Neuroprotective effects of rhizoma dioscoreae polysaccharides against neuronal apoptosis induced by in vitro hypoxia

Abstract

Rhizoma Dioscoreae polysaccharides (RDPS) are the primary active ingredient of Rhizoma Dioscoreae, which is a traditional Chinese medicine. RDPS have previously been shown to scavenge reactive oxygen species, and protect against D‑galactose‑induced mimetic aging. The present study aimed to investigate the neuroprotective effects of RDPS against hypoxia‑induced neuronal cell apoptosis. Neuronal cells harvested from pregnant Sprague‑Dawley rats were divided into groups, as follows: i) Normal control group; ii) hypoxia‑induced apoptosis neuronal cell model; iii) 0.025 g/l RDPS‑treated group; iv) 0.05 g/l RDPS‑treated group; v) 0.1 g/l RDPS‑treated group; and vi) 0.25 g/l RDPS treated group. Neuronal cell viability was investigated using an MTT assay, and neuronal cell apoptosis was analyzed using Annexin V‑fluorescein isothiocyanate/propidium iodide double‑staining, Hoechst 33342 fluorescent staining, Rhodamine 123 staining, polymerase chain reaction and immu­nocytochemical staining. The RDPS‑treated neuronal cells exhibited improved viability, and decreased hypoxia‑induced mitochondrial injury and apoptosis. In addition, the mRNA and protein expression levels of caspase‑3 and B‑cell lymphoma (Bcl)‑2‑associated X protein (Bax) were significantly downregu­lated, whereas the mRNA and protein expression levels of Bcl‑2 were significantly upregulated, in the RDPS‑treated hypoxic neurons, as compared with the apoptosis model (P<0.05). Furthermore, the ratio of Bcl‑2 expression:Bax expression significantly increased following RDPS treatment, as compared with the apoptosis model (P<0.05). The results of the present study suggested that RDPS may attenuate hypoxia‑induced neuronal cell apoptosis by altering the expression levels of key apoptosis‑regulating proteins in hypoxic neurons.