Experimental hyperhomocysteinemia disturbs bone metabolism in rats.
OBJECTIVE
To investigate whether experimental hyperhomocysteinemia (HHCY) can induce adverse changes in bone metabolism.


METHODS
Blood and urine samples were collected from rats fed with a methionine-enriched diet (HHCY, n = 18) or an isocaloric control diet (control, n = 10) for 12 weeks. Biochemical bone turnover markers (osteocalcin, hydroxyproline, N-terminal collagen I telopeptides and homocysteine (HCY), folate and vitamin B12) were measured. Whole body bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry.


RESULTS
HCY was significantly higher in HHCY than in control rats (16.2 versus 3.2 micromol/L; p = 0.0006). Bone resorption parameters hydroxyproline (1.60 +/- 0.6 versus 0.85 +/- 0.4; p<0.05) and N-terminal collagen I telopeptides (150.8 +/- 78 versus 48.1 +/- 26 nmol/L BCE; p<0.05) increased, whereas bone formation marker osteocalcin (9.01 +/- 3.8 versus 15.07 +/- 4.2 ng/mL; p<0.05) decreased in HHCY compared to control rats. The relation N-terminal collagen I telopeptides/osteocalcin significantly increased in HHCY compared to control rats (13.14 +/- 3.1 versus 4.14 +/- 1.9). BMD measurement did not reveal any differences between groups.


CONCLUSIONS
These findings demonstrate a significant modification of bone turnover in HHCY rats. The relation between bone resorption and formation indicates a shift toward bone resorption, which might be a plausible explanation for the relation between HHCY and fracture risk.
Ozdem
S
S
Medical Faculty, Central Laboratory Biochemistry Unit, Akdeniz University, Antalya, Turkey. ozdem@akdeniz.edu.tr
Samanci
S
S
Tasatargil
A
A
Yildiz
A
A
Sadan
G
G
Donmez
L
L
Herrmann
M
M
D000818:Animals; D001835:Body Weight; D015519:Bone Density; D001862:Bone Resorption / Q000209:etiology / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism*; D024042:Collagen Type I / Q000652:urine; D003401:Creatine / Q000652:urine; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006909:Hydroxyproline / Q000652:urine; D020138:Hyperhomocysteinemia / Q000139:chemically induced / Q000150:complications / Q000503:physiopathology*; D008715:Methionine / Q000008:administration & dosage / Q000097:blood; D015675:Osteocalcin / Q000097:blood; D010012:Osteogenesis / Q000502:physiology; D010455:Peptides / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D014805:Vitamin B 12 / Q000097:blood
D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D006710:Homocysteine; D015675:Osteocalcin; D005492:Folic Acid; D008715:Methionine; D003401:Creatine; D014805:Vitamin B 12; D006909:Hydroxyproline