Effects of ginkgobalide B on neurocyte apoptosis and the expression of protein kinase B after experimental hypoxic-ischemic brain injury

Abstract

Objective To observe the effect of ginkgobalide B (GB) on neurocyte apoptosis and protein kinase B expression in neonatal rats after hypoxic-ischemic brain damage (HIBD). Methods Ninety seven-day-old Sprague-Dawley rats were randomly divided into a sham group, an HIBD group and a GB group, each of 30. HIBD was induced in the HIBD and GB groups using the classical Rice method, while the sham group was given a sham operation. GB (10 mg/kg) was injected intraperitoneally to the rats in the GB group at 0 h and 24 h after the modeling. Then 6 rats were killed 6 h, 12 h, 24 h and 48 h after the modeling, and the expression of caspase-3 mRNA was detected using a real-time PCR to find the time point of maximum effectiveness. Then to further explore the role of the PI3K-AKT pathway in the anti-apoptosis effect of ginkgolide B, a a GB+ LY294002 group of 6 rats, which was injected with PI3K-AKT pathway inhibitor LY294002 (1.8 mg/kg) intraperitoneally at 30 min before the modeling and with GB(10 mg/kg) at 0 h and 24 h after the modeling, was added to the experiment. Hematoxylin-eosin staining, terminal-deoxynucleotidyl transferase-mediated nick end labeling and immunohistochemical staining were then used to observe any morphological changes in the cortex, to detect neuronal apoptosis and to quantify the expression of P-AKT protein. Results The expression of caspase-3 in the HI and GB groups began to increase 6 hours after the HIBD and reached a peak after 24 hours, followed by a gradual decline. The expression of caspase-3 in the GB group was significantly lower than in the HI group throughout, while that of both of those groups was significantly higher than in the sham group. Apoptosis-positive cells and the expression of caspase-3increased had significantly in the HI, GB and GB+ LY294002 groups 24 hours after the HIBD compared with the sham group, while the expression of P-AKT protein had decreased significantly. Moreover, the apoptosis-positive cells and the expression of caspase-3 of the HI and GB+ LY294002 groups were significantly higher than those of the GB group, while their expression of P-AKT protein was significantly lower after 24 hours. Conclusion Ginkgobalide B can decrease neurocyte apoptosis caused by hypoxic-ischemic brain damage, especially at 24 h after the damage. The PI3K-AKT signaling pathway plays an important role in this effect. Key words: Ginkgobalide B; Hypoxic-ischemic brain injury; Apoptosis