OBJECTIVETo observe the effects of acute immobilization stress on the mRNA expression of tyrosine kinase B (TrkB) in rats' hippocampus.

METHODSEighteen SD rats were randomly divided into three groups, i.e., the normal control group, the model group, and the medication group, 6 in each group. The acute immobilization stress model was prepared in the model group using acute immobilization for 2 h. Ginsenoside Rb1 (40 mg/kg) was peritoneally injected to rats in the medication group 30 min before modeling, with the same procedure as those for rats in the model group. No treatment was performed to rats in the normal control group. The plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT) contents were detected using ELISA. The mRNA expression of TrkB in the rats' hippocampus was detected using real-time fluorescence quantitative RT-PCR.

RESULTSBefore modeling there was no statistical difference of plasma CORT or ACTH concentrations among three groups (P >0.05). The plasma CORT and ACTH concentrations increased in the model group and the medication group more significantly after modeling than before modeling, showing statistical difference (P <0.05). Besides, they were obviously higher in the model group than in the normal control group (P <0.05). They were obviously higher in the medication group than in the model control group (P <0.05). Compared with the normal control group, the mRNA expression of TrkB significantly decreased in the model group (87.73 +/- 7.62 vs 50.65 +/- 5.19, P < 0.05), showing statistical difference. The mRNA expression of TrkB was significantly higher in the medication group (78.91 +/- 18.07) than in the model group, showing statistical difference (P <0.05).

CONCLUSIONPretreatment by ginsenoside Rb1 could increase the plasma CORT and ACTH concentrations, maintain the mRNA expression of TrkB, thus relieving injury induced by acute immobilization stress.