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.