Corticostriatal Neurons in the Anterior Auditory Field Regulate Frequency Discrimination Behavior.

The anterior auditory field (AAF) is a core region of the auditory cortex and plays a vital role in discrimination tasks. However, the role of the AAF corticostriatal neurons in frequency discrimination remains unclear. Here, we used c-Fos staining, fiber photometry recording, and pharmacogenetic manipulation to investigate the function of the AAF corticostriatal neurons in a frequency discrimination task. c-Fos staining and fiber photometry recording revealed that the activity of AAF pyramidal neurons was significantly elevated during the frequency discrimination task. Pharmacogenetic inhibition of AAF pyramidal neurons significantly impaired frequency discrimination. In addition, histological results revealed that AAF pyramidal neurons send strong projections to the striatum. Moreover, pharmacogenetic suppression of the striatal projections from pyramidal neurons in the AAF significantly disrupted the frequency discrimination. Collectively, our findings show that AAF pyramidal neurons, particularly the AAF-striatum projections, play a crucial role in frequency discrimination behavior.

Chemokine CCL14 affected the clinical outcome and correlated with immune infiltrates in thyroid carcinoma.

BACKGROUND: As an important member of the chemokines, CCL14 plays a vital role in cancer progression. However, the role of CCL14 in THCA has not been investigated. This study aimed to reveal the clinical significance of CCL14 in THCA. MATERIAL AND METHODS: This study evaluated the expression and prognostic value of CCL14 in THCA. Also, the correlation between CCL14 and immune infiltrates was assessed. Enrichment analysis was finally performed to predict CCL14-associated pathways involved in THCA. RESULTS: The mRNA and protein expressions of CCL14 in THCA tissues were down-regulated compared with normal tissues. CCL14 high expression predicted favorable DFI and PFI but did not influence the DSS and OS. Further, CCL14 showed a good prediction performance on the PFI of patients. Enrichment analysis found that CCL14 was negatively correlated with migration-related pathways such as Notch signaling, ECM-receptor interaction, and cell adhesion molecules. Further, we found that CCL14 was negatively related to immune infiltrates and their gene markers. A negative relationship was also observed between CCL14 and immune checkpoint genes. These results implied the potential effect of CCL14 on the immune response and immune therapy in THCA. CONCLUSIONS: CCL14 high expression prolonged the DFI and PFI of THCA patients. It was negatively correlated with the migration-related pathways, suggesting that CCL14 might participate in the recurrence of THCA. Further, CCL14 was also shown to be important in immune response and immune therapy in THCA.

Proprietary Medicines Containing Bupleurum chinense DC. (Chaihu) for Depression: Network Meta-Analysis and Network Pharmacology Prediction.

Background and Aims: The rapid development of society has resulted in great competitive pressures, leading to the increase in suicide rates as well as incidence and recurrence of depression in recent years. Proprietary Chinese medicines containing Bupleurum chinense DC. (Chaihu) are widely used in clinical practice. This study aimed at evaluating the efficacy and safety of oral proprietary Chinese medicines containing Chaihu for treating depression by network meta-analysis (NMA) and exploring the potential pharmacological mechanisms of the optimal drugs obtained based on NMA. Methods: This study searched for clinical randomized controlled trial studies (RCTs) about Chaihu-containing products alone or in combination with selective serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), and cyclic antidepressants (CAS) for depression in eight databases. The search deadline is from data inception to April 2021. For efficacy assessment, the clinical response rate, the Hamilton Depression Scale-17 (HAMD-17), and adverse reactions were calculated. The methodological quality of the included studies was assessed for risk of bias following the Cochrane Handbook for Systematic Reviews of Interventions, and the data were subjected to NMA via the Stata version 16.0 software. Subsequently, the optimal drug obtained from the NMA results, Danzhi Xiaoyao pill (DZXY), was used to conduct network pharmacology analysis. We searched databases to acquire bioactive and potential targets of DZXY and depression-related targets. The protein-protein interaction (PPI) network, component-target network, the Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed by the STRING database, Cytoscape 3.9.0 software, and R version 4.1.2, respectively. Results: Thirty-seven RCTs, with a total of 3,263 patients, involving seven oral proprietary Chinese medicines containing Chaihu, were finally included. The results of the NMA demonstrated that the top four interventions with the best efficiency were Jiawei Xiaoyao + SSRI, DZXY + SNRI, Xiaoyao pill + SSRI, and Jieyu pill + SNRI; the top four interventions reducing HAMD score were DZXY + SNRI, Jiawei Xiaoyao, Jieyu pill, and Puyu pill + SNRI; the top four interventions with the least adverse effects were Jieyu pill, Anle pill + SSRI, DZXY + SNRI, and Puyu pill + SNRI. In the aspects above, DZXY + SNRI performed better than other treatments. After network meta-analysis, we conducted a network pharmacology-based strategy on the optimal drugs, DZXY, to provide the pharmacological basis for a conclusion. A total of 147 active compounds and 248 targets in DZXY were identified, of which 175 overlapping targets related to depression. Bioinformatics analysis revealed that MAPK3, JUN, MAPK14, MYC, MAPK1, etc. could become potential therapeutic targets. The MAPK signaling pathway might play an essential role in DZXY against depression. Conclusion: This is the very first systematic review and network meta-analysis evaluating different oral proprietary Chinese medicines containing Chaihu in depressive disorder. This study suggested that the combination of proprietary Chinese medicines containing Chaihu with antidepressants was generally better than antidepressant treatment. The incidence of adverse reactions with antidepressants alone was higher than that with proprietary Chinese medicines containing Chaihu alone or in combination with antidepressants. DZXY + SNRI showed significantly better results in efficacy, HAMD scores, and safety. The antidepressant effect of DZXY may be related to its regulation of neuroinflammation and apoptosis.

Comparison of outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal GIST: An inverse probability of treatment weighting analysis.

BACKGROUND AND OBJECTIVES: This study aimed to compare outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal gastrointestinal stromal tumors (GIST) patients. METHODS: Eighty-five patients with localized rectal GIST were divided into two groups: upfront surgery ± adjuvant imatinib (Group A, n = 33) and the neoadjuvant imatinib + surgery + adjuvant imatinib (Group B, n = 52). Baseline characteristics between groups were controlled for with inverse probability of treatment weighting (IPTW) adjusted analysis. RESULTS: The response rate to neoadjuvant imatinib was 65.9%. After the IPTW-adjusted analysis, patients who underwent neoadjuvant therapy had better distant recurrence-free survival (DRFS) and disease-specific survival (DSS) compared with those who underwent upfront surgery (5-year DRFS 97.8 vs. 71.9%, hazard ratio [HR], 0.15; 95% CI, 0.03-0.87; p = 0.03; 5-year DSS 100 vs. 77.1%; HR, 0.11; 95% CI, 0.01-0.92; p = 0.04). While no significant association was found between overall survival (OS) and treatment groups (p = 0.07), 5-year OS was higher for the neoadjuvant group than upfront surgery group (97.8% vs. 71.9%; HR, 0.2; 95% CI, 0.03-1.15). CONCLUSIONS: In patients with localized rectal GIST, neoadjuvant imatinib not only shrunk the tumor size but also decreased the risk of metastasis and tumor-related deaths when compared to upfront surgery and adjuvant imatinib alone.

The projections from the anterior cingulate cortex to the nucleus accumbens and ventral tegmental area contribute to neuropathic pain-evoked aversion in rats.

Although the anterior cingulate cortex (ACC) plays a vital role in neuropathic pain-related aversion, the underlying mechanisms haven't been fully studied. The mesolimbic dopamine system encodes reward and aversion, and participates in the exacerbation of chronic pain. Therefore, we investigated whether the ACC modulates aversion to neuropathic pain via control of the mesolimbic dopamine system, in a rat model of chronic constriction injury (CCI) to the sciatic nerve. Using anterograde and retrograde tracings, we confirmed that a subgroup of ACC neurons projected to the nucleus accumbens (NAc) and ventral tegmental area (VTA), which are two crucial nodes of the mesolimbic dopamine system. Combining electrophysiology in juvenile rats 7 days post-CCI, we found that the NAc/VTA-projecting neurons were hyperexcitable after CCI. Chemogenetic inhibition of these projections induced conditioned place preference in young adult rats 10-14 days post-CCI, without modulating the evoked pain threshold, whereas activation of these projections in sham rats mimicked aversive behavior. Furthermore, the function of the ACC projections was probably mediated by NAc D2-type medium spiny neurons and VTA GABAergic neurons. Taken together, our findings suggest that projections from the ACC to the NAc and VTA mediate neuropathic pain-related aversive behavior.

Parameter Optimization Analysis of Prolonged Analgesia Effect of tDCS on Neuropathic Pain Rats.

Background: Transcranial direct current stimulation (tDCS) is widely used to treat human nerve disorders and neuropathic pain by modulating the excitability of cortex. The effectiveness of tDCS is influenced by its stimulation parameters, but there have been no systematic studies to help guide the selection of different parameters. Objective: This study aims to assess the effects of tDCS of primary motor cortex (M1) on chronic neuropathic pain in rats and to test for the optimal parameter combinations for analgesia. Methods: Using the chronic neuropathic pain models of chronic constriction injury (CCI), we measured pain thresholds before and after anodal-tDCS (A-tDCS) using different parameter conditions, including stimulation intensity, stimulation time, intervention time and electrode located (ipsilateral or contralateral M1 of the ligated paw on male/female CCI models). Results: Following the application of A-tDCS over M1, we observed that the antinociceptive effects were depended on different parameters. First, we found that repetitive A-tDCS had a longer analgesic effect than single stimulus, and both ipsilateral-tDCS (ip-tDCS) and contralateral-tDCS (con-tDCS) produce a long-lasting analgesic effect on neuropathic pain. Second, the antinociceptive effects were intensity-dependent and time-dependent, high intensities worked better than low intensities and long stimulus durations worked better than short stimulus durations. Third, timing of the intervention after injury affected the stimulation outcome, early use of tDCS was an effective method to prevent the development of pain, and more frequent intervention induced more analgesia in CCI rats, finally, similar antinociceptive effects of con- and ip-tDCS were observed in both sexes of CCI rats. Conclusion: Optimized protocols of tDCS for treating antinociceptive effects were developed. These findings should be taken into consideration when using tDCS to produce analgesic effects in clinical applications.

Inhibition of Metabotropic Glutamate Receptor Subtype 1 Alters the Excitability of the Commissural Pyramidal Neuron in the Rat Anterior Cingulate Cortex after Chronic Constriction Injury to the Sciatic Nerve.

BACKGROUND: Inhibition of the metabotropic glutamate receptor subtype 1 in the anterior cingulate cortex has an analgesic effect during sustained nociceptive hypersensitivity. However, the specific changes in different subtypes of anterior cingulate cortex layer 5 pyramidal neurons, as well as the distinct effect of metabotropic glutamate receptor subtype 1 inhibition on different neuronal subtypes, have not been well studied. METHODS: Retrograde labeling combined with immunofluorescence, whole cell clamp recording, and behavioral tests combined with RNA interference were performed in a rat model of chronic constriction injury to the sciatic nerve. RESULTS: Commissural layer 5 pyramidal neurons (projecting to the contralateral cortex) existed in the anterior cingulate cortex. The voltage-gated potassium channel subunit 2-mediated current in these neurons were substantially reduced after chronic constriction injury (current densities at +30 mV for the sham, and chronic constriction injury neurons were [mean ± SD] 10.22 ± 3.42 pA/pF vs. 5.58 ± 2.71 pA/pF, respectively; n = 11; P < 0.01), which increased the spike width and fast afterhyperpolarization potential, resulting in hyperexcitability. Inhibition of metabotropic glutamate receptor subtype 1 alleviated the down-regulation of voltage-gated potassium channel subunit 2 currents (current density increased by 8.11 ± 3.22 pA/pF; n = 7; P < 0.01). Furthermore, knockdown of voltage-gated potassium channel subunit 2 current in the commissural neurons attenuated the analgesic effect of metabotropic glutamate receptor subtype 1 inhibition (n = 6 rats; P < 0.05). CONCLUSIONS: The effect of metabotropic glutamate receptor subtype 1 inhibition on commissural anterior cingulate cortex layer 5 pyramidal neurons is likely different with the modification of previously studied hyperpolarization-activated/cyclic nucleotide-gated channel-dependent neurons but relies on the alteration of voltage-gated potassium channel subunit 2 currents. These results will contribute to a better understanding of the therapeutic role of metabotropic glutamate receptor subtype 1 in chronic pain.

Activation of mGluR1 contributes to neuronal hyperexcitability in the rat anterior cingulate cortex via inhibition of HCN channels.

Neuronal hyperexcitability in the anterior cingulate cortex (ACC) is considered as one of the most important pathological changes responsible for the chronification of neuropathic pain. However, the underlying mechanisms remain elusive. In the present study, we investigated the possible mechanisms using a rat model of chronic constriction injury (CCI) to the sciatic nerve. We found a substantial decrease in hyperpolarization-activated/cyclic nucleotide-gated (HCN) currents in layer 5 pyramidal neurons (L5 PNs) in ACC slices, which dramatically increased the excitability of these neurons. This effect could be mimicked in sham slices by activating group 1 metabotropic glutamate receptors, and be blocked in CCI slices by inhibiting metabotropic glutamate receptor subtype 1 (mGluR1). Next, the inhibition of HCN currents was reversed by a protein kinase C (PKC) inhibitor, followed by a reduced neuronal hyperexcitability. Furthermore, HCN channel subtype 1 (HCN1) level was significantly reduced after CCI, whereas mGluR1 level increased. These changes were mainly observed in L5 of the ACC, where HCN1 and mGluR1 were highly colocalized. For behavioral tests, intra-ACC microinjection of mGluR1-shRNA suppressed the CCI-induced behavioral hypersensitivity, particularly thermal hyperalgesia, but not aversive behavior, and this effect was attenuated by the pre-blockade of HCN channels. Taken together, the neuronal hyperexcitability of ACC L5 PNs likely results from an upregulation of mGluR1 and a downstream pathway involving PKC activation and a downregulation of HCN1 in the early phase of neuropathic pain. These alterations may at least in part contribute to the development of behavioral hypersensitivity in CCI rats.

Effects of Senegenin against hypoxia/reoxygenation-induced injury in PC12 cells.

OBJECTIVE: To investigate the effect and the potential mechanism of Senegenin (Sen) against injury induced by hypoxia/reoxygenation (H/R) in highly differentiated PC12 cells. METHODS: The cultured PC12 cells were treated with H/R in the presence or absence of Sen (60 µmol/L). Four groups were included in the experiment: control group, H/R group, H/R+Sen group and Sen group. Cell viability of each group and the level of lactate dehydrogenase (LDH) in culture medium were detected for the pharmacological effect of Sen. Hoechst 33258 staining and annexin V/propidium iodide double staining were used to analyze the apoptosis rate. Moreover, mitochondrial membrane potential (△Ψm), reactive oxygen species (ROS) and intracellular free calcium ([Ca(2+)]i) were measured by fluorescent staining and flow cytometry. Cleaved caspase-3 and activity of NADPH oxidase (NOX) were determined by colorimetric protease assay and enzyme linked immunosorbent assay, respectively. RESULTS: Sen significantly elevated cell viability (P<0.05), decreased the leakage of LDH (P<0.05) and apoptosis rate (P<0.05) in H/R-injured PC12 cells. Sen maintained the value of △Ψm (P<0.05) and suppressed the activity of caspase-3 (P<0.05). Moreover, Sen reduced ROS accumulation P<0.05) and [Ca(2+)]i increment (P<0.05) by inhibiting the activity of NOX (P<0.05). CONCLUSION: Sen may exert cytoprotection against H/R injury by decreasing the levels of intracellular ROS and [Ca(2+)]i, thereby suppressing the mitochondrial pathway of cellular apoptosis.

The management of benign lymphadenopathy during video-assisted thoracic surgery lobectomy in two-port method.

Despite the lobectomy in video-assisted thoracic surgery (VATS) is widely applied, in VATS the resection of benign lymphadenopathy is still less performed because of less importance in affecting the prognosis. We report our surgery procedure of benign lymphadenopathy in lobectomy with benign pulmonary disease performed in a two-port approach. A 50-year-old male was operated on by the thoracoscopic approach through two-port incision. And the postoperative recovery was uneventful with no complications occurred.

A polymorphism (-455G>A) in the ß-fibrinogen gene is associated with an increased risk of cerebral infarction in the Chinese population: A meta-analysis.

BACKGROUND: Previous studies have investigated the association between a polymorphism (-455 G>A) in the ß-fibrinogen gene and the risk of cerebral infarction. However, these results are controversial. To shed light on these inconclusive findings, we performed a meta-analysis of studies relating the ß-fibrinogen genetic polymorphism (-455 G>A) to the risk of cerebral infarction. METHODS: We identified literature published before July 2013 by searching PubMed, EMBASE, ISI Web of Science, the Chinese National Knowledge Infrastructure database (CNKI) and the Wanfang database in China and by reviewing the references of retrieved articles. We included studies that reported odds ratio (OR) with 95% confidence interval (CI) for the association between the ß-fibrinogen genetic polymorphism and cerebral infarction risk. Publication bias was tested by a funnel plot, and the OR of all studies were combined dependent on the results of the heterogeneity tests among the individual studies. The software Review Manager (Version 5.2) was used for meta-analysis. RESULTS: Twenty independent case-control studies containing 9477 subjects were included. Our results showed that the -455 G>A polymorphism in the ß-fibrinogen gene was associated with the increased risk of cerebral infarction [(AA+GA) vs. GG, OR=1.17, 95%CI: 1.04-1.31, p=0.008; A vs. G, OR=1.12, 95%CI: 1.01-1.23, p=0.03] in the Chinese population by a meta-analysis. However, we did not find this association in the Caucasian population [(AA+GA) vs. GG, OR=0.99, 95%CI: 0.87-1.11, p=0.84; A vs. G, OR=0.97, 95%CI: 0.84-1.13, p=0.73, respectively]. CONCLUSION: The results of our meta-analysis indicate that the -455 G>A polymorphism in the ß-fibrinogen gene is a susceptibility marker of ischemic cerebral infarction in the Chinese population.

Serum Brain-derived neurotrophic factor levels in post-stroke depression.

BACKGROUND: Depression is a frequent mood disorder that affects around a third of stroke patients and has been associated with poorer outcome. Our aim was to determine whether there is a relationship between serum Brain-derived neurotrophic factor (BDNF) levels and post-stroke depression (PSD). METHODS: Two hundred and sixteen ischemic stroke patients admitted to the hospital within the first 24h after stroke onset were consecutively recruited and followed up for 3 months. Based on the symptoms, diagnoses of depression were made in accordance with DSM-IV criteria for post-stroke depression at day 90. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of BDNF at admission. Multivariate analyses were performed using logistic regression models. RESULTS: In our study, 59 patients (27.3%) were diagnosed as having major depression at 3 months. Patients with major depression showed lower levels of serum BDNF [8.1 (5.6-9.4) vs. 13.7 (10.4-16.5)ng/ml, P<0.0001] at admission. In multivariate analyses, serum BDNF was an independent predictor of PSD at 3 months [odds ratio (OR): 0.79(0.72-0.87), P=0.003]. Serum levels of BDNF≤10.2ng/ml were independently associated with post-stroke (OR, 11.5; 95% CI, 5.6-23.4, P<0.0001), after adjustment for possible variables. CONCLUSION: The present study demonstrates a strong relationship between serum BDNF levels at admission and the development of PSD within 3 months. Further studies are necessary to confirm this association, which may open the way to the proposal of new therapeutic options.

Plasma levels of glutamate during stroke is associated with development of post-stroke depression.

BACKGROUND: Depression is a frequent mood disorder that affects around 33% of stroke patient. Our aim was to test the possible association between plasma glutamate and the development of post-stroke depression (PSD) in Chinese patients. METHODS: The subjects were first-ever acute ischemic stroke (AIS) patients who were hospitalized during the period from November 2011 to September 2013. Clinical information and stroke severity was collected at admission. Neurological and neuropsychological evaluations were conducted at the 3-month follow-up. Plasma glutamate levels were analyzed at baseline using liquid chromatography followed by tandem mass spectrometry. Glutamate oxaloacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT) and blood markers were also tested. Multivariate analyses were performed using logistic regression models. RESULTS: During the study period, 209 patients were included in the analysis. Seventy patients (33.5%) were diagnosed as having major depression at 3 month. Patients with major depression showed higher levels of plasma glutamate [299 (235-353) vs. 157 (108-206) µM, P<0.0001] and lower GOT [14 (11-20) vs. 21 (15-32)U/L, P<0.0001] at admission. In multivariate analyses, plasma glutamate and GOT were independent predictors of PSD at 3 months [odds ratio (OR): 1.03 (1.02-1.04), P<0.0001; 0.84 (0.75-0.97), P=0.003]. Plasma levels of glutamate >205 µM were independently associated with PSD (OR, 21.3; 95% CI, 8.28-67.36, P<0.0001), after adjustment for possible variables. CONCLUSION: The present study demonstrates a strong relationship between plasma glutamate and GOT levels at admission and the development of PSD within 3 months. Further studies are necessary to confirm this association, which may open the way to the proposal of new therapeutic options.

Dendritic development of hippocampal CA1 pyramidal cells in a neonatal hypoxia-ischemia injury model.

It is believed that neonatal hypoxia-ischemia (HI) brain injury causes neuron loss and brain functional defects. However, the effect of HI brain injury on dendritic development of the remaining pyramidal cells of the hippocampus and the reaction of contralateral hippocampal neurons require further studies. The Morris water maze and Golgi-Cox staining were used to evaluate the learning and memory and dendritic morphology of pyramidal cells. The results of Golgi-Cox staining showed CA1 pyramidal neurons of HI injury models with fewer bifurcations and shorter dendrite length than the naive control group. The density of dendritic spines of hippocampal CA1 pyramidal neurons was significantly lower in the HI brain injury group than in controls. With respect to hippocampal function, the HI brain injury group presented cognitive deficits in the reference memory task and probe trail. In the HI group, the pyramidal cells of left hippocampus that did not experienced ischemia but did experience hypoxia had more complex dendrites and higher density of spine than the HI injury side and control. The functional implementation of injured hippocampus might depend mainly on the hypertrophy of contralateral hippocampus after HI brain injury. Corticosterone can partially prevent the hippocampal pyramidal cells from HI injury and reduce the difference of the bilateral hippocampus pyramidal cells, but there was no improvement in learning and memory.

Expression of P2X5 receptors in the rat, cat, mouse and guinea pig dorsal root ganglion.

P2X receptors are ATP-gated cationic channels composed of seven cloned subunits (P2X(1 -7)). P2X(3) homomultimer and P2X(2/3) heteromultimer receptors expressed by primary afferent dorsal root ganglion (DRG) neurons are involved in pain processing. The aim of the study was to investigate the expression of the P2X(5) receptor subunit in DRG in different species including mouse, rat, cat and guinea pig. Immunohistochemistry showed that P2X(5) receptors exhibited low levels of immunostaining in rat DRG, but high levels in mouse and guinea pig. Only a few neurons were immunoreactive for P2X(5) receptors in cat. In mouse DRG, the P2X(5) receptor was expressed largely by medium-diameter neurons (42.9 %), less in small (29.3 %) and large (27.8 %) neurons. In contrast, in the guinea pig DRG, P2X(5) receptor expression was greatest in small-diameter (42.6 %), less in medium- (36.3 %) and large-diameter (21.1 %) neurons. Colocalization experiments revealed that, in mouse DRG, 65.5, 10.9 and 27.1 % of P2X(5) receptors were immunoreactive for NF-200, CGRP and calbindin, while only a few P2X(5)-immunoreactive (IR) neurons were coexpressed with IB4 or with NOS. In guinea pig DRG, a total of 60.5 and 40.5 % of P2X(5)-IR neurons were coexpressed with IB4 or with CGRP, while 20.3 and 24.5 % of P2X(5) receptors were coexpressed with NF-200 or with NOS. Only a few P2X(5)-IR neurons were coexpressed with calbindin in guinea pig DRG. It will be of great interest to clarify the relative physiological and pathophysiological roles of P2X(5) receptors.

Functional response of hippocampal CA1 pyramidal cells to neonatal hypoxic-ischemic brain damage.

Perinatal hypoxic-ischemic (H-I) is a major cause of brain injury in the newborn. The hippocampus is more sensitive to H-I injury than the other brain regions. It is believed that H-I brain damage causes a loss of neurons in the central nervous system. The patterns of neuronal death include apoptosis and necrosis. With regard to the responses of neurons, the neural functional changes should be earlier than the morphologic changes. The aim of the present study is to evaluate the electrophysiological characteristics and the synaptic transmission functions. Seven-day-old Sprague-Dawley rat pups were randomly divided into sham operation and H-I groups. The patch clamp, immunohistochemistry and Western blotting techniques were used to achieve this objective. The results of the study showed a decrease in neuronal excitability and a significant increase in the frequency of spontaneous excitatory postsynaptic currents and the duration of EPSCs in the CA1 pyramidal cells of H-I brain damage rats. The glutamate transporter subtype 1 (GLT-1) expression level of the hippocampal CA1 area in the H-I group was decreased compared with the control. There was no difference in the amplitude of excitatory postsynaptic currents and should be no difference in the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR), N-methyl-D-aspartate receptor (NMDAR) and synaptophysin between the control and H-I brain injury group. These results revealed that changes of electrophysiological characteristics and synaptic functions occur instantly after H-I brain damage in the hippocampal pyramidal cells of neonatal rats. The failure to eliminate glutamate should be one of the important factors of excitotoxicity injury on hippocampal CA1 pyramidal cells, while neuronal excitation was not increased in the H-I brain injury model.

Effect of hypobaric hypoxia on the P2X receptors of pyramidal cells in the immature rat hippocampus CA1 sub-field.

PRIMARY OBJECTIVE: This study was designed to evaluate the effect of hypobaric hypoxia (HH) on the function and expression of P2X receptors in rat hippocampus CA1 pyramidal cells. RESEARCH DESIGN: The functional changes of P2X receptors were investigated through the cell HH model and the expressional alterations of P2X receptors were observed through the animal HH model. METHODS AND PROCEDURE: P2X receptors mediated currents were recorded from the freshly dissociated CA1 pyramidal cells of 7-day-old SD rats by whole cell patch clamp recording. The expression and distribution of P2X receptors were observed through immunohistochemistry and western blot at HH 3-day and 7-day. MAIN OUTCOMES AND RESULTS: In acute HH conditions, the amplitudes of ATP evoked peak currents were decreased compared to control. The immunohistochemistry and western blot results reflected there was no change in P2X receptors expression after 3 days HH injury, while P2X receptors expression was up-regulated in response to 7 days HH injury. CONCLUSIONS: These findings supported the possibility that the function of P2X receptors was sensitive to HH damage and long-term function decrease should result in the expression increase of P2X receptors.

Spinal P2X(7) receptor mediates microglia activation-induced neuropathic pain in the sciatic nerve injury rat model.

P2X(7) receptor is an important member of ATP-sensitive ionotropic P2X receptors family, which includes seven receptor subtypes (P2X(1)-P2X(7)). Recent evidence indicates that P2X(7)R participates in the onset and persistence of neuropathic pain. In tetanic stimulation of the sciatic nerve model, P2X(7)R was involved in the activation of microglia, but whether this happens in other neuropathic pain models remains unclear. In this study we used immunohistochemistry and Western blot to explore the relationship of P2X(7)R expression with microglia activation, and with mechanical allodynia and thermal hypersensitivity in the chronic constriction of the sciatic nerve (CCI) rat model. The results show that following nerve ligature, mechanical allodynia and thermal hypersensitivity were developed within 3 days (d), peaked at 14d and persisted for 21d on the injured side. P2X(7)R levels in the ipsilateral L4-6 spinal cord were increased markedly after injury and the highest levels were observed on day 14, significant difference was observed at I-IV layers of the dorsal horn. The change in P2X(7)R levels in the spinal cord was consistent with the development of mechanical allodynia and thermal hypersensitivity. Intrathecal administration of the P2X(7)R antagonist Brilliant Blue G (BBG) reversed CCI-induced mechanical allodynia and thermal hypersensitivity. Double-labeled immunofluorescence showed that P2X(7)R expression were restricted to microglia, spinal microglia were activated after nerve injury, which was inhibited by BBG. These results indicated that spinal P2X(7)R mediate microglia activation, this process may play an important role in development of mechanical allodynia and thermal hypersensitivity in CCI model.

Prevention of extracellular ADP-induced ATP accumulation of the cultured rat spinal astrocytes via P2Y(1)-mediated inhibition of AMPK.

P2Y(1) is probably an important subtype of purinergic receptors (P2Rs) in modulation of the astrocyte activation in spinal cord. The aim of this study was to observe the effect of P2Y(1) receptor on the abnormal energy metabolism of the cultured rat spinal astrocyte induced by extracellular adenosine diphosphate (ADP). The results showed that adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) in the astrocytes were up-regulated in the presence of ADP, which could be enhanced by MRS2179, a specific antagonist for P2Y(1) receptor. A higher level of expression of the AMP-activated protein kinase (AMPK) was found in the presence of MRS2179 and ADP together than that ADP alone. Blocking of AMPK with Compound C could effectively inhibit the enhancing effect of MRS2179 on ADP-induced astrocyte proliferation and ATP accumulation. Our results suggested that the P2Y(1) receptor mediated inhibition of AMPK may help to prevent the astrocytes from over activation induced by extracellular ADP.

Effect of lappaconitine on neuropathic pain mediated by P2X3 receptor in rat dorsal root ganglion.

ATP facilitates initiation and transmission of the neuropathic pain at the dorsal root ganglion (DRG) level via the P2X receptors, especially the subtype P2X(3). Lappaconitine (LA) is an active principle isolated from Chinese herbal medicine and possesses analgesic effect. The aim of this study was to investigate the effect of LA on chronic constriction injury (CCI)-induced neuropathic pain mediated by P2X(3) receptor in the DRG neurons. In the presence of CCI and/or LA, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured and P2X(3) receptor expression in the DRG neurons was evaluated by immunohistochemistry and Western blotting. Following intrathecal administration of P2X(3) receptor oligonucleotide, the effect of LA on pain thresholds was assessed. Furthermore, the effect of LA on the P2X(3) receptor agonists ATP- and α,ß-meATP-induced inward currents (I(ATP) and I(α,ß-meATP)) in the acutely dissociated rat DRG neurons was investigated by whole cell patch-clamp. The results included: (1) There showed reduction of pain thresholds, enhancement of I(ATP) and I(α,ß-meATP) and up-regulation of P2X(3) receptor expression in rat DRG neurons when neuropathic pain occurred. (2) In the presence of LA, the decreased pain thresholds, the up-regulated P2X(3) receptor expression and the enhanced I(ATP) and I(α,ß-meATP) were reversible in the CCI rats. (3) The down-regulated P2X(3) receptor expression with pretreatment of P2X(3) receptor antisense oligonucleotide significantly attenuated the analgesic effect of LA. These results indicate that the analgesic effect of LA involves decrease of expression and sensitization of the P2X(3) receptors of the rat DRG neurons following CCI.