• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.5
• /
• pp.485-493
• /
• 1997

We investigated the effect of ${\alpha}-adrenergic$ and cholinergic receptor agonists on $Ca^{2+}$ current in adult rat trigeminal ganglion neurons using whole-cell patch clamp methods. The application of acetylcholine, carbachol, and oxotremorine ($50\;{\mu}M\;each$) produced a rapid and reversible reduction of the $Ca^{2+}$ current by $17{\pm}6%,\;19{\pm}3%,\;and\;18{\pm}4%$, respectively. Atropine, a muscarinic antagonist, blocked carbachol- induced $Ca^{2+}$ current inhibition to $3{\pm}1%$. Norepinephrine ($50\;{\mu}M$) reduced $Ca^{2+}$ current by $18{\pm}2%$, while clonidine ($50\;{\mu}M$), an ${\alpha}2-adrenergic$ receptor agonist, inhibited $Ca^{2+}$ current by only $4{\pm}1%$. Yohimbine, an ${\alpha}2-adrenergic$ receptor antagonist, did not block the inhibitory effect of norepinephrine on $Ca^{2+}$ current, whereas prazosin, an ${\alpha}1-adrenergic$ receptor antagonist, attenuated the inhibitory effect of norepinephrine on $Ca^{2+}$ current to $6{\pm}1%$. This pharmacology contrasts with ${\alpha}2-adrenergic$ receptor modulation of $Ca^{2+}$ channels in rat sympathetic neurons, which is sensitive to clonidine and blocked by yohimbine. Our data suggest that the modulation of voltage dependent $Ca^{2+}$ channel by norepinephrine is mediated via an α1-adrenergic receptor. Pretreatment with pertussis toxin (250 ng/ml) for 16 h greatly reduced norepinephrine- and carbachol-induced $Ca^{2+}$ current inhibition from $17{\pm}3%\;and\;18{\pm}3%\;to\;2{\pm}1%\;and\;2{\pm}1%$, respectively. These results demonstrate that norepinephrine, through an ${\alpha}1-adrenergic$ receptor, and carbachol, through a muscarinic receptor, inhibit $Ca^{2+}$ currents in adult rat trigeminal ganglion neurons via pertussis toxin sensitive GTP-binding proteins.

• Korean Journal of Clinical Pharmacy
• /
• v.8 no.2
• /
• pp.113-121
• /
• 1998

To clarify whether nizatidine, a $H_2$ receptor antagonist, has the cholinergic activity, the effects of nizatidine on the guinea pig ileum and on the acetylcholinesterase in human serum were studied. And, the mechanism of excitatory effect of nizatidine on the cholinergic system in ileum was also studied. Nizatidine caused a concentration-dependent contractile response by the guinea pig ileum. The $EC_{50}\;was\;53\;{\mu}M$ and the maximum response was at $300\;{\mu}M$. Ranitidine also caused a contractile response by the guinea pig ileum, but cimetidine and famotidine did not. The pretreatment with $H_1$ receptor antagonist did not affect the actions of nizatidine on the guinea pig ileum, but the pretreatment with atropine completely blocked them. Nizatidine significantly enhanced the acetylcholine-induced response of the guinea pig ileum, but not the pilocarpine-induced response. Nizatidine did not affect the histamine-induced response of the guinea pig ileum. Nizatidine still exerted the small excitatory effect on the guinea pig ileum pretreated with the high concentration of physostigmine. Nizatidine significantly inhibited the acetylcholinesterase in human serum. These results suggest that nizatidine exerts an excitatory effect on guinea pig ileum which seems to be associated with the cholinergic system, probably through an indirect mechanism, inhibition of acetylcholinesterase and/or increased release of acetylcholine.

• Korean Journal of Veterinary Research
• /
• v.33 no.2
• /
• pp.211-216
• /
• 1993

To elucidate the action of the cholinergic and ${\alpha}_2$-adrenergic nerve on the isolated ileal smooth muscle of the dog, effect a of electrical field stimulation were investigated on the pretreatment of the physostigmine; cholinestrase inhibitor, yohimbine; ${\alpha}_2$-adrenoceptor blocker, atropine ; cholinergic receptor blocker and phentolamine; non-selective $\alpha$-adrenoceptor blocker from physiograph. 1. The contractile response induced by electrical field stimulation was the frequency (2-40 Hz)-dependent manner. 2. The contractile response induced by electrical field stimulation was markedly increased by the pretreatment of physostigmine$(1{\mu}M)$; cholinestrase inhibitor. 3. The contractile response induced by electrical field stimulation was increased by the pretreatment of yohimbine$(1{\mu}M)$; ${\alpha}_2$-adrenoceptor blocker. These finding suggest that it was powerful excitatory action by cholinergic nerve and inhibitory action by ${\alpha}_2$-adrenergic nerve on ileal smooth muscle of the dog.

• The Korean Journal of Pharmacology
• /
• v.18 no.2
• /
• pp.69-77
• /
• 1982

$Na^+,\;K^+-ATPase$ is a component of plasma membrane in almost all animal cell, and maintains ionic distribution and membrane potential of normal cell. In the mechanism of adrenergic transmission, it is relatively well known that drug-receptor combination leads to stimulate adenylate cyclase and so on. In the cholinergic transmisison, the mechanism is not well known but is simply interpreted as the change of membrane permeability results from acetylcholine receptor interaction. To study the relationship between cholinergic transmission and membrane $Na^+,\;K^+-ATPase$, the effect of carbachol on $Na^+,\;K^+-ATPase$ activity in rabbit erythrocyte membrane is studied. The results are summarized as follows. 1) Total ATPase, $Mg^{+2}-ATPase$ and $Na^+,\;K^+-ATPase$ of rabbit erythrocyte membrane show maximum activities at 1mM of tris-ATP. 2) Total ATPase activity tends to increase when treated with carbachol $(10-^{-9}M-10^{-3}M)$. 3) The $Mg^{+2}-ATPase$ activity also tends to increase when treated with carbachol $(10-^{-9}M-10^{-3}M)$. 4) The $Na^+,\;K^+-ATPase$ activity is inhibited when treated with carbachol $(10-^{-9}M-10^{-7}M)$. It is suggested that the inhibition of $Na^+,\;K^+-ATPase$ by cholinergic drugs may be considered as one part of mechanism of cholinergic transmission.

• The Korean Journal of Nuclear Medicine
• /
• v.27 no.1
• /
• pp.28-34
• /
• 1993

Using in vitro autoradiography with a digital autoradiography system and radioreceptor assay, the distribution and the binding characteristics of the muscarinic cholinergic receptors (mAChR) were studied in regions of rat brain. Radioreceptor assay revealed that mAChR could be measured with saturation binding assay in the brain and heart homogenates: No difference in Kd or Bmax of the brain or heart was found between the normal Wistar rats and SHR rats. Specific binding of $^3H$ quinuclidinyl benzilate (QNB) increased and saturation was reached by 2 hours after incubation with slide-mounted brain tissue. The distribution of mAChR was heterogeneous along the fields of brain. Affinity (Kd) of mAChR was not different significantly among cortex, hippocampus and caudate-putamen. No difference was found between normal rats and SHR strain. More receptors (Bmax) were found in the cortex and hippocampus than in the caudate-putamen in normal rats. More receptors were found in the cortex and caudate-putamen in SHR rats than in normal rats. Radioreceptor assay and digital autoradiographic analysis of affinity and number of mAChR gave the same results. With the above findings, we concluded that we could use digital autoradiographic system with $^3H$-QNB in the characterization of mAChR of rats and that the cortex and caudate-putamen of SHR strain rats have more receptors than those of normal rats.

• International Journal of Oral Biology
• /
• v.41 no.3
• /
• pp.119-123
• /
• 2016

Acetylcholine receptors (AChR) including muscarinic and nicotinic AChR are widely expressed and mediate a variety of physiological cellular responses in neuronal and non-neuronal cells. Notably, a functional cholinergic system exists in oral epithelial cells, and nicotinic AChR (nAChR) mediates cholinergic anti-inflammatory responses. However, the pathophysiological roles of AChR in periodontitis are unclear. Here, we show that activation of AChR elicits increased cytosolic $Ca^{2+}([Ca^{2+}]_i)$, transient cytotoxicity, and induction of receptor activator of nuclear factor kappa-B ligand (RANKL) expression. Intracellular $Ca^{2+}$ mobilization in human gingival fibroblast-1 (hGF-1) cells was measured using the fluorescent $Ca^{2+}$ indicator, fura-2/AM. Cytotoxicity and induction of gene expression were evaluated by measuring the release of glucose-6-phosphate dehydrogenase and RT-PCR. Activation of AChR in hGF-1 cells by carbachol (Cch) induced $[Ca^{2+}]_i$ increase in a dose-dependent manner. Treatment with a high concentration of Cch on hGF-1 cells caused transient cytotoxicity. Notably, treatment of hGF-1 cells with Cch resulted in upregulated RANKL expression. The findings may indicate potential roles of AChR in gingival fibroblast cells in bone remodeling.

• The Korean Journal of Physiology and Pharmacology
• /
• v.20 no.4
• /
• pp.407-414
• /
• 2016

This study was performed to investigate whether the spinal cholinergic and serotonergic analgesic systems mediate the relieving effect of electroacupuncture (EA) on oxaliplatin-induced neuropathic cold allodynia in rats. The cold allodynia induced by an oxaliplatin injection (6 mg/kg, i.p.) was evaluated by immersing the rat's tail into cold water ($4^{\circ}C$) and measuring the withdrawal latency. EA stimulation (2 Hz, 0.3-ms pulse duration, 0.2~0.3 mA) at the acupoint ST36, GV3, or LI11 all showed a significant anti-allodynic effect, which was stronger at ST36. The analgesic effect of EA at ST36 was blocked by intraperitoneal injection of muscarinic acetylcholine receptor antagonist (atropine, 1 mg/kg), but not by nicotinic (mecamylamine, 2 mg/kg) receptor antagonist. Furthermore, intrathecal administration of $M_2$ (methoctramine, $10{\mu}g$) and $M_3$ (4-DAMP, $10{\mu}g$) receptor antagonist, but not $M_1$ (pirenzepine, $10{\mu}g$) receptor antagonist, blocked the effect. Also, spinal administration of $5-HT_3$ (MDL-72222, $12{\mu}g$) receptor antagonist, but not $5-HT_{1A}$ (NAN-190, $15{\mu}g$) or $5-HT_{2A}$ (ketanserin, $30{\mu}g$) receptor antagonist, prevented the anti-allodynic effect of EA. These results suggest that EA may have a significant analgesic action against oxaliplatin-induced neuropathic pain, which is mediated by spinal cholinergic ($M_2$, $M_3$) and serotonergic ($5-HT_3$) receptors.

• Journal of Yeungnam Medical Science
• /
• v.12 no.2
• /
• pp.246-259
• /
• 1995

This study aimed to investigate the mechanism of action of baclofen on the detrusor muscle isolated from rat. Rats (Sprague-Dawley) were sacrificed by decapitation and exsanguination. Horizontal muscle strips of $2mm{\times}15mm$ were prepared for isometric myography in isolated muscle chamber bubbled with 95% / 5%-$O_2$ / $CO_2$ at $37^{\circ}C$, and the pH was maintained at 7.4. Detrusor strips contracted responding to the electrical field stimulation (EFS) by 2 Hz, 20 msec, monophasic square wave of 60 VDC. The initial peak of EFS-Induced contraction was tended to be suppresed by ${\alpha},{\beta}$-methylene-adenosine 5'-triphosphate (mATP), a partial agonist of purinergic receptor, and baclofen, a $GABA_B$ receptor agonist (statistically nonsignificant). The late sustained contraction by EFS was suppressed significantly (p < 0.05) by additions of atropione, a cholinergic muscarinic receptor antagonist and baclofen. The adenosine 5'-triphosphate-induced contraction was completely abolished by mA TP but not by baclofen. In the presence of atropine, the subsequent addition of acetylcholine could not contract the muscle strips: but the addition of acetylcholine in the presence of baclofen evoked a contraction to a remarkable extent. These results suggest that in the condition of present study, the cholinergic innervation may play a more important role than the purinergic one, and baclofen suppresses the contractility of rat detrusor by the stimulation of the $GABA_B$ receptors to inhibit the release of neurotransmitter from the cholinergic nerve ending.

• The Korean Journal of Physiology and Pharmacology
• /
• v.24 no.6
• /
• pp.517-527
• /
• 2020

Layer 2/3 pyramidal neurons (L2/3 PyNs) of the cortex extend their basal dendrites near the soma and as apical dendritic tufts in layer 1, which mainly receive feedforward and feedback inputs, respectively. It is suggested that neuromodulators such as serotonin and acetylcholine may regulate the information flow between brain structures depending on the brain state. However, little is known about the dendritic compartment-specific induction of synaptic transmission in single PyNs. Here, we studied layer-specific serotonergic and cholinergic induction of long-term synaptic plasticity in L2/3 PyNs of the agranular insular cortex, a lateral component of the orbitofrontal cortex. Using FM1-43 dye unloading, we verified that local electrical stimulation to layers 1 (L1) and 3 (L3) activated axon terminals mostly located in L1 and perisomatic area (L2/3). Independent and AMPA receptor-mediated excitatory postsynaptic potential was evoked by local electrical stimulation of either L1 or L3. Application of serotonin (5-HT, 10 μM) induced activity-dependent longterm depression (LTD) in L2/3 but not in L1 inputs. LTD induced by 5-HT was blocked by the 5-HT₂ receptor antagonist ketanserin, an NMDA receptor antagonist and by intracellular Ca²⁺ chelation. The 5-HT₂ receptor agonist α-me-5-HT mimicked the LTD induced by 5-HT. However, the application of carbachol induced muscarinic receptor-dependent LTD in both inputs. The differential layer-specific induction of LTD by neuromodulators might play an important role in information processing mechanism of the prefrontal cortex.

• The Korean Journal of Physiology and Pharmacology
• /
• v.7 no.3
• /
• pp.169-174
• /
• 2003

${\gamma}$-Aminobutyric acid (GABA) has been reported to enhance exocrine secretion evoked not only by secretagogues but also by intrinsic neuronal excitation in the pancreas. The pancreas contains cholinergic neurons abundantly that exert a stimulatory role in exocrine secretion. This study was undertaken to examine effects of GABA on an action of cholinergic neurons in exocrine secretion of the pancreas. Intrinsic neurons were excited by electrical field stimulation (EFS; 15 V, 2 msec, 8 Hz, 45 min) in the isolated, perfused rat pancreas. Tetrodotoxin or atropine was used to block neuronal or cholinergic action. Acetylcholine was infused to mimic cholinergic excitation. GABA $(30{\mu}M)$ and muscimol $(10{\mu}M)$, given intra-arterially, did not change spontaneous secretion but enhanced cholecystokinin (CCK; 10 pM)-induced secretions of fluid and amylase. GABA (3, 10, $30{\mu}M$) further elevated EFS-evoked secretions of fluid and amylase dose-dependently. GABA (10, 30, $100{\mu}M$) also further increased acetylcholine $(5{\mu}M)$-induced secretions of fluid and amylase in a dose-dependent manner. Bicuculline $(10{\mu}M)$ effectively blocked the enhancing effects of GABA $(30{\mu}M)$ on the pancreatic secretions evoked by either EFS or CCK. Both atropine $(2{\mu}M)$ and tetrodotoxin $(1{\mu}M)$ markedly reduced the GABA $(10{\mu}M)$-enhanced EFS- or CCK-induced pancreatic secretions. The results indicate that GABA enhances intrinsic cholinergic neuronal action on exocrine secretion via the $GABA_A$ receptors in the rat pancreas.