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

OBJECTIVETo observe the effects of subchronic benzo[a]pyrene (B[a]P) exposure on the neurobehavior and hippocampal acetylcholine (Ach) level, acetylcholinesterase (AChE) activity, and mRNA and protein expression of nicotinic acetylcholine receptor α7 subtype (nAChR α7) in rats, and to investigate the neurotoxic mechanism of B[a]P.

METHODSSixty healthy male SD rats were randomly divided into blank control group, solvent control group, and B [a]P exposure groups. Each rat in the exposure groups was intraperitoneally injected with B[a]P at 1.0, 2.5, or 6.25 mg/kg once every other day for 90 days. The learning and memory ability of the rats was examined by Morris water maze test and step-down test; the hippocampal Ach level was measured by alkaline hydroxylamine method; the AChE activity was measured by DNTB method; the mRNA and protein expression levels of hippocampal nAChR α7 were measured by quantitative PCR and Western blot.

RESULTSThe 2.5 and 6.25 mg/kg B[a]P exposure groups showed significantly lower learning and memory abilities than the blank control group and solvent control group (P < 0.05); also, the two groups had significantly lower hippocampal Ach levels than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The 6.25 mg/kg B[a]P exposure group showed significantly lower hippocampal AChE activity than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). There were no significant differences in the mRNA and protein expression levels of nAChR α7 among all groups (P > 0.05). The hippocampal Ach level was negatively correlated with the mean escape latency period and total distance travelled (r = -0.567, P < 0.01; r = -0.503, P < 0.01) but positively correlated with the time in platform quadrant (r = 0.800, P < 0.01).

CONCLUSIONSubchronic B[a]P exposure may impair the learning and memory ability in rats, which is related to the downregulation of hippocampal Ach level.

Acetylcholine ; metabolism ; Acetylcholinesterase ; metabolism ; Animals ; Benzo(a)pyrene ; toxicity ; Hippocampus ; drug effects ; metabolism ; Male ; Maze Learning ; drug effects ; Memory ; drug effects ; Rats ; Rats, Sprague-Dawley ; Receptors, Cholinergic ; metabolism ; Toxicity Tests, Subchronic ; alpha7 Nicotinic Acetylcholine Receptor ; metabolism

OBJECTIVETo investigate the effects of α3 neuronal nicotinic acetylcholine receptor (nAChR) on apoptosis and p38 signal transduction pathway in SH-SY5Y cells and to assess the roles of α3 nAChR in the pathogenesis of Alzheimer's disease (AD).

METHODSThe levels of α3 nAChR mRNA and protein were measured by real-time PCR and Western blot, respectively, in SH-SY5Y cells transfected with α3 nAChR siRNA. The mRNA level of bcl-2 and bax was measured by the real-time PCR. The siRNA transfected SH-SY5Y cells and control were then treated with 10 µmol/L Aβ25-35 for another 48 h, and the change in apoptotic rate and the levels of p-p38 and p38 were measured by flow cytometry and Western blot. Subsequently these SH-SY5Y cells were exposed to a blocker of p38 protein, and the apoptotic rate was measured again.

RESULTSCompared to the controls, the expression of α3 nAChR at mRNA and protein levels in the SH-SY5Y cells transfected with α3 nAChR siRNA decreased by 95% and 86%, respectively; the mRNA levels of bax increased 2.11 times and that for bcl-2 decreased 0.53 times. The apoptotic rate was unaffected (3.40% ± 0.20%); but it increased after Aβ25-35 treatment (24.52% ± 1.59%); the level of p-p38 protein also increased by 178% in the α3 nAChR inhibited cells treated with Aβ25-35. Compared to controls, the Aβ25-35-treated SH-SY5Y cells and the Aβ25-35-treated and siRNA-transfected cells both showed a reduction in apoptosis after treatment with p38 blocker, especially in the former.

CONCLUSIONThe siRNA silencing of α3 nAChR mRNA may enhance the effect of Aβ25-35 on the cell apoptosis by increasing the levels of p38 protein and bax mRNA and decreasing the level of bcl-2 mRNA, which may play a role in the pathogenesis of AD.

Alzheimer Disease ; etiology ; Amyloid beta-Peptides ; metabolism ; Apoptosis ; Cell Line, Tumor ; Gene Silencing ; Humans ; Neuroblastoma ; metabolism ; pathology ; Peptide Fragments ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Receptors, Nicotinic ; genetics ; metabolism ; Signal Transduction ; Transfection ; bcl-2-Associated X Protein ; genetics ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the influence of inhibited α7 neuronal nicotinic acetylcholine receptor (nAChR) by small interference RNA (siRNA) in SH-SY5Y cells and to explore the connection of these changes with the β-amyloid precursor protein (APP) metabolism and the pathogenesis of Alzheimer's disease (AD).

METHODSThe siRNA of α7 nAChR was transfected into SH-SY5Y cells, and the expression of α7 nAChR and two subtypes of β-secretases (BACE1 and BACE2) at mRNA and protein levels was studied by real-time PCR and Western blot, respectively. The variation of Aβ(1-42) content was detected by ELISA.

RESULTSAs compared with controls, the expression of α7 nAChR at mRNA and protein levels in the SH-SY5Y cells transfected with the α7 nAChR siRNA were decreased by 84% and 79% (P < 0.01), respectively. The expressions of BACE1 mRNA and protein levels was increased by 527% and 71% (P < 0.01), respectively, while the expression of BACE2 decreased by 58% and 75% (P < 0.01), respectively. The Aβ(1-42) content increased by 208% (P < 0.01).

CONCLUSIONSAn inhibited α7 nAChR mRNA induced by siRNA may markedly stimulate the production of Aβ through the mechanism of increased expression of BACE1 and inhibited expression of BACE2, which may be related to the pathogenesis of AD.

Amyloid Precursor Protein Secretases ; genetics ; metabolism ; Amyloid beta-Peptides ; metabolism ; Aspartic Acid Endopeptidases ; genetics ; metabolism ; Cell Line, Tumor ; Humans ; Neuroblastoma ; metabolism ; pathology ; Peptide Fragments ; metabolism ; RNA Interference ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Receptors, Nicotinic ; genetics ; metabolism ; Transfection ; alpha7 Nicotinic Acetylcholine Receptor

BACKGROUNDTechnetium-99m or (99m)Tc is widely used for labeling peptide in nuclear medicine. Somatostatin and its analog can inhibit tumor cell growth after binding with its receptor. This research was to study the preclinical effect of a new (99m)Tc-6-hydrazinopyridine-3-carboxylic acid (HYNIC)-depreotide, indirect (99m)Tc labeling of depreotide using HYNIC as a bifunctional chelator.

METHODSThe cyclopeptide, cyclo-[(N-Me) Phe-Tyr-D-Trp-Lys-Val-Hcy], the linear peptide, and [ClCH(2)-CO×b-Dap-Lys- Cys-Lys×amide] were synthesized by Fmoc solid-phase synthesis. The cyclopeptide and the linear peptide were linked by liquid-phase synthesis. The product depreotide was isolated and purified by high performance liquid chromatography and was confirmed by mass spectrography. Depreotide was labeled with (99m)Tc through a direct labeling method, using HYNIC as a bifunctional chelator. Paper chromatography method was used to calculate the labeling rate, and through the comparative analysis selected the best mark conditions. The new (99m)Tc-HYNIC-depreotide was tested by high-performance liquid chromatography (HPLC). The internalization and externalization rates of the new (99m)Tc-HYNIC-depreotide were studied in A549 cells. Furthermore, biodistribution of the radiopeptide was studied in nude mice, bearing tumors from human lung carcinoma cells SPC-A1.

RESULTSThe molecular of synthesize depreotide was 1358, and the purity of it was 95.29%. The labeling efficiency of (99m)Tc-HYNIC-depreotide was highest at pH 6.0 and 15°C, about (70.95 ± 0.84)%. The labeling rate of the new (99m)Tc-HYNIC-depreotide rose to a peak of (20.75 ± 0.48)% at 60 minutes in A549 cells at 37°C and decreased slightly later, while it elevated gradually during the time course at 4°C and 25°C. The internalization rate of the new (99m)Tc-HYNIC-depreotide at 37°C increased gradually and reached the peak of 84.4% in 120 minutes, while the externalization rate of the new (99m)Tc-HYNIC-depreotide was always less than 20%. In mice bearing the experimental SPC-A1 tumor, the new (99m)Tc-HYNIC-depreotide demonstrated a high tumor uptake of (4.05 ± 0.04)% ID/g at 1.5 hpi and remained high ((2.51 ± 0.06)% ID/g) at 4 hpi. The tumor-to-lung activity concentration ratio (T/Lu) was very high for the new (99m)Tc-HYNIC-depreotide at all time points. So did the tumor-to-muscle activity (T/Mu) and tumor-to-blood activity concentration ratios (T/Bl).

CONCLUSIONThe findings suggested that the new (99m)Tc-HYNIC-depreotide might be a promising candidate radiopharmaceutical for imaging somatostatin receptor positive lung cancer.

Animals ; Cell Line, Tumor ; Humans ; Hydrazines ; chemistry ; Lung Neoplasms ; metabolism ; pathology ; Male ; Mice ; Mice, Nude ; Nicotinic Acids ; chemistry ; Receptors, Somatostatin ; metabolism ; Technetium ; chemistry

BACKGROUNDInflammation is one of important mechanisms for myocardial ischemia reperfusion injury (IRI). Ischemia postconditioning (IPOC) can protect the heart against IRI by inhibiting inflammation, but its cardioprotection is weaker than that of ischemia preconditioning. Recently, the α7 subunit-containing nicotinic acetylcholine receptor (α7nAChR) agonist has shown anti-inflammatory effects in many diseases related to inflammation. This randomized controlled experiment was designed to evaluate whether combined postconditioning with IPOC and the α7nAChR agonist could produce an enhanced cardioprotection in a rat in vivo model of acute myocardial IRI.

METHODSFifty Sprague-Dawley rats were randomly divided into five equal groups: sham group, control group, IPOC group, α7nAChR agonist postconditioning group (APOC group) and combined postconditioning with IPOC and α7nAChR agonist group (combined group). Hemodynamic parameters were recorded during the periods of ischemia and reperfusion. Serum concentrations of troponin I (TnI), tumor necrosis factor α (TNF-α) and high-mobility group box 1 (HMGB-1) at 180 minutes after reperfusion were assayed in all groups. At the end of the experiment, the infarct size was assessed from excised hearts by Evans blue and triphenyl tetrazolium chloride staining.

RESULTSAs compared to the sham group, the infarct size in the other four groups was significantly increased, serum levels of TnI, TNF-α and HMGB1 in the control group and TNF-α, HMGB1 in the IPOC group were significantly increased. The infarct size and serum concentrations of TNF-α, HMGB1 and TnI in the IPOC, APOC and combined groups were significantly lower than those in the control group. As compared to the IPOC group, the infarct size in the combined group was significantly decreased, serum concentrations of TnI, TNF-α and HMGB1 in the APOC and combined groups were significantly reduced. Although the infarct size was significantly smaller in the combined group than in the APOC group, serum levels of TNF-α and HMGB1 were significantly higher in the combined group than in the APOC group.

CONCLUSIONSIn a rat in vivo model of acute myocardial IRI, combined postconditioning with IPOC and the α7nAChR agonist can produce enhanced protection against myocardial IRI by increasing the anti-inflammatory effect.

Animals ; Heart ; drug effects ; Ischemic Preconditioning, Myocardial ; methods ; Male ; Myocardial Reperfusion Injury ; prevention & control ; Myocardium ; pathology ; Nicotinic Agonists ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Receptors, Nicotinic ; metabolism ; Tumor Necrosis Factor-alpha ; blood ; alpha7 Nicotinic Acetylcholine Receptor

Human amylin (hAmylin) is co-released with insulin from pancreatic B-cells and the actions of this peptide on its target tissues maintain the cell excitability and glucose homeostasis. Inappropriate control of hAmylin secretion may result in human disease, particularly Alzheimer's disease (AD). It's unknown that which kind of receptor is activated by human amylin, leading to the neurotoxicity in neurons of brain. Nicotinic acetylcholine receptors (nAChRs) are known to play a critical role in a variety of nervous diseases. In the present study, we sought to determine the inter-relationships between these two receptors by examining the actions of hAmylin and nicotine on whole-cell currents and membrane potential in basal forebrain neurons. Whole cell patch-clamp recordings were performed on enzymatically dissociated neurons of the diagonal band of Broca (DBB), a cholinergic basal forebrain nucleus. The results showed that either hAmylin or nicotine individually caused a dose-dependent (1 nmol/L-20 µmol/L) membrane depolarization and an increase in firing frequency of DBB neurons. Application of AC253, an amylin receptor antagonist, blocked the excitatory effects of not only hAmylin but also nicotine; dihydro-β-erythroidine (DHβE), a nAChR antagonist, also blocked the effects of nicotine and hAmylin. These electrophysiological results suggest that hAmylin receptor and nAChRs on DBB neurons are coupled and may function in a co-operative manner to influence the excitability of DBB neurons. This finding is important for us to understand the cause and mechanisms of AD.
Animals ; Brain ; metabolism ; physiology ; Diagonal Band of Broca ; metabolism ; physiology ; Humans ; Islet Amyloid Polypeptide ; pharmacology ; Male ; Neurons ; metabolism ; physiology ; Nicotine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Islet Amyloid Polypeptide ; physiology ; Receptors, Nicotinic ; physiology

OBJECTIVETo observe the effect of Scutellarin (Scu) on expressions of nicotinic acetylcholine receptor (nAChR) subunit protein and mRNA in dementia rats, and to study its possible mechanism on dementia.

METHODSForty-two Wistar rats were randomly divided into 5 groups, i.e., the normal control group (n=6), the sham-operative group (n=6), the memory deficit model group, the Scu treatment group (n=10), and the positive drug (piracetam) control group (n=10). The dementia rat model was established by bilateral ventricle injection with beta-amyloid peptide (Abeta)(25-35) and abdominal cavity injection with D-galactose. Rats in the Scu treatment group or the piracetam control group were treated with Scu or piracetam by gastrogavage. The learning and memory ability of rats were detected by Morris water maze test, nAChR alpha4, alpha7, and beta2 subunits at protein and mRNA levels were detected by Western blot and Real-time PCR respectively.

RESULTSCompared with the normal control group and the sham-operative group, the learning and memory ability decreased in rats of the model group (P<0.05). nAChR alpha4 and alpha7 subunit protein expressions were obviously lowered (P<0.05), but changes of beta2 were not obvious. No obvious change of mRNA expressions in all three nAChR subunits was seen (P>0.05). After treatment of Scu, the learning and memory ability was greatly improved, nAChRs alpha4 and alpha7 subunit protein expressions increased in rats with dementia (all P<0.05). No obvious change of mRNA expressions in all three nAChR subunits was seen (P>0.05). No obvious difference of each index was shown between the Scu treatment group and the positive drug (piracetam) control group.

CONCLUSIONSScutellarin could improve the learning and memory ability of dementia rats. Its mechanism might be associated with its up-regulation of nAChR expressions.

Alzheimer Disease ; drug therapy ; genetics ; metabolism ; Amyloid beta-Peptides ; metabolism ; Animals ; Apigenin ; pharmacology ; therapeutic use ; Brain ; drug effects ; metabolism ; Disease Models, Animal ; Female ; Glucuronates ; pharmacology ; therapeutic use ; Learning ; drug effects ; Male ; Memory ; drug effects ; RNA, Messenger ; genetics ; Rats ; Rats, Wistar ; Receptors, Nicotinic ; genetics ; metabolism ; Up-Regulation

Lung cancer is the leading cause of cancer death in men and women worldwide, with over a million deaths annually. Tobacco smoke is the major etiologic risk factor for lung cancer in current or previous smokers and has been strongly related to certain types of lung cancer, such as small cell lung carcinoma and squamous cell lung carcinoma. In recent years, there has been an increased incidence of lung adenocarcinoma. This change is strongly associated with changes in smoking behavior and cigarette design. Carcinogens present in tobacco products and their intermediate metabolites can activate multiple signaling pathways that contribute to lung cancer carcinogenesis. In this review, we summarize the smoking-activated signaling pathways involved in lung cancer.
Adenocarcinoma ; etiology ; metabolism ; pathology ; Carcinoma, Squamous Cell ; etiology ; metabolism ; pathology ; Humans ; Lung Neoplasms ; etiology ; metabolism ; pathology ; NF-kappa B ; metabolism ; Receptor, Epidermal Growth Factor ; metabolism ; Receptors, Adrenergic, beta ; metabolism ; Receptors, Nicotinic ; metabolism ; Signal Transduction ; Small Cell Lung Carcinoma ; etiology ; metabolism ; pathology ; Smoking ; adverse effects ; gamma-Aminobutyric Acid ; metabolism

OBJECTIVETo investigate the influence of APP(SWE) on the expression of neuronal acetylcholine receptors (nAChRs) and its relationship with Alzheimer's disease (AD).

METHODSAPP(SWE), carried the Swedish family AD double mutants, were transfected into SH-SY5Y cells and primary cultured neurons from rat brains to build a cellular model of AD. The mRNA levels of APP and nAChRs, and the protein levels of total APP, αAPPs and nAChRs in the cultured cells were measured using real-time PCR and Western blot, respectively. The numbers of α3 nAChR were determined by receptor-[³H]epibatidine binding assay.

RESULTSIncreased expressions of Swedish 670/671 APP at mRNA and protein levels, and down-regulation of αAPPs were observed in both of the cultured neuronal cells transfected with APP(SWE). A significant increase of α7 nAChR expression at protein and mRNA levels was detected in the APP(SWE) transfected SH-SY5Y cells. On the other hand, after transfection with APP(SWE), the expressions of α3 nAChR at protein and mRNA levels in SH-SY5Y cells, and α4 nAChR at mRNA level in primary cultured neurons were inhibited. In addition, the numbers of receptor binding sites were deceased in SH-SY5Y cells overexpressing with APP(SWE).

CONCLUSIONOverexpression of APP(SWE) can decrease αAPPs and modify nAChRs by increasing expression of α7 nAChR and decreasing α3 and α4 nAChRs, which might play an important role in the pathogenesis of AD.

Alzheimer Disease ; genetics ; Amyloid Precursor Protein Secretases ; secretion ; Amyloid beta-Protein Precursor ; genetics ; metabolism ; physiology ; Animals ; Brain Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cells, Cultured ; Cerebral Cortex ; cytology ; metabolism ; Down-Regulation ; Humans ; Neuroblastoma ; metabolism ; pathology ; Neurons ; cytology ; metabolism ; Plasmids ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Nicotinic ; genetics ; metabolism ; Transfection ; alpha7 Nicotinic Acetylcholine Receptor