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The apoptotic effects of oxidative stress and antiapoptotic effects of caspase inhibitors on rat notochordal cells.

Authors: Kim, KW  Ha, KY  Lee, JS  Rhyu, KW  An, HS  Woo, YK 
Citation: Kim KW, etal., Spine (Phila Pa 1976). 2007 Oct 15;32(22):2443-8.
Pubmed: (View Article at PubMed) PMID:18090083
DOI: Full-text: DOI:10.1097/BRS.0b013e318157395a

STUDY DESIGN: Western blotting and flow cytometric analyses were performed using rat notochordal cells. OBJECTIVE: To demonstrate the apoptotic effect of oxidative stress and the antiapoptotic effects of caspase inhibitors on rat notochordal cells. SUMMARY OF BACKGROUND DATA: Although oxidative stress causes apoptosis in many cell types, its effect on the apoptosis of notochordal cell and antiapoptotic effects of caspase inhibitors on the oxidative stress-induced apoptosis are unknown. METHODS: Cultured rat notochordal cells were exposed to oxidative stress [500 micromol/L of hydrogen peroxide (H2O2)]. To determine the oxidative stress-induced apoptotic pathways, activations of caspases (-3, -8, and -9) as well as cleavages of Bid and poly (ADP-ribose) polymerase (PARP) were evaluated with Western blotting 6 hours after oxidative stress. To elucidate the antiapoptotic effects of caspase inhibitors on the oxidative stress induced-apoptosis, apoptotic rates of notochordal cells with or without treatment of specific caspase inhibitors (z-IETD-fmk for caspase-8, z-LEHD-fmk for caspase-9, and z-DEVD-fmk for caspase-3) were quantified by flow cytometry. RESULTS: Oxidative stress significantly increased apoptosis of rat notochordal cells (2.1% vs. 4.75%, P = 0.008) and led to activations of initiators of intrinsic (caspases-9) and extrinsic (caspase-8) pathways as well as their common executioner (caspase-3). It also caused cleavages of Bid and PARP. Flow cytometric analysis showed that inhibition of only one of the intrinsic and extrinsic pathways by caspase-9 inhibitor (4.75% vs. 3.56%, P = 0.31) and caspase-8 inhibitor (4.75% vs. 5.24%, P = 0.84) did not significantly suppress the oxidative stress-induced apoptosis. However, inhibition of both pathways by caspase-3 inhibitor significantly reduced the oxidative stress-induced apoptosis (4.75% vs. 2.64%, P = 0.008) to the control level (2.1% vs. 2.64%, P = 0.15). CONCLUSION: Oxidative stress caused apoptosis of rat notochordal cells via both intrinsic and extrinsic (Type I and Type II) pathways. Because caspase inhibitors are being used in clinical trials, inhibition of both pathways using caspase inhibitors might be of future therapeutic importance in oxidative stress-induced apoptosis of notochordal cells. Our results suggest that inhibition of inappropriate or premature oxidative stress-induced apoptosis of notochordal cells may delay the starting point of disc degeneration.

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RGD Object Information
RGD ID: 2314002
Created: 2009-10-30
Species: All species
Last Modified: 2009-10-30
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.