ABSTRACT
<p><b>OBJECTIVE</b>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.</p><p><b>METHOD</b>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.</p><p><b>RESULT</b>(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)].</p><p><b>CONCLUSIONS</b>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.</p>