Assessment of changes due to the long-term effect of estrogen and calcium deficiency in the trabecular bone structure in rats

CER2539
2005 Vol.23, N°3
PI 0385, PF 0388
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Abstract

OBJECTIVES:
To assess structural changes, especially structural anisotropy, of rat bone trabecular system 6 months after ovariectomy followed by low-calcium diet.
METHODS:
The study was carried out on the group of 32 female rats, half of which were ovariectomized at the age of 75 days. The animals were divided into 4 groups: one receiving a normal diet (N), another receiving a low-calcium diet (LCa), ovariectomized rats receiving a normal diet (OVX), and ovariectomized animals receiving a low-calcium diet (OVX+LCa). After 6 months the animals were killed, bone specimens were collected and cut into sections of 6 &mgr;m thickness. Digital images of the sections were analyzed using a software package enabling analysis of the transversal and longitudinal trabeculae.
RESULTS:
Significant changes in trabecular structure due to a low-calcium diet (trabecular bone volume loss of 19%), ovariectomy (53%) and ovariectomy combined with low-calcium diet (71%) were observed. In all the analyzed groups, the percentage loss (as compared with controls) of transversal trabeculae was more significant than the loss of longitudinal trabeculae. In the LCa group, transversal trabecular loss was 39%, longitudinal 25%, in (Ovx): 63% and 54%, respectively, and in OVX + LCa: 77% and 72%. The structural anisotropy coefficient, defined as the ratio of transversal to longitudinal trabecular surface area was 0.64 for (N), 0.50 for LCa, 0.49 for OVX, and 0.54 for OVX+LCa groups.
CONCLUSIONS:
The effect of ovariectomy and low-calcium diet on trabecular structure can be assessed quantitatively by means of analysis of transversal and longitudinal trabeculae associated with the main direction of strain. The degree of transversal trabecular loss is much higher than the longitudinal trabecular loss; the difference becomes smaller with the progress of bone destruction, being greatest in the LCa group, the smallest in the (OVX+ LCa) group.