Abstract: Objective:To investigate the effects of dexmedetomidine (DEX) on hippocampal neuron development process and the expressions of molecules in brain-derived neurotropic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling pathway in neonatal rats. Methods: The hippocampal neurons were isolated from neonatal rats and cultured in vitro. The cells were seeded in 96-well plates,which were divided into 4 groups (control group, 1 μmol/L DEX treatment group, 5 μmol/L DEX treatment group, 50 μmol/L DEX treatment group), six wells were set in each group, and different concentrations of dexmedetomidine 1, 5 and 50 μmol/L were administered respectively. Cell viability was detected at 2, 4, 6, 8, and 10 d after treatment, and apoptosis was detected 10 days after treatment. The mRNA expression levels of synaptophysin (SYN) and postsynaptic density protein 95 (PSD95) were detected by q-PCR, and the expressions of BDNF, TrkB and N-methyl-D-aspartate receptor (NMDAR) protein were analyzed. Results: Compared with the control group, there was no significant difference in neuronal cell viability between the different doses of DEX treatment group. There was no significant difference in the expression of SYN and PSD95 mRNA and TrkB protein between the 1 μmol/L and 5 μmol/L DEX treatment groups (P＞0.05). The expression levels of SYN and PSD95 mRNA in the 50 μmol/L DEX group were increased significantly (P＜0.01), and the expression level of BDNF protein was up-regulated significantly (P＜0.01), the expression of the p-N-methyl-D-aspartate receptor was increased (P＜0.01). Conclusion: 50 μmol/L DEX has a certain effect on rat hippocampal neurons, which may be achieved by up-regulating the expression of BDNF and the phosphorylation level of N-methyl-D-aspartate receptor.

Key words: dexmedetomidine, hippocampal neuron, BDNF-TrkB, rat