[Expression of type II collagen gene and structural change in bone tissues of rats with experimental fluorosis].
OBJECTIVE
To investigate the effects of excessive intake of fluoride on the expression of type II collagen gene and types and morphological change of collagen fiber in the bone tissues of rats.


METHODS
A rat model with fluorosis was established by adding 221 mg/L of sodium fluoride (NaF) to drinking water for the rats for 15 days, 30 days and two months, respectively. Type II collagen alpha1 (II) cDNA probe was prepared, and cDNA-mRNA in-situ hybridization was employed to detect change in expression of type II collagen mRNA in the bone tissues of rats with excessive intake of fluoride (221 mg/L NaF). Picrosirius-polarization method was used to observe types of collagen and morphology of collagen fiber in the bone tissues.


RESULTS
Chondroblasts were found in the femur and other bone tissues of the rats after exposure to fluoride. cDNA-mRNA in-situ hybridization showed that expression of type II collagen gene could be observed in the cytoplasm of chondrocytic lacuna and chondrified bone tissues. mRNA in collagen of chondrocytes of the rib cartilage reached the peak level 15 days after exposure to fluoride, and decreased gradually one month and two months after exposure. Polychromatic type II collagen, breakage of collagen fiber, disorder array and reduced content of type II collagen could be found in the bone tissues with picrosirius-polarization method.


CONCLUSIONS
Excessive intake of fluoride could lead to changes in types and structure of collagen (cross-linkage) of bone tissues, which caused expression of type II collagen gene in the chondrified bone tissues and enhanced its expression in the rib cartilage tissues.
Liu
Bing-ci
BC
National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Xu
Zeng-lu
ZL
Miao
Qing
Q
Xu
Yuan-yuan
YY
Xu
Ming
M
Qian
Xiao-jing
XJ
You
Bao-rong
BR
Yuan
Bo-hua
BH
Kang
Ning
N
D000818:Animals; D001847:Bone Diseases / Q000378:metabolism / Q000473:pathology*; D019902:Chondrocytes / Q000378:metabolism; D024043:Collagen Type II / Q000096:biosynthesis* / Q000235:genetics; D005458:Fluoride Poisoning / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar
D024043:Collagen Type II; D012333:RNA, Messenger