Presynaptic imidazoline receptors mediate inhibition of noradrenaline release from sympathetic nerves in rat blood vessels

Summary— In rat vena cava and aorta preincubated with [³H]noradrenaline the involvement of imidazoline receptors in modulation of [³H]noradrenaline release from sympathetic nerves was investigated. In the vena cava, the guanidine 1,3-di(2-tolyl)guanidine (DTG) inhibited the electrically evoked [³H]noradrenaline release; the inhibitory effect was more pronounced in the presence than in the absence of the α₂-adrenoceptor antagonist rauwolscine. The concentration-response curves of BDF 6143 [4-chloro-2-(2-imidazolin-2-ylamino)-isoindoline], and idazoxan for their facilitatory effect on electrically evoked [³H]noradrenaline release was bell-shaped; in the presence of rauwolscine, BDF 6143 inhibited the evoked [³H)noradrenaline release, whereas idazoxan did not. After blockade of α₂-autoreceptors by rauwolscine, the electrically evoked [³H]noradrenaline release from vena cava was inhibited not only by DTG and BDF 6143 but also by aganodine, clonidine and cirazoline; the rank order of potency of most of the drugs was similar to that found at the presynaptic imidazoline receptors in the rabbit aorta and pulmonary artery as well as in human atrial appendages. In the presence of rauwolscine, clonidine-induced inhibition of electrically evoked [³H]noradrenaline release was counteracted by 1 μM of the selective CB₁ receptor antagonist SR141716A (N-[piperidin-1-yl]-5-[4-chlorophenyl]-1-[2,4-dichlorophenyl]-4-methyl-1H-pyrazole-3-carboxamide). In the aorta, BDF 6143 and cirazoline did not modify [³H]noradrenaline release in the absence of α₂-adrenoceptor blockade; in the presence of rauwolscine, the electrically evoked [³H]noradrenaline release from aorta was inhibited by BDF 6143, cirazoline, aganodine and Clonidine with a rank order of potency similar to that in the vena cava. SR141716A 1 μM antagonized the inhibitory effect of BDF 6143 and Clonidine (in the presence of rauwolscine). In conclusion, noradrenaline release in rat vena cava and aorta is inhibited via presynaptic imidazoline receptors which appear to be related to those previously characterized in rabbit and human cardiovascular tissue.     

The role of imidazoline receptors in blood pressure regulation.

Using the ligands [3H] clonidine and [3H] idazoxan, nonadrenergic imidazoline preferring binding sites have been identified in a range of tissues from several species including man. These sites may represent a new family of receptors. An endogenous ligand and potential clonidine displacing substance has been identified. There is strong evidence for an involvement of the nonadrenergic imidazoline [3H] clonidine labelled sites in the nucleus reticularis lateralis in blood pressure regulation, and some evidence for a role in sodium regulation in the kidney for the [3H] idazoxan labelled sites. Some drugs which were previously thought to act via alpha 2-adrenoceptors, may mediate their effects in part via these imidazoline sites.     

过敏性哮喘外周血细胞因子白细胞介素2、白细胞介素6及其受体的测定和临床意义

目的　动态检测过敏性哮喘外周血血浆中白细胞介素 2 (IL 2 )、白细胞介素 6(IL 6)及其受体 (IL - 2R、IL - 6R)的变化 ,探讨其在哮喘中的作用。方法　采用间接荧光标记、流式细胞仪和酶联免疫夹心法 (ELSA)进行表型及定量分析。结果　过敏性哮喘急性发作期外周血血浆中IL 2、IL 6及其可溶性受体皆升高 (P <0 .0 1) ,至缓解期也未恢复至正常范围 ;膜型白细胞介素 2受体 [mIL 2R ,即白细胞相关抗原 (CD2 5 ) ]在各期均无变化。结论　IL 2、IL 2R、IL 6、IL 6R参与了哮喘的发生、发展 ,动态观察有助于病情评估 ,同时提示哮喘患者缓解期气道炎症仍持续存在     

莫索尼定降压及逆转左室肥厚的临床效果观察

目的探讨莫索尼定降压效果和逆转患者左室肥厚的作用。方法将80例高血压合并左室肥厚患者分为莫索尼定(治疗)组和卡托普利(对照)组治疗,观察6个月,比较两组血压(BP)和左心室肥厚的变化。结果莫索尼定治疗使BP从(163.5/80.7±16.7/10.5)mmHg降至(125.7/71.3±13.6/8.53)mmHg(P<0.05),左心室质量指数(LVMI)从(145.8±13.0)g/m2降至(122.3±11.8)g/m2(P<0.05),但治疗组的BP和LVMI变化与对照组之间比较无差异。结论莫索尼定具有显著降压作用,长期使用能够显著逆转左心室肥厚。     

Characterization of brain imidazoline receptors in normotensive and hypertensive rats: differential regulation by chronic imidazoline drug treatment.

The binding of [3H]idazoxan in the presence of l-epinephrine was used to characterize and quantitate imidazoline receptors in the brain of spontaneously hypertensive (SHR), normotensive Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats before and after chronic imidazoline drug treatment. In the cerebral cortex of WKY and SHR rats, the rank order of potency of imidazoli(di)ne drugs (cirazoline greater than idazoxan greater than naphazoline greater than clonidine much greater than RX821002) competing with [3H]idazoxan showed the specificity for an imidazoline receptor which also appeared heterogeneous in nature. In SHR rats, the density of imidazoline receptors (hypothalamus greater than medulla oblongata greater than cerebral cortex) and proportion of high- and low-affinity sites for the receptor were not different from those in WKY and SD rats, suggesting that the receptor itself is not altered in hypertension. However, chronic treatment with idazoxan and cirazoline (10 and 1 mg/kg, i.p., every 12 h for 7 days) consistently increased (about 35%) the density of imidazoline receptors in the brain of WKY and SD, but not in SHR rats. A similar treatment with RX821002, the 2-methoxy analog of idazoxan, which is a highly selective alpha-2 adrenoceptor antagonist, did not increase the density of brain imidazoline receptors. Moreover, the up-regulation of these receptors induced by cirazoline was still present after alkylation of the alpha-2 adrenoceptors with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. The lack of regulation by idazoxan and cirazoline of the density of imidazoline receptors in the brain of SHR rats suggests the existence of a relevant abnormality in the adaptive process of these receptors in this genetic model of hypertension.     

Imidazoline-guanidine site: a subtype of imidazoline receptors]

Since the demonstration that imidazoline and guanidinium alpha-2 adrenergic agonists induce some of their functional effects by a "nonadrenergic" mechanism, many efforts have been done to identify an imidazoline receptor. Binding studies have allowed to characterize two classes of potential imidazoline receptors: the "(p-amino)clonidine" and the "idazoxan" binding sites. These last, that we named "imidazoline-guanidinium receptive sites" (IGRS) on the basis of their ligand-recognition properties, have been identified, for the first time, in the proximal tubule from rabbit and human kidney. In the present report we will summarize the studies that led us to the characterization of IGRS.     

Pharmacology of imidazoline receptors and cardiovascular regulation. Imidazoline receptors and blood pressure]

To explain the central hypotensive action of clonidine- and rilmenidine-type drugs, a recent hypothesis suggested the involvement of imidazoline preferring receptors (IPR) insensitive to catecholamines. Binding studies performed on neuronal membranes prepared from the human Nucleus Reticularis Lateralis area (NRL) showed that rilmenidine was twice as selective as clonidine for the medullary IPRs. Voltammetric experiments revealed that these substances preferentially inhibited the activity of catecholaminergic neurones within the NRL, privileged site for their hypotensive action, rather than the activity of the neurones of the Locus Coeruleus (LC) where these drugs induce their sedative effect. The mechanism of the inhibitory action of these compounds upon the neurones of the NRL definitely involved IPRs when the inhibition of the LC neurones involved classical alpha-2-adrenoceptors. These functional studies also showed that rilmenidine exhibited a selectivity twice as important as clonidine, the reference substance. Poly- and monoclonal anticlonidine antibodies cross-reacting only with imidazolines allowed to detect and immunoreactive substance in the human serum. The amounts of that substance thus measured were higher in some hypertensive patients than in normotensive subjects. The identity of that immunoreactive substance with "endazoline", the endogenous ligand of the IPRs, is presently analysed.     

Functional characterization of pheromone receptors in the tobacco budworm Heliothis virescens

Functional analyses of candidate Heliothis virescens pheromone odorant receptors (HvORs) were conducted using heterologous expression in Xenopus oocytes. HvOR6 was found to be highly tuned to Z9-14:Ald, while HvOR13, HvOR14 and HvOR16 showed specificity for Z11-16:Ald, Z11-16:OAc and Z11-16:OH, respectively. HvOR15, which had been considered a candidate receptor for Z9-14:Ald did not respond to any of the pheromone compounds tested, nor to 50 other general odorants. Thus, while HvOR15 is specifically expressed in H. virescens male antennae, its role in pheromone reception remains unknown. Based on our results and previous research we can now assign pheromone receptors in H. virescens males to each of the critical H. virescens agonistic pheromone compounds and two antagonistic compounds produced by heterospecific females.     

Involvement of α2‐adrenoceptors,imidazoline, and endothelin‐A receptors in the effect of agmatine on morphine and oxycodone‐induced hypothermia in mice

Potentiation of opioid analgesia by endothelin‐A (ET_A) receptor antagonist, BMS182874, and imidazoline receptor/α₂‐adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂‐adrenoceptors, imidazoline, and ET_A receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂‐adrenoceptors, imidazoline, and ET_A receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂‐adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET_A receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine‐induced hypothermia. Agmatine‐induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine‐induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂‐adrenoceptors are involved in agmatine‐induced reversal of oxycodone hypothermia. Our findings also suggest that ET_A receptors may be involved in blockade of oxycodone hypothermia by agmatine.     

Leukotriene receptors in atherosclerosis

Leukotriene‐forming enzymes are expressed within atherosclerotic lesions and locally produced leukotrienes exert pro‐inflammatory actions within the vascular wall by means of cell surface receptors of the BLT and CysLT receptor subtypes. The migration and accumulation of inflammatory cells that follow leukotriene receptor activation have been implicated in atherosclerosis initiation and progression. Leukotriene receptors are in addition expressed on endothelial and vascular smooth muscle cells, associated with intimal hyperplasia in early atherosclerosis and restenotic lesions after angioplasty. Taken together, recent evidence suggests that leukotriene receptors may be a potential target in the treatment of atherosclerosis and in the prevention of restenosis after coronary interventions.     

Metabotropic glutamate receptors: an original family of G protein-coupled receptors

Summary— In 1985, we discovered a new glutamate receptor which was coupled to phospholipase C via a G protein and which was later termed metabotropic glutamate receptor (mGluR). In this review, both the diversity of mGluRs and the cellular events they control are discussed, as well as their roles in physiological regulation and brain function.     

雌、孕激素受体在乳腺癌及增生性病变组织中的表达及意义

目的 探讨雌、孕激素受体在女性乳腺癌与各种增生性病变组织中的表达及临床意义.方法 取2006年2月至2007年2月中日联谊医院乳腺甲状腺外科手术后经病理科诊断证实的病例,乳腺增生性疾病52例(40人),乳腺癌52例(49人).其中普通型增生10例,轻度非典型增生12例,中度非典型增生9例,重度非典型增生21例,乳腺浸润性导管癌52例.用免疫组化SP法检测ER、PR的表达.结果 在乳腺普通型增生、轻、中、重度非典型增生及乳腺浸润性导管癌组织中ER表达的阳性率分别为30.00%、41.67%、44.44%、61.90%和69.23%,PR表达的阳性率分别为20.00%、25.00%、44.44%、52.38%和55.77%,ER阳性和/或PR阳性率分别为30.00%、41.67%、55.56%、66.67%、69.23%,仅普通型增生与乳腺癌组织中有显著性差异.结论 (1)乳腺普通型增生与乳腺癌组织无明显联系.其余三种非典型增生组织中ER、PR阳性表达率与乳腺癌组织差异不显著,且其相关性由轻、中、重度逐级递增.(2)ER、PR表达强度的逐级递增及单细胞中强阳性( )率的逐级增高表明这一过程与雌激素过刺激有关,因此对乳腺增生性疾病行ER、PR检测有利于早期发现乳腺癌,根据ER、PR检测结果判断病变向乳腺癌发展的风险性.(3)在ER和/或PR阳性的乳腺增生性疾病患者中可以考虑应用内分泌治疗.     

Detection of steroid receptors in breast cancer: Relationship between EIA and IHC methods

Lerma E, Esqué C, Peiró G, Mora J, Cerdá I, Prat J. Detection of steroid receptors in breast cancer: relationship between EIA and IHC methods. Scand J Clin Lab Invest 1994; 54: 591-4

The efficiency of EIA and IHC (frozen tissue) in the detection of ER and PR in 51 breast cancers were compared. ER were detected in 51 % of cases by IHC and in 49% of tumours by EIA. PR were detected in 56.8% of cases by IHC and in 54.8% of tumours by EIA. Concordance of the results of IHC and EIA reached 78.4% in ER and 82.4% in PR detection. Discordance between IHC and EIA seems to be related to minor changes in sensibility of methods, but we cannot conclude that one of the two techniques is superior to the other in the detection of hormonal receptors. There is a common trend of association between low grade of histologic or nuclear malignancy and a high expression of hormonal receptors.     

Soluble cytokine receptors in biological therapy

Due to their fundamental involvement in the pathogenesis of many diseases, cytokines constitute key targets for biotherapeutic approaches. The discovery that soluble forms of cytokine receptors are involved in the endogenous regulation of cytokine activity has prompted substantial interest in their potential application as immunotherapeutic agents. As such, soluble cytokine receptors have many advantages, including specificity, low immunogenicity and high affinity. Potential disadvantages, such as low avidity and short in vivo half-lifes, have been addressed by the use of genetically-designed receptors, hybrid proteins or chemical modifications. The ability of many soluble cytokine receptors to inhibit the binding and biological activity of their ligands makes them very specific cytokine antagonists. Several pharmaceutical companies have generated a number of therapeutic agents based on soluble cytokine receptors and many of them are undergoing clinical trials. The most advanced in terms of clinical development is etanercept (Enbrel?, Immunex), a fusion protein between soluble TNF receptor Type II and the Fc region of human IgG1. This TNF-α antagonist was the first soluble cytokine receptor to receive approval for use in humans. In general, most agents based on soluble cytokine receptors have been safe, well-tolerated and have shown only minor side effects in the majority of patients. Soluble cytokine receptors constitute a new generation of therapeutic agents with tremendous potential for applications in a wide variety of human diseases. Two current areas of research are the identification of their most promising applications and characterisation of their long-term effects.     

Toll样受体在大鼠急性胰腺炎发病中的作用研究

目的通过检测Toll受体(TLR)在大鼠急性胰腺炎(AP)胰腺中的表达,探讨TLR在AP炎症启动、AP由水肿向坏死转化、急性坏死性胰腺炎(ANP)肠黏膜损伤革兰阴性细菌的入侵机制。方法 Wistar大鼠42只,随机分为正常对照组、急性水肿性胰腺炎(AEP)组、ANP组、TLR4抗体处理组。检测大鼠胰腺组织形态学变化;TLRs的分布表达规律;血清及腹水胰淀粉酶;胰腺组织干湿比称重;胰腺坏死组织肿瘤坏死因子(TNF)-a、白细胞介素(IL)-1β、IL-6水平。结果与ANP组相比,TLR4抗体处理组胰腺组织坏死区域显著增多,炎性程度显著加重;血清淀粉酶、TNF-a、IL-1β、IL-6测得值在正常对照组与AEP组间、AEP组与ANP组间、ANP组与TLR4抗体处理组间的比较均有统计学差异(P<0.05);胰腺组织TLR蛋白信号表达,正常对照组与AEP组间、AEP组与ANP组间、ANP组与TLR4抗体处理组间的比较均有统计学差异(P<0.05)。结论 TLR在正常大鼠胰腺及血管等均有表达,AP时表达上调,TLR作为天然免疫受体在AP早期炎症启动中起到了重要作用,TLR参与了内毒素信号传递,TLR4在ANP发展过程中起重要的促进作用,进一步阻断内毒互信号通路有可能能改善ANP的预后。     

Fcgamma receptors in autoimmune diseases

Fcgamma-receptors (Fcgamma-R) recognise the Fc portion of IgG and thus form a link between humoral and cellular immunity. These receptors are expressed by a variety of immune cells, and they function in the binding of immune complexes or IgG-opsonised particles, such as microbial pathogens. The are three major types of Fcgamma-R, namely Fcgamma-RI (CD64), Fcgamma-RII (CD32) and Fcgamma-RIII (CD16), and these differ in their ability to bind IgG and complexes. There are many isoforms of these receptors and a number of recently identified polymorphisms in their structure. This review describes the structure and function of these Fcgamma-Rs, and highlights how gene deficiencies and polymorphisms may contribute to the pathology of human diseases.     

Significance of insulin receptors in the action of sulphonylurea drugs

The mechanisms by which sulphonylureas lower blood glucose are complex. Sulphonylureas increase insulin secretion and possibly also decrease glucagon release from the pancreas. In the periphery, they increase insulin binding to its receptors through direct or indirect mechanisms, primarily by increasing receptor number. Sulphonylureas also potentiate the action of insulin in peripheral glucose uptake and metabolism, even when no measurable effects on insulin receptors can be demonstrated. This post-receptor mode of action seems to play an important role in the spectrum of sulphonylurea effects.     

Soluble interleukin-2 receptors increase during the active periods in cluster headache

OBJECTIVE: To investigate whether cytokines are altered during the active period of cluster headache. BACKGROUND: Patients with cluster headache show activation of the hypothalamus in PET studies and via endocrinologic parameters. Data also suggest an inflammatory process occurs in cluster headache. A connection between the presumed inflammatory cause, an immunological activation, and the hypothalamus could be generated by certain cytokines. DESIGN AND METHODS: ELISA was used to determine the serum levels of soluble interleukin-2 receptors, interleukin-1, interleukin-6, and 2 soluble interleukin-6 receptors (sIL-6R and soluble gp130) in 18 patients with cluster headache (6 women and 12 men) during the cluster period and in 17 healthy controls who were headache-free (3 women and 14 men). RESULTS: Patients with cluster headache had significantly increased soluble interleukin-2 receptors (413.6+/-223 U/mL vs. 290.0+/-112 U/mL; P <.05) compared with controls. Serum levels of interleukin-1 (0.29+/-0.30 pg/mL vs. 0.13+/-0.13 pg/mL, n.s.), interleukin-6 (0.87+/-0.6 pg/mL vs. 0.91+/-0.7 pg/ml; n.s.), soluble interleukin-6 receptors (33,131+/-8,349 pg/mL vs. 35,063+/-7,606 pg/mL; n.s.), or soluble gp130 (289+/-59 pg/mL vs. 283+/-20 pg/mL; n.s.) did not differ between the 2 groups, although patients with cluster tended to have higher interleukin-1 values. CONCLUSIONS: Because elevated soluble interleukin-2 receptors indicate T cell activation, our findings suggest immune activation during cluster headache. Because interleukin-2 can activate the hypothalamus and stimulate the release of Corticotropin-releasing Factor (CRF), interleukin-2 could link a putative immunological cause of cluster headache with the observed hypothalamic activation. Systemic changes of interleukin-1 or the interleukin-6 system do not seem to play a role in cluster headache, as no alterations of serum levels were observed. Even so, unchanged serum levels do not exclude limited local production.     

Pathogen recognition by innate receptors

Microbial infection elicits host immune responses through germline-encoded pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are evolutionarily conserved membrane-bound PRRs that recognize a broad spectrum of microbial components. Recent studies have clarified that two classes of cytosolic receptors, retinoic acid-inducible gene I (RIG-I)-like helicases (RLHs) and nucleotide binding oligomerization domain (NOD)-like receptors (NLRs), play important roles in the cytosolic recognition of invading pathogens. After microbial infection, the host utilizes these receptors differentially to mount robust immune responses. This review will describe pathogen recognition by these receptors, signaling pathways, and their in vivo roles in innate antiviral immunity.