Introduction

DNA damage (genotoxic stress) and deficiency of intracellular DNA repair mechanisms strongly contribute to biological aging. Moreover, aging is a primary risk factor for loss of disc matrix proteoglycan (PG) and intervertebral disc degeneration (IDD). Indeed, our previous evidences in DNA repair deficient Ercc1^−/Δ mouse model strongly suggest that systemic aging and IDD correlate with nuclear DNA damage. Thus the aim of the current study was to test whether systemic or local (spine) genotoxic stress can induce disc degeneration and how DNA repair ability could help prevent negative effects of DNA damage on IDD. To test this hypothesis a total of twelve Ercc1^−/Δ mice (DNA repair deficient) and twelve wild-type mice (DNA repair competent) were challenged with two separate genotoxins to induce DNA damage, i.e. chemotherapeutic crosslinking agent mechlorethamine (MEC) and whole-body gamma irradiation. Local effects of gamma irradiation were also tested in six wild-type mice.