Stimulatory effect of acetylcholine on immunoreactive corticotropin-releasing factor release from the rat hypothalamus in vitro

Effects of acetylcholine (Ach) and gamma-aminobutyric acid (GABA) on immunoreactive corticotropin-releasing factor (CRF) release from the rat hypothalamus were examined using a rat hypothalamic perifusion system and a rat CRF RIA in vitro. Ach stimulated CRF release in a dose-dependent manner (1 pM-1 nM). One nM Ach-induced CRF release was inhibited by atropine in a dose-dependent manner (1-100 nM), but was inhibited by only a high concentration (100 nM) of hexamethonium. In addition, such Ach-induced CRF release was inhibited by norepinephrine. GABA did not influence basal CRF release. These results suggest that Ach stimulates CRF release mainly through muscarinic receptors at least under our conditions.     

Acetylcholine affects rat liver metabolism via type 3 muscarinic receptors in hepatocytes

Although the role of acetylcholine (Ach) in hepatic glucose metabolism is well elucidated, it is still unclear if it influences gluconeogenesis, glycogenolysis and high-energy phosphate metabolism, and if it does what the mechanisms of this influence are. Therefore, using isolated perfused rat liver as a model, we have studied the effect of Ach on oxygen consumption, synthesis of glucose from lactate and pyruvate, glycogen formation, mitochondrial oxidative phosphorylation and ATP-synthesis. We have established that effects of Ach on oxygen consumption depend on its concentration. When used at a concentration of 10(-7) M, Ach exerts maximum stimulatory effect, while its infusion at 10(-6) M causes a decrease of oxygen consumption by the liver. Moreover, when used at a concentration of 10(-6) M or 10(-7) M, Ach increases rates of glucose production from the gluconeogenic substrates lactate and pyruvate, leading to enhanced glycogen content in perfused liver. It was also shown that Ach possesses a stimulating effect on alanine and aspartate aminotransferases. As detected by 31P NMR spectroscopy, continuous liver perfusion with pyruvate and lactate in the presence of Ach leads to a significant decrease of ATP level, implying enhanced energy requirements for gluconeogenesis under these conditions. Elimination of the described effects of Ach by atropine, the antagonist of muscarinic receptors, and identification of the type 3 muscarinic receptors (m3) in isolated hepatocytes as well as in whole liver, imply that Ach may exert its effect on liver metabolism through m3 receptors.     

乙酰胆碱及其拮抗剂对人SK-N-SH细胞增殖及mAchR1表达的影响

用CCK-8比色法和流式细胞术,检测乙酰胆碱（acetylcholine,Ach）及拮抗剂阿托品（atropine,Atro）对SK-N-SH细胞增殖活性和周期分布的调节作用;进一步用荧光定量PCR、免疫印迹和流式细胞间接免疫荧光技术,分析SK-N-SH细胞毒蕈碱受体亚型Ⅰ型（mAchR1）和c-fos的表达差异。结果表明,1mmol／L Ach对SK-N-SH细胞有明显促增殖作用,而1mmoL／L Atro阻滞细胞从S期向G2／M期移行;1mmol／L Ach与1mmol／L Atro均反馈调节mAchR1的蛋白水平。但mAchR1 mRNA的表达不受影响;1mmol／L Ach显著上调c-fos mRNA和Fos蛋白的表达,但这种作用可被Atro逆转。提示胆碱类受体参与配基对肿瘤细胞的促增殖作用。     

乙酰胆碱及其拮抗剂对人SK-N-SH细胞增殖及mAchRl表达的影响

用CCK-8比色法和流式细胞术,检测乙酰胆碱(acetylcholine,Ach)及拮抗剂阿托品(at-ropine,Atro)对SK-N-SH细胞增殖活性和周期分布的调节作用;进一步用荧光定量PCR、免疫印迹和流式细胞间接免疫荧光技术,分析SK-N-SH细胞毒蕈碱受体亚型Ⅰ型(mAchR1)和c-fos的表达差异。结果表明,1mmol/LAch对SK-N-SH细胞有明显促增殖作用,而1mmol/LAtro阻滞细胞从S期向G_2/M期移行;1mmol/LAch与1mmol/LAtro均反馈调节mAchR1的蛋白水平,但mAchR1mRNA的表达不受影响;1mmol/LAch显著上调c-fosmRNA和Fos蛋白的表达,但这种作用可被Atro逆转。提示胆碱类受体参与配基对肿瘤细胞的促增殖作用。     

A Possible Neurochemical Basis of the Central Stimulatory Effects of pp'DDT

Abstract: The striatal neurochemical changes induced by pp'DDT (600 mg/kg) in mice were: an increase in the concentration of free ammonia, a decrease in the level of GABA and a reduction in the level of acetylcholine. These changes were maximal 5 h after treatment with pp'DDT, when the animals developed 'severe' convulsions. The convulsions and striatal neurochemical changes were modified to different degrees by barbiturates. Phenobarbitone protected all the animals from pp'DDT-induced convulsions. The levels of striatal acetylcholine and GABA in these animals were within normal limits. Prominal reduced the severity of convulsions in pp'DDT-treated animals. The levels of striatal acetylcholine and GABA were significantly lower than control values in these animals. Primidone neither modified the convulsions nor the striatal neurochemical changes in pp'DDT-treated animals. The increase in the concentration of free ammonia, in pp'DDT-treated animals, was not modified by barbiturates. Aminooxyacetic acid raised the GABA level above normal and abolished the convulsions in pp'DDT-treated animals; the level of acetylcholine was within normal limits in these animals. Hydroxylamine produced a similar but less marked effect. Pyridoxine had no effect on convulsions or striatal neurochemical changes induced by pp'DDT. The increase in the concentration of free ammonia in pp'DDT-treated animals was not modified by these agents. It is likely that pp'DDT produced stimulatory effects by increasing the concentration of free ammonia which may be involved in reducing the level of GABA, while changes in the level of acetylcholine may be an effect of pp'DDT-induced convulsions.     

4 Hz EMF treated physiological solution depresses Ach-induced neuromembrane current

The effect of 4 Hz EMF treated physiological solution (PS) on acetylcholine (Ach) sensitivity of the snail neuron was studied. The 4 Hz EMF treated normal PS at room temperature (23 degrees C) has a depressing effect on Ach induced current, while in cold medium (12 degrees C) this effect disappeared. EMF treated, ouabain containing, K-free PS elevates the Ach-induced current at room temperature. It is suggested that the metabotropic effect of EMF treated PS is due to the activation of cGMP-dependent Na:Ca exchange, leading to the decrease of the number of functional active receptors in the membrane, through Na-K pump-induced cell shrinkage, and to increase the receptors affinity to Ach, as the result of decrease of intracellular Ca concentration.     

Modulation of the Acetylcholine System in the Superior Cervical Ganglion of Rat: Effects of GABA and Hypoglossal Nerve Implantation After In Vivo GABA Treatment

gamma-Aminobutyric acid (GABA) was applied to the superior cervical ganglion (SCG) of CFY rats in vitro and in vivo, with or without implantation of a hypoglossal nerve, to evaluate the effects of these experimental interventions on the acetylcholine (ACh) system, which mainly serves the synaptic transmission of the preganglionic input. Long-lasting GABA microinfusion into the SCG in vivo apparently resulted in a "functional denervation." This treatment reduced the acetylcholinesterase (AChE; EC 3.1.1.7) activity by 30% (p less than 0.01) and transiently increased the number of nicotinic acetylcholine receptors, but had no significant effect on the choline acetyltransferase (acetyl-coenzyme A:choline-O-acetyltransferase; EC 2.3.1.6) activity, the ACh level, or the number of muscarinic acetylcholine receptors. The relative amounts of the different molecular forms of AChE did not change under these conditions. In vivo GABA application to the SCG with a hypoglossal nerve implanted in the presence of intact preganglionic afferent synapses exerted a significant modulatory effect on the AChE activity and its molecular forms. The "hyperinnervation" of the ganglia led to increases in the AChE activity (to 142.5%, p less than 0.01) and the 16S molecular form (to 200%, p less than 0.01). It is concluded that in vivo GABA microinfusion and GABA treatment in the presence of additional cholinergic synapses has a modulatory effect on the elements of the ACh system in the SCG of CFY rats.     

Effect of various amino acids and their antagonists on the cholinergic tremor and acetylcholine release in the CNS of the rat]

Glycine and GABA administered intraventricularly and intrastriatally were found to inhibit the oxotremorin tremor in rats. The two amino acids reduce both the spontaneous release of acetylcholine into the ventricle and the discharge measured under oxotremorin treatment. The inhibition of the tremor and of acetylcholine release can be blocked by amino acid antagonists (strychnine and picrotoxin), whose effects are not specific for one of these amino acids; this action can be interpreted as effect of interference with other central transmission systems. Structures located close to the ventricles (nigrostriatal path ways) are discussed as possible points of action.     

旋转刺激对大鼠七氟烷麻醉敏感性的影响

目的:探讨航海刺激对大鼠七氟烷麻醉敏感性的影响,为海上环境下七氟烷的合理使用提供依据。方法:以大鼠条件性厌食症作为判断指标,采用仿制Crampton旋转刺激器制作大鼠运动病模型。①60只SD大鼠随机分为对照组(n=15)和旋转组(n=45),观测2组大鼠的活动和行为变化、达到睡眠和麻醉状态所需七氟烷浓度以及麻醉苏醒时间。②32只SD大鼠随机分为四组(n=8):对照(Ⅰ)组、旋转(Ⅱ)组、麻醉(Ⅲ)组和旋转后再麻醉(Ⅳ)组,分别检测4组大鼠之大脑皮层、下丘脑和海马组织的乙酰胆碱、去甲肾上腺素、г-氨基丁酸及谷氨酸含量。结果:对照组大鼠达到睡眠和麻醉状态所需七氟烷浓度分别为1.74%±0.05%和3.54%±0.05%,旋转组分别为1.51%±0.06%和3.14%±0.08%,旋转组大鼠达到睡眠和麻醉状态所需七氟烷浓度明显降低(P<0.01)。神经递质变化以Ⅲ组大鼠各递质含量显著降低为其主要特点,在大脑皮层和海马组织中表现尤为明显(P<0.01)。Ⅱ组大鼠大脑皮层Ach显著升高,海马组织NE、GABA明显降低。Ⅳ组变化趋势更接近于Ⅱ组,即以旋转刺激的影响更为明显。结论:模拟航海刺激可明显增加大鼠对七氟烷麻醉的敏感性。     

The neuropharmacological restoration of cognitive functions in cats after damage to the forebrain basal nuclei (Meynert's nucleus)]

The cognitive functions were studied on experimental model of Alzheimer's disease (destruction of the basal nuclei of Meynert in cats) using the stimulation and inhibition of Ach, GABA, and DA brain systems. Ach system was found to be essential to form generalization function, DA system to improve simple learning, and GABA system to involve in formation of complex associations.     

Exocrine secretion of epidermal growth factor from Brunner's glands. Stimulation by VIP and acetylcholine

Brunner's glands of the duodenum are innervated by cholinergic and VIP-ergic nerves, and the glands have been shown to contain epidermal growth factor (EGF). In this study the effect of VIP and acetylcholine (Ach) on secretion of EGF from Brunner's glands was investigated in the rat. Intravenous infusion of VIP stimulated the flow rate of duodenal secretion, an effect which was inhibited by atropine. Ach alone did not significantly increase flow rate, and combined infusion of VIP and Ach induced the same flow as VIP alone. Concentration of EGF in duodenal secretion was increased by infusion of Ach, and this effect was potentiated by VIP. Infusion of VIP alone did not influence EGF concentration. EGF output from Brunner's glands was significantly stimulated by i.v. infusion of VIP and of Ach and combined infusion further increased EGF output. The study has demonstrated exocrine secretion of EGF from Brunner's glands, and it is suggested that stimulation is mediated by interaction of neuronal VIP and Ach.     

Regulation of Transmitter γ-Aminobutyric Acid (GABA) Synthesis and Metabolism Illustrated by the Effect of γ-Vinyl GABA and Hypoglycemia

The effect of different treatments on amino acid levels in neostriatum was studied to throw some light on the synthesis and metabolism of gamma-aminobutyric acid (GABA). Irreversible inhibition of GABA transaminase by microinjection of gamma-vinyl GABA (GVG) led to a decrease in aspartate, glutamate, and glutamine levels and an increase in the GABA level, such that the nitrogen pool remained constant. The results indicate that a large part of brain glutamine is derived from GABA. Hypoglycemia led to an increase in the aspartate level and a decrease in glutamate, glutamine, and GABA levels. The total amino acid pool was decreased compared with amino acid levels in normoglycemic rats. GVG treatment of hypoglycemic rats led to a decrease in the aspartate level and a further reduction in glutamate and glutamine levels. In this case, GABA accumulation continued, although the glutamine pool was almost depleted. The GABA level increased postmortem, but there were no detectable changes in levels of the other amino acids. Pretreatment of the rats with hypoglycemia reduced both glutamate and glutamine levels with a subsequent decreased postmortem GABA accumulation. The half-maximal GABA synthesis rate was obtained when the glutamate level was reduced by 50% and the glutamine level was reduced by 80%.     

Comparative actions of GABA and acetylcholine on the Xenopus laevis lateral line

The effects of GABA, acetylcholine and carbachol on the spontaneous activity of afferent nerve fibers in the lateral line of Xenopus laevis are characterized. Atropine and bicuculline were also tested on drug- and water motion-evoked activity. GABA (0.019-1.25 mM) suppressed and both acetylcholine (1.25-80 microM) and carbachol (1.25-40 microM) increased spontaneous activity. These actions were blocked by bicuculline (100 microM) and atropine (4 microM) respectively. Atropine (20 microM) and bicuculline (100 microM) had no effect on water motion-evoked activity. The results characterize actions of GABA and acetylcholine not previously described and provide evidence that does not support the hypothesis that GABA or acetylcholine are the afferent transmitter.     

The associations acetylcholine-eserine and acetylcholine-morphine studied on the frog rectus abdominis muscle

The interaction of morphine and eserine with acetylcholine (Ach) on frog rectus abdominis muscle was studied. Both eserine and morphine potentiate the effects of exogenous Ach and this effect is certainly not due to the anticholinesterase action of the two drugs. Morphine is less effective than eserine in potentiating the response of the muscle to the Ach introduced in the organ-bath. The synergisms Ach-eserine and Ach-morphine are synergisms with potentiation: it is concluded that eserine and morphine in amphibian muscle interact with specific receptors. These binding sites are different from both the esterase and the ACh binding sites of the cholinergic receptor but appear to influence its function.     

Identification and pharmacological characteristics of the two giant neurons, v-RPLN and v-VNAN, on the ventral surface in the suboesophageal ganglia of the African giant snail (Achatina fulica Férussac)

Two giant neurons, v- RPLN (ventral-right parietal large neuron) and v- VNAN (ventral-visceral noisy autoactive neuron), were identified on the ventral surface in the caudal part of the suboesophageal ganglia of the African giant snail (Achatina fulica F erussac ), and their pharmacological features to the common putative neurotransmitters and their related substances were examined. The giant neuron examined, v- RPLN , is situated in front of the exit of the right anterior pallial nerve in the right parietal ganglion. The neuron, which is 250-300 microns in diameter, one of the largest neurons in the ganglia, was usually silent without spontaneous firing. The neuron was excited by L-norepinephrine (L-NE), DL-octopamine (DL-OA), 5-hydroxytryptamine (5-HT), L-homocysteic acid (L-HCA) and erythro-beta-hydroxy-L-glutamic acid (erythro-L- BHGA ); and inhibited by dopamine (DA), GABA, acetylcholine (Ach) and its related substances. Another giant neuron examined, v- VNAN , is situated very close to the right side of the exit of the right posterior pallial nerve in the visceral ganglion. The neuron is elliptical and about 150 micron in diameter. It showed spontaneous firing highly modified by the synaptic influences. DA, 5-HT, glycine (Gly), GABA and its related substances, L-HCA, erythro-L- BHGA , and Ach and its related substances all had the direct (not via synaptic influences) excitatory effects on the neuromembrane examined. Some of them, for example, L-NE, 5-HT and Ach and its related substances caused transient excitation of the neuron, probably due to the synaptic influences, immediately after their application. No substance producing any inhibition of the neuron could be found in the present study.     

Changes in cyclic nucleotide levels during embryonic development of chick hearts

The effects of isoproterenol, acetylcholine (Ach), and adenosine, on cyclic AMP (cAMP) and cyclic GMP (cGMP) contents were examined in chick hearts at various stages of embryonic development. The basal cAMP content was highest (87.7 +/- 1.3 pmol/mg protein) in young (3-day) embryonic chick hearts and decreased during development (9.6 +/- 0.6 pmol/mg protein in 9-19-day-old hearts). On the other hand, the cGMP content was lowest (45.5 +/- 2.3 fmol/mg protein) in young (3-day) embryonic chick hearts and increased during development (338 +/- 15.0 fmol/mg protein in 14-19-day-old hearts). Iso increased the cAMP concentration in embryonic hearts at all ages. Ach and Ado had no effect on the cAMP content at all ages. However, the Isoproterenol-induced stimulation of cAMP was inhibited by Ach and Adenosine at all ages. In young embryonic hearts, Ach and Ado increased cGMP concentration only slightly, whereas these agents caused a substantial increase in cGMP concentration in the older hearts. Thus, there was a clear age difference in the effects of Ach and Adenosine on the cGMP and cAMP concentrations. Nitroprusside and hydrogen peroxide increased cGMP concentration in older hearts (greater than 5-day-old) but not in the 3-day-old embryonic hearts. Thus, guanylate cyclase activity may be low in young (3-day-old) hearts. It summary, the cGMP level is very low in young embryonic chick hearts, and increases markedly during development. The changes in cGMP are reciprocal to those of cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)     

The postradiation effect of acetylcholine and GABA on the active potassium uptake by slices of rat cerebral cortex]

Whole-body X irradiation (0.155 and 0.310 C/kg) was shown to modify the biphase effect of acetylcholine and GABA on antigradient K+ uptake by rat brain sections. Radiation made the effects of neuromediators on active K+ transport be differently directed: acetylcholine enhanced the inhibitory effect of radiation and GABA restored the Na-K-pump function.     

Classification of the responses of a giant neuron from the snail Acatina fulica Férussac, caused by inhibitory sugstances depending on chlorine ions]

GABA, three of its derivatives (l-GABOB, d-GABOB and delta-amino valeric acid), acetycholine (Ach), dopamine (DA) and l-Phe-Tyr all inhibit an identifiable giant neurone (the TAN, tonically autoactive neurone) of Achatina fulica. These effects were examined by microdrop application in two different conditions: in physiological solution and in the absence of chloride ions. The results show that the relatively transient (rapid) inhibitions caused by GABA, by its derivatives and by Ach are dependent on chloride ions; the relatively maintained (long-lasting) inhibitions, caused by DA and l-Phe-Tyr, are independent of chloride ions.     

Changes in content of neuroactive amino acids and acetylcholine in the rat hippocampus following transient forebrain ischemia.

Changes in content of selected neuroactive amino acids [glutamic acid, aspartic acid, glycine, gamma-aminobutyric acid (GABA) and taurine] and acetylcholine (ACh) in the rat hippocampus following transient forebrain ischemia were investigated using male Wistar rats. Rats were allowed to survive for 1 or 5 days following 10 or 20 min of 4-vessel occlusion, and killed by a focused microwave irradiation. A significant reduction in all neuroactive amino acids examined except GABA was noted in the hippocampus on the fifth day. One day after the 4-vessel occlusion for 10 min, no significant effect on the content of neuroactive amino acids in all brain areas was observed. gamma-Aminobutyric acid content in the hippocampus was only significantly reduced on the fifth day after the occlusion for 20 min. Similarly, a significant decrease in ACh content in the hippocampus was observed on the fifth day after the occlusion for 20 min. Considering the data that a significant loss of neuronal cells in the hippocampus (delayed neuronal death) was detected only 5 days after the 4-vessel occlusion, it can be said that the alterations in the hippocampus of neuroactive amino acids such as glutamic acid, aspartic acid, glycine and taurine are more sensitive than those in GABA and ACh against cerebral ischemia. A possible correlation of these changes of neuroactive amino acids in the occurrence of delayed neuronal death in the hippocampus is also suggested.     

Factors required for calcium dependent acetylcholine release from isolated torpedo synaptic vesicles.

The release of acetylcholine (Ach) from Torpedo synaptic vesicles has been investigated. Factors have been found which induce Ca⁺² dependent Ach release from the synaptic vesicles. In the absence of these factors, the vesicles are not affected by Ca⁺². Addition of a soluble factor to the vesicles induces a Ca⁺²-dependent release of their Ach. This secretion is enhanced by a non-vesicular membranous component which, by itself, does not induce the Ca⁺²-dependent release. These results demonstrate that vesicular Ach release may be studied $\text{in vitro}$ and thus will enable the study, at the molecular level, of the biochemical events underlying neurotransmission.