SIRT1 and SIRT5 activity expression and behavioral responses to calorie restriction.

To investigate the effects of calorie restriction (CR) on behavioral performance and expression of SIRT1 and SIRT5 in rat cerebral tissues. Beginning at 18 months of age, 60 rats were randomly divided into a CR group (n = 30) and a group that remained fed ad libitum (AL; n = 30). CR rats were restricted to a diet of 60% of their daily food consumption. After 6 months of CR, CR rats displayed a maximum 50% reduction in escape latency (AL 20 ± 0.3 s vs. CR 10 ± 0.2 s) and a 3.2 s decrease in time and distance to target when evaluated in Morris water maze tests. The levels of SIRT1 and SIRT5 protein in cerebral tissues of CR rats were elevated compared to AL rats (P < 0.05). CR retarded declines in cognitive ability and enhanced the expression of both SIRT1 and SIRT5 proteins in the cerebral tissue of CR rats compared with AL rats.

[Effects of caloric restriction on the oxidative stress injury and the expression of SIRT3 in PC12 cell].

OBJECTIVE: To study the regulation effects of CR (caloric restriction) and SIRT3 in the H2O2-induced oxidative stress injury of PC12 cell. METHODS: The cells were divided into four groups: H2O2, H2O2 + CR, CR and control (high glucose). For control and H2O2 group, cells were cultured in DMEM containing 0.45% glucose; for group in CR condition, cells were treated with the medium containing 0.1% glucose. For groups with H2O2, the H2O2 was diluted in EMEM medium to obtain the final concentration containing 60 µmol/L. Viability of PC12 cells were measured by MTT assay. The medium was refreshed with different concentration of H2O2 (from 10 to 120 µmol/L). The absorbance of the samples was measured at 492 nm using a microtiter plate reader. We detected TUNEL-positive cells using the In Situ Cell Apoptosis Detection kit pretreated with CR and H2O2. Immunofluorescence double staining detected the expression and localization of SIRT3. RT-PCR and Western-blot methods detected the expression of SIRT3, Caspase-3. RESULTS: After pretreating with 60 µmol/L H2O2 for 6 h, the viability of PC12 cells in H2O2 group (74.01 ± 2.21)% retained above 70%, and have statistical significance contrasted with control group (P < 0.05); After pretreating with 120 µmol/L H2O2, the viability of PC12 cells declined significantly (38.22 ± 3.34)%. So 60 µmol/L H2O2 is our experiment concentration. The viability of H2O2 group (74.01 ± 2.21)% was much lower than CR + H2O2 group (97.26 ± 1.92)% (P < 0.05). After pretreating with H2O2, TUNEL staining showed the apoptosis cells of CR + H2O2 group decreased significantly contrasted with H2O2 group. The immunofluorescence double staining results showed that SIRT3 was a mitochondria protein. Western-blot showed the expression of SIRT3 in CR group (6857 ± 157) (P < 0.05) increased and decreased in H2O2 group (3786 ± 160) (P < 0.05) contrasted with control group (5256 ± 143). The expression of SIRT3 in CR + H2O2 group (5056 ± 121) (P < 0.05) increased contrasted with H2O2 group (3786 ± 160). We also detected that Caspase-3 in H2O2 group (8499 ± 426) (P < 0.001) was much higher than control group than (5342 ± 420), but in the CR + H2O2 group (5750 ± 438) the expression of Caspase-3 was much lower than H2O2 group (8499 ± 426) (P < 0.001). RT-PCR also showed that the expression of SIRT3 in CR group (7214 ± 148) increased and decreased in H2O2 group (4807 ± 143) (P < 0.05) contrasted with control group (6204 ± 134). The expression of SIRT3 in CR + H2O2 group (6195 ± 166) increased contrasted with H2O2 group (4807 ± 143) (P < 0.05). CONCLUSION: CR causes anti-oxidative injury and has apoptotic effects in PC12 cell. It up-regulates the expression of SIRT3 and the effects of CR-SIRT3 can prevent PC12 cell from H2O2-induced apoptosis. And SIRT3 may be a novel molecule of regulating target in the delay of neuronal senescence.