Comparison Two Methods between Injection Saline and External Fixator in Rat Tail Disc Degeneration

Abstract

Purpose: Intervertebral disc is a leading avascular organ in the body. Hence, it may utilize autophagy and apoptosis to alive in unfavorable condition like stress and mechanical force. But excessive force and stress is a key cause to intervertebral disc degeneration (IVDD). Purpose of this study is to identify, external fixator (EF) and saline injection (SI) may induce autopahgy and apoptosis mediated nucleus pulposus (NP) cells death in rat tail’s disc and which method is better for studying autophagy and apoptosis. Methods: Sixteen 9-week-old male Sprague–Dawley rat tails were treated with 0.9% saline and EF (two-cross kirschner wires) for 6 weeks and 12 weeks as well. Treated discs were dissected for checking out participation of autopahgy and apoptosis to intervertebral disc degradation (IVDD). For identifying them, we performed H&E staining, Masson’s trichrome staining, and Immunohistochemistry (IHC) for LC3, Beclin-1and P62 as well as MMP-2, MMP-3 and TIMP-1.Furthermore, we performed quantitative polymerase chain reaction (qPCR)to check out autophagy related gene expression (beclin-1, LC3 and P62) and apoptosis related gene expression (MMP-2, MMP-3 and TIMP-1) respectively. Results: More insidious nucleus pulposus (NP) cell degeneration was indentified in (EF) group than in (Ctrl) control group. And rate of degradation was elevated with increasing duration of compression, but SI group cannot distinguish the margin of AF and NP cells. Highest along with lateral expression was found for LC3, Beclin-1, and P62 of both groups. Up-regulated and central expression was observed for MMP-2, MMP-3 and TIMP-1 of both groups, although SI group cannot recognize the margin between NP and AF cells. Utmost autophagy related gene expression was identified in EF group than in SI group. Besides, maximum autophagy accumulating materials was found in EF group than in SI group. And it was amplified along with increasing the duration of compression. Highest, apoptotic gene expression was observed in SI group, whereas, EF group showed lowest expression. Conclusion: External fixator (EF) method was better to study autophagy and apoptosis because it enhanced IVDD after compression which is actively linked with autophagy and apoptosis. Degeneration process was conversely proportional along with duration of compression. On contrary, saline injection (SI) could not distinguish AF and NP cell border.