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.

Adrenocorticotropic Hormone ; blood ; Animals ; Corticosterone ; blood ; Ginsenosides ; pharmacology ; Hippocampus ; metabolism ; Male ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptor, trkB ; genetics ; metabolism ; Stress, Psychological ; metabolism

OBJECTIVETo observe the effect of Polygala tenuifolia Willd YZ-50 on the mRNA expression of brain-derived neurotrophic factor (BNDF) and its receptor TrkB in rats with chronic stress depression.es.

METHODSNormal male Wistar rats were divided in to control group, model group, desipramine (20 mg/kg) group, and low and high-dose (2.8 and 5.6 g/kg) YZ-50 groups. The total RNA was extracted from the rats with chronic stress depression, and the mRNA expression of BDNF and TrkB was detected by RT-PCR.

RESULTSCompared with the model group, YZ-50 at both low and high doses significantly increased the mRNA expression of BDNF and TrkB in the hippocampus of rats with chronic stress depression, and the effect was more obvious in the high-dose group (P<0.01).

CONCLUSIONYZ-50 can up-regulate the expression of BDNF and TrkB mRNA to promote the recovery of the neurons from chronic stress-induced damages and produces anti-depressant effect.

Animals ; Brain-Derived Neurotrophic Factor ; genetics ; metabolism ; Depression ; drug therapy ; etiology ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Male ; Polygala ; chemistry ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Receptor, trkB ; genetics ; metabolism ; Stress, Physiological ; physiology ; Up-Regulation ; drug effects

PURPOSE: The purpose of this study is to explore the dynamic change of brain-derived neurotrophic factor (BDNF) mRNA, protein, and tyrosine kinase-coupled receptor (TrkB) mRNA of the rat hippocampus under different stress conditions and to explore the influence of senescence on the productions expression. MATERIALS AND METHODS: By using forced-swimming in 4degrees C cold ice water and 25degrees C warm water, young and aged male rats were randomly divided into acute stress (AS) and chronic mild repeated stress (CMRS) subgroups, respectively. BDNF productions and TrkB mRNA in the hippocampus were detected by using Western-blotting and reverse transcription-polymerase chain reaction (RT-PCR), separately, at 15, 30, 60, 180, and 720 min after the last stress session. RESULTS: The short AS induced a significant increase in BDNF mRNA and protein in both age groups, but the changes in the young group were substantially greater than those of the aged group (p < 0.005). The CMRS resulted in a decrease in BDNF mRNA and protein, but a significant increase in TrkB mRNA in both young and age groups. The expression of BDNF mRNA and protein in the AS groups were higher than in the CMRS groups at 15, 30, and 60 min after stress. CONCLUSION: The results indicated that the up/down-regulation of BDNF and TrkB were affected by aging and the stimulus paradigm, which might reflect important mechanisms by which the hippocampus copes with stressful stimuli.
Animals ; Blotting, Western ; Brain-Derived Neurotrophic Factor/genetics/*metabolism ; Corticosterone/blood ; *Gene Expression Regulation ; Hippocampus/*metabolism ; Male ; Radioimmunoassay ; Random Allocation ; Rats ; Rats, Wistar ; Receptor, trkB/genetics/*metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Stress, Physiological/genetics/*physiology

BACKGROUNDThe effect of chronic stress on cognitive functions has been one of the hot topics in neuroscience. But there has been much controversy over its mechanism. The aim of this study was to investigate the effects of chronic multiple stress on spatial learning and memory as well as the expression of Fyn, BDNF and TrkB in the hippocampus of rats.

METHODSAdult rats were randomly divided into control and chronic multiple stressed groups. Rats in the multiple stressed group were irregularly and alternatively exposed to situations of vertical revolution, sleep expropriation and restraint lasting for 6 weeks, 6 hours per day with night illumination for 6 weeks. Before and after the period of chronic multiple stresses, the performance of spatial learning and memory of all rats was measured using the Morris Water Maze (MWM). The expression of Fyn, BDNF and TrkB proteins in the hippocampus was assayed by Western blotting and immunohistochemical methods. The levels of Fyn and TrkB mRNAs in the hippocampus of rats were detected by RT-PCR technique.

RESULTSThe escape latency in the control group and the stressed group were 15.63 and 8.27 seconds respectively. The performance of spatial learning and memory of rats was increased in chronic multiple stressed group (P < 0.05). The levels of Fyn, BDNF and TrkB proteins in the stressed group were higher than those of the control group (P < 0.05). The results of immunoreactivity showed that Fyn was present in the CA3 region of the hippocampus and BDNF positive particles were distributed in the nuclei of CA1 and CA3 pyramidal cells as well as DG granular cells. Quantitative analysis indicated that level of Fyn mRNA was also upregulated in the hippocampus of the stressed group (P < 0.05).

CONCLUSIONSChronic multiple stress can enhance spatial learning and memory function of rats. The expression of Fyn, BDNF and TrkB proteins and the level of Fyn mRNA are increased in the stessed rat hippocampus. These suggest that Fyn and BDNF/TrkB signal transduction pathways may participate in the process of the enhanced learning and memory during chronic multiple stress.

Animals ; Blotting, Western ; Brain-Derived Neurotrophic Factor ; genetics ; metabolism ; Hippocampus ; metabolism ; Immunohistochemistry ; Learning ; physiology ; Male ; Memory ; physiology ; Proteins ; genetics ; metabolism ; Proto-Oncogene Proteins c-fyn ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Receptor, trkB ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Stress, Physiological ; physiopathology