molecular conformation of the sericin films varied depending on the casting solvent. In aqueous solution, the sericin film from the lower layer showed a b-sheet conformation, whereas that from the upper layer displayed a random coil conformation. All the sericin films showed a highly b-sheet-crystallized state when cast in formic acid, regardless of the separation layer.

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Enhancing Effects of Sericin on Corneal Wound Healing in Otsuka Long-Evans Tokushima Fatty Rats as a Model of Human Type 2 Diabetes

Cited by 50 publications

References 41 publications

Silk Peptide Intake Increases Fat Oxidation at Rest in Exercised Mice

Silk Peptide Intake Increases Fat Oxidation at Rest in Exercised Mice

Kinetic Analysis of the Rate of Corneal Wound Healing in Otsuka Long-Evans Tokushima Fatty Rats, a Model of Type 2 Diabetes Mellitus

Effect of centrifugation on the structure and properties of silk sericin

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