The protective mechanism of Ginkgolides and Ginkgo flavonoids on the TNF-α induced apoptosis of rat hippocampal neurons and its mechanisms in vitro

OBJECTIVE: To explore the neuroprotective mechanism of Ginkgolides or Ginkgo flavonoids on the TNF-α induced apoptosis of cultured rat hippocampal neurons. MATERIALS AND METHODS: Primary hippocampal neurons were isolated from rat brains and cultured with (model group) or without (control group) addition of tumor necrosis factor-α (TNF-α, final concentration of 40 ng/ml) to induce apoptosis. TNF-α induced cultures were divided into model group, Ginkgolides pre-treatment group (20 μg/ml) and Ginkgo flavonoids pre-treatment group (12 μg/ml). CCK8 was used to assess cell viability while Hoechst 33258 staining, Flow cytometry and TUNEL kits were all employed to determine apoptotic neurons. Expression levels of Bcl-2, Bax, Caspase-3, Caspase-7, Caspase-8, Caspase-9 and Cytc were estimated by qRT-PCR. RESULTS: Cell viability was significantly improved in Ginkgolides pre-treatment group or Ginkgo flavonoids pre-treatment group compared with that in model group. Apoptotic neurons were significantly less in Ginkgolides pre-treatment group or Ginkgo flavonoids pre-treatment group than those in model group. Transcription levels of caspase-7, caspase-8, caspase-3, caspase-9, Bax and Cytc were down-regulated, while transcription levels of Bcl-2 was up-regulated in Ginkgolides pre-treatment or Ginkgo flavonoids pre-treatment group than those in model group. CONCLUSIONS: Ginkgolides and Ginkgo flavonoids might protect against apoptosis of hippocampal neurons through inhibiting death receptor pathway or mitochondrial pathway under TNF-α background.