环磷酸腺苷/蛋白激酶A信号转导通路在重症急性胰腺炎肺损伤中的作用

目的 探讨环磷酸腺苷/蛋白激酶A(cAMP/PKA)信号转导通路在重症急性胰腺炎肺损伤的作用机制.方法 健康雄性SD大鼠72只,按完全随机法分为假手术(SO)组、重症急性胰腺炎组(SAP组)、SAP+ H89(cAMP抑制剂)组,后两组按取材时间不同又分为3、6、12及24 h四个亚组,共9组,每组8只.采用酶联免疫吸附法检测血清TNF-α、IL-1β,同时观察胰腺和肺组织的病理变化,免疫组织化学蛋白方法检测cAMP依赖PKA催化亚基C(PKA C)和磷酸化的血管扩张刺激磷蛋白(p-VASP),荧光定量聚合酶链反应检测肺组织VSAP mRNA表达水平.结果 与SO组比较,SAP组各时间点血清TNF-α 、IL-1β明显上升(P＜0.05),胰腺、肺病理学改变明显,肺组织PKA C蛋白、VASP磷酸化水平及VASPmRNA表达水平明显增强(P＜0.05),12 h达高峰[TNF-α(266.07±17.14) pg/mL、IL-1β (169.17±25.92) pg/mL、PKA C(210.69 ±6.32)×103、p-VASP(56.62 ±0.57)×103、VASPmRNA(2.06 ±0.21)],且与TNF-α、IL-1β之间存在明显的正相关性.与SAP组比较,SAP+ H89组各时间点胰腺、肺病理学改变明显减轻,肺组织PKA C蛋白、VASP磷酸化水平及VSAP mRNA表达水平明显下降(P＜0.05).结论 cAMP/PKA信号转导通路的活化参与了重症急性胰腺炎肺损伤的病理过程,可能与TNF-α及IL-1β水平上调及VASP磷酸化而发挥作用有关.     

Elevated cyclic adenosine monophosphate ameliorates ischemia-reperfusion injury in rat cardiac allografts.

BACKGROUND: Oxidative stress after ischemia and reperfusion leads to leukocyte activation, the production of injurious cytokines, and increased expression of inflammatory adhesion molecules. This initial event is one of the most important alloantigen-independent factors associated with graft coronary artery disease (GCAD). Cyclic adenosine monophosphate (cAMP) is an important second messenger that inhibits the expression of tumor necrosis factor alpha (TNF-alpha), vascular cell adhesion molecule 1 (VCAM-1), and endothelial leukocyte adhesion molecule 1 (ELAM-1) in vitro. Its levels decrease during organ preservation. We hypothesized that augmenting allograft cAMP levels with the water-soluble adenylate cyclase activator, NKH477, could decrease ischemia-reperfusion injury and inhibit the progression of GCAD. METHODS: PVG to ACI rat heterotopic cardiac allografts, treated with NKH477 solution or vehicle, were reperfused for 4 hours or 90 days after 60 minutes of ischemia. We analyzed grafts for intracellular adhesion molecule 1 (ICAM-1), VCAM-1, and ELAM-1 mRNA expression; TNF-alpha and interleukin-6 (IL-6) protein expression; and myeloperoxidase activity. We also performed immunohistochemical analysis for ICAM-1 and VCAM-1 protein expression. At post-operative Day 90, the progression of GCAD had increased morphometrically. RESULTS: NKH477-treated grafts had significantly decreased levels of myeloperoxidase activity compared with controls. In this group, TNF-alpha, IL-6, and VCAM-1 protein expression was inhibited; however, ICAM-1 and ELAM-1 expression did not alter. We found no differences in the degree of development of GCAD between groups. CONCLUSION: Although augmented intracellular cAMP prevented acute reperfusion injury, it was insufficient to prevent the development of GCAD. Intracellular adhesion molecule 1 and ELAM-1, whose expression NKH477 does not inhibit, may play important roles in the development of GCAD.     

Insulin inhibition of lipolysis of human adipocytes: the role of cyclic adenosine monophosphate.

To gain information on the manner in which insulin suppresses lipolysis in man, isolated adipocytes, prepared from subcutaneous adipose tissue, were incubated with insulin (100 microunits/ml) alone and in combination with isoproterenol (10(-7) M or 10(-8) M). Cyclic AMP concentration was measured at 60 min; glycerol release, used as an index of lipolysis, was determined at 45 and 75 min. Insulin consistently reduced both basal and stimulated cyclic AMP and glycerol release: the degree of suppression of each was comparable. In subsequent experiments, the ability of insulin to suppress glycerol release stimulated by isoproterenol, theophylline, and dibutyryl cyclic AMP (dbcAMP), respectively, was compared. Insulin substantially reduced the raised levels of cyclic AMP and glycerol release prompted by isoproterenol and theophylline, but it had little effect on increases caused by dbcAMP. These findings support the view that reduction in cyclic AMP is an important component in the regulation of fat mobilization by insulin.     

Superior protection in orthotopic rat lung transplantation with cyclic adenosine monophosphate and nitroglycerin-containing preservation solution.

BACKGROUND: Primary lung graft failure is common, and current lung preservation strategies are suboptimal. Because the decline in lung levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate during preservation could enhance adhesiveness of endothelial cells for leukocytes as well as increase vascular permeability and vasoconstriction, we hypothesized that buttressing these levels by means of a preservation solution would significantly improve lung preservation. METHODS: An orthotopic rat left lung transplantation model was used. Lungs were harvested from male Lewis rats and preserved for 6 hours at 4 degrees C with (1) Euro-Collins solution (n = 8); (2) University of Wisconsin solution (n = 8); (3) low-potassium dextran glucose solution (n = 8); (4) Columbia University solution (n = 8), which contains a cyclic adenosine monophosphate analog (dibutyryl cyclic adenosine monophosphate) and a nitric oxide donor (nitroglycerin) to buttress cyclic guanosine monophosphate levels; or (5) Columbia University solution without cyclic adenosine monophosphate or nitroglycerin (n = 8). PaO2, pulmonary vascular resistance, and recipient survival were evaluated 30 minutes after left lung transplantation and removal of the nontransplanted right lung from the pulmonary circulation. RESULTS: Among all groups studied, grafts stored with Columbia University solution demonstrated the highest Pa O2 (355 +/- 25 mm Hg for Columbia University solution versus 95 +/- 22 mm Hg for Euro-Collins solution, P <.01, 172 +/- 55 mm Hg for University of Wisconsin solution, P <.05, 76 +/- 15 mm Hg for low-potassium dextran glucose solution, P <.01, and 82 +/- 25 mm Hg for Columbia University solution without cyclic adenosine monophosphate or nitroglycerin, P <.01) and the lowest pulmonary vascular resistances (1 +/- 0.2 mm Hg * mL-1 * min-1 for Columbia University solution versus 12 +/- 4 mm Hg * mL-1 * min-1 for Euro-Collins solution, P <.01, 9 +/- 2 mm Hg * mL-1 * min-1 for University of Wisconsin solution, 14 +/- 6 mm Hg * mL-1 * min-1 for low-potassium dextran glucose solution, P <.01, and 8 +/- 2 mm Hg * mL-1 * min-1 for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin). These functional and hemodynamic improvements provided by Columbia University solution were accompanied by decreased graft leukostasis and decreased recipient tumor necrosis factor alpha and interleukin 1alpha levels compared with the other groups. In toto, these improvements translated into superior survival among recipients of Columbia University solution-preserved grafts (100% for Columbia University solution, 37% for Euro-Collins solution, P <.01, 50% for University of Wisconsin solution, P <.05, 50% for low-potassium dextran glucose solution, P <.05, and 13% for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin, P <.01). CONCLUSION: Nitroglycerin and cyclic adenosine monophosphate confer beneficial vascular effects that make Columbia University solution a superior lung preservation solution in a stringent rat lung transplantation model.     

Effects of plant extract neferine on cyclic adenosine monophosphate and cyclic guanosine monophosphate levels in rabbit corpus cavernosum in vitro

Aim： To further investigate the relaxation mechanism of neferine （NED, a bis-benzylisoquinoline alkaloid extracted （isolated） from the green seed embryo of Nelumbo nucifera Gaertn in China, on rabbit corpus cavernosum tissue in vitro. Methods： The effects of Nef on the concentrations of cyclic adenosine monophosphate （cAMP） and cyclic guanosine monophosphate （cGMP） in isolated and incubated rabbit corpus cavernosum tissue were recorded using ^125I radioimmunoassay. Results： The basal concentration of cAMP in corpus cavernosum tissue was 5.67 ± 0.97 pmol/mg. Nef increased the cAMP concentration in a dose-dependent manner （P 〈 0.05）, but this effect was not inhibited by an adenylate cyclase inhibitor （cis-N-[2-phenylcyclopentyl]azacyclotridec-1-en-2-amine, MDL-12, 330A） （P 〉 0.05）. The accumulation of cAMP induced by prostaglandin Et （PGEt, a stimulator of cAMP production） was also augmented by Nef in a dose-dependent manner （P 〈 0.05）. The basal concentration of cGMP in corpus cavernosum tissue is 0.44 ± 0.09 pmol/mg. Nef did not affect this concentration of cGMP, either in the presence or in the absence of a guanyl cyclase inhibitor （1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ） （P 〉 0.05）. Also, sodium nitroprusside （SNP, a stimulator of cGMP production）-induced cGMP production was not enhanced by Nef （P 〉 0.05）. Conclusion： Nef, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting phosphodiesterase activity. （Asian JAndro12008 Mar; 10： 307-312）     

ET-Kyoto solution plus dibutyryl cyclic adenosine monophosphate is superior to University of Wisconsin solution in rat liver preservation

ET-Kyoto solution (ET-K) is an extracellular-type organ preservation solution containing the cytoprotective disaccharide, trehalose. A previous study reported the supplement of dibutyryl cyclic adenosine monophosphate (db-cAMP) in conventional ET-K to attenuate lung ischemia-reperfusion injury. In this study, the efficacy of this modified ET-K for liver preservation was investigated by comparison with University of Wisconsin solution (UW). ET-K was supplemented with db-cAMP (2 mmol/L). Lewis rats were randomly assigned to two groups, and liver grafts were flushed and stored at 40C for 24 h with ET-K or UW before syngeneic liver transplantation. The graft function and histological changes at 4 h posttransplant as well as 7-day survival were evaluated. Recipient rat survival rate was significantly higher in the ET-K group than in the UW group. Preservation in ET-K resulted in a significant reduction in serum parenchymal transaminase level and promotion of bile production in comparison with UW. The serum hyaluronic acid level, an indicator of sinusoidal endothelial cell injury, was significantly lower after ET-K preservation than that in UW. Histologically, at 4 h after transplantation, the liver grafts preserved in UW solution demonstrated a greater degree of injury than those in ET-K, which appeared to be apoptosis, rather than necrosis. The continuity of the sinusoidal lining was better preserved in ET-K than in UW. In conclusion, ET-K supplemented with db-cAMP is superior to UW in rat liver preservation. This modified ET-K might therefore be a novel candidate for the procurement and preservation of multiple organs.     

Convergence of major physiological stimuli for renin release on the Gs-alpha/cyclic adenosine monophosphate signaling pathway

Control of the renin system by physiological mechanisms such as the baroreceptor or the macula densa (MD) is characterized by asymmetry in that the capacity for renin secretion and expression to increase is much larger than the magnitude of the inhibitory response. The large stimulatory reserve of the renin–angiotensin system may be one of the causes for the remarkable salt-conserving power of the mammalian kidney. Physiological stimulation of renin secretion and expression relies on the activation of regulatory pathways that converge on the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) pathway. Mice with selective Gs-alpha (Gsα) deficiency in juxtaglomerular granular cells show a marked reduction of basal renin secretion, and an almost complete unresponsiveness of renin release to furosemide, hydralazine, or isoproterenol. Cyclooxygenase-2 generating prostaglandin E₂ (PGE₂) and prostacyclin (PGI₂) in MD and thick ascending limb cells is one of the main effector systems utilizing Gsα-coupled receptors to stimulate the renin–angiotensin system. In addition, β-adrenergic receptors are critical for the expression of high basal levels of renin and for its release response to lowering blood pressure or MD sodium chloride concentration. Nitric oxide generated by nitric oxide synthases in the MD and in endothelial cells enhances cAMP-dependent signaling by stabilizing cAMP through cyclic guanosine monophosphate-dependent inhibition of phosphodiesterase 3. The stimulation of renin secretion by drugs that inhibit angiotensin II formation or action results from the convergent activation of cAMP probably through indirect augmentation of the activity of PGE₂ and PGI₂ receptors, β-adrenergic receptors, and nitric oxide.     

环腺苷酸效应元件结合蛋白在学习记忆中的作用及机制

背景 环腺苷酸效应元件结合蛋白(cAMP response-element binding protein,CREB)是新发现的学习记忆正调控因子.近年来的研究提示CREB可能通过多种途径调控学习记忆. 目的 阐述CREB在学习记忆中的作用及机制,为认知障碍相关疾病的防治提供思路. 内容 阐述CREB的来源、结构及其在学习记忆中的作用.分析其调控学习记忆的相关机制. 趋向 CREB的确切上游调控机制及自身的表达调控需要进一步明确,对其深入研究可为多种认知障碍疾病的防治提供新的靶点与思路.     

Smooth muscle contractility in prostatic hyperplasia: Role of cyclic adenosine monophosphate

The role of cyclic 3′-5′ adenosine monophosphate (cAMP) on α₁-adreno-ceptor (α₁-receptor) induced smooth muscle contractions in symptomatic benign prostatic hyperplasia (BPH) was investigated. Application of the selective α₁-receptor agonist phenylephrine (PE) induced fully reversible contractions in a dose-dependent fashion. Phosphodiesterase (PDE) inhibitors blocking the degradation of cAMP suppressed the PE induced contractions as follows: theophylline (1 mM), 91.1 ± 1.4%; papaverine (0.5 mM), 822.8 ± 3.2%; milrinone (0.5 mM), 68.2 ± 0.6%. Forskolin (50 μM), which elevates cAMP through direct activation of adenylatecyclase (AC), inhibited the PE induced contractions by 82.4 ± 3.6%. To further increase the intracellular cAMP concentration ([cAMP]_i), the membrane permeable cAMP analogue N⁶-2′-O-dibutyryladenosine derivative (dBcAMP; 1 mM) was applied and reduced the PE evoked contractions by 69.8 ± 2.3%. We conclude that elevation of [cAMP]_i is an important step in inducing smooth muscle relaxation. © 1994 Wiley-Liss, Inc.     

Effects of exogenous cyclic adenosine monophosphate in hemorrhagic shock.

Hemorrhageic shock produces potentially damaging alterations in the metabolism of cyclic adenosine 3',5'-monophosphate (cAMP), which is an intracellular second messenger for many hormones. The hypothesis that the administration of exogenous cAMP might have salutary effects on cardiovascular hemodynamics in shock was tested in canine experimetns. Intravenous bolus injection of dibutyryl cAMP (2 mg. per kilogram) produced hyperglycemia, but no changes occurred in heart rate, arerial pressure cardiac output, or in the first derivative of left ventricualr pressure (dp/dt). The findings were similar in conscious and anesthetized (Nembutal) normotensive dogs, in dogs after 3 hours of shock (at blood pressure of 40 mm. Hg) and after the reinfusion of shed blood. The only hemodynamic change noted was a transient hypotensionupon injection of massive doses of dibutyryl-(db-) cAMP or cAMP (greater than 10 mg. per kilogram). The implication of these findings in light of earlier reported hemodynamic effects of cAMP is discussed.     

Effect of a cyclic adenosine monophosphate phosphodiesterase inhibitor, DN-9693, on myocardial reperfusion injury.

A new cyclic adenosine monophosphate phosphodiesterase inhibitor, DN-9693, was examined to see whether myocardial reperfusion injury could be reduced in a setting of cardioplegic arrest through its antiaggregation effect on leukocytes. Isolated rabbit heart models with whole blood perfusion were used, and 18 hearts were divided into three groups according to the reperfusion method: control (G-1, n = 5), DN-9693 (G-2, n = 7), and leukocyte depletion (G-3, n = 6). The hearts were subjected to 120 minutes of cold global ischemia under crystalloid cardioplegia followed by 30 minutes of reperfusion. A dose of 20 micrograms.kg-1.min-1 of DN-9693 was administered in G-2, and a leukocyte removal filter was used in G-3 during reperfusion. Ultrastructural changes in mitochondrial injuries, intracellular edema, and capillary injuries of the myocardium showed worse changes in G-1 than in G-2 and G-3. Under microscopic study, the intracapillary leukocyte count was significantly higher in G-1 than in G-2 and G-3. Recovery of rate-pressure product, left ventricular developed pressure, and coronary flow were significantly better in G-2 and G-3 than in G-1. There were no significant differences between G-2 and G-3 for all these indices. These results indicate that reperfusion with leukocyte-depleted blood attenuates reperfusion myocardial injury and DN-9693 has a comparable myocardial protective effect with possible inhibition of leukocyte aggregation.     

异氟醚对大鼠脑3’5’-环腺苷酸含量的影响

目的 了解异氟醚对大鼠脑３’５’－环腺苷酸（ｃＡＭＰ）含量的影响。方法 ＳＤ大鼠４０只,随机分为五组,分别在未吸入异氟醚（对照组）,吸入１．４％异氟醚翻正反射消失时（翻正反射消失组）,吸入１．４％异氟醚平衡３０ｍｉｎ时（麻醉组）,吸入１．４％异氟醚平衡３０ｍｉｎ后将动物取出自制麻醉箱待翻正反射恢复时（恢复Ⅰ组）和吸入１．４％异氟醚平衡３０ｍｉｎ后将动物取出自制麻醉箱后３０ｍｉｎ时（恢复Ⅱ组）断头取     

Effect of dibutyryl cyclic adenosine monophosphate on canine pelviureteral discharge potentials

An electromyographic study of the responses of the pelviureter to dibutyryl cyclic AMP was performed using isolated canine pelviureteral preparations. Dibutyryl cyclic AMP caused a marked increase in the amplitude of discharge potential in the pelvicalyceal pacemaker region and this was associated with a decrease in renal pelvic pressure. The frequency of the pacemaker discharge did not increase. On the other hand, in the lower pelvis and ureter, dibutyryl cyclic AMP caused a small but significant decrease in the amplitude of discharge potentials and this was associated with a marked decrease in discharge frequencies in the lower pelvis and ureter.     

缺血预处理对大鼠移植肝脏保存再灌注损伤的保护及机制探讨

目的探讨缺血预处理 (ischemicpreconditioning ,IP)对大鼠移植肝脏保存再灌注损伤的保护作用及机理。方法采用SD大鼠原位肝移植动物模型 ,12 8只大鼠随机分成A(对照组 )、B(IP组 )、C(腺苷 ,Ado组 )、D(NO合成抑制剂 ,NAME组 )组 ,每组 32只。其中各组的半数用于观察存活率 ,另一半用于移植肝脏再灌注 2h后取血及肝脏检测。结果IP组和Ado组的 1周存活率、血清NO水平及肝组织腺苷含量分别为 88% (7/ 8)和 88% (7/ 8) ,(33 0± 6 1) μmol/l和 (2 9 1± 6 5 ) μmol/l,(7 2± 1 8) μmol/g和 (5 7± 1 3) μmol/g ,均高于对照组的 38% (3/ 8) ,(15 4± 3 0 )mol/L和 (3 6 9±0 5 4 ) μmol/g (P <0 0 5 ) ,血清ALT及TNF含量分别为 (2 87± 82 )IU/L和 (35 7± 93)IU/L ,(1 15± 0 2 3)ng/ml和 (1 14± 0 2 7)ng/ml,均低于对照组的 (5 88± 5 8)IU/L及 (1 5 9± 0 35 )ng/ml(P <0 0 5 ) ,组织的病理学改变也轻于对照组 ;NAME组的 1周存活率、血清NO及ALT含量等分别为 2 5 % (2 / 8)、(13 74± 3 11) μmol/l及 (6 34± 6 5 )IU/L ,与对照组相近 (P >0 0 5 ) ,而肝组织腺苷含量为 (5 5 6± 1 19)μmol/g ,与对照组差异有显著意义 (P <0 0 5 )。 结论IP对大鼠移植肝脏的保存再灌注损伤具有保护     

Impaired sperm function after spinal cord injury in the rat is associated with altered cyclic adenosine monophosphate signaling

Our previous observations of changes in the expression of cAMP-dependent genes and the cAMP-responsive element modulator (CREM) in rat testicular cells after spinal cord injury (SCI) implied abnormal cAMP signaling as one of the mechanisms underlying the effects of SCI on spermatogenesis. It was postulated that such effects might contribute to abnormal sperm function after SCI. In this study, we examined this possibility. In spinal cord-contused (SCC) and -transected (SCX) rats, impaired sperm motility was accompanied by an increase in sperm cAMP content. Treatment of SCX rats with exogenous testosterone or follicle-stimulating hormone resulted in a further decrease in sperm motility, whereas sperm cAMP either increased or remained unchanged. These effects differed from those in sham control rats that received identical treatments. Results of these experiments also demonstrated that impaired sperm motility in SCC and SCX rats was accompanied by decreases in sperm viability and mitochondrial potential, thus suggesting a possible link between these changes. We concluded that impaired sperm motility after SCI was associated with decreases in sperm viability and mitochondrial potential. These effects occurred in the face of elevated sperm cAMP content and changes in its regulation, suggesting that altered cAMP signaling events might contribute to impairment of sperm motility and perhaps other sperm functions after SCI.     

Influences of dibutyryl cyclic adenosine monophosphate and forskolin on human sperm motility in vitro

Aim: To study the influences of dibutyryl cyclic adenosine monophosphate (dbcAMP) and forskolin on human sperm motility in vitro. Methods: Semen samples, aseptically obtained by masturbation and prepared by swim-up technique from 20 fertile men, were incubated with different concenlrations of dbcAMP and forskolin at 37℃. Measurements were carried out after l0 min, 20 min, 30 min and 60 min incubation. Motility parameters were estimated by using an automatic analyzing system. Results: Treatment with dbcAMP or forskolin resulted in a significant increase in sperm motility and progressive motility. The larger the concenlrations of dbcAMP or forskolin,the greater the effect appeared. The straight linear velocity and curvilinear velocity were not affected by both agents.Conclusion: dbcAMP and forskolin increase the motility and progressive motility of human sperm in vitro. ( Asian J Androl 2003 Jun; 5: 113-115)