Jie Luo

Ion channel mechanism and ingredient bases of Shenfu Decoction's cardiac electrophysiological effects

AIM OF THE STUDY Ion channel mechanism of cardiac electrophysiological effects of Shenfu Decoction (SFD, Ginseng and Aconiti Praeparatae Decoction), a traditional Chinese medicine (TCM) prescription, and its ingredient bases were investigated in guinea pigs. MATERIALS AND METHODS After administration of an injection made from SFD (Shenfu Injection, SFI), the indexes of transmembrane action potential (TAP) in vivo and sodium channels in isolated ventricular myocyte were assayed by suspended microelectrodes and patch clamp techniques respectively, and ingredients of SFD were compared with. RESULTS After administration of SFI, the action potential amplitude (APA) and maximum velocity (V(max)) of TAP decreased. In the presence of either SFI or Fuzi active ingredient (FZAI)(5, 10, and 15%), not any other ingredient, the density of voltage-dependent sodium current (I(Na)) decreased significantly, while the inhibition ratio of SFI was larger. EC(50) of SFI was less than the one of FZAI, and SFI displayed effects on I(Na) in wider voltage scope than FZAI in current-voltage curve. Both SFI and FZAI shifted the steady-state inactivation curve of sodium channels to the left, and the recovery curve to the right. CONCLUSIONS The results indicated that the cardiac electrophysiological effects of SFI were exerted by blocking sodium channels, and FZAI contributed to such effects most but inferior to SFI, which justified its use in anti-arrhythmia, myocardial protection, etc.

Effects of electroconvulsive stimulation on long-term potentiation and synaptophysin in the hippocampus of rats with depressive behavior.

Objectives To evaluate the effects of electroconvulsive stimulation (ECS) on long-term potentiation (LTP) and synaptophysin (SYP) in the hippocampus of rats under chronic unpredictable mild stress (CUMS). Methods Sixty Sprague-Dawley rats were randomly divided into three groups (n = 20 for each group): the control group (no intervention), the CUMS group (subjected to 28 days of CUMS exposure followed by 7 days of mock ECS treatment), and the CUMS + ECS group (subjected to 28 days of CUMS exposure followed by 7 days of ECS treatment). Depressive behavior was assessed by a sucrose preference test and an open-field test. The LTP levels in rat hippocampal slices were examined through electrophysiological experiments. The SYP mean density in the hippocampal CA3 region was detected by immunohistochemistry. Hippocampal SYP mRNA was assessed through reverse transcriptase–polymerase chain reaction. Results Chronic unpredictable mild stress diminished sucrose preference and reduced measures of locomotor activity. In addition, CUMS impaired LTP in the hippocampal CA1 region and significantly decreased SYP mean density in the hippocampal CA3 region and hippocampal SYP mRNA levels. Electroconvulsive stimulation improved these harmful behavioral effects and ameliorated LTP impairment, as well as stabilized SYP mean density in the hippocampal CA3 region and hippocampal SYP mRNA levels. Conclusions These results suggest that ECS can reverse the harmful behavioral effects of CUMS in rats and that the behavioral alterations induced by ECS and/or CUMS may be associated with hippocampal neuroplasticity and SYP levels.

Nerve Growth Factor Protects the Ischemic Heart via Attenuation of the Endoplasmic Reticulum Stress Induced Apoptosis by Activation of Phosphatidylinositol 3-Kinase

Background: Increased expression of nerve growth factor (NGF) has been found in the myocardium suffered from ischemia and reperfusion (I/R). The pro-survival activity of NGF on ischemic heart has been supposed to be mediated by phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. Endoplasmic reticulum (ER) stress, which is activated initially as a defensive response to eliminate the accumulated unfolded proteins, has shown a critical involvement in the ischemia induced myocardial apoptosis. This study was aimed to investigate whether NGF induced heart protection against I/R injury includes a mechanism of attenuation of ER stress-induced myocardial apoptosis by activation of PI3K/Akt pathway. Methods: Isolated adult rat hearts were perfused with a Langendörff perfusion system. Hearts in the Sham group were subjected to 225 min of continuous Krebs-Henseleit buffer (KHB) perfusion without ischemia. Hearts in I/R group were perfused with KHB for a 75-min of equilibration period followed by 30 min of global ischemia and 120 min of KHB reperfusion. Hearts in the NGF group accepted 45 min of euilibration perfusion and 30 min of NGF pretreatment (with a final concentration of 100 ng/ml in the KHB) before 30 min of global ischemia and 120 min of reperfusion. Hearts in K252a and LY294002 groups were pretreated with either a TrkA inhibitor, K252a or a phosphatidyl inositol 3-kinase inhibitor, LY294002 for 30 min before NGF (100 ng/ml) administration. Cardiac hemodynamics were measured from the beginning of the perfusion. Cardiac enzymes and cardiac troponin I (cTnI) were assayed before ischemia and at the end of reperfusion. Myocardial apoptosis rate was measured by TUNEL staining, and expression of glucose-related protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12, total- and phospho-(Ser473)-Akt were assessed by Western blot analyses. Results: NGF pretreatment significantly improved the recovery of post-ischemia cardiac hemodynamics. Reduced creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) activity and cTnI levels, as well as decreased myocardial apoptosis ratio were observed in the NGF group. The improvement of NGF on recovery of cardiac function and alleviation of myocardial injury were completely abolished by K252a or LY294002. GRP78, caspase-12 and CHOP were highly expressed in ischemic myocardium, while NGF significantly inhibited the overexpression of these proteins which were involved in ER stress-induced myocardial apoptosis. NGF pretreatment also induced phosphorylation of Akt. When the activation of PI3K/Akt pathway is blocked by LY294002, the NGF induced suppression of the apoptosis-related proteins expression was reversed. Conclusions: NGF pretreatment may protect the ischemic heart via inhibition of the ER stress-induced apoptosis; this pro-survival effect is mediated by PI3K/Akt pathway.

Propofol interacts with stimulus intensities of electroconvulsive shock to regulate behavior and hippocampal BDNF in a rat model of depression.

As a psychiatric treatment, modern electroconvulsive therapy (ECT) requires anesthesia to enhance safety, but anesthetics may weaken its efficacy. Previous studies have provided inconsistent results and lack satisfactory details of the influence of anesthetics on ECT efficacy, which partially complicates the clinical selection of ECT protocols. To test our hypothesis that anesthetics interact with the intrinsic parameters of ECT to differentially regulate its therapeutic efficacy, we investigated the effects of the anesthetic propofol and the stimulus intensities of ECT on behavior and hippocampal brain-derived neurotrophic factor (BDNF) in a rodent model of depression. After treatment with chronic unpredictable mild stresses to produce the model, the depressed rats received anesthesia with propofol or normal saline, i.p., and electroconvulsive shock (ECS, an analog of ECT to animals) with different stimulus intensities. The sucrose preference and open field tests were performed to assess behavior, and BDNF level in hippocampus was measured with ELISA. We found that propofol regulated the efficacy of ECS differently at different stimulus intensities in both the behavioral and molecular levels. At medium intensities (120 and 180 mC), propofol enhanced the anti-depressant efficacy of ECS without largely compromising the recovering efficacy of ECS on spontaneous exploratory activities. The results indicated that propofol and ECS stimulus intensities interacted and resulted in different regulating efficacies at different intensities. Medium stimulus intensities were optimal for ECS efficacy under propofol anesthesia.

Ketamine-mediated alleviation of electroconvulsive shock-induced memory impairment is associated with the regulation of neuroinflammation and soluble amyloid-beta peptide in depressive-like rats.

Electroconvulsive therapy (ECT) is an effective treatment for depression, but can result in memory deficits. This study aimed to determine whether ketamine could alleviate electroconvulsive shock (ECS, an analog of ECT in animals)-induced memory impairment and the potential molecular mechanism. Chronic unpredictable mild stress was used to generate animal models of depressive-like symptoms. Sixty adult male Sprague-Dawley rats were randomly divided into the following five groups: control group (group C); depressive-like model group (group D); ECS group (group DE); ketamine+ECS group (group DKE); and ketamine group (group DK). The sucrose preference test and Morris water maze were used to assess behavioral changes. The expression levels of Iba-1, IL-1β and TNF-α were measured by immunohistochemistry and real-time PCR. Enzyme-linked immunosorbent assays were used to detect the levels of soluble Aβ. We found that ECS up-regulated the expression of Iba-1, promoted the release of IL-1β and TNF-α, increased the levels of Aβ1-40 and Aβ1-42 in the hippocampus, and aggravated memory impairment of the depressive-like rats. However, ketamine reversed these ECS-induced molecular changes and effectively attenuated ECS-induced memory impairment. This cognitive protective effect of ketamine may be attributed to its suppression of ECS-induced neuroinflammation and reduction of the levels of soluble Aβ.

Propofol prevents electroconvulsive-shock-induced memory impairment through regulation of hippocampal synaptic plasticity in a rat model of depression.

Background Although a rapid and efficient psychiatric treatment, electroconvulsive therapy (ECT) induces memory impairment. Modified ECT requires anesthesia for safety purposes. Although traditionally found to exert amnesic effects in general anesthesia, which is an inherent part of modified ECT, some anesthetics have been found to protect against ECT-induced cognitive impairment. However, the mechanisms remain unclear. We investigated the effects of propofol (2,6-diisopropylphenol) on memory in depressed rats undergoing electroconvulsive shock (ECS), the analog of ECT in animals, under anesthesia as well as its mechanisms. Methods Chronic unpredictable mild stresses were adopted to reproduce depression in a rodent model. Rats underwent ECS (or sham ECS) with anesthesia with propofol or normal saline. Behavior was assessed in sucrose preference, open field and Morris water maze tests. Hippocampal long-term potentiation (LTP) was measured using electrophysiological techniques. PSD-95, CREB, and p-CREB protein expression was assayed with Western blotting. Results Depression induced memory damage, and downregulated LTP, PSD-95, CREB, and p-CREB; these effects were exacerbated in depressed rats by ECS; propofol did not reverse the depression-induced changes, but when administered in modified ECS, propofol improved memory and reversed the downregulation of LTP and the proteins. Conclusion These findings suggest that propofol prevents ECS-induced memory impairment, and modified ECS under anesthesia with propofol improves memory in depressed rats, possibly by reversing the excessive changes in hippocampal synaptic plasticity. These observations provide a novel insight into potential targets for optimizing the clinical use of ECT for psychiatric disorders.

Pharmacodynamic changes with vecuronium in sepsis are associated with expression of α7- and γ-nicotinic acetylcholine receptor in an experimental rat model of neuromyopathy

BACKGROUND Resistance to non-depolarizing neuromuscular blocking agents induced by sepsis is associated with the qualitative change in the nicotinic acetylcholine receptor (nAChR). This study aims to investigate the effects of sepsis on the neuromuscular block properties of vecuronium in relation to the expression of fetal and neuronal α7 type nAChR. METHODS Male Sprague-Dawley rats were randomly divided into sham and sepsis groups. Sepsis was induced by caecal ligation and puncture (CLP). The rats were injected i.v. with ulinastatin or normal saline on Day 10. Neuromuscular block properties of vecuronium were evaluated and neuromuscular function was assessed by electromyography on Days 1, 3, 7, and 14 after CLP. Expression of fetal and neuronal type α7-nAChR on the tibialis anterior muscle was assessed using immunohistochemistry and western blot. The mRNA encoding for γ- and α7 subunits was evaluated by real-time polymerase chain reaction. RESULTS The half maximal inhibitory response of vecuronium in the sepsis group significantly increased, peaked on Day 7, and then declined on Day 14 (P<0.05). The neuromuscular function decreased with increasing postoperation time in the sepsis group (P<0.05). Sepsis significantly increased the expression of γ- and α7-nAchR along with expression of γ- and α7 subunits mRNA, peaked on Day 7, and declined on Day 14 (P<0.05). Ulinastatin suppressed the expression of receptor protein and mRNA encoding for γ- and α7 subunits (P<0.05). CONCLUSIONS Pharmacodynamic changes with vecuronium seem to be associated with the expression of γ- and α7-nAChR in the skeletal muscle. Ulinastatin can improve this effect by inhibiting the expression of these receptors.

Effects of propofol on the activation of hippocampal CaMKIIα in depressed rats receiving electroconvulsive therapy.

Objectives The aim of this study was to investigate the effects of propofol on the activation of hippocampal calcium/calmodulin-dependent protein kinase II&agr; (CaMKII&agr;) in electroconvulsive therapy (ECT) in a rat model of depression. Methods Sprague-Dawley rats were stressed repeatedly for 28 days to establish a depressed model. Forty depressed rats were then randomly assigned (n = 10 per group) to the depression group, propofol group (received propofol once a day for 1 week), ECT group (treated with ECT once a day for 1 week), or propofol + ECT group (treated with ECT pretreated and propofol once a day for 1 week). Their depressive state was assessed using the sucrose preference test and open-field test, whereas their learning and memory were evaluated using the Morris water maze task. The expression levels of CaMKII&agr; and phosphorylated CaMKII&agr; (pCaMKII&agr;) were detected by immunohistochemistry. Results Compared with the depression group, the ECT and propofol + ECT groups had higher sucrose preference percentages and scored higher on the open-field test. The ECT group exhibited longer escape latency, shorter space exploration time, down-regulated expressions of CaMKII&agr; and pCaMKII&agr; in the hippocampus, and lower pCaMKII&agr;/CaMKII&agr; values. The propofol + ECT group showed up-regulated expressions of CaMKII&agr; and pCaMKII&agr; in the hippocampus. Compared with the ECT group, the propofol + ECT group exhibited shorter escape latency, longer space exploration time, up-regulated expressions of CaMKII&agr; and pCaMKII&agr;, and higher pCaMKII&agr;/CaMKII&agr; values. Conclusions Propofol may potentially alleviate ECT-induced learning/memory impairment in depressed rats by enhancing CaMKII&agr; activation in the hippocampus.

Effects of low-dose ketamine combined with propofol on phosphorylation of AMPA receptor GluR1 subunit and GABAA receptor in hippocampus of stressed rats receiving electroconvulsive shock.

Objectives To investigate the effects of low-dose ketamine combined with propofol on the antidepressant efficacy in stressed rats undergoing electroconvulsive shock (ECS) and its impact on phosphorylation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor subunit glutamate receptor 1 (GluR1) and &ggr;-aminobutyric acid receptor subunit A (GABAAR). Methods Sprague-Dawley rats were stressed by chronic unpredictable mild stress. Fifty stressed rats were randomly divided into 5 groups (n = 10 per group): depression group (with no application, group D), ECS group (applied with ECS after intraperitoneal injection of isotonic sodium chloride solution, 8 mL/kg, group E), ketamine + ECS group (applied with ECS after intraperitoneal injection of ketamine, 10 mg/kg, group KE), propofol + ECS group (applied with ECS after intraperitoneal injection of propofol, 80 mg/kg, group PE), and ketamine + propofol + ECS group (applied with ECS after intraperitoneal injection of ketamine, 10 mg/kg, and propofol, 80 mg/kg, group KPE). All groups except group D underwent ECS once a day for 7 consecutive days. Sucrose preference test, open-field test, and Morris water maze were performed to assess the depressive behavior. Phosphorylation of GluR1 and GABAAR were evaluated by Western blot. Results Compared with group D, sucrose preference percentage and open-field scores were increased after ECS application in the 4 other groups; rats in group E reported prolonged escape latency and shortened space exploration time, whereas the escape latency were decreased and space exploration time were prolonged in group KPE; the ratio of p-GluR1/p-GABAAR in hippocampus were increased in the 4 other groups. When using group E as control, rats in group KPE exhibited higher sucrose preference percentage and open-field scores; the escape latency was shortened and space exploration time was prolonged in groups KE, PE, and KPE; the ratio of p-GluR1/p-GABAAR in the hippocampus was up-regulated in groups KE and KPE. When compared with groups KE and PE, the rats in group KPE exhibited higher sucrose preference percentage and open-field scores, the escape latency of group KPE was shortened and space exploration time was prolonged, the ratio of p-GluR1/p-GABAAR in the hippocampus of group KEP is between those of groups KE and PE. Conclusions Low-dose ketamine combined with propofol may play a role in enhancing the antidepressant efficacy of ECS in stressed rats, ameliorating the cognitive impairment associated with ECS by balancing the expression of p-GluR1 and p-GABAAR in the hippocampus of stressed rats.

Behavioral and molecular responses to electroconvulsive shock differ between genetic and environmental rat models of depression

Depression׳s causes play a role in individuals׳ different responses to antidepressant treatments, which require advancements. We investigated the mechanisms behind and responses to a highly effective antidepressant treatment, electroconvulsive therapy (ECT), in rat models with different (genetic or environmental) depression causes. Wistar Kyoto (WKY) rats and Wistar rats treated with chronic unpredictable mild stresses (CUMS) were used as genetic and environmental rat models of depression, respectively. The rats underwent electroconvulsive shock (ECS, the animal analog of ECT) or sham ECS. We performed a sucrose preference test, open field test, and Morris water maze to assess behavior. Hippocampal neuron numbers were measured with Nissl stain. Hippocampal BDNF, CREB, and p-CREB proteins were assayed with ELISA or western blotting. The main results showed that ECS impaired WKY rats׳ memories but improved CUMS rats׳ memories. It elevated hippocampal BDNF and CREB proteins only in CUMS rats, while it improved depressive behavior and hippocampal p-CREB protein levels in both rats, with more effective regulations in the CUMS rats. ECS did not change the hippocampal neuron number in both rats. These findings suggest that ECS exerted up-regulating effects on hippocampal BDNF and CREB (and its phosphorylation) in depressed rats, and the environmental model responded better.