Erythropoietin attenuates propofol-induced hippocampal neuronal cell injury in developing rats by inhibiting toll-like receptor 4 expression

•Erythropoietin can attenuate propofol-induced hippocampal neuronal cell injury in developing rats.•Erythropoietin can attenuate hippocampal neuronal cell injury via inhibiting TLR4 expression.•Erythropoietin up-regulated the expression of Ki-67, PCNA, Bcl-2, NGF, BDNF and NT-3 in developing rats.•Erythropoietin decreased the expression of Bax, Caspase-3, TLR4 and p65. This study was to investigate the neuroprotective effect of erythropoietin (EPO) on hippocampal neuronal cell injury in developing rats. The hippocampal neurons cells were obtained from SD rats aged 10 days and divided into control, propofol, EPO, and propofol + erythropoietin (E + P) groups. Cell proliferation and apoptosis were measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Ki-67 immunofluorescence, and flow cytometry, respectively. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4 and IL-10 were detected by enzyme-linked immunosorbent assay (ELISA). Cellular immunohistochemistry was utilized to detect the expression of proliferating cell nuclear antigen (PCNA), nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3). Quantitative real time polymerase chain reaction (qRT-PCR) and western blot were used to detect the expression of Bax, Bcl-2, Caspase-3, toll-like receptor 4 (TLR4) and p65. Furthermore, TLR4 antagonist (TAK-242) and activator (LPS) were used to study the relationship between EPO and TLR4. Propofol treatment caused morphological and structural damage of hippocampal neurons. However, EPO significantly improved this damage, enhanced cell proliferation, decreased apoptosis and pro-inflammatory factor content, up-regulated the expression of Ki-67, PCNA, Bcl-2, NGF, BDNF and NT-3, as well as decreased the expression of Bax, Caspase-3, TLR4 and p65 (p