J Korean Neurosurg Soc.  2012 Jul;52(1):1-6. 10.3340/jkns.2012.52.1.1.

Histomorphometric Analysis of the Spine and Femur in Ovariectomized Rats Using Micro-Computed Tomographic Scan

• Shin YH
• Cho DC
• Yu SH
• Kim KT
• Cho HJ
• Sung JK

• KMID: 2190515
• DOI: http://doi.org/10.3340/jkns.2012.52.1.1

Abstract

OBJECTIVE
The purpose of this study was to evaluate the different patterns of bone loss between the lumbar spine and the femur after ovariectomy in rats.
METHODS
Twenty-four female Sprague-Dawley rats underwent a sham operation (the sham group) or bilateral ovariectomy (the ovariectomized group). Four and eight weeks after operation, six rats from each of the two groups were euthanized. Serum biochemical markers of bone turnover including osteocalcin and alkaline phosphatase (ALP), which are sensitive biochemical markers of bone formation, and the telopeptide fragment of type I collagen C-terminus (CTX), which is a sensitive biochemical marker of bone resorption, were analyzed. Bone histomorphometric parameters of the 4th lumbar vertebrae and femur were determined by micro-computed tomography.
RESULTS
Ovariectomized rats were found to have higher osteocalcin, ALP and CTX levels than sham controls. Additionally, 8 weeks after ovariectomy in the OVX group, serum levels of osteocalcin, ALP and CTX were significantly higher than those of 4 weeks after ovariectomy. Bone loss after ovariectomy was more extensive in the 4th lumbar spine compared to the femur. Bone loss in the 4th lumbar spine was mainly caused by trabecular thinning, but in the femur, it was mainly caused by trabecular elimination.
CONCLUSION
The present study demonstrates different patterns of bone loss between the 4th lumbar spine and the femur in ovariectomized rats. Therefore, when considering animal models of osteoporosis, it is important that bone sites should be taken into account.

Keyword

Bone loss; Micro-CT; Osteoporosis; Ovariectomy; Rat

MeSH Terms

Alkaline Phosphatase
Animals
Biomarkers
Bone Resorption
Collagen Type I
Female
Femur
Humans
Lumbar Vertebrae
Models, Animal
Osteocalcin
Osteogenesis
Osteoporosis
Ovariectomy
Rats
Rats, Sprague-Dawley
Salicylamides
Spine
Alkaline Phosphatase
Collagen Type I
Osteocalcin
Salicylamides

Figure

• 

  Fig. 1 Graph showing temporal changes of body weights of the twelve rats euthanized 8 weeks after ovariectomy or sham operations. Values represent mean±standard deviations (n=12). *indicates p<0.05 for OVX vs. sham group comparisons. OVX: ovariectomized.

• 

  Fig. 2 Serum estrogen levels in the two study groups at 4 and 8 weeks after ovariectomy or sham operations. *indicates p<0.05 for 4 weeks vs. 8 weeks in the OVX group. OVX: ovariectomized.

• 

  Fig. 3 The serum osteocalcin (A) and ALP (B) concentrations were used as markers of bone formation. Type I collagen C-telopeptide (CTX) (C) concentration was used as a marker of bone resorption. Values are mean±standard deviations. *indicates p<0.05 for 4 weeks vs. 8 weeks in the OVX group. ALP: alkaline phosphatase, OVX: ovariectomized.

• 

  Fig. 4 Representative micro-CT images of the 4th lumbar spine (A) and the femur (B) in the OVX group. OVX rats 8 weeks after ovariectomy had less trabecular bone than at baseline and 4 weeks after ovariectomy. OVX: ovariectomized, CT: computed tomography.

• 

  Fig. 5 Bar graph showing the result of histomorphometric analyses of 4th lumbar vertebrae in the sham and OVX groups at 4 and 8 weeks post-operation: bone mineral density (BMD) (A), trabecular bone volume fraction (BV/TV) (B), cortical bone mineral density (CrBMD) (C), trabecular thickness (Tb.Th.) (D), trabecular separation (Tb.Sp.) (E), and trabecular number (Tb.N.) (F). All values represent 100% minus the percentage of the value of the sham group/the value of the OVX group. OVX: ovariectomized.

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