• 대한약리학회지
• /
• 제2권1호
• /
• pp.71-82
• /
• 1966

The inhibitory effect of 5-hydroxytryptamine (5-HT) on the isolated intestinal strips of the tortoise (Amyda japonica), rat, rabbit and guinea pig was investigated. 1) The strips from the middle or lower part of the tortoise intestine responded with relaxation to 5-HT $(10^{-9}{\sim}10^{-5}g/ml)$, and the magnitude of the relaxation was proportional to the dose of 5-HT. The rectal part of the tortoise intestine, in contrast, showed contraction, the magnitude of which also was proportional to the dose of 5-HT. 2) Various blocking agents such as methysergide, morphine, tetracaine, nethalide, bretylium, hexamethonium, mecamylamine and chlorisondamine, showed no selective blocking activity on the relaxant effect of 5-HT on the tortoise intestine. The inhibitory effect of isoproterenol on the tortoise intestine, however, was selectively blocked by nethalide, and the stimulatory effect of 5-HT on the rectal part of the tortoise was blocked by methysergide. 3) In the presence of 5-HT, the stimulatory effect of DMPP on the tortoise intestine was remarkably attenuated, whereas that of acetylcholine and $BaCl_2$ was little affected. In the presence of isoproterenol, the stimulatory effect of acetylcholine and $BaCl_2$ were affected, but that of DMPP was little affected. 4) Large dose of 5-HT($10^{-4}$g/ml) produced inhibitory effect on the strips from the distal part of the isolated colon of the rat, rabbit and guinea pig, when the strips had been exposed to 5-HT($10^{-4}$g/ml), methysergide or phen`oxybenzamine. 5) Bretylium, as well as nethalide, abolished or remarkably reduced, in a few cases of the experiments, the inhibitory effect of the large dose of 5-HT on the distal part of the colon, whereas morphine did not affect it. 6) The ileal strips of the guinea pig also showed relaxation, as in the colonic strips, having been exposed to the large dose of 5-HT or phenoxybenzamine. This effect, however, was not obsered in the case of the rabbit ileum. 7) The property of the action-site of 5-HT in the tortoise intestine seemd to be different from the 5-HT receptors which have been revealed by several investigators. 8) Adrenergic component seemed to be participated in the inhibitory effect of 5-HT on the colon of the rat and rabbit.

• The Korean Journal of Physiology and Pharmacology
• /
• 제4권6호
• /
• pp.471-477
• /
• 2000

In the rabbit renal artery, acetylcholine $(ACh,\;1\;nM{\sim}10\;{\mu}M)$ induced endothelium-dependent relaxation of arterial rings precontracted with norepinephrine $(NE,\;1\;{\mu}M)$ in a dose-dependent manner. $N^G-nitro- L-arginine$ (L-NAME, 0.1 mM), an inhibitor of NO synthase, or ODQ $(1\;{\mu}M),$ a soluble guanylate cyclase inhibitor, partially inhibited the ACh-induced endothelium-dependent relaxation. The ACh-induced relaxation was abolished in the presence of 25 mM KCl and L-NAME. The cytochrome P450 inhibitors, 7- ethoxyresorufin $(7-ER,\;10\;{\mu}M),$ miconazole $(10\;{\mu}M),$ or 17-octadecynoic acid $(17-ODYA,\;10\;{\mu}M),$ failed to inhibit the ACh-induced relaxation in the presence of L-NAME. 11,12-epoxyeicosatrienoic acid $(11,12-EET,\;10\;{\mu}M)$ had no relaxant effect. The ACh-induced relaxation observed in the presence of L-NAME was significantly reduced by a combination of iberiotoxin $(0.3\;{\mu}M)$ and apamin $(1\;{\mu}M),$ and almost completely blocked by 4-aminopyridine (5 mM). The ACh-induced relaxation was antagonized by $P_{2Y}$ receptor antagonist, cibacron blue $(10\;and\;100\;{\mu}M),$ in a dose-dependent manner. Furthermore, 2-methylthio-ATP (2MeSATP), a potent $P_{2Y}$ agonist, induced the endothelium-dependent relaxation, and this relaxation was markedly reduced by either the combination of iberiotoxin and apamin or by cibacron blue. In conclusion, in renal arteries isolated from rabbit, ACh produced non-NO relaxation that is mediated by an EDHF. The results also suggest that ACh may activate the release of ATP from endothelial cells, which in turn activates $P_{2Y}$ receptor on the endothelial cells. Activation of endothelial $P_{2Y}$ receptors induces a release of EDHF resulting in a vasorelaxation via a mechanism that involves activation of both the voltage-gated $K^+$ channels and the $Ca^{2+}-activated\;K^+\;channels$. The results further suggest that EDHF does not appear to be a cytochrome P450 metabolite.

• Biomolecules & Therapeutics
• /
• 제20권6호
• /
• pp.538-543
• /
• 2012

The Maillard Reaction Products (MRPs) are chemical compounds which have been known to be effective in chemoprevention. Death receptors (DR) play a central role in directing apoptosis in several cancer cells. In our previous study, we demonstrated that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal, a MRP product, inhibited human colon cancer cell growth by inducing apoptosis via nuclear factor-${\kappa}B$ (NF-${\kappa}B$) inactivation and $G_2$/M phase cell cycle arrest. In this study, (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate, a new (E)-2,4-bis(p-hydroxyphenyl)-2-butenal derivative, was synthesized to improve their solubility and stability in water and then evaluated against NCI-H460 and A549 human lung cancer cells. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate reduced the viability in both cell lines in a time and dose-dependent manner. We also found that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate increased apoptotic cell death through the upregulation of the expression of death receptor (DR)-3 and DR6 in both lung cancer cell lines. In addition to this, the transfection of DR3 siRNA diminished the growth inhibitory and apoptosis inducing effect of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate on lung cancer cells, however these effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate was not changed by DR6 siRNA. These results indicated that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal diacetate inhibits human lung cancer cell growth via increasing apoptotic cell death by upregulation of the expression of DR3.

• Journal of Ginseng Research
• /
• 제34권3호
• /
• pp.246-253
• /
• 2010

Ginsenoside $Rg_3$ ($Rg_3$), one of the active ingredients in Panax ginseng, attenuates NMDA receptor-mediated currents in vitro and antagonizes NMDA receptors through a glycine modulatory site in rat cultured hippocampal neurons. In the present study, we examined the neuroprotective effects of $Rg_3$ on 24-hydroxycholesterol (24-OH-chol)-induced cytotoxicity in vitro. The results showed that $Rg_3$ treatment significantly and dose-dependently inhibited 24-OH-chol-induced cell death in rat cultured cortical neurons, with an $IC_{50}$ value of $28.7{\pm}7.5\;{\mu}m$. Furthermore, the $Rg_3$ treatment not only significantly reduced DNA damage, but also dose-dependently attenuated 24-OH-chol-induced caspase-3 activity. To study the mechanisms underlying the in vitro neuroprotective effects of $Rg_3$ against 25-OH-chol-induced cytotoxicity, we also examined the effect of $Rg_3$ on intracellular $Ca^{2+}$ elevations in cultured neurons and found that $Rg_3$ treatment dose-dependently inhibited increases in intracellular $Ca^{2+}$, with an $IC_{50}$ value of $40.37{\pm}12.88\;{\mu}m$. Additionally, $Rg_3$ treatment dose-dependently inhibited apoptosis with an $IC_{50}$ of $47.3{\pm}14.2\;{\mu}m$. Finally, after confirming the protective effect of $Rg_3$ using a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, we found that $Rg_3$ is an active component in ginseng-mediated neuroprotection. These results collectively indicate that $Rg_3$-induced neuroprotection against 24-OH-chol in rat cortical neurons might be achieved via inhibition of a 24-OH-chol-mediated $Ca^{2+}$ channel. This is the first report to employ cortical neurons to study the neuroprotective effects of $Rg_3$ against 24-OH-chol. In conclusion, $Rg_3$ was effective for protecting cells against 24-OH-chol-induced cytotoxicity in rat cortical neurons. This protective ability makes $Rg_3$ a promising agent in pathologies implicating neurodegeneration such as apoptosis or neuronal cell death.

• Molecules and Cells
• /
• 제37권11호
• /
• pp.833-840
• /
• 2014

Cullin4-RING ubiquitin ligase (CRL4) is a family of multi-subunit E3 ligases. To investigate the possible involvement of CRL4 in heat stress response, we screened T-DNA insertion mutants of putative CRL4 substrate receptors that exhibited altered patterns in response to heat stress. One of the mutants exhibited heat stress tolerance and was named heat stress tolerant DWD1 (htd1). Introduction of HTD1 gene into htd1-1 led to recovery of heat sensitivity to the wild type level, confirming that the decrease of HTD1 transcripts resulted in heat tolerance. Therefore, HTD1 plays a negative role in thermotolerance in Arabidopsis. Additionally, HTD1 directly interacted with DDB1a in yeast two-hybrid assays and associated with DDB1b in vivo, supporting that it could be a part of a CRL4 complex. Various heat-inducible genes such as HSP14.7, HSP21, At2g03020 and WRKY28 were hyper-induced in htd1-1, indicating that HTD1 could function as a negative regulator for the expression of such genes and that these genes might contribute to thermotolerance of htd1-1, at least in part. HTD1 was associated with HSP90-1, a crucial regulator of thermotolerance, in vivo, even though the decrease of HTD1 did not affect the accumulation pattern of HSP90-1 in Arabidopsis. These findings indicate that a negative role of HTD1 in thermotolerance might be achieved through its association with HSP90-1, possibly by disturbing the action of HSP90-1, not by the degradation of HSP90-1. This study will serve as an important step toward understanding of the functional connection between CRL4-mediated processes and plant heat stress signaling.

• Journal of Yeungnam Medical Science
• /
• 제7권1호
• /
• pp.39-50
• /
• 1990

세포막의 정보전달기전중 phosphoinositide system은 정보가 전달될때 phospholipase C 효소의 작용으로 phosphatidyl inositol bisphosphate로부터 inositol triphosphate($IP_3$)와 diacylglycerol이 생성되며 $IP_3$는 다시 $IP_3$kinase에 의해 inositol tetrakisphosphate($IP_4$)로 되어 이차전령 물로서 작용한다. 본 연구는 $IP_3$kinase효소가 $Ca^{2+}$와 calmodulin에 의해 활성화되는 성질을 이용하여 calmodulin을 정제하고 $IP_3$kinase효소와의 친화도를 비교 관찰하였다. Calmodulin정제는 phenyl-Sepharose resin을 이용하여 column chromatography를 시행하여 정제확인하였으며 분자량이 17,000임을 SDS-polyacrylamide gel 전기영동으로 확인하였다. 정제된 calmodulin을 affigel column에 결합시킨 gel에 소의 뇌로부터 분리한 $IP_3$kinase효소가 담긴 시료를 calmodulin-affigel column에 적용하여 결합 및 유출정도를 비교하였으며 $Ca^{2+}$이 든 buffer에서 친화도가 가장 컸으며 유출은 EGTA용액에서 일부 유출되었으며 calmodulin/$Ca^{2+}$이 든 buffer에선 강한 유출정도를 관찰하였다. 그러나 calmodulin/$Ca^{2+}$는 $IP_3$kinase효소의 활성을 증가시키며 calmodulin이 단백질이어서 정제면에서 효소와의 분리가 쉽지않아 여러 다른 detergent를 적용하였으나 0.2% chaps buffer에서 집중된 유출을 관찰하였다.

• Experimental and Molecular Medicine
• /
• 제50권12호
• /
• pp.2.1-2.12
• /
• 2018

Glucagon-like peptide-1 (GLP-1) has a broad spectrum of biological activity by regulating metabolic processes via both the direct activation of the class B family of G protein-coupled receptors and indirect nonreceptor-mediated pathways. GLP-1 receptor (GLP-1R) agonists have significant therapeutic effects on non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) in animal models. However, clinical studies indicated that GLP-1 treatment had little effect on hepatic steatosis in some NAFLD patients, suggesting that GLP-1 resistance may occur in these patients. It is well-known that the gut metabolite sodium butyrate (NaB) could promote GLP-1 secretion from intestinal L cells. However, it is unclear whether NaB improves hepatic GLP-1 responsiveness in NAFLD. In the current study, we showed that the serum GLP-1 levels of NAFLD patients were similar to those of normal controls, but hepatic GLP-1R expression was significantly downregulated in NAFLD patients. Similarly, in the NAFLD mouse model, mice fed with a high-fat diet showed reduced hepatic GLP-1R expression, which was reversed by NaB treatment and accompanied by markedly alleviated liver steatosis. In addition, NaB treatment also upregulated the hepatic p-AMPK/p-ACC and insulin receptor/insulin receptor substrate-1 expression levels. Furthermore, NaB-enhanced GLP-1R expression in HepG2 cells by inhibiting histone deacetylase-2 independent of GPR43/GPR109a. These results indicate that NaB is able to prevent the progression of NAFL to NASH via promoting hepatic GLP-1R expression. NaB is a GLP-1 sensitizer and represents a potential therapeutic adjuvant to prevent NAFL progression to NASH.

• 생명과학회지
• /
• 제32권3호
• /
• pp.256-262
• /
• 2022

옥시스테롤은 담즙산 합성 동안 일련의 효소 반응에 의해 생성된 콜레스테롤의 산화물로써, 콜레스테롤과 유사하게 세포내 영역으로 빠르게 이동하여 면역 세포 반응, 지질 대사 및 콜레스테롤 항상성과 같은 다양한 세포 과정을 조절한다. 글루코코르티코이드 수용체(GR), 에스트로겐 수용체(ER) 및 간 X 수용체(LXR)와 같은 종류의 핵 수용체는 여러 조직에서 옥시스테롤에 의해 조절될 수 있다. 가장 풍부한 옥시스테롤인 27-하이드록시콜레스테롤(27-OHC)은 조직 특이적 방식에 의해 에스트로겐 수용체 활성을 활성화하거나 억제하기 때문에 선택적 에스트로겐 수용체 조절자로 규명되었다. 특히 27-하이드록시콜레스테롤이 동맥 경화증 플라크에서 많이 발견되고 대식세포가 거품 세포로 변형되는 것을 가속화하기 때문에 동맥 경화증 발병에 기여하는 것이 분명해 보이나, 다른 연구들에서는 27-하이드록시콜레스테롤이 간 및 지방 조직을 포함한 다양한 대사 기관에 미치는 영향에 대해 반대 의견이 존재한다. 따라서 본 총설을 통해 대사 조직에서의 27-하이드록시콜레스테롤 역할에 대한 논의와 함께, 죽상 동맥 경화증 및 대사 증후군에 영향을 주는 27-하이드록시콜레스테롤의 세부 기전에 대해 논의하고자 한다.

• 한국자원식물학회:학술대회논문집
• /
• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
• /
• pp.50-50
• /
• 2023

Prostaglandin E2(PGE2), a major product of cyclooxygenase-2 (COX-2), plays an important role in the carcinogenesis of many solid tumors, including colorectal cancer. Because PGE2 functions by signaling through PGE2 receptors (Eps), which regulate tumor cell growth, invasion, and migration, there has been a growing amount of interest in the therapeutic potential of targeting Eps. In the present study, we investigated the role of EP4 on the effectiveness of cordycepin in inhibititing the migration and invasion of HCT116 human colorectal carcinoma cells. Our data indicate that cordycepin suppressed lipopolysaccharide (LPS)-enhanced cell migration and invasion through the inactivation of matrix metalloproteinases (MMP)-9 as well as the down-regulation of COX-2 expression and PGE2 production. These events were shown to be associated with the inactivation of EP4 and activation of AMP-activated protein kinase (AMPK). Moreover, the AMPK inhibitor, compound C, as well as AMPK knockdown via siRNA, attenuated the cordycepin-induced inhibition of EP4 expression. Cordycepin treatment also reduced the activation of CREB. These findings indicate that cordycepin suppresses the migration and invasion of HCT116 cells. Through modulating EP4 expression and the AMPK-CREB signaling pathway. Therefore, cordycepin has the potential to serve as a potent anti-cancer agent in therapeutic strategies against colorectal cancer metastasis.

• 한국발생생물학회지:발생과생식
• /
• 제17권4호
• /
• pp.441-449
• /
• 2013

Recent study showed that T cells in the immune organs and peripheral blood are influenced by estradiol, leading to a dysfunction of the immune system. However, little is known about the thymic-gonadal relationship during the estrous cycle in mouse. Therefore, the purpose of this study was to elucidate the mechanism by which a change in estradiol levels during the estrous cycle regulates the development of T cells in the mouse thymus. Six-week-old ICR mice were used and divided into four groups, including diestrous, proestrous, estrous, and metestrous. We first confirmed that ER-${\alpha}$ and - ${\beta}$ estrogen receptors were expressed in thymic epithelial cells, showing that their expression was not different during the estrous cycle. There was also no significant difference in thymic weight and total number of thymocytes during the estrous cycle. To determine the degree of thymocyte differentiation during the estrous cycle, we analyzed thymocytes by flow cytometry. As a result, the percentage of CD4+CD8+ double-positive (DP) T cells was significantly decreased in the proestrous phase compared to the diestrous phase. However, CD4+CD8- or CD4-CD8+ (SP) T cells were significantly increased in the proestrous phase compared to the diestrous phase. In addition, the percentage of CD44+CD25- (DN1) T cells was significantly decreased in the estrous phase compared to other phases, whereas the percentages of CD44+CD25+ (DN2), CD44-CD25+ (DN3), and CD44-CD25- (DN4) were not changed during the estrous cycle. These results indicate that the development of thymocytes may arrest in the DP to SP transition stage in the proestrous phase displaying the highest serum level of estradiol. This study suggests that a change in estradiol levels during the estrous cycle may be involved in the regulation of thymocyte differentiation in the mouse thymus.