• 생약학회지
• /
• 제52권3호
• /
• pp.127-133
• /
• 2021

Platelet activation plays a major role in cardiovascular disorders (CVDs). Thus, disrupting platelet activation represents an attractive therapeutic target on CVDs. Esculetin, a bioactive 6,7-dihydroxy derivative of coumarin, possesses pharmacological activities against obesity, diabetes, renal failure, and CVDs. In other report, the effect of esculetin has been examined in human platelet activation and experimental mouse models, and esculetin inhibited collagen- and arachidonic acid-induced platelet aggregation in washed human platelets. However, it had no effects on other agonists such as thrombin and U46619, and its mechanism is not also clearly known. This study investigated the effect of esculetin on collagen-induced human platelet aggregation, and we clarified the mechanism. Esuletin has effects on the down regulation of PI3K/Akt and MAPK, phosphoproteins that act in the signaling process in platelet aggregation. The effects of esculetin reduced of TXA₂ production and phospholipase A₂ activation, and intracellular granule secretion including ATP and serotonin, leading to inhibit platelet aggregation. These results clearly clarified the effect of esculetin in inhibiting platelet activity and thrombus formation in humans.

• Animal cells and systems
• /
• 제3권2호
• /
• pp.103-113
• /
• 1999

Many in-depth reviews related to regulations of prolactin secretion are available. We will, therefore, focus on controversial aspects using personal opinion in this review. The neuroendocrine control of prolactin secretion from the anterior pituitary gland involves multiple factors including prolactin-release inhibiting factor (PIF) and prolactin releasing factor (PRF). The PIF exerts a tonic inhibitory control in the physiological conditions. The PIF should be able to effectively inhibit prolactin release or a lifetime, but the inhibitory action of dopamine cannot be sustained for a long period of time. Perifusion of a high concentration of dopamine (l ,000 nM) could not sustain inhibitory action on prolactin release but when a small amount of ascorbic acid (0.1 mM) is added in a low concentration of dopamine (3 nM) solution, prolactin release was inhibited for a long period. Ascorbate is essential for dopamine action to inhibit prolactin release. We have, therefore, concluded that the PIF is dopamine plus ascorbate. The major transduction system for dopamine to inhibit prolactin release is the adenylyl cyclase system. Dopamine decreases cyclic AMP concentration by inhibiting adenylyl cyclase, and cyclic AMP stimulates prolactin release. However, the inhibitory mechanism of dopamine on prolactin release is much more complex than simple inhibition of CAMP production. The dopamine not only inhibits cyclic AMP synthesis but also inhibits prolactin release by acting on a link(s) after the CAMP event in a chain reaction for inhibiting prolactin release. Low concentrations of dopamine stimulate prolactin release. Lactotropes are made of several different subtypes of cells and several different dopamine receptors are found in pituitary. The inhibitory and stimulatory actions induced by dopamine can be generated by different subtype of receptors. The GH$_4$ZR$_7$ cells express only the short isoform (D$_{2s}$) of the dopamine receptor, as a result of transfecting the D$_{2s}$ receptors into GH$_4$C$_1$ cells which do not express any dopamine receptors. When dopamine stimulates or inhibits prolactin release in GH$_4$ZR$_7$ cells, it is clear that the dopamine should act on dopamine D$_{2s}$ receptors since there is no other dopamine receptor in the GH$_4$ZR$_7$. Dopamine is able to stimulate prolactin release in a relatively low concentration while it inhibits in a high concentration in GH$_4$ZR$_7$. These observations indicate that the dopamine D$_2$ receptor can activate stimulatory and/or inhibitory transduction system depending upon dopamine concentrations.

• The Korean Journal of Physiology and Pharmacology
• /
• 제8권5호
• /
• pp.265-272
• /
• 2004

The present study was attempted to investigate the effect of cilnidipine (FRC-8635), which is a newly synthesised novel dihydropyridine (DHP) type of organic $Ca^{2+}$ channel blockers, on secretion of catecholamines (CA) evoked by acetylcholine (ACh), high $K^+$, DMPP and McN-A-343 from the isolated perfused rat adrenal gland. Cilnidipine $(1{\sim}10{\mu}M)$ perfused into an adrenal vein for 60 min produced relatively dose- and time-dependent inhibition in CA secretory responses evoked by ACh $(5.32{\times}10^{-3}M),\;DMPP\;(10^{-4}M\;for\;2\;min)$ and McN-A-343 $(10^{-4}M\;for\;2\;min)$. However, lower dose of cilnidipine did not affect CA secretion by high $K^+\;(5.6{\times}10^{-2}\;M)$, higher dose of it reduced greatly CA secretion of high $K^{+}$. Cilnidipine itself did fail to affect basal catecholamine output. In the presence of cilnidipine $(10{\mu}M)$, the CA secretory responses evoked by Bay-K-8644 $(10{\mu}M)$, an activator of L-type $Ca^{2+}$ channels and cyclopiazonic acid $(10{\mu}M)$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase were also inhibited. Moreover, ${\omega}-conotoxin\;GVIA\;(1{\mu}M)$, a selective blocker of the N-type $Ca^{2+}$ channels, given into the adrenal gland for 60 min, also inhibited time-dependently CA secretory responses evoked by Ach, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid. Taken together, these results demostrate that cilnidipine inhibits CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors from the isolated perfused rat adrenal gland without affecting the basal release. However, at lower dose, cilnidipine did not affect CA release by membrane depolarization while at larger dose inhibited that. It seems likely that this inhibitory effect of cilnidipine is exerted by blocking both L- and N-type voltage-dependent $Ca^{2+}$ channels (VDCCs) on the rat adrenomedullary chromaffin cells, which is relevant to inhibition of both the $Ca^{2+}$ influx into the adrenal chromaffin cells and intracellular $Ca^{2+}$ release from the cytoplasmic store. It is thought that N-type VDCCs may play an important role in regulation of CA release from the rat adrenal medulla.

• The Korean Journal of Physiology and Pharmacology
• /
• 제11권3호
• /
• pp.97-106
• /
• 2007

The present study was attempted to investigate the effect of nicorandil, which is an ATP-sensitive potassium ($K_{ATP}$) channel opener, on secretion of catecholamines (CA) evoked by cholinergic stimulation and membrane depolarization from the isolated perfused rat adrenal glands. The perfusion of nicorandil ($0.3{\sim}3.0mM$) into an adrenal vein for 90 min produced relatively dose-and time-dependent inhibition in CA secretion evoked by ACh (5.32 mM), high $k^+$ (a direct membrane depolarizer, 56 mM), DMPP (a selective neuronal nicotinic receptor agonist, $100{\mu}M$ for 2 min), McN-A-343 (a selective muscarinic $M_1$ receptor agonist, $100{\mu}M$ for 4 min), Bay-K-8644 (an activator of L-type dihydropyridine $Ca^{2+}$ channels, $10{\mu}M$ for 4 min) and cyclopiazonic acid (an activator of cytoplasmic $Ca^{2+}$-ATPase, $10{\mu}M$ for 4 min). In adrenal glands simultaneously preloaded with nicorandil (1.0 mM) and glibenclamide (a nonspecific $K_{ATP}$-channel blocker, 1.0 mM), the CA secretory responses evoked by ACh, high potassium, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were recovered to the considerable extent of the control release in comparison with that of nicorandil-treatment only. Taken together, the present study demonstrates that nicorandil inhibits the adrenal CA secretion in response to stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as by membrane depolarization from the isolated perfused rat adrenal glands. It seems that this inhibitory effect of nicorandil may be mediated by inhibiting both $Ca^{2+}$ influx and the $Ca^{2+}$ release from intracellular store through activation of $K_{ATP}$ channels in the rat adrenomedullary chromaffin cells. These results suggest that nicorandil-sensitive $K_{ATP}$ channels may play an inhibitory role in the regulation of the rat adrenomedullary CA secretion.

• Asian-Australasian Journal of Animal Sciences
• /
• 제20권6호
• /
• pp.850-855
• /
• 2007

Leptin is the adipocyte-specific product of the obese gene and plays a major role in food intake and energy metabolism. Leptin research was mainly focused on mammalian species, but understanding of leptin and its function in poultry is very poor. In this study, the duck leptin gene was amplified using the reverse transcription-polymerase chain reaction (RT-PCR) from duck liver RNA. The cDNA fragment was inserted into the pET-28a expression vector, and the resulting plasmid was expressed in Escherichia coli BL21 (DE3). Experimental mice were given an intraperitoneal injection of 10 mg/kg leptin dissolved in phosphate buffered saline (PBS), while the control mice were injected with PBS. The effect of leptin on food intake, body weight and fatty deposition in mice was detected. Sequence analysis revealed that duck leptin had a length of 438 nucleotides which encoded a peptide with 146 amino acid residues. The sequence shares highly homology to other animals. The coding sequence of duck leptin was 84 and 86% identical to human and pig leptin nucleotides sequence. Highest identity was with the rat coding sequence (95%). The identity of the amino acid sequence was 84, 82 and 96% respectively compared to that of the human, pig and rat. Results of SDS-PAGE analysis indicated that a fusion protein was specifically expressed in E. coli BL21 (DE3). The purified product was found to be biologically active during tests. Continuous administration of recombinant duck leptin inhibited food intake. Despite the decrease of food intake, leptin significantly induced body weight and fatty deposition. These changes were accompanied by a significant down-secretion of plasma glucose, cholesterol, triglyceride and insulin levels in mice. The observations provide evidence for an inhibitory effect of leptin in the regulation of food intake and for a potential role of duck leptin in the regulation of lipogenesis.

• Animal Bioscience
• /
• 제35권9호
• /
• pp.1303-1313
• /
• 2022

Objective: The current study aimed to perform whole-genome resequencing of Chinese indigenous Mongolian sheep breeds including Ujimqin, Sunit, and Wu Ranke sheep breeds (UJMQ, SNT, WRK) and deeply analyze genetic variation, population structure, domestication, and selection for domestication traits among these Mongolian sheep breeds. Methods: Blood samples were collected from a total of 60 individuals comprising 20 WRK, 20 UJMQ, and 20 SNT. For genome sequencing, about 1.5 ㎍ of genomic DNA was used for library construction with an insert size of about 350 bp. Pair-end sequencing were performed on Illumina NovaSeq platform, with the read length of 150 bp at each end. We then investigated the domestication and signatures of selection in these sheep breeds. Results: According to the population and demographic analyses, WRK and SNT populations were very similar, which were different from UJMQ populations. Genome wide association study identified 468 and 779 significant loci from SNT vs UJMQ, and UJMQ vs WRK, respectively. However, only 3 loci were identified from SNT vs WRK. Genomic comparison and selective sweep analysis among these sheep breeds suggested that genes associated with regulation of secretion, metabolic pathways including estrogen metabolism and amino acid metabolism, and neuron development have undergone strong selection during domestication. Conclusion: Our findings will facilitate the understanding of Chinese indigenous Mongolian sheep breeds domestication and selection for complex traits and provide a valuable genomic resource for future studies of sheep and other domestic animal breeding.

• 한국응용과학기술학회지
• /
• 제35권4호
• /
• pp.1250-1259
• /
• 2018

여주(Momordica charantia) 열수 추출물을 젖산균(Leuconostoc mesenteroidesies)으로 발효하여 얻은 생산물의 항산화 및 항당뇨 효과를 관찰하였다. 여주 발효물(MC-LM)과 여주 추출물(MC)의 항산화 활성은 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) radical 소거 측정법을 사용하여 관찰하였다. MC 처리군은 radical 소거활성이 거의 나타나지 않았으나 MC-LM의 경우 $500{\mu}g/mL$ 농도에서 47%의 활성이 관찰되었으며 MC-LM의 농도가 증가함에 따라 활성이 유의하게(p<0.05) 증가하는 것을 확인 할 수 있었다. MC-LM은 MC에 비해 peroxyl radical에 의한 DNA의 산화적 손상을 더 효과적으로 억제하였으며 MC-LM의 농도가 증가함에 따라 strand breakage의 억제가 유의적으로 증가 하였다(p<0.05). 혈당량과 밀접한 관련이 있는 ${\alpha}-glucosidase$의 활성 억제정도를 측정한 결과 MC는 8 mg/mL 농도에서 ${\alpha}-glucosidase$의 활성을 30.1% 감소시켰고 같은 농도에서 MC-LM은 58.9% 감소 시켰다. 또한 alloxan에 의한 RIN-m5F 췌장세포 사멸에 발효물의 영향을 관찰한 결과 MC-LM을 농도별로 처리한 군에서 세포생존율이 유의적으로(p<0.05) 증가하였으며 $1000{\mu}g/mL$ 농도에서 MC군 보다 20% 높게 증가되었다. Alloxan에 의한 ${\beta}-cell$파괴를 유도하여 RIN-m5F cell이 분비한 인슐린의 측정결과 MC-LM을 농도별로 첨가한 모든 군에서 인슐린 분비능이 증가하는 경향을 보였으며, $1000{\mu}g/mL$ 농도에서 MC군 보다 15% 높게 증가되었다. 결론적으로 본 연구에서 관찰된 결과들을 통해 여주 발효물은 항산화 및 항당뇨 효과가 있는 것으로 확인되었다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제12권1호
• /
• pp.13-23
• /
• 2008

The aim of the present study was designed to establish comparatively the inhibitory effects of $D_1$-like and $D_2$-like dopaminergic receptor agonists, SKF81297 and R(-)-TNPA on the release of catecholamines (CA) evoked by cholinergic stimulation and membrane depolarization from the isolated perfused model of the rat adrenal medulla. SKF81297 $(30{\mu}M)$ and R-(-)-TNPA $(30{\mu}M)$ perfused into an adrenal vein for 60 min, produced great inhibition in the CA secretory responses evoked by ACh $(5.32{\times}10^{-3}\;M)$, DMPP $(10^{-4}\;M)$, McN-A-343 $(10^{-4}\;M)$, high $K^+$ $(5.6{\times}10^{-2}\;M)$, Bay-K-8644 $(10{\mu}M)$, and cyclopiazonic acid $(10{\mu}M)$, respectively. For the release of CA evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid, the following rank order of inhibitory potency was obtained: SKF81297>R-(-)-TNPA. However, R(+)-SCH23390, a selectve $D_1$-like dopaminergic receptor antagonist, and S(-)-raclopride, a selectve $D_2$-like dopaminergic receptor antagonist, enhanced the CA secretory responses evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid only for $0{\sim}4$ min. The rank order for the enhancement of CA release evoked by high $K^+$, McN-A-343 and cyclopiazonic acid was R(+)-SCH23390>S(-)-raclopride. Also, the rank order for ACh, DMPP and Bay-K-8644 was S(-)-raclopride > R(+)-SCH23390. Taken together, these results demonstrate that both SKF81297 and R-(-)-TNPA inhibit the CA release evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors and the membrane depolarization from the isolated perfused rat adrenal gland without affecting the basal release, respectively, but both R(+)-SCH23390 and S(-)-raclopride facilitate the CA release evoked by them. It seems likely that the inhibitory effects of SKF81297 and R-(-)-TNPA are mediated by the activation of $D_1$-like and $D_2$-like dopaminergic receptors located on the rat adrenomedullary chromaffin cells, respectively, whereas the facilitatory effects of R(+)-SCH23390 and S(-)-raclopride are mediated by the blockade of $D_1$-like and $D_2$-like dopaminergic receptors, respectively: this action is possibly associated with extra- and intracellular calcium mobilization. Based on these results, it is thought that the presence of dopaminergic $D_1$ receptors may play an important role in regulation of the rat adrenomedullary CA secretion, in addition to well-known dopaminergic $D_2$ receptors.

• Nutrition Research and Practice
• /
• 제9권4호
• /
• pp.343-349
• /
• 2015

BACKGROUND/OBJECTIVES: Fermentation of dietary fiber results in production of various short chain fatty acids in the colon. In particular, butyrate is reported to regulate the physical and functional integrity of the normal colonic mucosa by altering mucin gene expression or the number of goblet cells. The objective of this study was to investigate whether butyrate modulates mucin secretion in LS174T human colorectal cells, thereby influencing the adhesion of probiotics such as Lactobacillus and Bifidobacterium strains and subsequently inhibiting pathogenic bacteria such as E. coli. In addition, possible signaling pathways involved in mucin gene regulation induced by butyrate treatment were also investigated. MATERIALS/METHODS: Mucin protein content assay and periodic acid-Schiff (PAS) staining were performed in LS174T cells treated with butyrate at various concentrations. Effects of butyrate on the ability of probiotics to adhere to LS174T cells and their competition with E. coli strains were examined. Real time polymerase chain reaction for mucin gene expression and Taqman array 96-well fast plate-based pathway analysis were performed on butyrate-treated LS174T cells. RESULTS: Treatment with butyrate resulted in a dose-dependent increase in mucin protein contents in LS174T cells with peak effects at 6 or 9 mM, which was further confirmed by PAS staining. Increase in mucin protein contents resulted in elevated adherence of probiotics, which subsequently reduced the adherent ability of E. coli. Treatment with butyrate also increased transcriptional levels of MUC3, MUC4, and MUC12, which was accompanied by higher gene expressions of signaling kinases and transcription factors involved in mitogen-activated protein kinase (MAPK) signaling pathways. CONCLUSIONS: Based on our results, butyrate is an effective regulator of modulation of mucin protein production at the transcriptional and translational levels, resulting in changes in the adherence of gut microflora. Butyrate potentially stimulates the MAPK signaling pathway in intestinal cells, which is positively correlated with gut defense.

• Journal of Ginseng Research
• /
• 제42권2호
• /
• pp.218-224
• /
• 2018

Background: Compound K (CK) is a ginsenoside, a metabolite of Panax ginseng. There is interest both in increasing skin health and antiaging using natural skin care products. In this study, we explored the possibility of using CK as a cosmetic ingredient. Methods: To assess the antiaging effect of CK, RT-PCR was performed, and expression levels of matrix metalloproteinase-1, cyclooxygenase-2, and type I collagen were measured under UVB irradiation conditions. The skin hydrating effect of CK was tested by RT-PCR, and its regulation was explored through immunoblotting. Melanin content, melanin secretion, and tyrosinase activity assays were performed. Results: CK treatment reduced the production of matrix metalloproteinase-1 and cyclooxygenase-2 in UVB irradiated NIH3T3 cells and recovered type I collagen expression level. Expression of skin hydrating factors-filaggrin, transglutaminase, and hyaluronic acid synthases-1 and -2-were augmented by CK and were modulated through the inhibitor of ${\kappa}B{\alpha}$, c-Jun N-terminal kinase, or extracellular signal-regulated kinases pathway. In the melanogenic response, CK did not regulate tyrosinase activity and melanin secretion, but increased melanin content in B16F10 cells was observed. Conclusion: Our data showed that CK has antiaging and hydrating effects. We suggest that CK could be used in cosmetic products to protect the skin from UVB rays and increase skin moisture level.