Acetylcholine (ACh) is an important neuromodulator in various cognitive functions. However, it is unclear how ACh influences neural circuit dynamics by altering cellular properties. Here, we investigated how ACh influences reverberatory activity in cultured neuronal networks. We found that ACh suppressed the occurrence of evoked reverberation at low to moderate doses, but to a much lesser extent at high doses. Moreover, high doses of ACh caused a longer duration of evoked reverberation, and a higher occurrence of spontaneous activity. With whole-cell recording from single neurons, we found that ACh inhibited excitatory postsynaptic currents (EPSCs) while elevating neuronal firing in a dose-dependent manner. Furthermore, all ACh-induced cellular and network changes were blocked by muscarinic, but not nicotinic receptor antagonists. With computational modeling, we found that simulated changes in EPSCs and the excitability of single cells mimicking the effects of ACh indeed modulated the evoked network reverberation similar to experimental observations. Thus, ACh modulates network dynamics in a biphasic fashion, probably by inhibiting excitatory synaptic transmission and facilitating neuronal excitability through muscarinic signaling pathways.
Cholinergic Agents/pharmacology* ; Acetylcholine/metabolism* ; Neurons/metabolism* ; Synaptic Transmission/physiology*

OBJECTIVETo observe a turning performance in the rats excited by using a proper electrical stimuli of the barrel cortex region (BC), and the expression of choline acetyltransferase (ChAT) in the BC regions after electoral stimulation.

METHODSSD rats were divided into three groups. The stimulation electrodes were surgically implanted into the bilateral BC regions in the control group and the experimental group rats. The experiment group post surgery for seven days was given the electrical impulses via connection with the electrodes for three times each day through consecutive three days. Three groups of the rats were killed and the brains were quickly removed for frozen sections and then performed with conventional HE and immunohistochemistry staining. And protein samples were prepared from brain and the hippocampus tissues of the three groups to detect the level of the ChAT protein by Western blot.

RESULTSThe experimental rats turn left or right when continuously stimulation in the bilateral BC regions with electric pulse. HE staining showed no significant damage around electrodes in the cerebral cortex. Compared with the control and blank groups, the ChAT positive rate in the brain section in the experimental rats was significantly high by immunohistochemistry assay; the level of the ChAT protein in the rats given the electrical stimulation increased.

CONCLUSIONTurnings performance of the rat could be initiated hy electrical stimuli in the BC region. Expression of ChAT is significantly higher in the BC regions of rat under electrical stimulation, suggesting that acetylcholine might be associated with signal transmission between senses and movement behavior in the nervous central system.

Acetylcholine ; metabolism ; Animals ; Cerebral Cortex ; metabolism ; Choline O-Acetyltransferase ; metabolism ; Electric Stimulation ; Rats ; Rats, Sprague-Dawley

Acetylcholine ; pharmacology ; Adenocarcinoma ; metabolism ; Cell Line, Tumor ; Gastric Mucosa ; cytology ; drug effects ; metabolism ; Humans ; Receptors, Cholinergic ; metabolism ; Stomach Neoplasms ; metabolism

BACKGROUND: Although impaired endothelial function is well known in patients with diabetes mellitus, the precise mechanism and the factors that contribute to this dysfunction remain to be clarified. We examined the effect of acute hyperglycemia on patients with impaired glucose metabolism in vivo by plethysmography. METHODS: Seven patients with diabetes mellitus or impaired glucose metabolism were studied. In each patient, endothelial function was examined in the fasting state and at two levels of hyperglycemia, which were achieved by the infusion of glucose, insulin, and somatostatin. Forearm blood flow was measured while acetylcholine was infused in increasing concentrations(7.5, 15, and 30 microgram/min) through the brachial artery. RESULTS: Glucose concentrations increased accordingly at each stage, from 135.3+/-18.4 mg/dl at stage 1(the fasting state), to 239.0+/-15.2 mg/dl at stage 2(the first level of hyperglycemia), and to 378.3+/-25.3 at stage 3 (the second level of hyperglycemia) [p<0.01]. Maximal acetylcholine-dependent vasodilation achieved by infusion of acetylcholine at 30 microgram/min was significantly aftenuated during stages 2 and 3 compared with stage 1(p<0.05 by AVOVA; forearm blood flow ratio was 2.87+/-0.18 and 2.56+/-0.14 versus 3.58+/-0.21, respectively). This was also evident during the infusion of 15 microgram/min and 7.5 microgram/min of acetylcholine. CONCLUSIONS: Endothelium-dependent vasodilation is significantly aftenuated by acute hyperglycemia in patients with diabetes mellitus or impaired glucose metabolism. Our findings suggest that elevated glucose may contribute to the endothelial dysfunction observed in patients with diabetes mellitus or impaired glucose metabolism.
Acetylcholine ; Brachial Artery ; Diabetes Mellitus* ; Endothelium ; Fasting ; Forearm ; Glucose* ; Humans ; Hyperglycemia* ; Insulin ; Metabolism* ; Plethysmography ; Somatostatin ; Vasodilation*

BACKGROUND: Neostigmine, a cholinesterase inhibitor, is known to reverse the neuromuscular blocking action induced by nondepolarizing muscle relaxants at the end of general anesthesia. Some authors, however, reported that neostigmine has the properties of a neuromuscular block in skeletal muscles while others reported that neostigmine caused the smooth muscles such as the diaphragm to relax rather than to contract. The purpose of this study was to evaluate the effect of neostigmine at different doses on the tracheal smooth muscle in rabbits. METHODS: Isolated tracheal ring preparation in rabbits was used. Groups were divided into 7 groups; acetylcholine group (acetylcholine cumulative administered at doses of 10 8, 10 7, 10 6, 10 5, 10 4 and 10 3 M), neostigmine group (neostigmine cumulative administered at doses of 10 8, 10 7, 10 6, 10 5, 10 4 and 10 3 M), acetylcholine 10 6 M + neostigmine group (acetylcholine 10 6 M prior to neostigmine administered at doses of 10 8, 10 7, 10 6, 10 5, 10 4 and 10 3 M), acetylcholine 10 4 M + neostigmine group (acetylcholine 10 4 M prior to neostigmine administered at doses of 10 8, 10 7, 10 6, 10 5, 10 4 and 10 3 M), neostigmine 10 5, 10 4 and 10 3 M groups (neostigmine administered at doses of 10 5, 10 4 and 10 3 M). Smooth muscle contraction was evaluated in isometric tension per gram of tissue. RESULTS: In the acetylcholine group, the contractions increased as the dosage increased (10 8 10 3 M). In the neostigmine group, the contractions increased as the dosage increased (10 8 10 4 M), but at 10 3 M of neostigmine, contractions suddenly decreased. In addition when acetylcholine 10 6 M was given as a pretreatment, there was a sudden decrease in muscle contractions induced by neostigmine at 10 3 M. Also the contractions induced by 10 3 M neostigmine were less than that of 10 4 and 10 5 M. CONCLUSIONS: We concluded that neostigmine caused smooth muscle contraction at low concentrations by blocking acetylcholine metabolism, but at high concentrations, smooth muscle contractions were decreased and this might be due to direct action at the acetylcholine receptor.
Acetylcholine ; Anesthesia, General ; Cholinesterases ; Diaphragm ; Metabolism ; Muscle Contraction ; Muscle, Skeletal ; Muscle, Smooth* ; Neostigmine* ; Neuromuscular Blockade ; Rabbits*

AIM AND METHODSThe properties and sensitivity to acetylcholine of PC12 cells differentiated with nerve growth factor (NGF) have been investigated by using whole-cell clamp technique.

RESULTSWhen cultured in the presence of NGF, PC12 cells not only differentiated to resemble sympathetic neurons morphologically, but also developed electrical excitability. NGF-treated PC12 cells were highly sensitive to ACh than untreated cells. The I(Ach) proved to be generated by nAChR by pharmacological identification. Nicotinic receptor was characterized by desensitization. The macroscopic I(ACh) was inward rectified and concentration dependent.

CONCLUSIONPC12 cells are easily cultured and provides a homogenous population of cells. When culture in NGF, they differentiate to sympathetic-like neurons that contain on their surface neuronal nAChR, it can be used as good model system for studying regulation of a sympathetic neuronal nAChR.

Acetylcholine ; pharmacology ; Animals ; Cell Differentiation ; Nerve Growth Factor ; metabolism ; Neurons ; metabolism ; PC12 Cells ; Patch-Clamp Techniques ; Rats ; Receptors, Nicotinic ; metabolism

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

In view of the effective traditional Chinese medicine (TCM) in the treatment of clinical depression, the mechanism is not clear, this study attempts to research the cause of depression in a complex situation to lay the foundation for the next step of TCM curative effect evaluation. Based on the brain wave of 120 depression patients and 40 ordinary person, the change regulation of acetylcholine, dopamine, norepinephrine, depression neurotransmitters and excited neurotransmitters in the whole and various encephalic regions' multi-neurotransmitters of depression patients-serotonin are analysed by search of encephalo-telex (SET) system, which lays the foundation for the diagnosis of depression. The result showed that: contrased with the normal person group, the mean value of the six neurotransmitters in depression patients group are: (1) in the whole encephalic region of depression patients group the dopamine fall (P < 0.05), and in the double centralregions, right temporal region and right parietal region distinct fall (P < 0.01); (2) in the right temporal region of depression patients group the serotonin rise (P < 0.05); (3) in the right central region, left parietal region of depression patients group the acetylcholine fall (P < 0.05), left rear temporal region fall obviously (P < 0.01). The correlation research between antagonizing pairs of neurotransmitters and neurotransmitters: (1) the three antagonizing pairs of neurotransmitters-serotonin and dopamine, acetylcholine and norepinephrine, depression neurotransmitters and excited neurotransmitters, in ordinary person group and depression patients group are characterizeed by middle or strong negative correlation. Serotonin and dopamine, which are characterized by weak negative correlation in the right rear temporal region of ordinary person group, are characterized by strong negative correlation in the other encephalic regions and the whole encephalic (ordinary person group except the right rear temporal region: the range of [r] is [0.82, 0.92], P < 0.01)/(depression patients group:the range of [r] is [0.88, 0.94], P < 0.01); acetylcholine and norepinephrine, in the whole and various encephalic region are characterized by middle negative correlation(ordinary person group:the range of [r] is [0.39, 0.76], P < 0.01 or P < 0.05)/(depression patients group: the range of [Ir] is [0.56, 0.64], P < 0.01); depression neurotransmitters and excited neurotransmitters are characterized by middle strong negative correlation (ordinary person group: the range of [r] is [0.57, 0.80], P < 0.01)/(depression patients group: the range of [r] is [0.68, 0.78], P < 0.01). (2) The two neurotransmitters which are not antagonizing pairs of neurotransmitters, serotonin and excited neurotransmitters, or acetylcholine and depression neurotra-nsmitters, or dopamine and depression neurotransmitters in the various encephalic regions are characterized by weak negative correlation. Serotonin and excited neurotransmitters are characterizeed by weak negative correlation (ordinary person group: in the right central region, left parietal region, double front temporal regions, right rear temporal region, the range of [r] is [0.25, 0.50], P < 0.01 or P < 0.05)/(depression patients group: in the whole encephalic regions, double parietal regions, double occipital regions, right front temporal region, left central region, left frontal region, the range of [r] is [0.18, 0.37], P < 0.01 or P < 0.05); acetylcholine and depression, neurotransmitters are characterized by weak negative correlation (ordinary person group: in the double frontal regions, left parietal region, left front temporal region, right rear temporal region, the range of [r] is [0.31, 0.46], P < 0.01 or P < 0.05)/(depression patients group: in double rear temporal regions, right front temporal region, double occipital regions, left central region, the range of [r] is [0.20, 0.32] , P < 0.01 or P < 0.05); do-pamine and depression neurotransmitters are characterized by weak middle negative correlation (ordinary person group: in left parietal region, right central region, left frontal region, left occipital region, double front temporal regions, the range of [r] is [0.33, 0.68], P < 0.01 or P < 0.05)/(depression patients group: in the whole region and other various regions except the left frontal region, right central region, the range of Irl is [0.21, 0.34], P < 0.01 or P < 0.05). Dopamine and acetylcholine or norepinephrine and serotonin are characterized by weak positive correlation in all encephalic regions. Dopamine and acetylcholine are characterized by weak positive correlation (ordinary person group: in left frontal region, right parietal region, left front temporal region and left rear temporal region, the range of [r] is [0.37, 0.46], P < 0.01)/(depression patients group: in the whole region and the orther various regions except the double central regions, the range of [r] is [0.23, 0.5], P < 0.01 or P < 0.05); norepinephrine and serotonin are characterized by weak positive correlation (ordinary person group: in double front temporal regions, double rear temporal regions, right frontal region and left parietal region, the range of [r] is [0.34, 0.48], P < 0.01 or P < 0.05)/(depression patients group: in the whole and various regions, the range of [r] is [0.18, 0.42], P < 0.01). The main differences between the depression patients group and ordinary person group are: (1) In the whole regin, left frontal region and right central region of depression patients group, the six neurotransmitters all fall normally (P < 0.05). (2) The percent of dopamine falling or including dopamine falling, or including dopamine falling and serotonin rising in depression patients group increases. The percent of dopamine falling or including dopamine falling in the whole region, right frontal region, right central region increases (P < 0.01), such as dopamine decreasing, serotonin increasing dopamine decreasing, serotonin increasing acetylcholine decreasing dopamine decreasing, dopamine decreasing norepinephrine increasing depression neurotransmitters decreasing, serotonin increasing acetylcholine decreasing dopamine decreasing neurotransmitters increasing and so on. (3) The percent of acetylcholine falling, or including acetylcholine falling, or including acetylcholine falling and neurotransmitters (beta)-receptor)rising in depression patients group increases. The percent of acetylcholine falling, or including acetylcholine falling in the right temporal region, double central regions increases (P < 0.05 or P < 0.01), such as acetylcholine decreasing, acetylcholine decreasing neurotransmitters increaseng, acetylcholine decreasing neurotransmitters increasing depression neurotransmitters decreasing, serotonin increasing acetylcholine decreasing dopamine decreasing neurotransmitters increasing and so on. It's showed in research that depression patients' brain are characterized by multi-neurotransmitters abnormal, the synchronous change of multi-neurotransmitters has some certain regularities, which are not the simple linear relation. It's conformed that the three antagonizing pairs, neurotransmitters-serotonin and dopamine, acetylcholine and norepinephrine, depression eurotransmitters and excited neurotransmitters of ordinary person group and depression patients group, are both characterized by strong antagonizing relation, that the two neurotransmitters which are not antagonizing pairs of neurotransmitters are characterized by weak positive correlation or negative correlation, prompt maybe has the indirect causal relationship. And the change of six neurotransmitters in depression patients' various encephalic regions is rather complex. It's conformed preliminarily that the right frontal region and right central region are characterized by dopamine decreasing, acetylcholine decreasing, serotonin increasing dopamine decreasing, serotonin increasing acetylcholine decreasing dopamine decreasing, dopamine decreasing norepinephrine increasing excited neurotransmitters decreasing, serotonin increasing acetylcholine decreasing dopamine decreasing neurotransmitters increasing, acetylchoine decreasing neurotransmitters increasing, acetylcholine decreasing neurotransmitters increasing excited neurotransmitters decreasing and so on. Contrasted with the ordinary person group, the depression patients group have the notable difference.
Acetylcholine ; metabolism ; Adolescent ; Adult ; Aged ; Brain ; metabolism ; Case-Control Studies ; Depression ; metabolism ; Dopamine ; metabolism ; Female ; Humans ; Male ; Middle Aged ; Neurotransmitter Agents ; metabolism ; Norepinephrine ; metabolism ; Serotonin ; metabolism ; Young Adult

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

We found previously that ACh can significantly inhibit the proliferation of cultured human pituitary adenoma cells. In order to make a further investigation of the mechanism of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, we observed the levels of protein kinase C (PKC), [Ca(2+)](i) and cAMP/cGMP in cultured pituitary adenoma cells after treatment with ACh. The results demonstrate that (1) compared with control, PMA, a PKC activator, increased the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells. However, after a 15-min treatment with ACh (10 micromol/L), a significant reduction of the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells was observed, and the reduction effect could be blocked by atropine. (2) The level of [Ca(2+)](i) of single adenoma cells was found to decrease immediately on the addition of ACh (10 micromol/L), which could also be blocked by atropine. (3) ACh increased the amount of cAMP in the cytoplasm of human pituitary adenoma cells, but had no effect on that of cGMP. These data provide an important clue to explore the molecular mechanisms of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, and suggest that the modulating effect of ACh on the proliferation of pituitary adenoma cells results from the interactions of several cellular signaling pathways.
Acetylcholine ; physiology ; Adenoma ; metabolism ; pathology ; Calcium ; metabolism ; Cyclic AMP ; metabolism ; Cyclic GMP ; metabolism ; Humans ; Pituitary Neoplasms ; metabolism ; pathology ; Protein Kinase C ; metabolism ; Signal Transduction ; physiology ; Tumor Cells, Cultured