ABSTRACT
Objective:To observe the effect of Sinisan on the brain-derived neurotrophic factor （BDNF）/tyrosine kinase receptor B （TrKB）， 5-hydroxytryptamine （5-HT）/5-HT1A receptor （5-HT1AR）， and hypothalamus-pituitary-adrenal （HPA） axis in depressed rats， and explore the antidepressant mechanism of Sinisan based on BDNF/TrKB， 5-HT/5-HT1AR， and HPA axis. Method:A total of 120 male Wistar rats were randomly divided into a normal group， a model group， a fluoxetine （0.01 g·kg<sup>-1</sup>） group， and low- （1.25 g·kg<sup>-1</sup>）， medium- （2.5 g·kg<sup>-1</sup>）， and high-dose （5 g·kg<sup>-1</sup>） Sinisan groups， with 20 rats in each group. The depression model was induced by isolation combined with chronic unpredictable mild stimulation（CUMS） in rats except for those in the normal group for 21 days. Rats were then treated correspondingly once a day for 21 days by gavage. Those in the normal group and the model group received an equal volume of normal saline. During the intervention， the model rats were stimulated continuously. The depressive state of CUMS model rats was evaluated by sucrose preference test and open field test. Enzyme-linked immunosorbent assay （ELISA） was used to determine the levels of corticotropin-releasing hormone （CRH）， adrenocorticotropic hormone （ACTH）， and corticosterone （CORT） in the plasma and BDNF and 5-HT levels in the hippocampal homogenate. The mRNA expression of hippocampal TrKB， 5-HT1AR， glucocorticoid receptor （GR）， and mineralocorticoid receptor （MR） was detected by real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR）. The protein expression of hippocampal TrKB， 5-HT1AR， GR， and MR was detected by Western blot. The histomorphological changes of the hippocampus were observed by hematoxylin-eosin （HE） staining. Result:Compared with the normal group， the model group showed decreased sucrose preference rate （<italic>P</italic><0.01）， reduced horizontal and vertical scores in the open field test （<italic>P</italic><0.01）， increased plasma content of CRH， ACTH， and CORT （<italic>P</italic><0.01）， declining content of BDNF and 5-HT in the hippocampus （<italic>P</italic><0.01）， dwindled mRNA and protein expression levels of TrKB， 5-HT1AR， and GR （<italic>P</italic><0.01）， elevated mRNA and protein expression of MR （<italic>P</italic><0.01）， and damaged hippocampal neurons revealed by HE staining. Compared with the model group， the groups with drug intervention showed increased sucrose preference rate （<italic>P</italic><0.01） and horizontal and vertical scores in the open field test （<italic>P</italic><0.05， <italic>P</italic><0.01）， decreased content of plasma CRH， ACTH， and CORT （<italic>P</italic><0.05， <italic>P</italic><0.01）， elevated content of hippocampal BDNF and 5-HT （<italic>P</italic><0.05， <italic>P</italic><0.01）， elevated mRNA and protein expression levels of hippocampal TrKB， 5-HT1AR， and GR （<italic>P</italic><0.05， <italic>P</italic><0.01）， reduced mRNA and protein expression levels of hippocampal MR （<italic>P</italic><0.05， <italic>P</italic><0.01）， and recovered hippocampal neurons as revealed by HE staining. Conclusion:Sinisan can exert a significant antidepressant effect by increasing hippocampal BDNF and 5-HT content， up-regulating TrKB， 5-HT1AR， and GR mRNA and protein expression， down-regulating MR mRNA and protein expression， inhibiting HPA axis hypertrophy， and enhancing the regeneration and repair of hippocampal neurons.
ABSTRACT
Objective:To investigate the effect of Tianwang Buxin pills on behavior， hypothalamus pituitary adrenal axis （HPA axis）， hippocampal glycogen synthase kinase 3β （GSK3β） phosphorylation and brain-derived neurotrophic factor （BDNF） expression in mice with chronic unpredictable stress， and explore its mechanisms for antidepressant-like action. Method:Totally 60 male ICR mice were randomly divided into normal group， chronic stress model group， fluoxetine hydrochloride group （10 mg·kg-1） and Tianwang Buxin pills high， middle and low dose groups （3.6， 1.8， 0.9 g·kg-1）. The mice were subjected to the chronic unpredictable stress （CUS） protocol for a period of 28 d to induce depressive-like behavior. Then， a sucrose preference test， open-field test and novelty-suppressed feeding test were performed to detect the behavior changes. The blood， adrenal gland and hippocampus of mice were collected. The contents of adrenocorticotropic hormone （ACTH） and corticosterone （CORT） in serum were detected by enzyme-linked immunosorbent assay （ELISA）. The changes of GSK3β phosphorylation and BDNF expression in hippocampus were detected by Western blot， and the adrenal index was then calculated. Result:As compared with the normal group， the sucrose water preference was significantly decreased （P<0.01）， the number of opening activities was significantly reduced （P<0.05）， the feeding latency of novelty inhibition was prolonged （P<0.01）， the serum ACTH and CORT contents were significantly increased （P<0.05，P<0.01）， GSK3β phosphorylation and BDNF expression levels in hippocampus were significantly decreased （P<0.01）， and adrenal index was significantly increased in model group （P<0.01）. As compared with the model group， Tianwang Buxin pills treatment significantly reversed the CUS-induced behavioral abnormalities in depression model mice （P<0.05， P<0.01）， significantly decreased the levels of plasma ACTH and CORT （P<0.01） and adrenal and adrenal gland index （P<0.01）， while increased GSK3β phosphorylation and BDNF expression in hippocampus （P<0.05， P<0.01）， with its effect similar to that of fluoxetine hydrochloride. Conclusion:Tianwang Buxin pills produced antidepressant-like effects in chronic unpredictable stress mice， and its mechanism may be associated with inhibiting HPA axis activity and up-regulating GSK3β phosphorylation and BDNF protein expression in hippocampus.