title: [Oxidative stress inhibits the protective effects of insulin-like growth factor-1 on cortical neurons of neonatal rat].
abstract: OBJECTIVE
  To explore the protective effects of insulin-like growth factor-1(IGF-1) on the survival and apoptosis of cortical neurons of neonatal rat under oxidative stress and its significance.
  
  
  METHODS
  Primary cortical neurons from newborn rat were cultured and the oxidative stress model was established. Then cells were randomly divided into IGF-1 group and control group. The concentration of LDH in supernatant was detected. Cell survival was determined with MTT assay and the expression of active Caspase-3 was measured using Western Blotting.
  
  
  RESULTS
  (1) The values of LDH gradually decreased with the increasing IGF-1 added to the cells [(0.5065 ± 0.0064) to (0.435 ± 0.0065), (P < 0.01)], but when the concentration of IGF-1 reached a certain level (> 25 ng/ml), there were no longer obvious effects on the level of LDH [(0.42 ± 0.012) to (0.418 ± 0.0098), (P > 0.05)]; Western blot showed that the level of active Caspase-3 was significantly decreased after treatment with IGF-1 [(0.662 ± 0.033) to (0.199 ± 0.01), (P < 0.01)]. (2) Compared with control group, without or with low concentration of H2O2 (0 - 40 µM), the values of LDH and the expression of active Caspase-3 in IGF-1 group were significantly decreased[(1.518 ± 0.137) to (1.068 ± 0.067), (P < 0.05) and 0.850 ± 0.042 to 0.597 ± 0.03, P < 0.01, respectively] while the values of MTT obviously elevated [(0.773 ± 0.062) to (1.196 ± 0.057), (P < 0.05)]; but with higher concentration (≥ 60 µM) of H2O2, the values of LDH and MTT and the expression of active Caspase-3 in IGF-1 group all had no significant difference (P > 0.05). (3) When the concentration of H2O2 reached 60 µM and higher, whatever concentration of IGF-1 could not lower the level of LDH compared with control group [(2.376 ± 0.04) to (2.442 ± 0.046), (P > 0.05)].
  
  
  CONCLUSIONS
  Oxidative stress can induce IGF-1 resistance of cortical neurons in neonatal rat, and even increasing the concentration of IGF-1 can not restore their sensitivity to IGF-1.
authors.affiliation: Department of Pediatrics, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Li-wen
authors.initials: LW
authors.lastname: Chang
authors.forename: Wen-bin
authors.initials: WB
authors.lastname: Li
authors.forename: Zhi-jun
authors.initials: ZJ
authors.lastname: Chen
authors.forename: Wei-hua
authors.initials: WH
authors.lastname: Lee
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism*; D002470:Cell Survival; D002478:Cells, Cultured; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018696:Neuroprotective Agents; D007334:Insulin-Like Growth Factor I; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; C505410:Casp3 protein, rat; D053148:Caspase 3