Objective To investigate the effect of estrogen deficiency on the degeneration of endplate chondrocytes.
Methods Forty six month old rats were divided into two groups: ovariectomized rats (OVX) and sham operated rats (SHAM). Nine weeks after operation, the cartilage endplate tissues were extracted and the primary endplate chondrocytes were cultured. The expression of type II collagen (COL-II) in cartilage endplate of SHAM group and OVX group was compared by immunohistochemistry. Inverted phase contrast microscope and toluidine blue staining were used to observe the cell morphology to identify the chondrocytes of the endplate. CCK-8 method was used to compare the viability of endplate chondrocytes in the two groups. The changes of F-actin in endplate chondrocytes after OVX were observed by rhodamine labeled ghost pen cyclic peptide fluorescence staining. The changes of COL-II in endplate chondrocytes after estrogen deficiency were detected by cellular immunofluorescence. The expressions of SOX9, ACAN, ADAMTS-5, MMP13 and COL-X in the two groups were compared by RT qPCR.
Results Compared with the control group, the expression of COL-II protein in cartilage endplate of OVX group decreased. The chondrocytes of the endplate were mostly polygonal and spindle shaped, and arranged like paving stones. The activity of cartilage cells in the end plate of OVX decreased, the cytoskeleton became more disordered, the stress fibers increased, the migration ability decreased, and the expression of COL-II decreased. Compared with the control group, the expression of SOX9 and ACAN in the end plate chondrocytes of OVX group decreased, and the expression of MMP13, ADAMTS-5 and COL-X increased.
Conclusion Estrogen deficiency can cause degeneration of endplate chondrocytes. After OVX, the activity and migration of endplate chondrocytes decreased, bone synthesis decreased, and extracellular matrix degradation and cell hypertrophy and differentiation increased.