ABSTRACT
@#Objective To explore the protective effects and mechanism of Zuogui Jiangtang Jieyu Formula (左归降糖解郁方, ZGJTJYF) on hippocampal neurons in rats of diabetes complicated with depression (DD) via the TRP/KYN metabolic pathway. Methods (i) In vivo experiments: 60 specified pathogen free (SPF) grade male Sprague-Dawley (SD) rats were randomly divided into six groups with 10 rats in each groups: control, DD model, positive (1.8 mg/kg fluoxetine + 0.18 g/kg metformin), high-dose ZGJTJYF (ZGJTJYF-H, 40.500 g/kg ZGJTJYF), middle-dose ZGJTJYF (ZGJTJYF-M, 20.250 g/kg ZGJTJYF), and low-dose ZGJTJYF (ZGJTJYF-L, 10.125 g/kg ZGJTJYF) groups. Except for the control group, other groups were established DD model by high-fat emulsion intake with single tail vein streptozotocin (STZ) and four weeks of chronic unpredictable mild stress (CUMS). All drug administration groups were treated by gavage during CUMS modeling, and the control and model groups were given equal amount of distilled water. After four weeks, the serum levels of blood glucose and glycosylated hemoglobin were measured to determine the hypoglycemic effect of ZGJTJYF. Moreover, the open field test and Morris water maze test were performed to evaluate the antidepressant effect of ZGJTJYF. Changes in 5-hydroxytryptamine (5-HT) level were detected via high-performance liquid chromatography with electrochemical detection (HPLC-ECD); the levels of tryptophan (TRP), kynurenine (KYN), and indoleamine 2,3-dioxygenase (IDO) in the hippocampus were detected using enzyme-linked immunosorbent assay (ELISA); the protein expression levels of synaptophysin (SYN) and postsynaptic density material-95 (PSD-95) were detected via immunohistochemistry (IHC); and the protein expression levels of N-methyl-D-aspartate receptor (NR) 2A and NR2B were detected using Western blot. (ii) In vitro experiments: five SPF grade SD pregnant rats (E16 – 18) were used to obtain primary hippocampal neurons (Ne), six SD new-born rats were used to collected primary astrocytes (As) and microglia (MG), and to establish a Ne-As-MG co-culture system. All co-culture systems were divided into six groups: control (PBS), model [150 mmol/L glucose + 200 μmol/L corticosterone (G&P) + PBS], blank (G&P + blank serum), positive (G&P + positive drug-containing serum), ZGJTJYF (G&P + ZGJTJYF serum), and 1-methyl-D-tryptophan (1-MT, IDO inhibitor) (G&P + 1-MT) groups. After 18 h of intervention by corresponding treatment, immunofluorescence was used to analyze the protein expression levels of SYN, PSD-95, NR2A, and NR2B; ELISA was performed to measure the levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α , and TRP/KYN metabolic pathway-related factors [TRP, KYN, kynurenine acid (KYNA), quinolinic acid (QUIN)]. Results (i) In vivo experimental<italic/> results showed that ZGJTJYF-M and ZGJTJYF-L significantly improved the elevated blood glucose state of DD rats (P < 0.01 and P < 0.05, respectively); ZGJTJYF-H, ZGJTJYF-M, and ZGJTJYF-L increased their autonomous activity, learning, and memory ability (P < 0.01, P < 0.01, and P < 0.05, respectively). Moreover, the levels of 5-HT and TRP were significantly increased (P < 0.01), and the levels of KYN and IDO were significantly decreased in the hippocampus (P < 0.01) of rats after ZGJTJYF-M treatment. The protein expression levels of SYN and PSD-95 were significantly upregulated in hippocampal neurons (P < 0.01), while the abnormal activation of NR2A and NR2B was markedly inhibited in hippocampus (P < 0.05) of rats after ZGJTJYF-M treatment. (ii) In vitro experimental results showed that ZGJTJYF-containing serum significantly increased the protein expression levels of SYN and PSD-95 in hippocampal neurons (P < 0.01), decreased the levels of IL-1β (P < 0.01), IL-6 (P < 0.05), TNF-α (P < 0.01), IDO (P < 0.05), KYN (P < 0.05), and QUIN (P < 0.01), and increased the levels of TRP and KYNA (P < 0.01) in the simulated DD state. ZGJTJYF also had an significantly inhibitory effect on the abnormal activation of NR2A and NR2B in neurons (P < 0.05) in a stimulated DD state. Conclusion ZGJTJYF can effectively improve 5-HT deficiency in the hippocampus of rats by inhibiting IDO expression and regulating the TRP/KYN metabolic pathway, and it has a favorable protective effect on hippocampal neuron injury caused by DD. Therefore, ZGJTJYF is an effective potential therapeutic drug for the prevention and treatment of DD.
ABSTRACT
@#Objective To investigate the efficacy and mechanism of action of Compound Chaijin Jieyu Tablets (复方柴金解郁片, CCJJYT) in rats with insomnia complicated with depression. Methods Seventy-two Sprague-Dawley rats were randomly assigned into eight groups: the control, chronic unpredictable mild stress (CUMS), sleep deprivation (SD), CUMS + SD, positive drug (venlafaxine hydrochloride + diazepam), CCJJYT high-dose (CCJJYT˗2×), medium-dose (CCJJYT˗1×), and low-dose (CCJJYT˗0.5×) groups, with nine rats in each group. Depression-like behavior was evaluated by body weight, food intake, and behavioral tests such as the sucrose preference test (SPT), open field test (OFT), forced swimming test (FST), and pentobarbital-induced sleep test (PST). Hematoxylin-eosin (HE) staining and Golgi-Cox staining were used to observe changes in pathological tissue and synaptic morphology, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to detect the contents of orexin-A and acetylcholine. The expression levels of orexin receptor 1 (OXR1), melatonin receptor 1 (MT1A), melatonin receptor 2 (MT1B), acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) were detected by immunohistochemistry and Western blot. Results In the present study, rats in the model group showed significant behavioral changes as well as a reduction in hippocampal dendritic branch length and synaptic number, along with increasing the content of orexin A and acetylcholine (P< 0.05), and altered expression levels of OX1R, MT1A, MT1B, ChAT, and AChE in the hippocampus and prefrontal cortex after modeling (P < 0.05). CCJJYT can improve depressive insomnia behavior and synaptic plasticity of rats (P < 0.05), which is similar to that of the positive drug group. It can also decrease the content of orexin A and acetylcholine, and reduce the expression levels of OXR1 and ChAT in hippocampus and prefrontal cortex (P < 0.05), and increase the expression levels of MT1A, MT1B, and AChE proteins (P < 0.05). Conclusion CCJJYT has good antidepressant and insomnia effects, probably through the regu-lation of orexin-A, melatonin, and acetylcholine content in hippocampus and prefrontal cortex of rats, improving synaptic plasticity and thus exerting antidepressant and insomnia effects.