J Vet Sci.  2012 Dec;13(4):339-344.

Silk fibroin hydrolysate exerts an anti-diabetic effect by increasing pancreatic beta cell mass in C57BL/KsJ-db/db mice

• Do SG
• Park JH
• Nam H
• Kim JB
• Lee JY
• Oh YS
• Suh JG

Abstract

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 beta cell mass in the mice. In summary, our results suggest that SFH exerts anti-diabetic effects by increasing pancreatic beta cell mass in a non-insulin dependent diabetes mellitus mouse model.

Keyword

beta cell mass; db/db mouse; diabetes; HbA1c; silk fibroin

MeSH Terms

Animals
Diabetes Mellitus
Drinking Water
Fibroins
Glucose
Hemoglobin A, Glycosylated
Hyperglycemia
Insulin
Insulin-Secreting Cells
Medicine, East Asian Traditional
Mice
Models, Animal
Plasma
Silk

Figure

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  Fig. 1 Silk fibroin hydrolysate (SFH) decreases (A) blood glucose and (C) glycosylated hemoglobin (HbA1c) levels in C57BL/KsJ-db/db mice. SFH treatment did not induce changes in body weight of either normal or db/db mice (B). Data are presented as the mean ± SE. *p < 0.05 and **p < 0.01 compared to the DB group. DB: C57BL/KsJ-db/db mice (n = 12), ND: C57BL/KsJ-db/+ or +/+ mice (n = 12), DB-SF: SFH-treated C57BL/KsJ-db/db mice (n = 12), ND-SF: SFH-treated C57BL/KsJ-db/+ or +/+ mice (n = 12).

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  Fig. 2 SFH improves glucose tolerance in C57BL/KsJ-db/db mice. (A) Blood glucose, (B) plasma insulin, and (C) area under the curve (AUC) after glucose tolerance test in 12 week-old C57BL/sJ-db/db mice. AUC was calculated by trapezoid rule. Data are presented as the mean ± SE. **p < 0.01 compared to the DB group.

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  Fig. 3 SFH helps maintain pancreatic β cell integrity in the C57BL/KsJ-db/db mice. β cell morphology and distribution in the SFH-treated db/db mice were well organized. Insulin-specific (INS) (A~C) and glucagon-specific (GLU) immunohistochemical (D~F) staining, ×200.

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