[Effect of Tanshinone IIA on phosphorylated NMDA receptor 1 expression and intracellular free calcium concentration in neonatal SD rats with hypoxic ischemic brain damage].

OBJECTIVE

To determine the effect of Tanshinone IIA (TanIIA) on the phosphory-lated NMDA receptor 1 at Serine 897 site (phospho-NR1 S897) and intracellular free calcium concentration (Ca(2+)) in neonatal SD rats with hypoxic ischemic brain damage (HIBD), and to explore the neuroprotective mechanism of TanIIA in HIBD.

METHODS

Neonatal SD rats were randomly divided into a normal control, and an HIBD and TanIIA+HIBD group. Rice-Vannucci method was used for HIBD animal model. Time points were: 3, 6, 12, and 24 h after HIBD (n=10 in each group at each time point). TanIIA was intraperitoneally given at 1 μg/g every 12 h. Fura-2AM was used to mark the fluorescent calcium probe and Ca(2+) was measured by a Hitachi F-4500 Fluorescence Spectrophometer. Fluorescent immunohisotichemical study was used for the expression of phospho-NR1 S897.

RESULTS

(1) Compared with the normal control group, both the Ca(2+) absolute number and ipsi-/contra-lateral ratio were increased at each time point with statistical significance (P<0.05). Compared with the HIBD group, the Ca(2+) in the HIBD+ TanIIA group was decreased at each time point. At 24 h after HIBD, the ipsi-/contra-lateral ratio of HIBD+ TanIIA group was 24.9% less than that of HIBD group with statistical significance (P<0.05). (2) In the normal control group, abundant phospho-NR1 S897 positive cells were nicely distributed in the cortex. Compared with the normal control group, at each time point, both the absolute number of phospho-NR1 S897 positive cells and the fluorescent intensity of phospho-NR1 S897 in the ipsilateral cortex of the HIBD group were decreased with statistical significance (P<0.05). Compared with the HIBD group, both the absolute number of phospho-NR1 S897 positive cells and the fluorescent intensity of phospho-NR1 S897 in the ipsilateral cortex of HIBD+ TanIIA were increased. There was significant difference at 3 and 12 h after the HIBD (P<0.05).

CONCLUSION

TanIIA reduced the HIBD-caused down-regulation of phospho-NR1 S897 and the HIBD-caused Ca(2+) elevation in the cortex. The neuroprotective effect of TanIIA may be related to influencing NMDA receptor expression and decreasing intracellular free calcium aggregation.