This study investigated the mechanism by which Jianpi Bushen Yiqi Decoction promotes acetylcholine receptor(AChR) clustering in myasthenia gravis through the Agrin/low-density lipoprotein receptor-related protein 4(LRP4)/muscle-specific receptor tyrosine kinases(MuSK) signaling pathway. A total of 114 female C57BL/6J mice were divided into the normal group, modeling group, and solvent control group. The normal group and the solvent control group were immunized with phosphate-buffered saline(PBS), while the modeling group was established as an experimental autoimmune myasthenia gravis(EAMG) model using the murine-derived AChR-α subunit R97-116 peptide fragment. After successful modeling, the mice were randomly assigned to the model group, the low-, medium-, and high-dose Jianpi Bushen Yiqi Decoction groups, and the prednisone group. After four weeks of continuous treatment, muscle strength was assessed using Lennon scores and grip strength tests. Immunofluorescence staining was conducted on differentiated C2C12 myotubes incubated with a drug-containing serum to observe the number of AChR clusters. The integrity of AChR on myofilaments in mouse gastrocnemius muscles was further assessed by immunofluorescence staining. Hematoxylin-Eosin(HE)staining was applied to examine pathological changes in the gastrocnemius muscles of EAMG mice treated with Jianpi Bushen Yiqi Decoction. Western blot was utilized to detect the expression of key proteins in the Agrin/LRP4/MuSK signaling pathway in both C2C12 myotubes and mouse gastrocnemius muscles. The results demonstrated that compared to the model group, the prednisone group exhibited a significant decrease in the body weights of mice, whereas no significant differences in the body weights of mice were observed among the low-, medium-, and high-dose Jianpi Bushen Yiqi Decoction groups. All treatment groups showed significantly improved grip strength and Lennon scores. Additionally, the formula promoted AChR clustering on myotubes and enhanced AChR integrity in gastrocnemius myofilaments and reduced inflammatory infiltration between muscle tissue and fibrous hyperplasia. Furthermore, Jianpi Bushen Yiqi Decoction upregulated the protein expression of AChRα1, Agrin, and p-MuSK in C2C12 myotubes and increased the protein expression of AChRα1, Agrin, MuSK, p-MuSK, LRP4, and docking protein 7(Dok-7)in gastrocnemius tissue. In conclusion, Jianpi Bushen Yiqi Decoction may promote AChR clustering by targeting key proteins in the Agrin/LRP4/MuSK signaling pathway, thereby improving neuromuscular junction function and enhancing muscle strength.
Animals ; Agrin/genetics* ; Mice ; Drugs, Chinese Herbal/administration & dosage* ; Signal Transduction/drug effects* ; Receptors, Cholinergic/genetics* ; Female ; Mice, Inbred C57BL ; Receptor Protein-Tyrosine Kinases/genetics* ; Neuromuscular Junction/metabolism* ; Myasthenia Gravis, Autoimmune, Experimental/physiopathology* ; Humans ; LDL-Receptor Related Proteins

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

BACKGROUNDThe antagonistic actions of anticholinesterase drugs on non-depolarizing muscle relaxants are theoretically related to the activity of acetylcholinesterase (AChE) in the neuromuscular junction (NMJ). However, till date the changes of AChE activity in the NMJ during sepsis have not been directly investigated. We aimed to investigate the effects of sepsis on the antagonistic actions of neostigmine on rocuronium (Roc) and the underlying changes of AChE activity in the NMJ in a rat model of cecal ligation and puncture (CLP).

METHODSA total of 28 male adult Sprague-Dawley rats were randomized to undergo a sham surgery (the sham group, n = 12) or CLP (the septic group, n = 16). After 24 h, the time-response curves of the antagonistic actions of 0.1 or 0.5 μmol/L of neostigmine on Roc (10 μmol/L)-depressed diaphragm twitch tension were measured. Meanwhile, the activity of AChE in the NMJ was detected using a modified Karnovsky and Roots method. The mRNA levels of the primary transcript and the type T transcript of AChE (AChET) in the diaphragm were determined by real-time reverse transcription-polymerase chain reaction.

RESULTSFour of 16 rats in the septic group died within 24 h. The time-response curves of both two concentrations of neostigmine in the septic group showed significant upward shifts from those in the sham group (P < 0.001 for 0.1 μmol/L; P = 0.009 for 0.5 μmol/L). Meanwhile, the average optical density of AChE in the NMJ in the septic group was significantly lower than that in the sham group (0.517 ± 0.045 vs. 1.047 ± 0.087, P < 0.001). The AChE and AChETmRNA expression levels in the septic group were significantly lower than those in the sham group (P = 0.002 for AChE; P = 0.001 for AChET).

CONCLUSIONSSepsis strengthened the antagonistic actions of neostigmine on Roc-depressed twitch tension of the diaphragm by inhibiting the activity of AChE in the NMJ. The reduced content of AChE might be one of the possible causes of the decreased AChE activity in the NMJ.

Acetylcholinesterase ; metabolism ; Androstanols ; pharmacology ; Animals ; Cecum ; injuries ; Cholinesterase Inhibitors ; pharmacology ; Diaphragm ; drug effects ; metabolism ; Disease Models, Animal ; Ligation ; Male ; Neostigmine ; pharmacology ; Neuromuscular Junction ; enzymology ; Neuromuscular Nondepolarizing Agents ; pharmacology ; Punctures ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Sepsis ; physiopathology

BACKGROUNDMuscles present different responses to muscle relaxants, a mechanism of importance in surgeries requiring facial nerve evoked electromyography under general anaesthesia. The non-depolarizing muscle relaxants have multiple reaction formats in the neuromuscular junction, in which pre-synaptic quantal release of acetylcholine was one of the important mechanisms. This study was to compare the pre-synaptic quantal release of acetylcholine from the neuromuscular junctions innervated by normal/damaged facial nerves and somatic nerve under the effect of rocuronium in rats in vitro.

METHODSAcute right-sided facial nerve injury was induced by nerve crush axotomies. Both sided facial nerve connected orbicularis oris strips and tibial nerve connected gastrocnemius strips were isolated to measure endplate potentials (EPP) and miniature endplate potentials (MEPP) using an intracellular microelectrode gauge under different rocuronium concentrations. Then, the pre-synaptic quantal releases of acetylcholine were calculated by the ratios of the EPPs and the MEPPs, and compared among the damaged or normal facial nerve innervated orbicularis oris and tibial nerve innervated gastrocnemius.

RESULTSThe EPP/MEPP ratios of the three neuromuscular junctions decreased in a dose dependent manner with the increase of the rocuronium concentration. With the concentrations of rocuronium being 5 µg/ml, 7.5 µg/ml and 10 µg/ml, the decrease of the EPP/MEPP ratio in the damaged facial nerve group was greater than that in the normal facial nerve group. The decrease in the somatic nerve group was the biggest, with significant differences.

CONCLUSIONSRocuronium presented different levels of inhibition on the pre-synaptic quantal release of acetylcholine in the three groups of neuromuscular junctions. The levels of the inhibition showed the following sequence: somatic nerve > damaged facial nerve > normal facial nerve. The difference may be one of the reasons causing the different sensitivities to rocuronium among the muscles innervated by the normal/injured facial nerves and the somatic nerve. The results may provide some information for the proper usage of muscle relaxants in surgeries requiring electromyographic monitoring for the pre-surgically impaired facial nerves.

Acetylcholine ; metabolism ; Androstanols ; pharmacology ; Animals ; Facial Nerve ; drug effects ; metabolism ; Male ; Neuromuscular Junction ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the role of HLB-1 in regulating the organization and function of neuromuscular junctions in nematode Caenorhabditis elegans.

METHODSTo evaluate the functions of HLB-1 in regulating the organization and function of neuromuscular junctions, effects of hlb-1 mutation on the synaptic structures were revealed by uncovering the expression patterns of SNB-1::GFP and UNC-49::GFP, and pharmacologic assays with aldicarb and levamisole were also used to test the synaptic functions. Further rescue and mosaic analysis confirmed HLB-1's role in regulating the organization and function of neuromuscular junctions.

RESULTSLoss of HLB-1 function did not result in defects in neuronal outgrowth or neuronal loss, but caused obvious defects of SNB-1::GFP and UNC-49::GFP puncta localization, suggesting the altered presynaptic and postsynaptic structures. The mutant animals exhibited severe defects in locomotion behaviors and altered responses to an inhibitor of acetylcholinesterase and a cholinergic agonist, indicating the altered presynaptic and postsynaptic functions. Rescue and mosaic analysis experiments suggested that HLB-1 regulated synaptic functions in a cell nonautonomously way. Moreover, HLB-1 expression was not required for the presynaptic active zone morphology. Genetic evidence further demonstrated that hlb-1 acted in a parallel pathway with syd-2 to regulate the synaptic functions.

CONCLUSIONHLB-1 appeared as a new regulator for the organization and function of neuromuscular junctions in C. elegans.

Age Factors ; Amino Acid Motifs ; physiology ; Analysis of Variance ; Animals ; Animals, Genetically Modified ; Animals, Newborn ; Behavior, Animal ; physiology ; Caenorhabditis elegans ; Caenorhabditis elegans Proteins ; genetics ; metabolism ; physiology ; Carrier Proteins ; metabolism ; Cell Adhesion Molecules ; genetics ; physiology ; Green Fluorescent Proteins ; genetics ; Locomotion ; genetics ; Mutation ; physiology ; Neuromuscular Junction ; genetics ; physiology ; Phosphoproteins ; genetics ; physiology

Nitric oxide (NO) is a non-adrenergic, non-cholinergic neurotransmitter found in the enteric nervous system that plays a role in a variety of enteropathies, including inflammatory bowel disease. Alteration of nitrergic neurons has been reported to be dependent on the manner by which inflammation is caused. However, this observed alteration has not been reported with acetic acid-induced colitis. Therefore, the purpose of the current study was to investigate changes in nitrergic neuromuscular transmission in experimental colitis in a rat model. Distal colitis was induced by intracolonic administration of 4% acetic acid in the rat. Animals were sacrificed at 4 h and 48 h postacetic acid treatment. Myeloperoxidase activity was significantly increased in the acetic acid-treated groups. However, the response to 60 mM KCl was not significantly different in the three groups studied. The amplitude of phasic contractions was increased by Nomega-nitro-L-arginine methyl ester (L-NAME) in the normal control group, but not in the acetic acid-treated groups. Spontaneous contractions disappeared during electrical field stimulation (EFS) in normal group. However, for the colitis groups, these contractions initially disappeared, and then reappeared during EFS. Moreover, the observed disappearance was diminished by L-NAME; this suggests that these responses were NO-mediated. In addition, the number of NADPH-diaphorase positive nerve cell bodies, in the myenteric plexus, was not altered in the distal colon; whereas the area of NADPH-diaphorase positive fibers, in the circular muscle layer, was decreased in the acetic acidtreated groups. These results suggest that NO-mediated inhibitory neural input, to the circular muscle, was decreased in the acetic acid-treated groups.
Acetic Acid/toxicity ; Animals ; Colitis/chemically induced/*pathology/*physiopathology ; Colon/drug effects/enzymology/*innervation/pathology ; Indicators and Reagents/toxicity ; Male ; Muscle Contraction/drug effects ; Muscle, Smooth/drug effects/metabolism ; Myenteric Plexus/pathology ; NADPH Dehydrogenase/metabolism ; NG-Nitroarginine Methyl Ester/pharmacology ; Neuromuscular Junction/drug effects/*metabolism ; Nitrergic Neurons/drug effects/*metabolism ; Nitric Oxide/*metabolism ; Peroxidase/metabolism ; Potassium Chloride/pharmacology ; Rats ; Rats, Sprague-Dawley

Motor units comprise a motoneuron and the muscle fibers it innervates. Neuromuscular transmission is tightly regulated to match the activity of individual motor units. Activity-dependent release of neuromodulators at the neuromuscular junction (NMJ) determines the efficacy of transmission. The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) are produced by motoneurons and muscle fibers, and their release by skeletal muscle is regulated by muscle activity. BDNF and NT-4 enhance both spontaneous and evoked synaptic transmission at NMJs via activation of the tyrosine kinase receptor B (TrkB). Improvements in neuromuscular transmission may result from increased release of synaptic vesicles, either by presynaptic alterations in Ca(2+) transients or facilitated vesicular exocytosis. In fact, BDNF potentiates intracellular Ca(2+) release presynaptically and BDNF-induced TrkB activation also results in phosphorylation of synapsin I via mitogen activated protein kinase, which increases the number of synaptic vesicles available for release. Neurotrophins may also regulate synaptic transmission at the NMJ by increasing local release of neuregulin or other nerve-derived modulators. We review recent studies on the regulation of neuromuscular transmission, the motor unit-specific properties of NMJs and the effects of neurotrophins on synaptic efficacy at the NMJ.
Animals ; Brain-Derived Neurotrophic Factor ; physiology ; Calcium ; metabolism ; Humans ; Nerve Growth Factors ; physiology ; Neuromuscular Junction ; physiology ; Neuronal Plasticity ; Receptor, trkB ; metabolism ; Synapses ; metabolism ; Synapsins ; metabolism ; Synaptic Vesicles

It is well known that the plasma concentration is important in determining the rate of recovery from neuromuscular block. However, nondepolarizing neuromuscular blockade are retained at the neuromuscular junction and are not readily displaced in response of changes in plasma drug concentration, for instance, the neuromuscular block induced by mivacurium appears to considerably outlast the theoretical plasma half-life of the drug and is continued long after the plasma level has fallen to subparalytic levels due to rapid metabolism by pseudocholinesterase. It has been suggested that although plasma concentration may be the key determinant of recovery from neuromuscular block, recovery will depend upon the dissociation from the affinity of drug in the effect compartrnent and not upon its plasma concentration. In an attempt to confirm these evidences, we have investigated the response of changes in neuromuscular block after releasing tourniquet at 50% twitch depression using the isolated forearm experiment with various neuromuscular blocking agents. The results of this study demonstrated the further increase of block after early toumiquet release in the isolated forarm in all agents; 66+/-14% in vecuronium, 90+/-9% in atracurium, 92+/-7% in pancuronium, and 73+/-18% in mivacurium Conclusively, the further block continued to increase in spite of the negligible plasma drug concentration after early tourniquet release may be caused by more in affinity of drugs in binding sites than plasma drug concentration. Therfore, it is evident that both the affinity of drug to the receptor and the plasma drug concentration have influenced on the recovery from the neuromuscular block.
Atracurium ; Binding Sites ; Depression ; Forearm ; Half-Life ; Metabolism ; Neuromuscular Blockade* ; Neuromuscular Blocking Agents* ; Neuromuscular Junction ; Pancuronium ; Plasma ; Pseudocholinesterase ; Tourniquets ; Vecuronium Bromide

Anesthesiologists may have close relationship with muscle relaxants in clinical practice fortunately, few of the new muscle relaxants were discovered and used in clinic recently. In this moment we have to look back the old muscle relaxants. Undesirable side effects of thIn old ones are less common, but encountered often enough to be troublesome. For example, succinylcholine(depolarizer) mar enhance drsrhythmia, rise in plasma pot-assium, increase in intraocular pressure, rise in intragastric pressure, triggering malignant hrperpyrexia Trestle Pain and dual block etc. Is there a simple screen test for the atypical cholinesterase? Unfortunately it's not available now. Nevertheless depolarizer was still used in many decades. That's the matter? Muscle relaxants are also affected by many factors those are renal excretion, metabolism of the drug, lilver or disease, effect of jaundice, muscle blood flow, production and release of acetylcholine, bod)'temperature, antibiotics, other drug interactions, electrolyte imbalance, pathological status, individual differences and species differences etc. Sometimes it will make a trouble for the anesthesia practice. So anesthesiologists must be familiar with the use of muscle relaxants. And also we have to think twice about it's clinical use before given to the patients. What Is the right methods of rational use of muscle relaxants? What is the right way to reverse muscle relaxation? Obviously, return of normal muscle function followin? muscle relaxant administration is of prime importance to restoration of adequate spontaneous ventilation because it is clini-call velr i rnportant. In human study; supramaximal ulnar nerve stimulation was delitrered br a Peripheral nerIFe stimulatur(Ml'oftest, Biometer MK II) through electrode at the wrist. Stimuli were detail erect continuousl) by either 7 TOF or sin 91e twitch stimuli. The resultant force of thumb adduction was measured and recorded by Biophysiograph(San Ei, Japan) through the force displacoment transducer. In animal study: all animals were intubated through a tracheostomr under the intraper-itoneal urethane anesthesia with nembutal given intravenously. Respiration was controlled by means of Shinano animal respirator. The body temperature 7as kept at 35 degrees C with a thermo-blanket. The common peroneal nerve and anterior tibial muscle was exposed and nerve stimulator was applied to the nerve-muscle preparation. The twitch height of the muscle contraction was recorded on a Biophrsiograph through the force displacement Ira-nsfucer. The common peroneal nerve was stimulated supramaximally using a peripheral nerve stimulator with a "TOF" stimulation or single twitch stimulation. Obviously, newly introduced muscle relaxants are certainly have advantage over the old ones but we should hatre further studies on them. Conclusions ; 1) Minimal dose of muscle relaxant which may produce 90~100% of twitch depression may use depend on the types of surgery. 2) To evaluate the type and degree of muscle relaxation intermittently by use of the peripheral nerve stimulator is essential. 3) Best choice of the muscle relaxants are should be non-depolarizers those mar promp-tly reversed by anticholinesterases.
Acetylcholine ; Anesthesia ; Animals ; Anti-Bacterial Agents ; Body Temperature ; Cholinesterase Inhibitors ; Cholinesterases ; Cimetidine ; Depression ; Drug Interactions ; Electrodes ; Humans ; Individuality ; Intraocular Pressure ; Jaundice ; Metabolism ; Muscle Contraction ; Muscle Relaxation ; Muscle, Skeletal ; Neuromuscular Blockade* ; Neuromuscular Blocking Agents* ; Neuromuscular Junction ; Pentobarbital ; Peripheral Nerves ; Peroneal Nerve ; Plasma ; Respiration ; Thumb ; Transducers ; Ulnar Nerve ; Urethane ; Ventilation ; Ventilators, Mechanical ; Wrist