Relationship Between Osteopenia and Lumbar Intervertebral Disc Degeneration in Ovariectomized Rats

Abstract

Ovariectomy (OVX) can cause bone loss in rats, but little is known about how it also induces lumbar intervertebral disc degeneration (LVD). This study investigated how estrogen deficiency affected intervertebral discs in OVX rats. Thirty 3-month-old female Sprague-Dawley rats were divided randomly into three equal groups. The baseline control group (BL) was killed at the beginning of the experiment. An ovariectomy was performed in 10 rats (OVX group) and another group of 10 rats was subjected to a sham surgery (Sham group). The OVX rats were untreated after the surgery to allow for the development of moderate osteopenia. Bone mineral density (BMD) measurement and bone histomorphometric analysis were applied to the segments of lumbar spines in all rats killed 6 months after surgery. The pathological changes of intervertebral discs were observed and the degree of LVD was scored by a histological scoring system. The BMD of the spines (L3-L5) in the OVX group decreased significantly compared with the Sham group. The bone volume indices in the OVX group were significantly lower, but the bone turnover rate parameters were significantly higher than those in the Sham group (P < 0.01). The histological scores for LVD in the OVX group were significantly higher than those in the Sham group (P< 0.01). There was a significant negative correlation between the BMD and Grade II discs in the OVX rats (P = 0.042). In conclusion, LVD occurs in the OVX rats and the degeneration of cartilage end plates may be a pathogenic factor in disc degeneration.

Relationship between gender, bone mineral density, and disc degeneration in the lumbar spine: a study in elderly subjects using an eight-level MRI-based disc degeneration grading system

“…Manson et al [17] reported that although disc degenerative changes are observed in both sexes, women seem to be more susceptible to instability, malalignment, and structural deterioration. Recently, it was reported that ovariectomy can induce intervertebral disc degeneration in female rats [10]. Untreated postmenopausal women have reduced total lumbar disc height compared to postmenopausal women treated with hormone replacement therapy [18].…”

“…It has been proposed that osteoporosis may be an etiological factor in the development of lumbar disc degeneration with osteoporosis inducing loss of vertebral height, leading to instability, facet arthrosis, and disc degeneration [9]. In an experimental setting, it has been shown that, together with vertebral osteoporosis, ovariectomized female rats develop lumbar disc degeneration [10].…”

Calcitonin suppresses intervertebral disk degeneration and preserves lumbar vertebral bone mineral density and bone strength in ovariectomized rats

“…Degenerative changes in the intervertebral disks were observed and the degrees of change in the stained sections were scored independently by three individuals blinded to the experimental protocol, using the disk degeneration assessment scoring system (Table 1) described by Wang et al [7].…”

“…Relative estrogen deficiency may contribute to accelerated disk degeneration in postmenopausal females [6]. In addition, our previous studies have revealed a strong association between osteopenia and disk degeneration in OVX rats, and intervention by alendronate, a widely accepted antiresorptive agent, could not only prevent osteopenia but also inhibit intervertebral disk degeneration [7,8].…”

Effect of Menopause on Lumbar Disk Degeneration: Potential Etiology

“…Imada et al ( 13 ) reported that the incidence of degenerative lumbar spondylolisthesis was about three times higher in women with a history of ovariectomy, compared with age-matched control subjects who did not undergo ovariectomy. Female rats have an increased tendency to develop intervertebral disk degeneration after undergoing ovariectomy ( 14 ), and estrogen supplementation can halt the development of this ovariectomy-associated disk degeneration (Wang YX et al, unpublished data, 2010). Estrogen, which has a variety of biologic effects, also seems to infl uence disk degeneration.…”