Molecular and Cellular Pharmacology
Curcumin suppresses increased bone resorption by inhibiting osteoclastogenesis in rats with streptozotocin-induced diabetes

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Abstract

Curcumin is a potent inhibitor of the transcription factor activator protein-1 which plays an essential role in osteoclastogenesis. However, the effects of curcumin on bone metabolism have not been clarified in vivo. We reported herein the inhibitory effects of curcumin on the stimulated osteoclastic activity in insulin-dependent diabetes mellitus using rats with streptozotocin-induced diabetes. A dietary supplement of curcumin reversed the increase in levels of activity and mRNA of tartrate-resistant acid phosphatase (TRAP) and cathepsin K to control values. A histochemical analysis showed that the increase in TRAP-positive cells in the distal femur of the diabetic rats was reduced to the control level by the supplement. These results suggested that curcumin reduced diabetes-stimulated bone resorptive activity and the number of osteoclasts.

When bone marrow cells were cultured with macrophage colony stimulating factor and receptor activator NF-κB ligand (RANKL), the increased activity to form TRAP-positive multinucleated cells and the increased levels of mRNA and protein of c-fos and c-jun in the cultured cells from diabetic rats decreased to control levels in the curcumin-supplemented rats. Similarly, the increased expression of c-fos and c-jun in the distal femur of the diabetic rats was significantly reduced by the supplement. These results suggested that curcumin suppressed the increased bone resorptive activity through the prevention of osteoclastogenesis associated with inhibition of the expression of c-fos and c-jun in the diabetic rats.

Introduction

Insulin-dependent diabetes mellitus is associated with decreased bone mass and osteoporosis (Krakauer et al., 1995, Tuominen et al., 1999, Kemink et al., 2000). Streptozotocin-induced diabetes in rats is a well-recognized model of insulin-dependent diabetes mellitus (Szkudelski, 2001). The effects of insulin-dependent diabetes mellitus have generally been attributed to insulin deficiency and to an impairment in osteoblastic function since insulin has a stimulatory effect on osteoblasts. However, increases in markers of osteoclastic function such as the excretion of calcium, hydroxyproline, and deoxypyridinoline in urine were reported in subjects with insulin-dependent diabetes mellitus (Selby et al., 1995, Bjorgaas et al., 1999). In fact, we have reported increases in the expression of cathepsin K and tartrate-resistant acid phosphatase (TRAP) at the early stages of streptozotocin-induced diabetes in rats (Hie et al., 2007). The increase in osteoclastic activity associated with the decreased osteoblastic activity leads to a diabetic osteopenia later on. The suppression of the increased bone resorptive activity at the early stages of diabetes would be useful for preventing, or at least delaying, the later loss of bone mass.

Bone resorption is carried out by hematopoietically derived osteoclasts (Udagawa et al., 1990, Kurihara et al., 1990). Their number and activity is determined by cell lineage allocation, the proliferation and differentiation of osteoclast precursors and the resorptive efficacy of mature osteoclasts (Harada and Rodan, 2003). Osteoclastic differentiation which requires macrophage colony-stimulating factor (M-CSF) and receptor for activation of NF-κB ligand (RANKL) is a multi-step process that eventually leads to the expression of TRAP, multinucleation, and bone-resorbing activity (Boyle et al., 2003, Asagiri and Takayanagi, 2007). The binding of M-CSF to c-Fms stimulates the expression of RANK in the hematopoietic osteoclast precursor cells. The binding of RANKL to its receptor RANK activates NF-κB and activator protein-1(AP-1) in osteoclast precursors and induces osteoclastic differentiation (Asagiri and Takayanagi, 2007). From a clinical point of view, the RANKL signaling pathway has promise as a strategy for suppressing excessive osteoclastic formation.

Curcumin (diferuloyl methane), a polyphenolic phytochemical, is a primary component of the dietary spice tumeric. It has been used for centuries in indigenous medicine for the treatment of a variety of inflammatory conditions and other diseases (Ammon and Wahl, 1991). Curcumin has been demonstrated to be a powerful inhibitor of AP-1 (Hanazawa et al., 1993, Bierhaus et al., 1997, Chen and Tan, 1998, Squires et al., 2003). The transcription factor AP-1, a dimeric complex composed of Fos and Jun, is activated by RANKL and induces the expression of osteoclast-specific genes. c-Fos is crucial for AP-1 interaction with its specific transcriptional partner, which is required in osteoclastogenesis. Mice expressing an inactivated c-fos or deficient in c-fos manifested arrested osteoclastic development and osteopetrosis (Wang et al., 1992, Grigoriadis et al., 1994). These findings suggest a potential role for curcumin in treatment for preventing bone resorptive activity.

In the present study, we examined the effects of a dietary supplement of curcumin on the stimulated osteoclastic activity and demonstrated that curcumin inhibited bone resorptive activity with the suppression of osteoclastogenesis in rats with streptozotocin-induced diabetes.

Section snippets

Animals and study design

Ten-week-old female rats of the Wistar/ST strain were purchased from Japan SLC (Shizuoka, Japan) and housed individually in a temperature-controlled room with a 12-h light cycle. After fasting overnight, sixteen rats were treated with streptozotocin (45 mg/kg body weight in 0.05 M citrate buffer, pH 4.5, i.p.), a pancreatic beta-cell cytotoxin, to render them diabetic. Eight control animals received the same volume of the streptozotocin diluent. The diagnosis of diabetes was based on glycosuria

Streptozotocin-induced diabetes and effects of curcumin on glucose levels in urine and serum, food intake, body weight, and bone length and weight

The injection of streptozotocin increased glucose levels in urine before the curcumin supplement was given (at 4 days after the Streptozotocin-injection) (Table 1). The diabetic status induced by streptozotocin persisted throughout the study period as evidenced by hyperglycemia, high water intake, high food intake and polyuria. The curcumin supplement did not affect the serum glucose levels and food intakes of diabetic rats.

Body weight (final) and bone weights of the femur, tibia and distal

Discussion

This study clearly demonstrated that the dietary supplement of curcumin suppressed the increased bone resorptive activity in rats with streptozotocin-induced diabetes. Consistent with previous findings at 1 week after the injection of streptozotocin (Hie et al., 2007), the TRAP and cathepsin K activity in the distal femoral bone increased at 2 weeks. In diabetic rats, the elevated level of cathepsin K activity stimulated degradation of the bone matrix, resulting in a decrease in the amount of

Acknowledgment

This work was supported in part by Grants-in-Aids for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

References (34)

  • BierhausA. et al.

    The dietary pigment curcumin reduces endothelial tissue factor gene expression by inhibiting binding of AP-1 to the DNA and activation of NF-kappa B

    Thromb. Haemost.

    (1997)
  • BjorgaasM. et al.

    The urinary excretion of deoxypyridinium cross-links is higher in diabetic than in nondiabetic adolescents

    Calcif. Tissue Int.

    (1999)
  • BoyleW.J. et al.

    Osteoclast differentiation and activation

    Nature

    (2003)
  • GotoA. et al.

    Increase in tartrate-resistant acid phosphatase of bone at the early stage of ascorbic acid deficiency in the ascorbate-requiring Osteogenic Disorder Shionogi (ODS) rat

    Calcif. Tissue Int.

    (2003)
  • GrigoriadisA.E. et al.

    c-Fos: a key regulator of osteoclast-macrophage lineage determination and bone remodeling

    Science

    (1994)
  • HaradaS. et al.

    Control of osteoblast function and regulation of bone mass

    Nat. Med.

    (2003)
  • HayashiS. et al.

    Osteoclast precursors in bone marrow and peritoneal cavity

    J. Cell. Physiol.

    (1997)
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