A histological and anatomical profile of pacinian corpuscles from Dupuytren's contracture and the expression of nerve growth factor receptor

The etiology of Dupuytren's disease is unknown. The causes of the fibroplastic response of nodules, fibrosis of cords, and prominence of pacinian corpuscles are not evident. Histological and immunohistology differences in pacinian corpuscles from the hands of five patients with Dupuytren's disease compared with 17 Dupuytren's-free patients are presented. Histological sections of pacinian corpuscle specimens were stained with hematoxylin and eosin and immunostained for nerve growth factor receptor. The length and width of intact pacinian corpuscles were measured, and the number of layers within each corpuscle was counted and recorded. Grossly, the pacinian corpuscles from Dupuytren's patients were larger and more numerous compared with those from unaffected patients. When measured microscopically, the pacinian corpuscles from Dupuytren's diseased fascia were significantly larger (2.0 x 1.1 mm) compared with controls (1.5 x 0.78 mm). The pacinian corpuscles from Dupuytren's-affected patients had significantly more layers (64 +/- 14) compared with those from control patients (40 +/- 9). Nerve growth factor receptor staining of pacinian corpuscles from patients affected with Dupuytren's disease showed greater intensity and more area stained compared with unaffected controls. It is suggested that nerve growth factor may be involved in the increased size of pacinian corpuscles in Dupuytren's-affected fascia. It is proposed that the cellular outgrowth from pacinian corpuscles may generate the cells that develop into Dupuytren's nodules.     

Effect of acetylcholine on the tail artery reaction in rats

The response to acetylcholine (10(-5) g/ml) was studied on the rat tail artery perfused with Krebs buffer. Perfusion with acetylcholine produced vasodilation (by 69%) in arteries pre-constricted with transmural nerve stimulation. Atropine (10(-6) g/ml) blocked more than 95% of this response. Acetylcholine had a vasodilating effect on arteries pre-constricted with norepinephrine.     

The influence of several surface-active substances on neuromuscular transmission of excitation]

Microelectrode method was applied to the study of the influence of sodium bile salts (BS), saponin and between-80 on the end-plate potentials (EPP) of m. sartorius of Rana ridibunda. Bile salts in a concentration of 10(-5) g/ml did not change these potentials significantly. With increase of the BS concentration up to 10(-4) g/ml the amplitude of EPP increased 1.5- 3 times. The action of these substances in a concentration up to 10(-3) g/ml caused similar, but more rapid, increase in the EPP amplitude, and then the amplitude decreased. Saponin and tween-80 were less efffective in their action on EPP, but evoked muscle contraction. It is suggested that an increase in the EPP amplitude as a result of the action of the mentioned agents was chiefly connected with stimulation of the acetylcholine release by the nerve terminals.     

Effect of acetycholine and cholinolytics on activity of pacinian corpuscles

The effect of acetylcholine and cholinolytics on excitability of the isolated mechanoreceptors of Pacinian corpuscles was studied by the external perfusion method. Addition of acetylcholine to the solution in a concentration of 10^–5–10^–3 g/ml increased the excitability of the receptors. The amplitude of the receptor potential fell in a solution with acetylcholine. Cholinolytics (D-tubocurarine, hexamethonium, and atropine) did not block receptor activity. It is concluded that acetylcholine does not participate in primary processes in Pacinian corpuscles.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 9, No. 2, pp. 185–190, March–April, 1977.     

Parasympathetic cholinergic vasodilator mechanism in the terminal liver microcirculation in rats.

Changes in the diameter of liver sinusoids were studied by an intravital television microscope method in pentobarbital-anaesthetized rats. Dilatation of liver sinusoids was observed during parasympathetic neural stimulation and during acetylcholine administration. Frequency-dependent stimulation-effect relationships were obtained by electrical excitation of intact vagus nerves at supramaximal intensity from 2 to 8 Hz. Acetylcholine concentration-effect relationships were also obtained by intraportal venous infusions of acetylcholine 30 microliter for 5 s from 10(-9) to 10(-2) mol.1(-1). Systemic cholinergic receptor blockade with atropine (1 mg.kg-1) markedly reduced dilatation of liver sinusoids produced by both vagus nerve stimulation and acetylcholine administration. Changes in diameter of liver sinusoids with frequency of neural stimulation and with concentration of administered acetylcholine were also expressed as percentage of observed maximum effect and the respective stimulation-effect curves were constructed such that at a certain percentage of diameter change, the equivalent level of vagus nerve activity was represented by a given concentration of administered acetylcholine. Liver plasma concentration of acetylcholine presumably released during electrical vagal stimulation and reaching liver sinusoids was also estimated and found to be within physiological range. It is therefore proposed that rat liver sinusoids have the capacity for parasympathetic cholinergic vasodilatation.     

Influence of ethacizin (the diethyl analog of ethmozine) on phase-dependent parasympathetic effects on the heart

The influence of ethacizin (a diethylamine analog of ethmozine) (1.10(-7)-1.10(-6) g/ml) upon the phase-dependent chronotropic parasympathetic effects was studied on the perfused frog heart. The vagolytic influence of ethacizin (5.10(-7) and 1.10(-6) g/ml) was detected; the concentration of 1.10(-7) g/ml was found ineffective. The vagolytic effect consisted of a decreased maximum of phase-dependent effect, reduced latency and time required for the manifestation of the maximum increase. The period of inhibitory vagal stimulus effectiveness did not change significantly.     

Biochemical characterization of two nicotinic receptors from the optic lobe of the chick

We have studied putative nicotinic acetylcholine receptors in the optic lobe of the newborn chick, using 125I-labeled alpha-bungarotoxin, a specific blocker of acetylcholine receptors in the neuromuscular junction, and [3H]acetylcholine, a ligand which in the presence of atropine selectively labels binding sites of nicotinic character in rat brain cortex (Schwartz et al., 1982). [3H]Acetylcholine binds reversibly to a single class of high affinity binding sites (KD = 2.2 X 10(-8) M) which occur at a tissue concentration of 5.7 pmol/g. A large fraction (approximately 60%) of these binding sites is solubilized by Triton X-100, sodium cholate, or the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Solubilization increases the affinity for acetylcholine and several nicotinic drugs from 1.5- to 7-fold. The acetylcholine-binding macromolecule resembles the receptor for alpha-bungarotoxin present in the same tissue with respect to subcellular distribution, hydrodynamic properties, lectin binding, and agonist affinity rank order. It differs from the toxin receptor in affinity for nicotinic antagonists, sensitivity to thermal inactivation, and regional distribution. The solubilized [3H]acetylcholine binding activity is separated from the toxin receptor by incubation with agarose-linked acetylcholine, by affinity chromatography on immobilized Naja naja siamensis alpha-toxin, and by precipitation with a monoclonal antibody to chick optic lobe toxin receptor.     

Effect of acetylcholine of substrate oxidation in heart mitochondria

Acetylcholine has been studied for its effect on respiration and oxidative phosphorylation in mitochondria from the heart of a rat and guinea pig. Acetylcholine in doses of 25, 50 and 100 mg per 100 g of the body weight 5, 15 and 30 min after intraperitoneal injection intensifies the rate of phosphorylative respiration at ketoglutarate oxidation and moderately lowers it at succinate oxidation. Malonate increases the activating influence of acetylcholine on oxidation of alpha-ketoglutarate in the heart mitochondria and aminooxyacetate decreases it. Phosphorylative respiration with oxidation of pyruvate and isocitrate is not changed essentially under the action of acetylcholine. Introduction of acetylcholine stimulated most strongly the aminooxyacetate-sensitive portion of respiration, a mixture of aminotransferases in the activation of alpha-ketoglutarate oxidation under effect of acetylcholine. The stimulating action of acetylcholine on alpha-ketoglutarate oxidation is mediated by M- and H-cholinoreceptors, since it is abolished by their blockers: atropine and benzohexonium. Stimulation of alpha-ketoglutarate oxidation by acetylcholine is mostly expressed under introduction of beta-adrenoblocker obsidan which provides prevalence of the parasympathetic nervous system. This stimulation is more intensive in the guinea pig as a more cholinergic animal in comparison with a rat.     

First description of mechanoreceptors in the corpus adiposum infrapatellare of man

The sensory innervation of the corpus adiposum infrapatellare of the human knee joint was studied by light microscopy. Small lamellated corpuscles (pacinian corpuscles) were found in the adipose tissue of the corpus adiposum infrapatellare. The lamellated corpuscles measured about 20 microns and consisted of 3-4 lamellae. It is discussed whether the corpus adiposum infrapatellare might perform a sensory function, influencing the muscle tone via polysynaptic reflexes.     

M-cholinergic regulation of Na+,K+-ATPase activity of vesicular preparations of sarcolemma from the myocardium and intestinal smooth muscles

Acetylcholine (10(-7)-10(-2) M) enhanced the Na+, K+-ATPase activity in sarcolemmal vesicles from myocardium and intestinal smooth muscle. The stimulation of the enzyme from canine ventricles reaches 150% and was less pronounced (10-20%) in the case of frog myocardium and canine ileal muscles. The activating action of the neurotransmitter was simulated by gramicidin D (1-5 microM), but not by valinomycin 1-5 microM), blocked both by ouabain (200 microM) and atropine (0.1 microM), a muscarinic cholinergic antagonist. The activating action disappeared after treatment of membranes with alamethicin, a pore-producing antibiotic (0.8 mg/mg of protein). It is suggested that an increase in the Na+, K+-ATPase activity caused by acetylcholine is induced by Na+ which permeate the sarcolemmal vesicles through the ionic channel coupled with muscarinic acetylcholine receptor.     

Effect of armin on synaptic transmission in frog neuromuscular preparations

The action of armin, an organophosphorus inhibitor of cholinesterases, on synaptic transmission parameters was studied by means of intracellular registration of end plate potentials and currents (EPP and EPC) in the frog. On 10-minute exposure the increase in the temporary parameters became manifest provided the drug was administered at a concentration of 10(-6) g/ml and over. EPC reversal potential and cholinoreceptor sensitivity to armin did not change substantially. At a concentration of 10-(-8) g/ml armin exerted a potentiating effect on the frequency of miniature EPP and quantum composition of EPP, while that effect was not related to armin anticholinesterase activity. The presynaptic acetylcholine release was suppressed by high concentration of armin (10(-5) g/ml). Under the conditions cited there was a decrease in the depot of the available transmitter quanta in nerve terminals.     

Simultaneous monitoring of acetylcholine and catecholamine release in the in vivo rat adrenal medulla

To simultaneously monitor acetylcholine release from pre-ganglionic adrenal sympathetic nerve endings and catecholamine release from post-ganglionic adrenal chromaffin cells in the in vivo state, we applied microdialysis technique to anesthetized rats. Dialysis probe was implanted in the left adrenal medulla and perfused with Ringer's solution containing neostigmine (a cholinesterase inhibitor). After transection of splanchnic nerves, we electrically stimulated splanchnic nerves or locally administered acetylcholine through dialysis probes for 2 min and investigated dialysate acetylcholine, choline, norepinephrine and epinephrine responses. Acetylcholine was not detected in dialysate before nerve stimulation, but substantial acetylcholine was detected by nerve stimulation. In contrast, choline was detected in dialysate before stimulation, and dialysate choline concentration did not change with repetitive nerve stimulation. The estimated interstitial acetylcholine levels and dialysate catecholamine responses were almost identical between exogenous acetylcholine (10 microM) and nerve stimulation (2 Hz). Dialysate acetylcholine, norepinephrine and epinephrine responses were correlated with the frequencies of electrical nerve stimulation, and dialysate norepinephrine and epinephrine responses were quantitatively correlated with dialysate acetylcholine responses. Neither hexamethonium (a nicotinic receptor antagonist) nor atropine (a muscarinic receptor antagonist) affected the dialysate acetylcholine response to nerve stimulation. Microdialysis technique made it possible to simultaneously assess activities of pre-ganglionic adrenal sympathetic nerves and post-ganglionic adrenal chromaffin cells in the in vivo state and provided quantitative information about input-output relationship in the adrenal medulla.     

Effects of acetylcholine and succinylcholine on isolated frog neuromuscular spindle]

The mode of action of acetylcholine (ACh) and succinylcholine (SCh) on the isolated frog's muscle spindle has been studied. Receptor afferent nervous supply was maintained; the appropriate spinal roots were dissected for stimulating motor axons and recording from sensory fibres. Excitatory effects on the afferent activity, when the receptor was held still and during stretching, were found with ACh or SCh concentrations of 10(-8) to 10(-3); 10(-6) g/ml being usually effective. These effects are similar to those obtained by stimulating fusimotor nerve fibres. The contractile activity of intrafusal muscle fibres which occurred during these effects was observed. Seldom, and only for high concentrations of ACh and SCh, a decrease in afferent activity following the excitatory effects was found. Tubocurarine chloride (10(-5)-10(04) g/ml) in the bath prevented both motor fibres and drugs effects. Sometimes slight transient excitation occurred at very high concentrations of the two tested substances; however, this effect was prevented by stronger curarization. The observed blocking effects were always reversed by removing tubocurarine from the bath. No more excitatory effects by motor fibres stimulation and by ACh and SCh action could be found after destruction of intrafusal muscle fibres, by pinching them as close as possible to the ends of the spindle. It is suggested that ACh and SCh act indirectly by causing mechanical changes in intrafusal muscle fibres, and that a direct action on sensory nerve endings, if any, cannot, by itself, increase the afferent activity of the receptor.     

α7 Nicotinic Acetylcholine Receptor Signaling Inhibits Inflammasome Activation by Preventing Mitochondrial DNA Release

The mammalian immune system and the nervous system coevolved under the influence of cellular and environmental stress. Cellular stress is associated with changes in immunity and activation of the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome, a key component of innate immunity. Here we show that α7 nicotinic acetylcholine receptor (α7 nAchR)-signaling inhibits inflammasome activation and prevents release of mitochondrial DNA, an NLRP3 ligand. Cholinergic receptor agonists or vagus nerve stimulation significantly inhibits inflammasome activation, whereas genetic deletion of α7 nAchR significantly enhances inflammasome activation. Acetylcholine accumulates in macrophage cytoplasm after adenosine triphosphate (ATP) stimulation in an α7 nAchR-independent manner. Acetylcholine significantly attenuated calcium or hydrogen oxide–induced mitochondrial damage and mitochondrial DNA release. Together, these findings reveal a novel neurotransmitter-mediated signaling pathway: acetylcholine translocates into the cytoplasm of immune cells during inflammation and inhibits NLRP3 inflammasome activation by preventing mitochondrial DNA release.     

Possible role of voltage-sensitive potassium channels in generation of response in Pacinian corpuscles

The effects of 20 mM tetraethylammonium (TEA) and 5 mM 4-aminopyridine (4-AP) on mechanically and electrically excitable membranes of Pacinian corpuscles were investigated using the air gap technique for producing constant superfusion and recording electrical response at the receptor. The effects of TEA led to a 150% rise in the duration of receptor potential, the amplitude of which declined by 40%. No statistically significant changes in response to mechanical stimulation could be detected after applying 4-AP to the receptor membrane. The two blockers mentioned did modify the membrane of the first nodes of Ranvier, producing a 2–3-fold increase in the duration of action potentials. Computations based on the Dodge model would indicate that the observed effects may be explained by inhibition of voltage-dependent potassium channels which help to transform receptor current into spike response in the intact receptor.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 20, No. 5, pp. 623–630, September–October, 1988.     

Effect of ozone exposure on contractile activity and chemoreactivity of uterus horns longitudinal muscles of nonpregnant rats

With the purpose of studying the mechanism of ozone action on uterus smooth muscles it was investigated the influence of ozone-content (approximately 0.50 mkg/ml) Krebs' solution or its 10- and 100-fold dissolution on contractile activity and beta-adrenoreactivity of 56 longitudinal strips of uterus horns of 17 nonpregnant rats. Ozone at concentration approximately 0.50 mkg/ml (but not in concentration of approximately 0.05 and approximately 0.005 mkg/ml) reversibly raised frequency, amplitude and total contractile activity of intact myometrium strips, and also fast and reversibly reducel its beta-adrenoreactivity, i.e. decreased of inhibitory action of adrenaline (10(-8), 10(-7), 10(-6) g/ml), but did not change uterostimulatory effect of acetylcholine (10(-6) g/ml) and oxiyocin (5 x 10(-4) ME/ml), what evident about specificity of ozone beta-adrenoblokate effect. Ozone (approximately 0.50 and 0.05 mkg/ml) did not change ov value of potassium contracture of myometrium strips which was depolarized by hyperpotassium (60 mM KCL) Krebs' solution, but reduced inhibitory action of adrenaline (10(-8) g/ml). The question is being discussed about mechanisms of ozone beta-adrenoblocade actions, about clinical role of this phenomenon, and the possibility of using beta-adrenoreceptor sensibilizators direct action (histidine, tryptophan, tyrosine, trimetazidin and mildronat) at ozonotherapy with the purpose reduction of its negative effects.     

Cholinergic muscarinic stimulation of steroidogenesis in bovine adrenal cortex fasciculata cell suspensions

Acetylcholine was found t acutely stimulate cortisol production by bovine fasciculata adrenocortical cell suspensions. This effect was maximal at 10^?4 M acetylcholine concentration, resulted in a 5-fold increase in cortisol production over the control after 1 h incubation, and represented about one fifth of the ACTH maximal stimulation under the same conditions. Acetylcholine-stimulated steroidogenesis was concentration-dependent (10^?8–10^?5 M), propotional to the cell numbe (5 · 10⁵–2 · 10⁶) and reached a plateau after 30 min incubation. Use of various cholinergic specific agonists and antagonists showed that thet steroidogenic action of acetylcholine was a typical muscarinic effect. This character is in agreement with the previously demonstrated presence of muscarinic receptors in bovine adrenocortical tissue. The steroidogenic effect of acetylcholine required the presence of extracellular calcium in the medium and was impaired upon addition of tetracaine and procaine. No change in cyclic AMP nor cyclic GMP levels could be detected in the system under acetylcholine stimulation. Acetylcholine appeared to exhibit a synergistic in combination with ACTH, and exogenous cyclic AMP; these observations suggest a different mechanism of action for acetylcholine and ACTH and point to a possible cholinergic participation in the regulation of adrenocortical differentiated functions in vivo.     

Role of depolarization and calcium in contractions of canine trachealis from endogenous or exogenous acetylcholine

The relationships of the electrical to the mechanical responses of the canine trachealis muscle during stimulation of its cholinergic nerves or exposure to exogenous acetylcholine were recorded in the single or the double sucrose gap. At 27 degrees C, the responses to a train of stimuli consisted of a transient depolarization excitatory junction potential of 10-30 mV followed by fading oscillations and contractions. When stimulus parameters were varied in the single sucrose gap, contractions were more closely associated with the occurrence of and varied in duration with the oscillations rather than with the amplitude of the EJP. Acetylcholine superfused at a concentration of 10(-6) M for 30 s caused a prolonged depolarization of 10-20 mV, but a much larger contraction than could be elicited by nerve stimulation. None of the responses to acetylcholine was significantly affected by the Ca channel antagonists, nifedipine, nitrendipine, or verapamil in Ca channel blocking concentrations. When tissues were exposed to a Ca-free medium, the excitatory junction potentials and oscillations rapidly disappeared, but the electrical and mechanical responses to acetylcholine persisted and only gradually disappeared with repetitive exposures. Furthermore, in a medium with normal Ca2+ in the double sucrose gap, depolarization by 10-15 mV with an applied current caused no contraction, and repolarization to the normal membrane potential during acetylcholine-induced contraction caused no relaxation. Tetraethylammonium ion (20 mM) depolarized the membrane, increased membrane resistance, and enhanced the secondary oscillations and contractions after field stimulation. No other K(+)-channel blocker tested (Ba2+, apamin, 4-aminopyridine, glibenclamide, charybdotoxin) had the effect of prolonging secondary oscillations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cholinergic mechanisms of interneuronal transmission in the retina

Acetylcholine, applied to the isolated perfused frog and human retina, induces a corneopositive potential. This electrogenic action of acetylcholine, in conjunction with existing data, confirms the view that transmission in the retina is cholinergic. The magnitude and the temporal course of the potential evoked by acetylcholine depends both on its concentration and on the state of adaptation of the retina. Photic stimulation reduces the response to acetylcholine; under these circumstances flashes are more effective than a steady illumination. On the other hand the response of the retina to light decreases during perfusion with acetylcholine. The positive component of the ERG is particularly strongly inhibited, leaving only the negative P_III. The results indicate that acetylcholine acts on synapses between the first and second retinal neurons. They can be explained in terms of the hypthesis of the desensitization of cholinergic receptors in the retina.     

Muscarinic receptor modulation of glucose-induced electrical activity in mouse pancreatic B-cells

Acetylcholine (1-10 microM) depolarized the membrane and stimulated glucose-induced bursts of electrical activity in mouse pancreatic B-cells. The acetylcholine effects were mimicked by muscarine while nicotine had no effect on membrane potential. Pirenzepine, an antagonist of the classical M1-type muscarinic receptors, but not gallamine (1-100 microM), an antagonist of the classical M2-type receptors, antagonized the acetylcholine action on glucose-induced electrical activity (IC50 = 0.25 microM). Bethanechol, an agonist of the classical M2-type muscarinic receptors, was approximately 100 times less effective than acetylcholine in stimulating the electrical activity. In addition, acetylcholine (1 microM) induced a marked increase (25%) in input resistance to the B-cell membrane. The results indicate that acetylcholine exerted its effects on the B-cell membrane by inhibiting K+ conductance via activation of a muscarinic receptor subtype distinct from the classical M2-type receptor.