µ-opioid receptor (MOR) is a class of opioid receptors with a high affinity for enkephalins and beta-endorphin. In hippocampus, activation of MOR is known to enhance the neuronal excitability of pyramidal neurons, which has been mainly attributed to a disinhibition of pyramidal neurons via activating Gαi subunit to suppress the presynaptic release of GABA in hippocampal interneurons. In contrast, the potential role of MOR in hippocampal astrocytes, the most abundant cell type in the brain, has remained unexplored. Here, we determine the cellular and subcellular distribution of MOR in different cell types of the hippocampus by utilizing MOR-mCherry mice and two different antibodies against MOR. Consistent with previous findings, we demonstrate that MOR expression in the CA1 pyramidal layer is co-localized with axon terminals from GABAergic inhibitory neurons but not with soma of pyramidal neurons. More importantly, we demonstrate that MOR is highly expressed in CA1 hippocampal astrocytes. The ultrastructural analysis further demonstrates that the astrocytic MOR is localized in soma and processes, but not in microdomains near synapses. Lastly, we demonstrate that astrocytes in ventral tegmental area and nucleus accumbens also express MOR. Our results provide the unprecedented evidence for the presence of MOR in astrocytes, implicating potential roles of astrocytic MOR in addictive behaviors.
Animals ; Antibodies ; Astrocytes* ; Behavior, Addictive ; beta-Endorphin ; Brain ; Carisoprodol ; Enkephalins ; gamma-Aminobutyric Acid ; Hippocampus ; Interneurons ; Mice ; Microscopy, Electron ; Neurons ; Nucleus Accumbens ; Presynaptic Terminals ; Pyramidal Cells ; Receptors, Opioid ; Synapses ; Ventral Tegmental Area

Neuromuscular blockade plays an important role in the safe management of patient airways, surgical field improvement, and respiratory care. Rapid-sequence induction of anesthesia is indispensable to emergency surgery and obstetric anesthesia, and its purpose is to obtain a stable airway, adequate depth of anesthesia, and appropriate respiration within a short period of time without causing irritation or damage to the patient. There has been a continued search for new neuromuscular blocking drugs (NMBDs) with a rapid onset of action. Factors that affect the onset time include the potency of the NMBDs, the rate of NMBDs reaching the effect site, the onset time by dose control, metabolism and elimination of NMBDs, buffered diffusion to the effect site, nicotinic acetylcholine receptor subunit affinity, drugs that affect acetylcholine (ACh) production and release at the neuromuscular junction, drugs that inhibit plasma cholinesterase, presynaptic receptors responsible for ACh release at the neuromuscular junction, anesthetics or drugs that affect muscle contractility, site and methods for monitoring neuromuscular function, individual variability, and coexisting disease. NMBDs with rapid onset without major adverse events are expected in the next few years, and the development of lower potency NMBDs will continue. Anesthesiologists should be aware of the use of NMBDs in the management of anesthesia. The choice of NMBD and determination of the appropriate dosage to modulate neuromuscular blockade characteristics such as onset time and duration of neuromuscular blockade should be considered along with factors that affect the effects of the NMBDs. In this review, we discuss the factors that affect the onset time of NMBDs.
Acetylcholine ; Anesthesia ; Anesthesia, Obstetrical ; Anesthetics ; Cholinesterases ; Diffusion ; Drug Interactions ; Emergencies ; Humans ; Metabolism ; Neuromuscular Blockade* ; Neuromuscular Blocking Agents* ; Neuromuscular Junction ; Neuromuscular Monitoring ; Pharmacokinetics ; Plasma ; Receptors, Nicotinic ; Receptors, Presynaptic ; Respiration

PICK1, a PDZ domain-containing protein, is known to increase the reuptake activities of dopamine transporters by increasing their expressions on the cell surface. Here, we report a direct and functional interaction between PICK1 and dopamine D₃ receptors (D₃R), which act as autoreceptors to negatively regulate dopaminergic neurons. PICK1 colocalized with both dopamine D₂ receptor (D₂R) and D₃R in clusters but exerted different functional influences on them. The cell surface expression, agonist affinity, endocytosis, and signaling of D₂R were unaffected by the coexpression of PICK1. On the other hand, the surface expression and tolerance of D₃R were inhibited by the coexpression of PICK1. These findings show that PICK1 exerts multiple effects on D₃R functions.
Autoreceptors ; Dopamine Plasma Membrane Transport Proteins ; Dopamine* ; Dopaminergic Neurons ; Endocytosis ; Hand

Migraine is one of the common and frequently encountered diseases. The study proves that 5-hydroxytryptamine (5-HT) receptor, plays an important role in the occurrence of migraine. Rat striatum was used for preparation of the cell membrane stationary phase (CMSP) in our experiments. The cell membrane chromatography (CMC)-offline-HPLC system was applied to specifically recognize the components from the drug pair of Chuanxiong Rhizoma and Angelicae Dahuricae Radix, which interact with the receptors on CMSP. The dissociation equilibrium constant (KD) was measured in a rat striatum/CMC system, performed by continuously pumping sumatriptan, a 5-HT1D agonist, ranging from 2.42 x 10(-8) to 4.84 x 10(-7) mol · L(-1) through a CMC column, and the capacity factors (k') were recorded. The KD value obtained from the model was (4.59 ± 0.33) x 10(-6) mol · L(-1) for imperatorin, and the rat model of migraine induced by nitroglycerin was applied to validate the pharmacological effects of the drug pair. The results indicated that the CMC method could be a quick and efficient way for characterizing the drug-receptor interactions in vitro.
Angelica ; chemistry ; Animals ; Cell Membrane ; chemistry ; Chromatography, High Pressure Liquid ; methods ; Drug Evaluation, Preclinical ; methods ; Drugs, Chinese Herbal ; chemistry ; Male ; Migraine Disorders ; drug therapy ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT1D ; chemistry ; Serotonin Receptor Agonists ; analysis

Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.
Brain Ischemia ; Cell Death ; Dendrites ; Endoplasmic Reticulum ; Ethanol ; Mitochondria ; N-Methylaspartate ; Neurons ; Organelles ; Phosphotungstic Acid ; Post-Synaptic Density ; Presynaptic Terminals ; Protein Kinases ; Proteins ; Receptors, N-Methyl-D-Aspartate ; Reperfusion

Late-phase long-term potentiation (L-LTP) plays a very important role in the maintenance of long-term memory in hippocampus. However, studies have shown that L-LTP can be reversed by subsequent neuronal activity. The aim of the present study is to investigate whether the presynaptic mechanism and the change of AMPARs expressions are involved in the reversal of L-LTP in hippocampal CA1 area. Standard extracellular recording technique was used to record the potential change in the stratum radiatum of CA1 area of adult rat hippocampal slices. Two hours after LTP induction, which was induced by high-frequency stimulation (HFS), two episodes of high-intensity paired-pulse low-frequency stimulation (HI-PP-LFS) were delivered to induce L-LTP reversal. Paired-pulse ratios (PPR) were obtained before LTP induction, 2 h after LTP induction and 30 min after LTP reversal. On the other hand, immunofluorescence histochemistry was used to detect AMPARs expressions before and after L-LTP reversal. The results showed that, after 2 h of induction, L-LTP was partially reversed by two episodes of HI-PP-LFS, and the percentage of depotentiation was 61.79%+/-14.51%. PPR obtained before and after LTP induction, and as well that after LTP reversal, are all more than 1, showing paired-pulse facilitation (PPF). Multiple comparison indicated PPR before LTP induction was the greatest one, and PPR after LTP induction was the smallest. In addition, no significant difference was observed in the intensity of AMPAR/GluR2 immunoreactivity in CA1 area among control group, LTP group and LTP reversal group. These results suggest that the presynaptic mechanism is involved in both the maintenance and reversal of L-LTP and there is no change in AMPAR/GluR2 expression before and after the reversal of L-LTP.
Animals ; CA1 Region, Hippocampal ; metabolism ; physiology ; Electric Stimulation ; Long-Term Potentiation ; physiology ; Male ; Presynaptic Terminals ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA ; metabolism

OBJECTIVETo assess whether HTR1A and HTR1B polymorphisms are associated with the predisposition, gender, PUMC Classification and/or severity of adolescent idiopathic scoliosis (AIS).

METHODSRs6294 (HTR1A) and rs6296 (HTR1B) were genotyped in 103 AIS patients treated from January 2006 to March 2007, and 108 controls with matched gender and age. The data were analyzed by the allelic and genotypic association analysis, and the genotype-phenotype (gender, PUMC Classification, and Cobb angle) association analysis.

RESULTSThe distributions of the alleles of all the 2 SNPs met Hardy-Weinberg equilibrium in the controls (goodness-of-fit chi(2) test, P > 0.05). The allele A of rs6294 was related with the occurrence of AIS (P = 0.041), but differences of the allele frequencies of rs6296 and the genotype frequencies of both SNPs between 2 groups had no statistical significance (P > 0.05). The genotype A/A + A/G of rs6294 was associated with AIS PUMC type III, and there was no other positive results in genotype-phenotype association analysis.

CONCLUSIONThese results suggest that HTR1A may be a predisposition gene of AIS PUMC type III, and PUMC Classification may has its genetic basis.

Adolescent ; Gene Frequency ; Genetic Association Studies ; Genotype ; Humans ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Receptor, Serotonin, 5-HT1A ; genetics ; Receptor, Serotonin, 5-HT1B ; genetics ; Scoliosis ; genetics

Migraine and anxiety disorders are frequently co-morbid with balance disorders. Potential mechanisms for migrainous vertigo include sites of action of 5-HT (serotonin) 1B and 1D receptor agonists such as rizatriptan, which attenuate motion sickness in migraineurs. Selective serotonin reuptake inhibitors (SSRIs) are also known to be efficacious in the treatment of vertigo. Relative distribution of the 5-HT receptor subtypes and their functional roles in the vestibular nuclei and inner ear is still unknown. Using 5-HT1A, 1B, AND 1D receptors-specific antibody, we have demonstrated a differential distribution of these receptor subtypes within the rat vestibular nuclei and inner ear. For 5-HT receptor subtypes expression in the vestibular and auditory periphery, most ganglion cells in the vestibular ganglion showed immunoreactivity for 5-HT1A, 5-HT1B and 5-HT1D receptors. In addition, 5-HT1B and 1D receptors immunopositive reactivities were associated with endothelial cells of small blood vessels in the vestibular ganglion and nerve, endothelial cells in both the spiral ligament deep to the spiral prominence and stria vascularis and endothelial cells on blood vessels along the margins of the spiral ganglion. For 5-HT receptor subtypes expression in the vestibular nuclei (VN), the 5-HT1A, 1B and 1D receptors were expressed differentially in the VN. Fine varicose axons in the periventricular plexus showed intense 5-HT1A receptor expression in the medial VN (MVN) and extended into the superior VN (SVN). By contrast, 5-HT1B receptors were not expressed the ventricular plexus axons. Rather, 5-HT1B and 1D receptors immunopositive cell bodies and neuronal processes were dense in rostral MVN, dorsal SVN, lateral VN (LVN) and ventral aspect of nucleus prepositus hypoglossi (NPH). In the present study, inner ear and vestibular nuclei showed distinct distributions of 5- HT1A, 1B and 1D receptors expressions that are parallel to their distribution in peripheral and central nociceptive pathways. These differentially distributed 5-HT receptor subtypes are potential targets to explain the efficacy of SSRIs and triptans in treating migraine and migrainous vertigo.
Animals ; Anxiety Disorders ; Axons ; Blood Vessels ; Ear, Inner ; Endothelial Cells ; Ganglion Cysts ; Migraine Disorders ; Motion Sickness ; Neurons ; Rats ; Receptor, Serotonin, 5-HT1A ; Receptor, Serotonin, 5-HT1B ; Receptor, Serotonin, 5-HT1D ; Serotonin ; Serotonin Uptake Inhibitors ; Spiral Ganglion ; Spiral Ligament of Cochlea ; Stria Vascularis ; Triazoles ; Tryptamines ; Vertigo ; Vestibular Nuclei

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABAA-receptor that allows chloride to pass through a ligand gated ion channel and GABAB-receptor that uses G-proteins for signaling. The GABAA-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABAA-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with 11C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, 18F-fluoroflumazenil (FFMZ) has been developed to overcome 11C's short half-life. 18F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using 11C-FMZ PET instead of 18F-FDG PET, restrict the foci better and may also help find lesions better than high resolution MR. GABAA receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.
Benzodiazepines ; Binding Sites ; Brain Ischemia ; Cell Survival ; Cerebral Cortex ; Cerebral Palsy ; Depression ; Epilepsy ; Flumazenil ; Fluorodeoxyglucose F18 ; gamma-Aminobutyric Acid* ; GTP-Binding Proteins ; Half-Life ; Interneurons ; Ion Channels ; Neuronal Plasticity ; Neurons ; Neurotransmitter Agents ; Plastics ; Presynaptic Terminals ; Receptors, GABA* ; Receptors, GABA-A ; Schizophrenia

5-HT(1A) receptor is implicated in the pathogenesis and the therapeutic mechanism of various psychiatric disorders. Especially, the mechanism of action of selective serotonin reuptake inhibitors (SSRIs) was hypothesized that 5-HT(1A) autoreceptor desensitization plays an important role in the treatment of depression and anxiety. 5-HT(1A) receptor stimulation may also mediate the neurogenesis of prefrontal cortex and hippocampus. The 5-HT(1A) agonism has an important meaning in the treatment of schizophrenia. Most atyptical antipsychotics have the property of 5-HT(2A) antagonist, and some have that of 5-HT(1A) agonist. In the various regions of brain, 5-HT(1A) and 5-HT(2A) have the functionally antagonistic properties. Recently, 5-HT(1A) receptor-related agents have been investigated in the treatment of acute ischemic stroke and Alzheimer's disease. Therefore, the further understanding about the 5-HT(1A) receptors in the brain functions will provide the development of future drugs and the advancement of psychopharmacology.
Alzheimer Disease ; Antipsychotic Agents ; Anxiety ; Autoreceptors ; Brain ; Depression ; Drug Therapy* ; Felodipine ; Hippocampus ; Neurogenesis ; Prefrontal Cortex ; Psychopharmacology ; Receptor, Serotonin, 5-HT1A* ; Schizophrenia ; Serotonin ; Serotonin Uptake Inhibitors ; Stroke