Effects of habitual chitosan intake on bone mass, bone-related metabolic markers and duodenum CaBP D9K mRNA in ovariectomized SHRSP rats.
We have demonstrated that the habitual intake of chitosan can decrease bone mass in ovariectomized (OVX) SHRSP rats fed a low-Ca diet (0.1%). In the present study, we examined both the etiology of bone loss induced by dietary chitosan and the preventive effect of vitamin C supplementation. Rats were OVX and maintained on one of the following diets for 6 wk: 10% cellulose (CE). 10% chitosan (CH) or 10% chitosan with sodium ascorbate (CHVC). CH caused a significant reduction in bone mineral density (BMD) and stiffness in femurs and the fourth lumbar vertebrae (L4). There was no significant difference in intestinal Ca absorption between CH and CE, whereas CH intake significantly reduced intestinal P absorption. The bone loss in CH rats was accompanied with an increase in urinary Ca excretion and a decrease in serum Ca as well as a significant increment In serum PTH and 1,25(OH)2D3. The vitamin D receptor and calcium binding protein D9K mRNAs were also significantly increased in the duodenum of CH rats. Vitamin C supplementation to CH caused an increase in the Ca and P contents of femurs as well as BMD of the L4, with a decrease in urinary Ca excretion. These results indicate that dietary chitosan with low Ca intake possibly induces the loss of bone mass by enhancing urinary Ca excretion rather than by inhibiting Ca absorption, and that vitamin C supplementation could prevent bone loss caused by chitosan through the increment of retained Ca followed by suppression of urinary Ca excretion.
Yang
Chu-Ya
CY
Department of Sports Sciences, Waseda University School of Human Sciences, Tokorozawa 359-1192, Japan. kkbycy@din.or.jp
Oh
Tae-Woong
TW
Nakajima
Daito
D
Maeda
Atsuko
A
Naka
Tatsuki
T
Kim
Chang-Sun
CS
Igawa
Shoji
S
Ohta
Fukio
F
D000704:Analysis of Variance; D000818:Animals; D000924:Anticholesteremic Agents / Q000008:administration & dosage* / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D000975:Antioxidants / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000627:therapeutic use*; D015415:Biomarkers / Q000032:analysis; D015519:Bone Density / Q000187:drug effects*; D002686:Chitin / Q000008:administration & dosage* / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D048271:Chitosan; D004386:Duodenum / Q000187:drug effects*; D005260:Female; D010024:Osteoporosis / Q000097:blood / Q000139:chemically induced* / Q000517:prevention & control* / Q000652:urine; D010052:Ovariectomy; D012333:RNA, Messenger / Q000187:drug effects*; D051381:Rats; D011918:Rats, Inbred SHR; D020133:Reverse Transcriptase Polymerase Chain Reaction; D064030:S100 Calcium Binding Protein G / Q000187:drug effects*; D013997:Time Factors
D000924:Anticholesteremic Agents; D000975:Antioxidants; D015415:Biomarkers; D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G; D002686:Chitin; D048271:Chitosan; D001205:Ascorbic Acid