• Asian-Australasian Journal of Animal Sciences
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• 제27권5호
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• pp.757-766
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• 2014

Postnatal muscle hypertrophy of beef cattle is the result of enhanced myofibrillar protein synthesis and reduced protein turnover. Skeletal muscle hypertrophy has been studied in cattle fed ${\beta}$-adrenergic agonists (${\beta}$-AA), which are receptor-mediated enhancers of protein synthesis and inhibitors of protein degradation. Feeding ${\beta}$-AA to beef cattle increases longissimus muscle cross-sectional area 6% to 40% compared to non-treated cattle. The ${\beta}$-AA have been reported to improve live animal performance, including average daily gain, feed efficiency, hot carcass weight, and dressing percentage. Treatment with ${\beta}$-AA increased mRNA concentration of the ${\beta}_2$ or ${\beta}_1$-adrenergic receptor and myosin heavy chain IIX in bovine skeletal muscle tissue. This review will examine the effects of skeletal muscle and adipose development with ${\beta}$-AA, and will interpret how the use of ${\beta}$-AA affects performance, body composition, and growth in beef cattle.

• Biomolecules & Therapeutics
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• 제4권1호
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• pp.103-109
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• 1996

To investigate the effect of the third intracellular loop (i3 loop) peptide of human $\beta$$_2$-adrenergic receptor on receptor agonist binding, we expressed third intracellular loop region of human $\beta$$_2$-adrenergic receptor as glutathione S-transferase fusion protein in E. coli. DNA fragment of the receptor gene which encodes amino acid 221-274 of human $\beta$$_2$-adrenergic receptor was amplified by polymerase chain reaction and subcloned into the bacterial fusion protein expression vector pGEX-CS and expressed as a form of glutathione-S-transferase (GST) fusion protein in E. coli DH5$\alpha$. The receptor fusion protein was identified by SDS-PAGE and Western blot using monoclonal anti-GST antibody. The fusion protein expressed in this study was purified to an apparent homogeneity by glutathione Sepharose CL-4B affinity chromatography. The purified i3 loop fusion proteins at a concentration of 10 $\mu\textrm{g}$/ι caused right shift of the isoproterenol competition curve of [$^3$H]Dihydroalprenolol binding to hamster lung $\beta$$_2$-adrenergic receptor indicating lowered affinity of isoproterenol to $\beta$$_2$-adrenergic receptor possibly due to the uncoupling of receptor and G protein in the presence of the fusion protein. The uncoupling of receptor and G protein suggests that i3 loop region plays a critical role on $\beta$$_2$-adrenergic receptor G protein coupling.

• Biomolecules & Therapeutics
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• 제4권1호
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• pp.97-102
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• 1996

To investigate whether human $\beta$$_2$-adrenergic receptor devoid of the C-terminal two transmembrane helices retain its ligand binding activity and specificity, 5'780-bp DNA fragment of the receptor gene which encodes amino acid 1-260 of human $\beta$$_2$-adrenergic receptor was subcloned into the bacterial fusion protein expression vector and expressed as a form of glutathione-S-transferase (GST) fusion protein in E. coli DH5$\alpha$. The receptor fusion protein was expressed as a membrane bound form which was verified by SDS-PAGE and Western blot. The fusion protein expressed in this study specifically bound $\beta$-adrenergic receptor ligand [$^3$H] Dihydroalprenolol. In saturation ligand binding assay, the $K_{d}$ value was 7.6 nM which was similar to that of intact $\beta$$_2$-adrenergic receptor in normal animal tissue ( $K_{d}$=1~2 nM) and the $B_{max}$ value was 266 fmol/mg membrane protein. In competition binding assay, the order of binding affinity of various adrenergic receptor agonists to the fusion protein was isoproterenol》epinephrine norepinephrine, which was similar to that of intact receptor in normal animal tissue. These results suggest that N-terminal five transmembrane helices of the $\beta$$_2$-adrenergic receptor be sufficient to determine the ligand binding activity and specificity, irrespective of the presence or absence of the C-terminal two transmembrane helices.s.s.s.

• The Korean Journal of Physiology and Pharmacology
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• 제2권6호
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• pp.753-761
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• 1998

Preconditioning of a heart with small doses of catecholamines induces a tolerance against the subsequent lethal ischemia. The present study was performed to find a specific receptor pathway involved with the catecholamine preconditioning and to test if adenosine plays a role in this cardioprotective effect. Isolated rat hearts, pretreated with small doses of ${\alpha}-\;or\;{\beta}-adrenergic$ agonists/antagonists, were subjected to 20 minutes ischemia and 20 minutes reperfusion by Langendorff perfusion method. Cardiac mechanical functions, lactate dehydrogenase and adenosine release from the hearts were measured before and after the drug treatments and ischemia. In another series of experiments, adenosine $A_1\;or\;A_2$ receptor blockers were treated prior to administration of adrenergic agonists. Pretreatments of a ${\beta}-agonist,\;isoproterenol(10^{-9}{\sim}10^{-7}\;M)$ markedly improved the post-ischemic mechanical function and reduced the lactate dehydrogenase release. Similar cardioprotective effect was observed with an ?-agonist, phenylephrine pretreatment, but much higher $concentration(10^{-4}\;M)$ was needed to achieve the same degree of cardioprotection. The cardioprotective effects of isoproterenol and phenylephrine pretreatments were blocked by a ${\beta}_1-adrenergic$ receptor antagonist, atenolol, but not by an ${\alpha}_1-antagonist,$ prazosin. Adenosine release from the heart was increased by isoproterenol, and the increase was also blocked by atenolol, but not by prazosin. A selective $A_1-adenosine$ receptor antagonist, 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX) blocked the cardioprotection by isoproterenol pretreatment. These results suggest that catecholamine pretreatment protects rat myocardium against ischemia and reperfusion injury by mediation of ${\beta}_1-adrenergic$ receptor pathway, and that adenosine is involved in this cardioprotective effect.

• 한국어류학회지
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• 제12권1호
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• pp.38-45
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• 2000

어종에 따라 혈관의 긴장도 조절은 다양한 신경전달물질에 의하여 조절되고 있다. 그러나 아직 대부분의 어종에서 자율신경계 신경전달물질 및 혈관긴장도 조절인자들의 기능에 대하여 명확하게 규명되어 있지 않다. 본 연구는 아직 연구되지 않은 분야인 이스라엘잉어에서의 자율신경계 신경전달물질들의 혈관긴장도 조절에서의 역할을 규명하고자 적출복대동맥을 이용하여 시험하였다. 이 적출혈관에서 아세틸콜린 (ACh)은 정상혈관과 미리 일정수준 수축시킨 혈관 모두에서 수축을 유발하였으며 수축작용은 무스카린성 길항제인 아트로핀에 의해 거의 완벽하게 차단되었다. 여러 가지 아드레날린성 수용체를 동시에 흥분시키는 내인성 물질인 에피네프린 (Epi)은 혈관의 조건에 상관없이 이완반응을 유발하였다. 그러나 유사한 내인성물질인 노르에피네프린 (NE)은 정상혈관에서는 미약한 수축율, 미리수축된 혈관에서는 이완작용을 유발하였다. 한편 ${\alpha}_1$ 아드레날린성 수용체 흥분제인 페닐에프린은 수축을, $\beta$수용체 홍분제인 이소프로테레놀은 이완을 각각 유발하였으며 ${\alpha}_2$수용체 흥분제인 클로니딘은 아무런 반응을 유발하지 않았다. Epi, NE 및 이소프로테레놀에 의해 유발된 혈관이완 반응은 $\beta$ 아드레날린성 수용체 길항제인 프로프라놀롤에 의해 유의하게 억제되었다. 따라서 살아있는 상태의 이스라엘 잉어에서는 ACh는 주로 무스카린성 수용체 활성화에 의한 혈관을 수축하는 기능을, Epi과 NE는 $\beta$수용체 흥분에 의한 이완작용을 각각 발휘하는 것으로 판단된다.

• 대한약리학회지
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• 제31권2호
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• pp.219-231
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• 1995

Vasoactive intestinal polypeptide(VIP) and ${\beta}-adrenergic$ agonists have immunomodultory effects on the peripheral blood T-lymphocytes of rat through their own receptors. Both of them utilize the same signal transduction pathway. That is, the stimulatory guanine nucleotide binding protein(G protein) mediates the receptor-adenylyl cyclase coupling, producing intracellular increase of cyclic adenosine monophosphate(cAMP). In the previous experiment, propranolol, a ${\beta}-adrenergic$ receptor blocker, inhibited the VIP-induced protein phosphorylation in lymphocytes. However, propranolol could not block the effect induced by forskolin. Therefore, this study was designed to elucidate the mechanism of the inhibitory action of propranolol on the effects of VIP. Using peripheral blood lymphocytes of rats, the effect of propranolol on the receptor binding characteristics of VIP was observed. And the effects of propranolol were compared to the effects of timolol on the cAMP increase induced by isoproterenol, VIP or forskolin. The results obtained are as follows. 1) Receptor binding study showed no significant differences in the affinity or density of VIP receptor between the control and propranolol-pretreated groups. 2) VIP-induced increase of cAMP was inhibited by propranolol, but not by timolol. 3) Both propranolol and timolol suppressed the isoproterenol-induced cAMP increase. 4) Propranolol also inhibited the histamine-induced cAMP increase. 5) Propranolol did not inhibit the increase of cAMP stimulated by forskolin. 6) Lidocaine did not block the VIP-induced cAMP increase. These results show that the inhibitory mechanism of propranolol is not related to ${\beta}-adrenergic$ receptor or its membrane stabilizing effect, and it is suggested that propranolol can block the effects of VIP by inhibiting the intermediate step between the VIP receptor and adenylyl cyclase.

• International Journal of Oral Biology
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• 제46권1호
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• pp.39-44
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• 2021

This study aimed to investigate whether neurotransmitter receptors in the nervous system were also expressed in oral keratinocytes. Expressions of various neurotransmitter receptor genes in immortalized mouse oral keratinocyte (IMOK) cells were examined by reverse transcriptase polymerase chain reaction. IMOK cells expressed calcitonin gene-related peptide (CGRP) receptor subunit genes Ramp1 and Ramp3 and glutamate receptor subunit genes Grina, Gria3, Grin1, Grin2a, and Grin2d. Moreover, IMOK cells expressed Adrb2 and Chrna5 that encode beta 2 adrenergic receptor and cholinergic receptor nicotinic alpha 5 for sympathetic and parasympathetic neurotransmitters, respectively. The expression of Bdkrb1 and Ptger4, which encode receptors for bradykinin and prostaglandin E2 involved in inflammatory responses, was also observed at low levels. Expressions of Ramp1 and Grina in the mouse gingival epithelium were also confirmed by immunohistochemistry. When the function of neurotransmitter receptors expressed on IMOK cells was tested by intracellular calcium response, CGRP, glutamate, and cholinergic receptors did not respond to their agonists, but the bradykinin receptor responded to bradykinin. Collectively, oral keratinocytes express several neurotransmitter receptors, suggesting the potential regulation of oral epithelial homeostasis by the nervous system.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2008-2014
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• 2011

Serotonin or 5-hydroxytryptamine subtype 2C ($5-HT_{2C}$) receptor belongs to class A amine subfamily of G-protein-coupled receptor (GPCR) super family and its ligands has therapeutic promise as anti-depressant and -obesity agents. So far, bovine rhodopsin from class A opsin subfamily was the mostly used X-ray crystal template to model this receptor. Here, we explained homology model using beta 2 adrenergic receptor (${\beta}$2AR), the model was energetically minimized and validated by flexible ligand docking with known agonists and antagonists. In the active site Asp134, Ser138 of transmembrane 3 (TM3), Arg195 of extracellular loop 2 (ECL2) and Tyr358 of TM7 were found as important residues to interact with agonists. In addition to these, V208 of ECL2 and N351 of TM7 was found to interact with antagonists. Several conserved residues including Trp324, Phe327 and Phe328 were also found to contribute hydrophobic interaction. The predicted ligand binding mode is in good agreement with published mutagenesis and homology model data. This new template derived homology model can be useful for further virtual screening based lead identification.

• 대한약리학회지
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• 제19권1호
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• pp.85-92
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• 1983

Intestine is innervated by an interconnected plexus of both sympathetic and parasympathetic nerve fibers. Sympathetic influence causes inhibition of intestinal motility mediated by both ${\alpha}-\;and\;{\beta}-adrenergic$ receptors. The mechanism of intestinal relaxation by ${\beta}-receptors$ has been extensively studied, but the function of ${\alpha}-receptors$ in intestinal motility is still unclear. Although it is suggested that catecholamine reduces acetylcholine release and this may play an important role in ${\alpha}-receptor$ mediated intestinal relaxation, there is no definite evidences about the mechanism and site of action of ${\alpha}-receptor$ mediated relaxation. In this experiment, therefore, the effect and site of action of ${\alpha}-receptor$ agonists were investigated in the guinea pig ileum using electrical field stimulation. The results are summarized as follows : 1) Electrical field stimulation elicited tonic contraction in isolated guinea pig ileum ana this contraction was completely inhibited by the pretreatment of tetrodotoxin or atropine. 2) Norepinephrine, epinephrine and dopamine inhibited the contraction induced by electrical field stimulation but methoxamine and phenylephrine had little effects. 3) Inhibitory effects of norepinephrine and dopamine was partially blocked by yohimbine and phentolamine pretreatment. But haloperidol and propranolol pretreatment cause no effects on the electrical field stimulation induced contraction. Inhibitory effect of dopamine was completely blocked by both haloperidol and yohimbine pretreatment. 4) Inhibitory effects of norepinephrine and dopamine were little affected by the pretreatment with hexamethonium. It is suggested that electrical field stimulation causes tonic contraction of guinea pig ileum by releasing acetylcholine from postganglionic fiber, and this release is blocked by presynaptic ${\alpha}-receptor$ activation.

• 대한약리학회지
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• 제22권1호
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• pp.24-33
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• 1986

본 연구에서는 개구리(Rana nigromaculata)의 피부에 있어서 전위차(PD), 단락전류(SCC) 및 total skin conductance(TSC)에 미치는 제종 adrenergic agonist 및 그 차단제의 영향을 관찰하여 개구리 피부에 adrenoceptors의 존재를 확인하고 Na 수송에 있어 그들의 역할을 구명코자 하였다. 1.Norepinephrine(NE, $6{\times}10^{-8}-6{\times}10^{-5}M$), phenylephrine($PE,5{\times}10^{-6}-5{\times}10^{-4}M$)의 PD 및 epinephrine(Epi, $5.5{\times}10^{-7}-5.5{\times}10^{-5}M$)의 PD 및 SCC 증가효과는 약물의 투여농도에 비례하였으며, Epi의 최대효과는 NE나 PE의 것보다 약하였다. 2. 이러한 PD 및 SCC의 증가효과는 alpha 1 adrenoceptor 차단체인 prazosin $2{\times}10^{-6}M$에 의해서 억제되었으며, 특히 Epi의 증가효과는 불가역성 alpha receptor 차단제인 phenoxybenzamine $3.3{\times}10^{-5}M$에 의하여 완전히 차단되며 대량의 Epi에 의해서는 PD 및 SCC의 감소를 초래하였다. 3. Beta adrenoceptor agonist인 isoproterenol$(5{\times}10^{-7}-5{\times}10^{-6}M)$에 의해 농도증가에 비례한 PD 및 SCC의 감소가 일어났으며, 이는 선택적 bete receptor 차단제인 propranolol $4{\times}10^{-6}M$에 의해 차단되었다. 또한 Epi의 PD 및 SCC 증가효과는 propranolol $4{\times}10M$에 의하여 강화됨을 볼 수 있었다. 4. Alpha 2 adrenoceptor agonist인 clonidine 및 guanabenz도 PD 및 SCC의 증가를 가져왔으며 이러한 효과는 alpha 2 receptor 차단제인 yohimbine에서 보다 Alpha 1 receptor 차단제인 prazosin에 의해 더 잘 억제되었다. 이상 실험의 결과 개구리 복부피부에도 포유동물에서와 같이 adrenergic alpha 및 beta receptor가 존재하며 alpha receptor는 PD 및 SCC의 증가를, beta receptor는 PD 및 SCC의 감소를 매개하여, 개구리 피부의 Na 수송에 있어 adrenergic system이 중요한 조절작용을 하고 있음을 알 수 있었다. 그러나 여기에 관여하는 alpha receptor는 다른 포유류에서와 같이 alpha 1 및 alpha 2 adrenoceptor로 구분할 수는 없었다.