INHIBITION OF SYMPATHETIC NEUROTRANSMISSION BY THE OPIOID δ-RECEPTOR AGONIST DAMA IN THE PITHED RAT

1. The effects of [D-Ala2,Met5]enkephalinamide (DAMA), an analogue of [Met5]-enkephalin that acts selectively on opioid receptors of the delta-subtype, were studied on pressor responses elicited by sympathetic stimulation in pithed rats. 2. Intravenous injections of bolus doses of 0.1 mg/kg and 0.3 mg/kg of DAMA did not affect either the basal blood pressure or pressor responses to noradrenaline. 3. Pressor responses elicited either by electrical stimulation of the spinal sympathetic outflow or by stimulation of sympathetic ganglion cells with the muscarinic agonist McN-A-343 were reduced by DAMA. 4. Naloxone (1 mg/kg + 0.5 mg/kg per h) had no significant effect on the basal blood pressure or on pressor responses to spinal sympathetic stimulation, but antagonised the inhibitory effect of DAMA. 5. These results indicate that activation of opioid delta-receptors on sympathetic vasomotor nerve terminals can inhibit noradrenergic neurotransmission.     

亮氨酸脑啡肽的电子结构及构效关系研究

对亮氨酸脑啡肽进行了量子化学(INDO)计算,研究其电子结构特征,讨论其活性部位、作用机理及构效关系。同吗啡和R31833进行了活性部位的电子结构与空间结构比较,推断它们的活性药效结构具有共同特点,与阿片受体相互作用时作用方式相同,作用部位有对应关系,因而具有相同的药理性质。     

Effects of three peptidase inhibitors, amastatin, captopril and phosphoramidon, on the hydrolysis of [Met5]-enkephalin-Arg6-Phe7 and other opioid peptides

The contents of [Met⁵]-enkephalin-Arg⁶-Phe⁷ (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37° C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the aminopeptidase inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu⁵]-enkephalin (leu-enk), α- and β-neoendorphins (α- and β-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: α-neoend, β-neoend, and dyn B. Received: 15 July 1997 / Accepted: 20 November 1997     

EFFECTS OF HISTAMINE BOLUS INJECTIONS AND CONTINUOUS INFUSIONS ON THE H1- AND H2-RECEPTORS IN THE HINDLIMB VESSELS OF THE RABBIT

1. Hindlimb vascular resistance (HVR) was continuously measured after pharmacological block of the autonomic effectors in unanaesthetized rabbits with previously implanted Doppler ultrasonic flowmeters. 2. Histamine bolus injections caused a dose-related short lived fall in HVR followed by a more sustained rise. The fall was due to H₂-receptor stimulation (blocked by burimamide or metiamide) and the rise to H₁-receptor stimulation (blocked by mepyramine). At the doses of histamine tested the magnitude of the H₁-mediated vasocoiistriction had a larger peak effect than the H₂-mediated vasodilatation. 3. Histamine infusions up to 200 μg kg^?1 min^?1 did not alter HVR significantly but both increases and decreases in HVR were observed after giving H₂- or H₁-antagonists, respectively. 4. From the double reciprocal plots of 1/peak HVR change and 1/dose of histamine the magnitude of the predicted H₁- and H₂-mediated peak HVR effects at large doses were the same. This suggested that the number of H₁-_- and H₂-receptors were similar in the hindlimb vascular bed, in agreement with the infusion data.     

EFFECTS OF Δ1 AND Δ6-TETRAHYDROCANNABINOL ON THE ADENYLATE CYCLASE ACTIVITY IN VENTRICULAR TISSUE OF THE RAT HEART

Adrenaline 1 micrograms markedly elevated the activity of adenylate cyclase in ventricular tissue of rat hearts. delta 1-THC 25, 50 and 100 micrograms significantly reduced the adenylate cyclase activity with the maximum effect observed with the dose of 25 micrograms. Doses below or above this range did not produce any significant effect on the enzyme activity. Neither delta 6-THC 25 and 100 micrograms nor PVP 400 micrograms had any significant action on adenylate cyclase. The delta 1-THC-induced lowering of the cyclic AMP concentration in ventricular tissue of rat hearts can be explained, at least partly, by its ability to reduce the activity of adenylate cyclase in these tissues. It is suggested that this enzyme inhibition underlies the cardiac depressant action of delta 1-THC.     

INHIBITORY EFFECTS OF VERAPAMIL ON [3H]-ACETYLCHOLINE RELEASE IN THE CENTRAL NERVOUS SYSTEM OF SPRAGUE-DAWLEY RATS

1. The purpose of the present study was to investigate the effects of verapamil, a Ca²⁺ channel blocker, on acetylcholine (ACh) release in the CNS. 2. Striatal slices of rats, prelabelled with [³H]-ACh, were superfused with Krebs'-Ringer solution. The slices were stimulated by electrical pulses (1 Hz) or by an excitatory amino acid, l -glutamate and the effects of verapamil on the release of ACh were examined. 3. Electrical stimulation produced an increase in [³H]-ACh release from the striatal slices. Exposure of the slices to verapamil significantly inhibited the stimulation-evoked [³H]-ACh release. 4. An endogenous excitatory amino acid, l -glutamate, also elicted the release of [³H]-ACh. Verapamil significantly reduced the l -glutamate-induced release of [³H]-ACh and the inhibitory effect of verapamil was more pronounced in the presence of Mg²⁺ in the medium. 5. The results of the present study demonstrate that verapamil inhibited both electrically- and chemically-stimulated [³H]-ACh release from the rat striatum. The inhibition of cholinergic transmission by verapamil might be related to the central effect of the Ca²⁺ channel blocker.     

疟疾防治药物的研究——Ⅹ.2,4-二氨基-6-N1,N2-二取代肼基-喹唑啉类衍生物的合成及其抗疟作用

本文报道了2,4-二氨基-6-N¹,N²-二取代肼基-喹唑啉类衍生物的合成及其抗疟活性的研究。这类化合物的合成是以2,4-二氨基6-取代苄基氨基-喹唑啉为原料经亚硝化、还原成为2,4-二氨基6-(N¹-取代苄基)—肼基喹唑啉,再与相应的醛缩合而成。此类化合物经伯氏鼠疟原虫抑制性治疗初筛表明有少数具有一定的效果。有11个化合物经约氏鼠疟原虫—斯氏按蚊系统病因性初筛有效。其中化合物Ⅱ_1,7,8,11,15和Ⅲ₁口服2.5mg/kg,连续3天,可使受试小鼠全部得到保护。     

TMB-8对去甲肾上腺素和BHQ引起新生大鼠单个脑细胞内游离钙增高的影响

应用AR-CM-MIC阳离子测定系统,研究TMB-8对体外新生SD大鼠单个脑细胞内游离钙的抑制作用及其机制。结果表明,在无细胞外钙情况下,静息[Ca²⁺]i为79±13nmol·L^-1。TMB-810,30μmol·L^-1能明显降低静息[Ca²⁺]i。TMB-8100μmol·L^-1对高钾去极化引起的[Ca²⁺]i显著增高无明显影响。在细胞外钙为1.3mmol·L^-1时,去甲肾上腺素诱导的细胞内[Ca²⁺]i升高可部分被TMB-8抑制;TMB-8(30μmol·L^-1)对BHQ引起的[Ca²⁺]i的升高无明显抑制作用。而当细胞外液[Ca²⁺]i为0时,TMB-8几乎完全抑制了去甲肾上腺素和BHQ的作用。提示TMB-8降低脑细胞内游离钙的作用机制是通过促使细胞内钙进入肌浆网以抑制内钙的释放,并通过饱和肌浆网内Ca²⁺间接地阻滞细胞膜钙通道。     

(1R,3R,4S,5R)-1,4-二羟基-3-二苯叔丁硅氧基-6-氧代双环[3.2.1]-辛-7-酮的合成

报道以（一）-奎尼酸为手性源有效地合成（1R，2R，4S，5R）-1，4-二羟基-3-二苯叔丁硅氧基-6-氧代双环[3．2．1]-辛-7-酮的方法。     

钙拮抗剂TMB-8抑制BHQ,NE和KCl引起的培养乳牛基底动脉单个平滑肌细胞内游离钙的升高

用AR CM MIC阳离子测定系统,测量单个细胞内游离钙浓度([Ca²⁺]i),研究8-(N,N-二乙胺)-n-辛基 3,4,5-三甲氧基苯甲酸酯(TMB-8)对培养乳牛基底动脉平滑肌[Ca²⁺]i的作用。在细胞外钙浓度为1.3mmol·L^-1时,TMB-8(30μmol·L^-1)可明显抑制BHQ,NE及KCl引起[Ca²⁺]i的升高。在细胞外钙为零+EGTA 0.1mmol·L^-1时,TMB-8(10,30及100μmol·L^-1)可浓度依赖性地降低静息[Ca²⁺]i,TMB-8(30μmol·L^-1)可几乎完全阻断BHQ及NE引起[Ca²⁺]i的增加。研究表明TMB-8降低培养乳牛基底动脉平滑肌[Ca²⁺]i的机制,主要是抑制肌浆网Ca²⁺的释放,或增加肌浆网对Ca²⁺的摄入,并由此间接地抑制细胞外钙的内流。     

6-(αα-二苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)-哒嗪酮对兔血小板聚集及TXB2,cAMP的影响

6-(αα-二苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)-哒嗪酮(简称DMDP)是我院新合成的哒嗪酮的衍生物。DMDP可以显著抑制由花生四烯酸(AA(?),ADP和血小板活化因子(PAF)诱导的免血小板聚集,其IC₅₀分别为1.12±0.1.4.19±0.5和2.97±0.1μmol/L。实验还表明DMDP在1～500 μmol/L浓度范围内呈剂量依赖性地抑制兔血小板内血栓素B₂含量,但升高兔血小板内环腺苷酸水平,这可能是其抑制血小板聚集的作用机理之一。     

Synthesis of C‐14 and C‐13, H‐2‐labeled IKK inhibitor: [14C] and [13C4,D3]‐N‐(6‐chloro‐7‐methoxy‐9H‐pyrido[3,4‐b]indol‐8‐yl)‐2‐methyl‐3‐pyridinecarboxamide

[¹⁴C]‐N‐(6‐Chloro‐7‐methoxy‐9H‐pyrido [3,4‐b]indol‐8‐yl)‐2‐methyl‐3‐pyridinecarboxamide (5B ), an IKK inhibitor, was synthesized from [¹⁴C]‐barium carbonate in two steps in an overall radiochemical yield of 41%. The intermediate, [carboxyl‐¹⁴C]‐2‐methylnicotinic acid, was prepared by the lithiation and carbonation of 3‐bromo‐2‐methylpyridine. [¹³C₄,D₃]‐N‐(6‐chloro‐7‐methoxy‐9H‐pyrido [3,4‐b]indol‐8‐yl)‐2‐methyl‐3‐pyridinecarboxamide (5C ) was synthesized from [1,2,3,4‐¹³C₄]‐ethyl acetoacetate and [D₄]‐methanol in six steps in an overall yield of 2%. [¹³C₄]‐2‐methylnicotic acid, was prepared by condensation of [¹³C₄]‐ethyl 3‐aminocrotonate and acrolein, followed by hydrolysis with lithium hydroxide. Copyright © 2006 John Wiley & Sons, Ltd.     

R-(+)-[2,3-Dihydro-5-methyl-3-(4-morpholinylmethyl)-pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphtalenylmethanone (WIN-2) ameliorates experimental autoimmune encephalomyelitis and induces encephalitogenic T cell apoptosis: partial involvement of the CB(2) receptor

Many reports have shown that cannabinoids might be beneficial in the symptomatic treatment of multiple sclerosis (MS). We have investigated the therapeutic properties of the non-selective cannabinoid receptor agonist WIN-2 as a suppressive drug in the experimental autoimmune encephalomyelitis (EAE) model of MS. In the passive variety of EAE, induced in Lewis rats by adoptive transfer of myelin-reactive T cells, WIN-2 ameliorates the clinical signs and diminishes the cell infiltration of the spinal cord. Due to the involvement of cannabinoids in the regulation of cell death and survival, we investigated the effects of WIN-2 on the encephalitogenic T cell population. WIN-2 induced a profound increase of apoptosis in a dose- and time-dependent manner. The potential involvement of cannabinoid receptors (CB) was investigated by encephalitogenic T cell stimulation in the presence of the CB(1) (SR141716A) and CB(2) (SR144528) antagonists, pertussis toxin (PTX) and the inactive enantiomer WIN-3. WIN-2-induced apoptosis was partially blocked by SR144528 and PTX, whereas, WIN-3 only exerted a mild effect on cell viability. These results point to the partial involvement of CB(2) receptor together with other receptor-independent mechanism or by yet unknown cannabinoid receptors. Moreover, WIN-2 induced the extrinsic pathway of apoptosis, as shown by caspase-10 and -3 activation. These results suggest that cannabinoid-induced apoptosis of encephalitogenic T cells may cooperate in their anti-inflammatory action in EAE models. The partial involvement of CB(2) receptors in WIN-2 action may open new therapeutic doors in the management of MS by non-psychoactive selective cannabinoid agonists.