• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.275-281
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• 2000

Cholecystokinin (CCK) is a gastrointestinal hormone which plays an important role in satiety and gastric motility. It is also widely distributed throughout the central nervous system, where it appears to be involved in the central control of anxiety, feeding behavior and nociception. Two distinct CCK receptor types, $CCK_A$ and $CCK_B,$ have been found in the brain. Both CCK receptors coexist in the rat nucleus tractus solitarius (NTS), which is the primary center for the coordination of peripheral and central activities related to gastrointestinal, cardiovascular and respiratory functions. In order to study ionic actions of CCK on each type of receptor, we investigated the effects of CCK-8S on neurons located in the NTS of the rat using whole-cell patch-clamp recordings in brainstem slices. Application of CCK-8S, under current clamp, produced a membrane depolarization accompanied by action potential firing. This CCK-evoked excitation was dose-dependent $(10\;nM{\sim}10\;{\mu}M)$ and observed in more than 60% of NTS neurons. Under voltage clamp conditions, CCK-8S induced an inward current with a notably increased spontaneous excitatory synaptic activity. However, CCK-8S did not significantly change the amplitude of pharmacologically isolated and evoked EPSP(C)s. Using selective $CCK_A$ and $CCK_B$ receptor antagonists, we observed two different effects of CCK-8S, which suggest $CCK_A$ receptor-mediated inhibitory and $CCK_B$ receptor-mediated excitatory effects in the NTS. These results may help to explain the ability of CCK to modulate gastrointestinal and other reflex systems in the NTS.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.27-31
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• 2002

${\gamma}-Aminobutyric$ Acid (GABA) is contained in pancreatic islet ${\beta}-cells$ although its physiological role in pancreatic exocrine function is completely unknown at the present time. Recently, we have reported that exogenous GABA enhances secretagogue-evoked exocrine secretion in the isolated, perfused rat pancreas. This study was aimed to investigate an effect of exogenous GABA on pancreatic exocrine secretion in vivo evoked by intestinal stimulation. Rats were anesthetized with urethane (1.4 g/kg) after 24-h fast with free access to water. GABA $(10,\;30\;and\;100\;{\mu}mol/kg/h),$ given intravenously, did not change spontaneous pancreatic amylase secretion but dose-dependently elevated the amylase secretion evoked by intraduodenal sodium oleate (0.05 mmol/h). GABA $(30\;{\mu}mol/kg/h)$ also further increased the amylase secretion stimulated by CCK (30 pmol/kg/h) plus secretin (20 pmol/kg/h) but failed to modify the amylase secretion induced by secretin alone. GABA $(10,\;30\;and\;100\;{\mu}mol/kg/h)$ also dose-dependently elevated pancreatic amylase secretion evoked by CCK alone. Bicuculline $(100\;{\mu}mol/kg/h),$ a $GABA_A-receptor$ antagonist, markedly reduced the GABA-enhanced pancreatic responses to sodium oleate, CCK plus secretin or CCK alone. The results indicate that GABA enhances the sodium oleate-evoked pancreatic amylase secretion via $GABA_A-receptor$ in anesthetized rats, which may account for elevating the action of CCK released by sodium oleate.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.3
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• pp.181-186
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• 2012

Fenofibrate is a selective peroxisome proliferator-activated receptor ${\alpha}$ ($PPAR{\alpha}$) activator and is prescribed to treat hyperlipidemia. The mechanism through which $PPAR{\alpha}$ agonists reduce food intake, body weight, and adiposity remains unclear. One explanation for the reduction of food intake is that fenofibrate promotes fatty acid oxidation and increases the production of ketone bodies upon a standard experimental dose of the drug (100~300 mg/kg/day). We observed that low-dose treatment of fenofibrate (30 mg/kg/day), which does not cause significant changes in ketone body synthesis, reduced food intake in Long-Evans Tokushima (LETO) rats. LETO rats are the physiologically normal controls for Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which are obese and cholecystokinin (CCK)-A receptor deficient. We hypothesized that the reduced food intake by fenofibrate-treated LETO rats may be associated with CCK production. To investigate the anorexic effects of fenofibrate in vivo and to determine whether CCK production may be involved, we examined the amount of food intake and CCK production. Fenofibrate-treated OLETF rats did not significantly change their food intake while LETO rats decreased their food intake. Treatment of fenofibrate increased CCK synthesis in the duodenal epithelial cells of both LETO and OLETF rats. The absence of a change in the food intake of OLETF rats, despite the increase in CCK production, may be explained by the absence of CCK-A receptors. Contrary to the OLETF rats, LETO rats, which have normal CCK receptors, presented a decrease in food intake and an increase in CCK production. These results suggest that reduced food intake by fenofibrate treatment may be associated with CCK production.

• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.34-45
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• 1998

We provide the reader with a brief introduction to the neurobiology of neuropeptides. Several comprehensive reviews of the distribution and neurochemical, neurophysiological, neuropharmacological and behavioral effects of the major neuropeptides have recently appeared. In reviews of the large number of neuropeptides in brain and their occurance in brain regions thought to be involved in the pathogenesis of major psychiatric disorders, investigators have sought to determine whether alternations in neuropeptide systems are associated with schizophrenia, mood disorders, anxiety disorders, alcoholism and neurodegenerative disease. There is no longer any doubt that neuropeptide-containing neurons are altered in several neuropsychiatric disorders. One of the factors that has hindered neuropeptide research to a considerable extent is the lack of pharmacological agents that specifically alter the synaptic availability of neuropeptides. With the exception of naloxone and naltrexone, the opiate-receptor antagonists, there are few available neuropeptide- receptor antagonists. Two independent classes of neuropeptide-receptor antagonists has been expected to be clinically useful. Naltrexone, a potent ${\mu}$-receptor antagonist, has been used successfully to reduce the need for alcohol consumption. And cholecycstokinin antagonists are now in development as a new class of anxiolytics, which would be expected to be free from tolerance and physical dependence and lack of sedation. In this review, we deal with these two kinds of neuropeptide system, the opioid system and cholesystokinins in the brain. The role of opioid systems in the reinforcement after alcohol consumtion and that of cholesystokinins in the pathogenesis of anxiety will be discussed briefly. As we know, the future for neuropeptides in psychiatry remains bright indeed.

• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.243-257
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• 1996

CCK and cholinergic agonist stimulate enzyme release from the pancreatic acini via G-protein-mediated activation of phospholipase C, In contrast secretin and related peptides increase the level of cAMP and activate cAMP-dependent protein kinase. Camostat, a synthetic protease inhibitor, causes pancreatic hypertrophy and hyperplasia by increasing the CCK release. In this study, the secretagogue-induced changes of intracellular proteins were examined in the dispersed pancreatic acini of rats with or without camostat treatment. Camostat(FOY-305, 200 mg/kg, p.o.) was given for 4 days twice daily and the dispersed acini were prepared at 12 bouts after last treatment. The profiles of Intracellular phosphoproteins were analyzed by two-dimensional gel electrophoresis after incubating the acini with $^{32}P$. The amylase release from the dispersed acini was measured. The pancreatic weight was increased to 126% of control, while amylase activity per mg acinar protein decreased to 41% of control, The maximum response of amylase release from dispersed acini to CCK-8 or carbachol was markedly decreased(65% or 46% of control, respectively). The group of intracellular proteins(24 kD, pI $4.5{\sim}8.5$) was increased in quantity by camostat. CCK-8 or secretin increased phosphorylation of a protein(34 kD, pI 4.7) in camostat-treated as well as control rats. CCK-8 increased tyrosine phosphoryiation in the acini of control rats. However, in camostat-treated rats, the basal level of tyrosine phosphorylation was increased and it was rather decreased by CCK-8. Secretin had no effect on the level of tyrosine phosphorylation in acini. These results indicate that both phospholipase C and adenylate cyclase induce phosphorylation of an intracellular acinar protein(34 kD, pI 4.7) and camostat treatment increases the basal level of tyrosine phosphorylation in acinar cells. And these results suggest that not only serine/threonine protein kinase but also protein tyrosine kinase/phosphatase are involved in the process of CCK receptor mediated stimulation-secrelion coupling.

• The Korean Journal of Physiology
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• v.20 no.2
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• pp.192-198
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• 1986

The present study was undertaken to see an interaction of dopamine and cholecystokinin on spontaneous contractility of the small intestine including the duodenal bulb. A possible neural mechanism of the interaction was alto examined. The spontaneous isometric contractility of a segment of the duodenal bulb, duodenum, jejunum and ileum obtained from the rabbit anesthetized with ether was recorded in a chamber filled with Krebs-Ringer's solution. The solution was constantly kept at $37^{\circ}C$ and aerated with $O_2$ containing 5% $CO_2$. After 20 min from beginning of the contraction, dopamine $(10^{-4}M)$, CCK-8($10^{-8}M$), domperidone($10^{-5}M$) and tetrodotoxin ($10^{-6}M$) were administered into the chamber The following results were obtained by analyzing changes in the contractility of the intestinal segments. 1) Dopamine inhibited the spontaneous contractility of the duodenal bulb, duodenum, jejunum and ileum. The inhibitory action of dopamine on all parts of the small intestine except the ileum was reduced by tetrodotoxin. 2) Domperidone knwon to be a specific peripheral dopamine receptor antagonist blocked the inhibitory action of dopamine on all parts of the small intestine. The antagonistic action of domperidone on all parts of the small intestine except the ileum was completely abolished by tetrodotoxin. 3) CCK-8 reduced the inhibitory action of dopamine on all parts of the small intestine. The effect of CCK-8 on the dopamine action was diminished by tetrodotoxin. These results suggest that dopamine inhibits the spontaneous contractility of the small intestine including the duodenal bulb and CCK-8 reduces the inhibitory action of dopamine through the enteric nervous system.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.657-663
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• 1998

The enzyme responsible for the synthesis of nitric oxide (NO) from L-arginine in mammalian tissues is known as nitric oxide synthase (NOS) (EC.1.14.13.39). In the present study, the role of NO in the regulation of exocrine secretion was investigated in rat pancreatic acinar cells. Treatment of rat pancreatic acinar cells with cholecystokinin-octapeptide (CCK-OP) resulted in an increase in the arginine conversion to citrulline, the amount of $NO_X$, the release of amylase, and the level of CGMP. Especially, CCK-OP-stimulated increase of arginine to citrulline transformation, the amount of $NO_X$, and CGMP level were completely counteracted by the inhibitor of NOS, NG-monomethyl-L-arginine (MMA), by contrast, that of amylase release was partially reduced. Furthermore, MMA-induced decrease of NOS activity and amylase release showed dose-dependent pattern. The data on the time course of CCK-OP-induced citrulline formation and CGMP rise indicate that NOS and guanylate cyclase were activated by treatment of CCK-OP. However, the mechanism of agonist-stimulated guanylate cyclase activation in acinar cells remains unknown. Therefore, activation of NOS is one of the early events in receptor-mediated cascade of reactions in pancreatic acinar cells and NO, not completely, but partially mediate pancreatic enzyme exocrine secretion.

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

• Animal Bioscience
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• v.36 no.2
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• pp.200-208
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• 2023

Objective: Muscle acetylcholine receptors have five alpha subunits (α, β, δ, ε, or γ), and cholinergic receptor nicotinic gamma subunit (CHRNG) is the γ subunit. It may also play an essential role in biological processes, including cell differentiation, growth, and survival, while the role of CHRNG has not been studied in the literature. Therefore, the purpose of this study is to clarify the effect of CHRNG on the proliferation and differentiation of bovine preadipocytes. Methods: We constructed a CHRNG overexpression adenovirus vector and successfully overexpressed it on bovine preadipocytes. The effects of CHRNG on bovine preadipocyte proliferation were detected by Edu assay, cell counting Kit-8 (CCK-8), real-time fluorescence quantitative polymerase chain reaction (RT-qPCR), Western blot and other techniques. We also performed oil red O, RT-qPCR, Western blot to explore its effect on the differentiation of preadipocytes. Results: The results of Edu proliferation experiments showed that the number of EDU-positive cells in the overexpression group was significantly less. CCK-8 experiments found that the optical density values of the cells in the overexpression group were lower than those of the control group, the mRNA levels of proliferating cell nuclear antigen (PCNA), cyclin A2 (CCNA2), cyclin B1 (CCNB1), cyclin D2 (CCND2) decreased significantly after CHRNG gene overexpression, the mRNA levels of cyclin dependent kinase inhibitor 1A (CDKN1A) increased significantly, and the protein levels of PCNA, CCNB1, CCND2 decreased significantly. Overexpression of CHRNG inhibited the differentiation of bovine preadipocytes. The results of oil red O and triglyceride determination showed that the size and speed of lipid droplets accumulation in the overexpression group were significantly lower. The mRNA and protein levels of peroxisome proliferator activated receptor gamma (PPAR class="checkNonKBPoint">γ), CCAAT enhancer binding protein alpha (CEBPα), fatty acid binding protein 4 (FABP4), fatty acid synthase (FASN) decreased significantly. Conclusion: Overexpression of CHRNG in bovine preadipocytes inhibits the proliferation and differentiation of bovine preadipocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.10
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• pp.1674-1682
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• 2020

Objective: This study aimed to elucidate the effect of miR-140 on the proliferation of porcine fetal fibroblasts (PFFs) and identify the target genes of miR-140 in PFFs. Methods: In this study, bioinformatics software was used to predict and verify target genes of miR-140. Quantitative polymerase chain reaction and western blot were used to detect the relationship between miR-140 and its target genes in PFFs. Dual luciferase reporter gene assays were performed to assess the interactions among miR-140, type 1 insulin-like growth factor receptor (IGF1R), and SRY-box 4 (SOX4). The effect of miR-140 on the proliferation of PFFs was measured by CCK-8 when PFFs were transfected with a miR-140 mimic or inhibitor. The transcription factor SOX4 binding to promoter of IGF1R was detected by chromatin immunoprecipitation assay (ChIP). Results: miR-140 directly targeted IGF1R and inhibited proliferation of PFFs. Meanwhile, miR-140 targeted transcription factor SOX4 that binds to promoter of porcine IGF1R to indirectly inhibit the expression of IGF1R. In addition, miR-140 inhibitor promoted PFFs proliferation, which is abrogated by SOX4 or IGF1R knockdown. Conclusion: miR-140 inhibited PFFs proliferation by directly targeting IGF1R and indirectly inhibiting IGF1R expression via SOX4, which play an important role in the development of porcine fetal.