title: Effects of IGF-1 on IL-1β-induced apoptosis in rabbit nucleus pulposus cells in vitro.
abstract: Excessive apoptosis in intervertebral disc (IVD) cells is important in IVD degeneration. Interleukin (IL)-1β has been shown to induce apoptosis in these cells. However, whether insulin-like growth factor-1 (IGF-1) inhibits IL-1β-induced apoptosis in the nucleus pulposus remains unclear. The purpose of this study was to investigate the effects of IGF-1 on IL-1β-induced apoptosis in the nucleus pulposus. Cells isolated from the nucleus pulposus were grown in culture to a monolayer. These cells were identified using immuno-histochemistry for type II collagen and toluidine blue staining for glycosaminoglycans. Following exposure to IGF-1 or IL-1β, the cells were observed using light microscopy. Giemsa staining, TdT-mediated dUTP-biotin nick end-labeling (TUNEL) and flow cytometry (FCM) were used to detect the rate of early cell death, which served as an indicator of apoptosis. In the IL-1β group, a large number of these cells underwent apoptosis and demonstrated morphological changes associated with apoptosis. A small proportion of cells exposed to IGF-1 alone underwent apoptosis. No obvious signs of apoptosis were observed in the control group. TUNEL results revealed that the rate of apoptosis in the IGF-1 group was significantly reduced compared with that in the IL-1β group (P<0.01), confirmed using FCM. Compared with the control group, the apoptotic rate was also significantly increased in IL-1β-exposed cells (P<0.01). These findings strongly suggested that IGF-1 inhibits IL-1β-induced apoptosis in the nucleus pulposus.
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Bengbu                     Medical College, Bengbu 233004, P.R. China.
authors.forename: Chang-Chun
authors.initials: CC
authors.lastname: Zhang
authors.forename: Jian-Sheng
authors.initials: JS
authors.lastname: Zhou
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Hu
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.forename: Xin-She
authors.initials: XS
authors.lastname: Zhou
authors.forename: Bao-An
authors.initials: BA
authors.lastname: Sun
authors.forename: Chen
authors.initials: C
authors.lastname: Shao
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Lin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000494:pharmacology*; D007403:Intervertebral Disc / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits
chemical_list: D053583:Interleukin-1beta; D007334:Insulin-Like Growth Factor I