ABSTRACT
Nerve regeneration and circuit reconstruction remain a challenge following spinal cord injury (SCI). Corticospinal pyramidal neurons possess strong axon projection ability. In this study, human induced pluripotent stem cells (iPSCs) were differentiated into pyramidal neuronal precursors (PNPs) by addition of small molecule dorsomorphin into the culture. iPSC-derived PNPs were transplanted acutely into a rat contusion SCI model on the same day of injury. Following engraftment, the SCI rats showed significantly improved motor functions compared with vehicle control group as revealed by behavioral tests. Eight weeks following engraftment, the PNPs matured into corticospinal pyramidal neurons and extended axons into distant host spinal cord tissues, mostly in a caudal direction. Host neurons rostral to the lesion site also grew axons into the graft. Possible synaptic connections as a bridging relay may have been formed between host and graft-derived neurons, as indicated by pre- and post-synaptic marker staining and the regulation of chemogenetic regulatory systems. PNP graft showed an anti-inflammatory effect at the injury site and could bias microglia/macrophages towards a M2 phenotype. In addition, PNP graft was safe and no tumor formation was detected after transplantation into immunodeficient mice and SCI rats. The potential to reconstruct a neuronal relay circuitry across the lesion site and to modulate the microenvironment in SCI makes PNPs a promising cellular candidate for treatment of SCI.
Subject(s)
Cell Differentiation , Disease Models, Animal , Induced Pluripotent Stem Cells , Spinal Cord Injuries , Animals , Spinal Cord Injuries/therapy , Spinal Cord Injuries/pathology , Humans , Induced Pluripotent Stem Cells/cytology , Induced Pluripotent Stem Cells/transplantation , Induced Pluripotent Stem Cells/metabolism , Rats , Rats, Sprague-Dawley , Pyramidal Cells/metabolism , Pyramidal Cells/pathology , Mice , Neural Stem Cells/transplantation , Neural Stem Cells/cytology , Neural Stem Cells/metabolism , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Female , Nerve Regeneration , Axons/metabolismABSTRACT
The locus coeruleus (LC) is a small nucleus in the pons from which ascending and descending projections innervate major parts of the central nervous system. Its major transmitter is norepinephrine (NE). This system is evolutionarily conserved, including in humans, and its functions are associated with wakefulness and related to disorders, such as depression. Here, we performed single-cell ribonucleic acid-sequencing (RNA-seq) to subdivide neurons in the LC (24 clusters in total) into 3 NE, 17 glutamate, and 5 γ-aminobutyric acid (GABA) subtypes, and to chart their neuropeptide, cotransmitter, and receptor profiles. We found that NE neurons expressed at least 19 neuropeptide transcripts, notably galanin (Gal) but not Npy, and >30 neuropeptide receptors. Among the galanin receptors, Galr1 was expressed in ~19% of NE neurons, as was also confirmed by in situ hybridization. Unexpectedly, Galr1 was highly expressed in GABA neurons surrounding the NE ensemble. Patch-clamp electrophysiology and cell-type-specific Ca2+-imaging using GCaMP6s revealed that a GalR1 agonist inhibits up to ~35% of NE neurons. This effect is direct and does not rely on feed-forward GABA inhibition. Our results define a role for the galanin system in NE functions, and a conceptual framework for the action of many other peptides and their receptors.
Subject(s)
Galanin , Peptide Hormones , Humans , Animals , Mice , Locus Coeruleus , Neurons , Glutamic Acid , NorepinephrineABSTRACT
Background: Stress is an important risk factor to induce psychiatric disorders such as depression. Phloretin (PHL), a natural dihydrochalcone compound, has been shown to exhibit anti-inflammatory and anti-oxidative effects. However, the impact of PHL on the depression and the underlying mechanism remain unclear. Methods: The animal behavior tests were used to determine the protective of PHL on the chronic mild stress (CMS)-induced depression-like behaviors. The Magnetic Resonance Imaging (MRI), electron microscopy analysis, fiber photometry, electrophysiology, and Structure Illumination Microscopy (SIM) were used to investigate the protective of PHL on the structural and functional impairments induced by CMS exposure in the mPFC. The RNA sequencing, western blot, reporter gene assay, and chromatin immunoprecipitation were adopted to investigate the mechanisms. Results: We showed that PHL efficiently prevented the CMS-induced depressive-like behaviors. Moreover, PHL not only attenuated the decrease of synapse losses but also improved the dendritic spine density and neuronal activity in the mPFC after CMS exposure. Furthermore, PHL remarkably inhibited the CMS-induced microglial activation and phagocytic activity in the mPFC. In addition, we demonstrated that PHL decreased the CMS-induced synapse losses by inhibiting the deposition of complement C3 deposition onto synapses and subsequent microglia-mediated synaptic engulfment. Finally, we revealed that PHL inhibited the NF-κB-C3 axis to display neuroprotective effects. Conclusions: Our results indicate that PHL represses the NF-κB-C3 axis and subsequent microglia-mediated synaptic engulfment to protect against CMS-induced depression in the mPFC.
Subject(s)
Depression , Microglia , Animals , Depression/drug therapy , Depression/prevention & control , Depression/etiology , NF-kappa B , Phloretin/pharmacology , Neurons/pathologyABSTRACT
Serum amyloid P component (SAP) is a universal constituent of human amyloid deposits including those in Alzheimer's disease. SAP has been observed to be elevated in patients with depression, and higher SAP levels are associated with better response to the antidepressant escitalopram. The mechanisms underlying these clinical observations remain unclear. We examined the effect of SAP on serotonin transporter (SERT) expression and localization using Western blot, confocal microscopy, and positron emission tomography with the radioligand [11C]DASB. We also investigated the effect of SAP on treatment response to escitalopram in mice with the forced swim test (FST), a classical behaviour paradigm to assess antidepressant effects. SAP reduced [11C]DASB binding as an index of SERT levels, consistent with Western blots showing decreased total SAP protein because of increased protein degradation. In conjunction with the global decrease in SERT levels, SAP also promotes VAMP-2 mediated SERT membrane insertion. SAP levels are correlated with behavioural despair and SSRI treatment response in mice with FST. In MDD patients, the SAP and membrane SERT levels are correlated with response to SSRI treatment. SAP has complex effects on SERT levels and localization, thereby modulating the effect of SSRIs, which could partially explain clinical variability in antidepressant treatment response. These results add to our understanding of the mechanism for antidepressant drug action, and with further work could be of clinical utility.
Subject(s)
Serotonin Plasma Membrane Transport Proteins , Serum Amyloid P-Component , Humans , Mice , Animals , Serotonin Plasma Membrane Transport Proteins/metabolism , Serum Amyloid P-Component/metabolism , Escitalopram , Antidepressive Agents/pharmacology , Selective Serotonin Reuptake Inhibitors/pharmacologyABSTRACT
The norepinephrine neurons in locus coeruleus (LC-NE neurons) are essential for sleep arousal, pain sensation, and cocaine addiction. According to previous studies, cocaine increases NE overflow (the profile of extracellular NE level in response to stimulation) by blocking the NE reuptake. NE overflow is determined by NE release via exocytosis and reuptake through NE transporter (NET). However, whether cocaine directly affects vesicular NE release has not been directly tested. By recording quantal NE release from LC-NE neurons, we report that cocaine directly increases the frequency of quantal NE release through regulation of NET and downstream protein kinase C (PKC) signaling, and this facilitation of NE release modulates the activity of LC-NE neurons and cocaine-induced stimulant behavior. Thus, these findings expand the repertoire of mechanisms underlying the effects of cocaine on NE (pro-release and anti-reuptake), demonstrate NET as a release enhancer in LC-NE neurons, and provide potential sites for treatment of cocaine addiction.
Subject(s)
Cocaine-Related Disorders , Cocaine , Cocaine/pharmacology , Cocaine-Related Disorders/metabolism , Humans , Locus Coeruleus/metabolism , Neurons/metabolism , Norepinephrine/metabolism , Norepinephrine/pharmacologyABSTRACT
Traditional antidepressants largely interfere with monoaminergic transport or degradation systems, taking several weeks to have their therapeutic actions. Moreover, a large proportion of depressed patients are resistant to these therapies. Several atypical antidepressants have been developed which interact with G protein coupled receptors (GPCRs) instead, as direct targeting of receptors may achieve more efficacious and faster antidepressant actions. The focus of this review is to provide an update on how distinct GPCRs mediate antidepressant actions and discuss recent insights into how GPCRs regulate the pathophysiology of Major Depressive Disorder (MDD). We also discuss the therapeutic potential of novel GPCR targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles. Finally, we highlight recent advances in understanding GPCR pharmacology and structure, and how they may provide new avenues for drug development.
Subject(s)
Depressive Disorder, Major , Antidepressive Agents/pharmacology , Antidepressive Agents/therapeutic use , Depressive Disorder, Major/drug therapy , Humans , Ligands , Receptors, G-Protein-Coupled/metabolismABSTRACT
Galanin receptor1 (GalR1) transcript levels are elevated in the rat ventral periaqueductal gray (vPAG) after chronic mild stress (CMS) and are related to depression-like behavior. To explore the mechanisms underlying the elevated GalR1 expression, we carried out molecular biological experiments in vitro and in animal behavioral experiments in vivo. It was found that a restricted upstream region of the GalR1 gene, from -250 to -220, harbors an E-box and plays a negative role in the GalR1 promoter activity. The transcription factor Scratch2 bound to the E-box to down-regulate GalR1 promoter activity and lower expression levels of the GalR1 gene. The expression of Scratch2 was significantly decreased in the vPAG of CMS rats. Importantly, local knockdown of Scratch2 in the vPAG caused elevated expression of GalR1 in the same region, as well as depression-like behaviors. RNAscope analysis revealed that GalR1 mRNA is expressed together with Scratch2 in both GABA and glutamate neurons. Taking these data together, our study further supports the involvement of GalR1 in mood control and suggests a role for Scratch2 as a regulator of depression-like behavior by repressing the GalR1 gene in the vPAG.
Subject(s)
Behavior, Animal , Depression/pathology , Periaqueductal Gray/pathology , Receptor, Galanin, Type 1/metabolism , Transcription Factors/metabolism , Animals , E-Box Elements/genetics , GABAergic Neurons/metabolism , Gene Expression Regulation , Glutamic Acid/metabolism , PC12 Cells , Promoter Regions, Genetic/genetics , Protein Binding , Rats , Receptor, Galanin, Type 1/genetics , Stress, Psychological/complications , Transcription Factors/genetics , Transcription Initiation SiteABSTRACT
OBJECTIVE: Palmar hyperhidrosis affects 0.6-10% of the general population, having an important impact in patients' quality of life. The definitive treatment for palmar hyperhidrosis is thoracic sympathectomy. The purpose of this study is to evaluate the quality of life after thoracic sympathectomy for palmar hyperhidrosis. METHODS: The interest studies were searched in six comprehensive databases. The quality of the studies was assessed using the risk of bias tool recommended by the Cochrane system evaluation manual. Meta-analysis was performed with RevMan version 5.3. The outcome of interest was quality of life. The subgroup analysis and sensitive analysis were performed. RESULTS: Nine trials, including 895 patients, with accessible data comparing preoperative quality of life score with postoperative quality-of-life score were used for data analysis. Compared with preoperative quality-of-life score, application of thoracic sympathectomy improved the postoperative quality of life of palmar hyperhidrosis patients (MD = 57.81, 95% CI 53.33-62.30). Subgroup analysis of the different thoracic sympathectomy segment showed that there was no significant difference in the results obtained when operated with single segment or multiple segments (single segment: MD = 61.16, 95% CI [56.10, 66.22], multiple segments: MD = 52.14, 95% CI [48.39, 55.88]). CONCLUSION: The meta-analysis provided evidence of the improved quality of life after thoracic sympathectomy for palmar hyperhidrosis.
Subject(s)
Hyperhidrosis/surgery , Quality of Life , Humans , Hyperhidrosis/psychology , Postoperative Period , Sympathectomy , Thoracic Surgical ProceduresABSTRACT
Following publication of the original article [1], the authors reported errors in Figure 4.
ABSTRACT
The neuropeptide galanin functions via three G-protein coupled receptors, Gal1-3-R. Both Gal1-R and 2-R are involved in pain signaling at the spinal level. Here a Gal2-R-EGFP transgenic (TG) mouse was generated and studied in pain tests and by characterizing Gal2-R expression in both sensory ganglia and spinal cord. After peripheral spared nerve injury, mechanical allodynia developed and was ipsilaterally similar between wild type (WT) and TG mice. A Gal2-R-EGFP-positive signal was primarily observed in small and medium-sized dorsal root ganglion (DRG) neurons and in spinal interneurons and processes. No significant difference in size distribution of DRG neuronal profiles was found between TG and WT mice. Both percentage and fluorescence intensity of Gal2-R-EGFP-positive neuronal profiles were overall significantly upregulated in ipsilateral DRGs as compared to contralateral DRGs. There was an ipsilateral reduction in substance P-positive and calcitonin gene-related peptide (CGRP)-positive neuronal profiles, and this reduction was more pronounced in TG as compared to WT mice. Moreover, Gal2-R-EGFP partly co-localized with three pain-related neuropeptides, CGRP, neuropeptide Y and galanin, both in intact and injured DRGs, and with galanin also in local neurons in the superficial dorsal horn. Taken together, the present results provide novel information on the localization and phenotype of DRG and spinal neurons expressing the second galanin receptor, Gal2-R, and on phenotypic changes following peripheral nerve injury. Gal2-R may also be involved in autoreceptor signaling.
Subject(s)
Calcitonin Gene-Related Peptide/metabolism , Ganglia, Spinal/metabolism , Neurons/metabolism , Spinal Cord/metabolism , Animals , Mice, Transgenic , Neurons, Afferent/metabolism , Neuropeptide Y/metabolism , Neuropeptides/metabolism , Substance P/metabolismABSTRACT
We report the identification of a de novo GABRA1 (R214C) variant in a child with epileptic encephalopathy (EE), describe its functional characterization and pathophysiology, and evaluate its potential therapeutic options. The GABRA1 (R214C) variant was identified using whole exome sequencing, and the pathogenic effect of this mutation was investigated by comparing wild-type (WT) α1 and R214C α1 GABAA receptor-expressing HEK cells. GABA-evoked currents in these cells were recorded using whole-cell, outside-out macro-patch and cell-attached single-channel patch-clamp recordings. Changes to surface and total protein expression levels of WT α1 and R214C α1 were quantified using surface biotinylation assay and western blotting, respectively. Finally, potential therapeutic options were explored by determining the effects of modulators, including diazepam, insulin, and verapamil, on channel gating and receptor trafficking of WT and R214C GABAA receptors. We found that the GABRA1 (R214C) variant decreased whole-cell GABA-evoked currents by reducing single channel open time and both surface and total GABAA receptor expression levels. The GABA-evoked currents in R214C GABAA receptors could only be partially restored with benzodiazepine (diazepam) and insulin. However, verapamil treatment for 24 h fully restored the function of R214C mutant receptors, primarily by increasing channel open time. We conclude that the GABRA1 (R214C) variant reduces channel activity and surface expression of mutant receptors, thereby contributing to the pathogenesis of genetic EE. The functional restoration by verapamil suggests that it is a potentially new therapeutic option for patients with the R214C variant and highlights the value of precision medicine in the treatment of genetic EEs.
Subject(s)
Epilepsy/genetics , Epilepsy/physiopathology , Mutation/genetics , Receptors, GABA-A/genetics , Amino Acid Sequence , Child , Chloride Channels/metabolism , Diazepam/pharmacology , Electroencephalography , Epilepsy/diagnostic imaging , Female , Genotype , HEK293 Cells , Humans , Insulin/pharmacology , Ion Channel Gating/drug effects , Kinetics , Magnetic Resonance Imaging , Phenotype , Protein Subunits/genetics , Receptors, GABA-A/chemistry , Verapamil/pharmacologyABSTRACT
Accumulated evidences show that neuroinflammation play a pivotal role in the pathogenesis of depression. Neuropeptide Y (NPY) and its receptors have been demonstrated to have anti-inflammative as well as antidepressant effects. In the present study, the ability of NPY to modulate depressive-like behaviors induced by lipopolysaccharides (LPS) in rats and the receptors and signaling mechanisms involved were investigated. Continuous injection LPS (i.p) for 4 days led to development of depressive-like behaviors in rats, accompanied with M1-type microglia activation and increased levels of IL-1ß as well as decreased levels of NPY and Y2R expression in the mPFC selectively. Local injection of NPY into the medial prefrontal cortex (mPFC) ameliorated the depression-like behaviors and suppressed the NLRP3 inflammasome signaling pathway. Y2R agonist PYY (3-36) mimicked and Y2R antagonist BIIE0246 abolished the NPY effects in the mPFC. All these results suggest that NPY and Y2R in the mPFC are involved in the pathophysiology of depression and NPY plays an antidepressant role in the mPFC mainly via Y2R, which suppresses the NLRP3 signaling pathway, in LPS-induced depression model rats.
Subject(s)
Lipopolysaccharides/pharmacology , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Receptors, Neuropeptide Y/metabolism , Animals , Blotting, Western , Depression/metabolism , Interleukin-1beta/metabolism , Rats , Rats, Sprague-Dawley , Real-Time Polymerase Chain Reaction , Signal Transduction/drug effectsABSTRACT
ETS-1 is a transcription factor that is a member of the E26 transformation-specific (ETS) family. Galanin receptor 2 (GalR2), a subtype of receptors of the neuropeptide galanin, has been shown to have an antidepressant-like effect after activation in rodents. Our previous study has shown that overexpression of ETS-1 increases the expression of GalR2 in PC12 phaeochromocytoma cells. However, whether ETS-1 has an antidepressant-like effect is still unclear. In this study, we found that chronic mild stress (CMS) decreased the expression of both ETS-1 and GalR2 in the ventral hippocampus of rats. Meanwhile, we demonstrated that overexpression of ETS-1 increased the expression of GalR2 in primary hippocampal neurons. Importantly, we showed that overexpression of ETS-1 in the ventral hippocampus counteracted the depression-like behaviors of CMS rats. Furthermore, we found that overexpression of ETS-1 increased the level of downstream phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ERK1/2) of GalR2 in the ventral hippocampus of CMS rats. Taken together, our findings suggest that ETS-1 has an antidepressant-like effect in rats, which might be mediated by increasing the level of GalR2 and its downstream p-ERK1/2 in the ventral hippocampus.
Subject(s)
Depression/metabolism , Hippocampus/metabolism , Proto-Oncogene Protein c-ets-1/metabolism , Anhedonia , Animals , MAP Kinase Signaling System , Male , Rats , Rats, Sprague-Dawley , Receptor, Galanin, Type 2/metabolism , Sucrose , SwimmingABSTRACT
The neuropeptide galanin and its receptors have been found to have protective effects on neurons. However, the role of galanin on astrocytes is still unclear. The present study is aimed at investigating the effects of galanin on the viability of cultured rat cortical astrocytes after oxidative stress induced by H2O2 and possible receptor and signaling mechanisms involved. Treatment of galanin had significant protective effects against H2O2-induced toxicity in the cultured cortical astrocytes. H2O2 induced an upregulation of phosphorylated extracellular signal-related kinase1/2 (pERK1/2) in astrocytes, which was suppressed by coapplication of galanin, suggesting an involvement of the pERK1/2 signal pathway in the protective effects of galanin. GalR2 has higher expression levels than GalR1 and GalR3 in the cultured cortical astrocytes, and GalR2 agonist AR-M1896 mimicked galanin effects on the astrocytes, implying that galanin protective effects mainly mediated by GalR2. Meanwhile, galanin had no effect on the A1-type transformation of rat cortical astrocytes. All those results suggest that galanin protects rat cortical astrocytes from oxidative stress by suppressing H2O2-induced upregulation of pERK1/2, mainly through GalR2.
Subject(s)
Astrocytes/drug effects , Astrocytes/metabolism , Galanin/pharmacology , MAP Kinase Signaling System/drug effects , Animals , Blotting, Western , Cells, Cultured , Hydrogen Peroxide/pharmacology , Immunohistochemistry , MAP Kinase Signaling System/genetics , Oxidative Stress/drug effects , Polymerase Chain Reaction , Rats , Rats, Sprague-Dawley , Receptor, Galanin, Type 2/genetics , Receptor, Galanin, Type 2/metabolism , Signal Transduction/drug effectsABSTRACT
Estrogen (E2) withdrawal is a core pathology mechanism for postpartum depression (PPD). Galanin (GAL), an estrogen-inducible neuropeptide has also been reported to be associated with depression. However, it still remains unclear which GAL receptors (GALRs) are involved in PPD pathologic process. In the present study, we discovered that the expression of GALR1, rather than GALR2/3, was upregulated with a region-specific pattern in the prefrontal cortex (PFC) of E2 withdrawal induced PPD model rats. Meanwhile, c-fos was also upregulated only in PFC in the same animal model. Injection of GALR1-siRNA into the bilateral PFC ameliorated depressive-like behavior of PPD rats, suggesting that the upregulation of GALR1 in PFC is involved in PPD. Moreover, Western Blot and HPLC assays demonstrated that the downregulation of CREB-BDNF signaling and 5-HT levels in the PFC of PPD rats were reversed after GALR1-siRNA injection. These comprehensive results suggest that the knock down of GALR1 in PFC alleviates depressive-like behaviors and reverse downregulation of CREB-BDNF and 5-HT levels in PPD rat model. HIGHLIGHTS Expression level of GALR1 mRNA was significantly increased in PFC of estrogen withdraw-induced PPD rats. Injecting GALR1-siRNA into PFC alleviated depressive-like behavior and reversed the decrease of 5-HT level and CREB/BDNF signaling in PFC of PPD rats.
ABSTRACT
Autologous neural stem cells (NSCs) may offer a promising source for deriving dopaminergic (DA) cells for treatment of Parkinson's disease (PD). Methods: By using Sendai virus, human peripheral blood mononuclear cells (PBMNCs) were reprogrammed to induced NSCs (iNSCs), which were then differentiated to dopaminergic neurons in vitro. Whole-genome deep sequencing was performed to search for mutations that had accumulated during the reprogramming and expansion processes. To find the optimal differentiation stage of cells for transplantation, DA precursors obtained at various differentiation time points were tested by engraftment into brains of naïve immunodeficient mice. At last, the safety and efficacy of iNSC-derived DA precursors were tested by transplantation into the striatum of immunodeficient PD mouse models. Results: PBMNC-derived iNSCs showed similar characteristics to fetal NSCs, and were able to specifically differentiate to DA neurons with high efficiency in vitro. The sequencing data proved that no harmful SNVs, Indels and CNVs were generated during the reprogramming and expansion processes. DA precursors obtained between differentiation day 10 to 13 in vitro were most suitable for transplantation when a balanced graft survival and maturation were taken into account. Two weeks after transplantation of DA precursors into mouse PD models, the motor functions of PD mice started to improve, and continued to improve until the end of the experiments. No graft overgrowth or tumor was observed, and a significant number of A9-specific midbrain DA neurons were surviving in the striatum. Conclusion: This study confirmed the efficacy of iNSC-derived DA precursors in a mouse PD model, and emphasized the necessity of genomic sequencing and vigorous safety assessment before any clinical translation using iNSCs.
Subject(s)
Cell Transplantation/methods , Dopaminergic Neurons/physiology , Neural Stem Cells/physiology , Parkinson Disease/therapy , Animals , Blood Cells , Cell Differentiation , Cellular Reprogramming Techniques , Disease Models, Animal , Humans , Locomotion , Mice , Parkinson Disease/pathologyABSTRACT
BACKGROUND: Various neurological and psychological disorders are related to cortical volume changes in specific brain regions, which can be measured in vivo using structural magnetic resonance imaging (sMRI). There is an increasing interest in MRI studies using rat models, especially in longitudinal studies of brain disorders and pharmacologic interventions. However, morphometric changes observed in sMRI are only meaningful if the measurements are reliable. To date, a systematic evaluation of the test-retest reliability of the morphometric measures in the rat brain is still lacking. NEW METHOD: We rigorously evaluated the test-retest reliability of morphometric measures derived from the voxel-based morphometry (VBM) analysis. 37 Sprague-Dawley rats were scanned twice at an interval of six hours and the gray matter volume was estimated using the VBM-DARTEL method. The intraclass coefficient, percent volume change and Pearson correlation coefficient were used to evaluate the reliability in 96 subregions of the rat brain. RESULTS: Most subregions showed excellent test-retest reliabilities within an interval of 6â¯h while a few regions demonstrated lower reliability, especially in the retrosplenial granular cortex. The results were consistent between different methods of reliability assessment. COMPARISON WITH EXISTING METHOD: To the best of our knowledge, this is the first study to quantify the test-retest reliability of the VBM measurements of the rat brain. CONCLUSION: Atlas-based cortical volume of the rat brain can be reliably estimated using the VBM-DARTEL method in most subregions. However, findings in subregions with lower reliability must be interpreted with caution.
Subject(s)
Brain Mapping , Cerebral Cortex/diagnostic imaging , Animals , Gray Matter/diagnostic imaging , Image Processing, Computer-Assisted , Magnetic Resonance Imaging , Male , Rats , Rats, Sprague-Dawley , Reference Values , Reproducibility of Results , White Matter/diagnostic imagingABSTRACT
The noradrenergic neurons of the locus coeruleus (LC) are associated with various brain functions and psychiatric disorders, such as addiction and depression. It has been shown that neuropeptide galanin (GAL) inhibits neuronal excitability in LC, but the mechanisms remain unclear. In the present study, we investigated the ionic and signal transduction mechanisms underlying inhibitory effect of GAL on LC neurons using whole-cell patch clamp recording in rat brain slices. Bath application of GAL decreased the spontaneous firings and induced a dose-dependent hyperpolarization of LC neurons and this effect was attenuated by knockdown of Galr1, but not Galr2, confirming that mainly GALR1 mediates the inhibition effect of GAL. The inhibitory effect of GAL was also blocked by treatments of pertussis toxin (PTX), GTP-γ-s or GDP-ß-s, respectively, indicating that the functions of PTX sensitive Gi/o protein are required for GAL-induced hyperpolarization. Moreover, the blockers of GIRK (tertiapin-Q or SCH2 3390 hydrochloride) attenuated the GAL response while blocker of BK/SK/KATP channels or TASK-1/3 channels did not affect it significantly, suggesting that GIRK channels play an important role in GAL-induced hyperpolarization in LC neurons. Taken together, the inhibitory effect of GAL on LC neurons is mediated by GALR1 via PTX-sensitive Gi/o proteins, which activate GIRK channels.
Subject(s)
G Protein-Coupled Inwardly-Rectifying Potassium Channels/metabolism , Locus Coeruleus/metabolism , Receptor, Galanin, Type 1/metabolism , Adrenergic Neurons/drug effects , Adrenergic Neurons/metabolism , Animals , G Protein-Coupled Inwardly-Rectifying Potassium Channels/antagonists & inhibitors , GTP-Binding Protein alpha Subunits, Gi-Go/metabolism , Galanin/metabolism , Gene Knockdown Techniques , Locus Coeruleus/cytology , Locus Coeruleus/drug effects , Male , Patch-Clamp Techniques , Pertussis Toxin/pharmacology , Potassium Channel Blockers/pharmacology , Protein Precursors/metabolism , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/genetics , Rats , Rats, Sprague-Dawley , Receptor, Galanin, Type 1/antagonists & inhibitors , Receptor, Galanin, Type 1/genetics , Receptor, Galanin, Type 2/antagonists & inhibitors , Receptor, Galanin, Type 2/genetics , Receptor, Galanin, Type 2/metabolism , Signal TransductionABSTRACT
Previous studies demonstrated that Nav1.5 splice variants, including Nav1.5a and Nav1.5c, were expressed in dorsal root ganglia (DRG) neurons. However, since nine Nav1.5 isoforms have been identified, whether other Nav1.5 splice variants, especially the neonatal Nav1.5 splice variant, express in the DRG neurons is still unknown. In this study, we systematically investigated the expression of adult and neonatal Nav1.5 isoforms in the DRG neurons and axon of peripheral sensory neurons of rats with spared nerve injury (SNI) by RT-PCR, DNA sequencing, restriction enzyme digestion, immunohistochemistry and immunofluorescence methods. The results demonstrated that both adult and neonatal Nav1.5 isoforms were expressed in the DRG neurons, but their expression ratio was ~2.5:1. In SNI rat models, the expression of both adult and neonatal Nav1.5 decreased by approximately a half in both mRNA and protein levels. In contrast, the expression of protein kinase C (PKC)-γ, one of the negative modulators for sodium currents, increased by ~1-fold. Taken together, this study first confirmed the expression of both adult and neonatal Nav1.5 isoforms in the DRG neurons and axon of peripheral sensory neurons of rat, but their expression level decreased in pain models. The upregulation of PKC-γ may directly or indirectly downregulate the expression of Nav1.5 isoforms in SNI rat models, which may further involve in the pathological process of neuropathic pain.
Subject(s)
Axons/pathology , Down-Regulation , Ganglia, Spinal/pathology , NAV1.5 Voltage-Gated Sodium Channel/genetics , Neuralgia/genetics , Sensory Receptor Cells/pathology , Animals , Axons/metabolism , Disease Models, Animal , Ganglia, Spinal/cytology , Ganglia, Spinal/metabolism , Male , NAV1.5 Voltage-Gated Sodium Channel/analysis , Neuralgia/pathology , RNA, Messenger/analysis , RNA, Messenger/genetics , Rats, Sprague-Dawley , Sensory Receptor Cells/cytology , Sensory Receptor Cells/metabolismABSTRACT
BACKGROUND Congenital single-side deafness (SSD) affects sound localization even after cochlear implantation (CI) in some conditions. The medial nucleus of the trapezoid body (MNTB) plays an important role in binaural benefit and sound localization, but little is known about intrinsic molecular changes in MNTB with SSD. We aimed to observe changes in MNTB in early-developmental SSD rats, including the key neurotransmitters (GABA, Gly, Glu) and major receptors (GABAa-R/GABAb-R for GABA, Gly-R for Gly, and AMPA/NMDA for Glu). MATERIAL AND METHODS The model of early-developmental SSD was acquired by right cochlear ablation at P12 and confirmed by ABR. High-performance liquid chromatography fluorescence detection (HPLC-FLD) was performed to measure the levels of neurotransmitters in MNTB. The relative expression of neurotransmitter receptors was tested by quantitative real-time PCR analysis. RESULTS (1) The right MNTB of experimental rats had an increase in GABA, Gly, and Glu at 4 weeks after right cochlear ablation (P<0.05). (2) At 2 weeks, the left MNTB of experimental rats showed increases in GABAa-R, GABAb-R, Gly-R, and AMPA, while the right MNTB showed lower expression of NMDA (P<0.05). The higher receptors in left MNTB decreased to a level at which we found no difference at 1 week for GABAa-R and GABAb-R (P>0.05), and was even reversed for Gly-R and AMPA (P<0.05). (3) Gly level was significantly increased at 2 weeks bilaterally and continued to 4 weeks in the left MNTB (P<0.05). CONCLUSIONS Early-developmental SSD can lead to asymmetric distribution of neurotransmitters and receptors in MNTB, which can be the fundamental cause of defective sound localization after cochlear implantation.