(d)-Amino acid analogues of DT-2 as highly selective and superior inhibitors of cGMP-dependent protein kinase Iα

The cGMP-dependent protein kinase type I (PKG I) is an essential regulator of cellular function in blood vessels throughout the body. DT-2, a peptidic inhibitor of PKG, has played a central role in determining the molecular mechanisms of vascular control involving PKG and its signaling partners. Here, we report the development of (d)-amino acid DT-2 derivatives, namely the retro-inverso ri-(d)-DT-2 and the all (d)-amino acid analog, (d)-DT-2. Both peptide analogs were potent PKG Iα inhibitors with K_i values of 5.5 nM (ri-(d)-DT-2) and 0.8 nM ((d)-DT-2) as determined using a hyperbolic mixed-type inhibition model. Also, both analogs were proteolytically stable in vivo, showed elevated selectivity, and displayed enhanced membrane translocation properties. Studies on isolated arteries from the resistance vasculature demonstrated that intraluminally perfused (d)-DT-2 significantly inhibited vasodilation induced by 8-Br-cGMP. Furthermore, in vivo application of (d)-DT-2 established a uniform translocation pattern in the resistance vasculature, with exception of the brain. Thus, (d)-DT-2 caused significant increases in mean arterial blood pressure in unrestrained, awake mice. Further, mesenteric arteries isolated from (d)-DT-2 treated animals showed a markedly reduced dilator response to 8-Br-cGMP in vitro. Our results clearly demonstrate that (d)-DT-2 is a superior inhibitor of PKG Iα and its application in vivo leads to sustained inhibition of PKG in vascular smooth muscle cells. The discovery of (d)-DT-2 may help our understanding of how blood vessels constrict and dilate and may also aid the development of new strategies and therapeutic agents targeted to the prevention and treatment of vascular disorders such as hypertension, stroke and coronary artery disease.     

Pain control using high-intensity pulsed magnetic stimulation

High-intensity pulsed magnetic stimulation (HIPMS) non-invasively depolarizes neurones, which can be deeply embedded in local tissues. Trans- or subcutaneous electrical stimulation can produce analgesia. To test the hypothesis that similar analgesia could be obtained using HIPMS, analgesia was determined in ten blinded subjects following HIPMS. Analgesia was consistently produced in all subjects with long-lasting pain relief occurring in half of the cases. ©1993 Wiley-Liss. Inc.     

Neurotensin. Immunohistochemical localization in central and peripheral nervous system and in endocrine cells and its functional role as neurotransmitter and endocrine hormone

The present study attempts to compile information on the possible physiologic role of the endogenous peptide neurotensin (NT) as a hormone and/or neurotransmitter. The methodological approach is immunohistochemical localization of NT in the entero-endocrine system as well as in the central and peripheral nervous systems. The results found in the three systems are first related to the pharmalogical and physiological findings in the literature. Subsequently their significance is discussed for each organ separately before attempting a final overall interpretation. Briefly, the present study reveals the following essential findings: The occurrence and distribution of NT-IR entero-endocrine cells (N-cells) in different mammals including man, as well as in representative members of all classes of vertebrates and higher invertebrates, are analyzed and evaluated morphometrically. The NT-IR cells in all investigated species are demonstrated to be of the open type. The innervation of paravertebral and prevertebral ganglia by NT-IR fibers is described; at least a portion of these fibers is thought to originate in NT-IR perikarya of the substantia intermedia of the spinal cord. The involvement of these NT-IR fibers in the regulation of systemic blood flow (hypertension) is suggested. The existence of NT-IR innervation of the gastro-intestinal tract is considered to be a general phenomenon. This notion is reaffirmed by phylogenetic investigation of the NT-IR enteric nerves. The pharmacological effects of NT in different portions of the gastro-intestinal tract, reported in the literature are related to the immunohistochemical localization of NT. In light of the present results, some of the effects of NT which were previously considered to be of an endocrine or paracrine nature - such as contraction of the guinea-pig ileum - are interpreted as effects of NT of neuronal origin. The specific NT-IR innervation of target cells in the exocrine pancreas (vascular smooth muscle, acinar cells) is demonstrated, and participation of NT-IR nerve fibers in regulation of the secretion of pancreatic juice is postulated. The innervation of the heart (coronary vasculature, myocardium, conduction system) by NT-IR fibers is demonstrated in various mammals and for the first time also in man. The cardiac NT-IR nerve fibers are thought to be the cytological substrate for different NT effects on heart action (coronary vasoconstriction, positive inotropy and chronotropy) reported in the literature.(ABSTRACT TRUNCATED AT 400 WORDS)     

电针刺激加速大鼠中枢脑啡肽的合成

应用放射免疫分析法测定大鼠纹状体、下丘脑、丘脑、桥延脑内甲啡肽和亮啡肽样免疫活性物质(Ir-MEK,Ir-LEK)的含量。脑室注射氨基肽酶抑制剂 bestatin(B)或“脑啡肽酶”抑制剂 thiorphan(T)各50μg 并不影响脑内 Ir 脑啡肽含量,合并应用 B T 各50μg 仅引起下丘脑 Ir-MEK 含量轻度上升。这说明安静状态下中枢脑啡肽的更新率不高。给大鼠电针30min 使纹状体和下丘脑 Ir-MEK 和 Ir-LEK 含量升高约40%(33—52%)(P<0.01)。在脑室注射 B T 各100μg 以及腹腔注射非特异性肽酶抑制剂 D-苯丙氨酸250mg/Kg的基础上电针,则使 Ir-MEK 和 Ir-LEK 含量升高约120%(94—147%)(P<0.01)。以上结果说明30min 电针刺激既促进脑啡肽的合成,也促进其释放。由于前者超过后者,因此静态含量升高。在中枢脑啡肽含量升高的同时,电针镇痛效果加强。说明由于肽酶抑制剂的保护作用而积聚于脑内的脑啡肽是具有功能意义的。     

镇痛指数在全麻手术中评估镇痛程度的临床价值

目的：探讨脑电镇痛指数（PRi）评估全身麻醉手术中镇痛程度的临床价值,为临床应用提供理论依据。方法：ASAI-Ⅱ级,拟于全身麻醉下行经腹手术的病人20例。患者入手术室后持续有创监测收缩压（SBP）、舒张压（DBP）、心率（HR）,实时监测脑电双频指数（BIS）和镇痛指数（PRi）。于麻醉诱导后气管插管前,气管插管后1 min、切皮前、切皮后2 min、追加芬太尼前,追加芬太尼5 min后记录BIS、PRi、SBP、DBP、HR的变化。结果：气管插管和切皮均引起SBP、DBP、HR的显著升高（P<0.05）;追加芬太尼后SBP、DBP、HR均降低（P<0.05）。气管插管和切皮均未引起BIS的显著变化（P>0.05）;追加芬太尼后BIS有所下降（P<0.05）。气管插管和切皮均引起PRi的显著升高（P<0.05）;追加芬太尼后PRi降低（P<0.05）。气管插管和切皮均引起SBP、DBP、HR、PRi的显著升高（P<0.05）,但均未引起BIS的显著变化（P>0.05）;追加芬太尼后SBP、DBP、HR、BIS和PRi均明显降低（P<0.05）。结论：在丙泊酚联合瑞芬太尼全身麻醉手术中,PRi能够反映伤害性刺激的变化,与伤害性刺激过程一致,对全身麻醉中镇痛程度的评估有指导意义。     

Exposure to oscillating magnetic fields influences sensitivity to electrical stimuli. I. experiments on pigeons

The comparison of two measurements of the pigeon threshold for electrical stimuli, performed 2 h apart, reveals stress-induced analgesia as a result of stressful manipulations between the two tests. When pigeons are exposed to a weak, oscillating magnetic field between the two measurements, the analgesic response is inhibited and a hyperalgesic effect is recorded. The present findings are in agreement with previous studies showing that magnetic treatments may alter pigeons' emotional state and some of their behavioral patterns. © 1995 Wiley-Liss, Inc.     

Effects ofPsychotria colorata alkaloids in brain opioid system

An ethnopharmacological survey showed that home remedies prepared with flowers and fruits ofPsychotria colorata are used by Amazonian peasants as pain killers. Psychopharmacological in vivo evaluation of alkaloids obtained from leaves and flowers of this species showed a marked dose-dependent naloxone-reversible analgesic activity, therefore suggesting an opioid-like pharmacological profile. This paper reports an inhibitory effect ofP. colorata flower alkaloids on [³H]naloxone binding in rat striata as well as a decrease in adenylate cyclase basal activity. The alkaloids did not affect [³H] GMP-PNP binding. These findings provide a neurochemical basis for the opioid-like activity previously detected in vivo and point toPsychotria alkaloids as a potential source of new bioactive opiate derivatives.     

Temporal Variation in the Interaction Between Calcium Channel Blockers and Morphine-Induced Analgesia

Circadian variations in the interaction between calcium channel blockers and morphine-induced analgesia were determined by the mouse hot-plate test. Calcium channel blockers diltiazem, verapamil, or nicardipine alone did not display any significant analgesic effect, but all of them potentiated morphine-induced analgesia when injected 30 min prior to morphine at most of the injection times. In terms of percent absolute potentiation, they produced more potentiation during the light period than darkness. Their potentiating effects decreased abruptly during darkness, and around the midtime of the dark period no significant potentiation of morphine-induced analgesia was observed. It is concluded that these fluctuations in the magnitude of interaction between calcium channel blockers and morphine must be taken into consideration particularly in studies dealing with the role of calcium in analgesia.     

孤啡肽在大鼠脑内对抗吗啡镇痛

脑内全新的阿片受体样受体（１９９４）及其内源性配体孤啡肽（１９９５）的发现形成了中枢神经系统阿片／抗阿片相互关系的研究领域中一个新的推动力。基于它们与阿片家族的高同源性及在脑内痛觉整合相关区域的丰富表达,本实验观察了ＯＦＱ在大鼠脑内对吗啡镇痛作用的影响。结果表明：（１）ＯＦＱ可以对抗脑室注射生理盐水引起的镇痛,后者可能是一种由内源性阿片系统介导的应激镇痛。（２）脑室注射ＯＦＱ在很大的剂量范围（４０