Maxadilan对人脂肪干细胞的影响

目的:探讨垂体腺苷酸环化酶激活肽Ⅰ型受体(PAC1受体)特异激动剂maxadilan对人脂肪干细胞(adipose-derived stem cells,ASCs)的增殖、凋亡和分化潜能的作用。方法:取人脂肪组织通过酶消化法分离培养ASCs。流式细胞术鉴定ASCs表面标志物,并进行ASCs向成骨成脂定向诱导。CCK-8法和流式细胞术检测maxadilan对ASCs活性的影响。采用波长为254 nm的紫外线(ultraviolet C,UVC)照射ASCs,CCK-8法测定不同剂量的UVC诱导ASCs凋亡后的吸光度。选择剂量为702 J/m2的UVC照射ASCs 24 h后,用流式细胞术和caspase 3和caspase 9试剂盒检测maxadilan对ASCs凋亡的影响。结果:流式细胞术检测表明细胞CD29、CD44、CD59和CD105表面抗原阳性,证实所提取的细胞是ASCs。CCK-8法检测发现80 nmol/L浓度的maxadilan对ASCs促增殖作用最强,流式细胞术分析也证实80 nmol/L maxadilan处理显著促进ASCs的增殖,与对照组比较差异有统计学意义(P0.05)。与仅被702 J/m2UVC照射的ASCs比较,80 nmol/L maxadilan显著抑制同等剂量UVC照射ASCs所诱导的、与caspase 3和caspase 9活性相关的细胞凋亡,2组比较差异有统计学意义(P0.05)。同时,2组细胞成骨和成脂的诱导分化均为阳性。结论:Maxadilan促进ASCs增殖,抑制ASCs凋亡,且不改变细胞向成骨和成脂诱导分化的潜能。Maxadilan有利于ASCs的体外生长与扩增。     

人Arresten基因的真核表达及其对血管平滑肌细胞增殖和迁移的影响

目的: 真核表达人Arresten蛋白，并研究其对体外培养大鼠胸主动脉血管平滑肌细胞（VSMCs）增殖和迁移的影响。方法: 用脂质体介导，将含有人Arresten基因的重组质粒pSecTag2-AT转染COS-7细胞；应用逆转录-聚合酶链反应（RT-PCR）检测转染细胞目的基因mRNA表达；收集转染48h后上清液，浓缩后Western blotting分析检测目的蛋白的表达。用转染细胞上清液处理平滑肌细胞后,CCK-8法检测细胞增殖；Transwell小室法检测细胞迁移。结果:RT-PCR结果显示转染Arresten基因的COS-7细胞基因组中存在有目的基因特异性片段（449 bp），表明基因转染成功；Western blotting结果表明转染细胞上清液中有目的蛋白表达。细胞体外增殖分析显示Arresten蛋白可显著抑制血管平滑肌细胞的增殖作用(F=40.154,P<0.01)；Transwell小室法检测显示经对照细胞，载体DNA转染及重组质粒转染的COS-7细胞培养上清液处理的平滑肌细胞迁移数为(28.70±3.97)个、(26.10±4.53)个、(14.00±3.33)个（F=38.915,P<0.01）。结论: 真核表达的人Arresten蛋白能有效抑制体外培养的血管平滑肌细胞的增殖和迁移。     

TRPC6在PDGF诱导的大鼠气道平滑肌细胞增殖中的作用

 目的：探讨经典瞬时受体电位通道6 (TRPC6) 对血小板源性生长因子 (PDGF) 诱导的气道平滑肌细胞 (ASMCs) 增殖的影响。方法：组织贴块联合酶消化法培养原代大鼠ASMCs。间接免疫荧光法鉴定平滑肌细胞及检测TRPC6在ASMCs上的表达。CCK-8法检测PDGF诱导ASMCs的增殖。Real-time PCR 检测PDGF作用后TRPC6 mRNA的表达。Western blotting检测PDGF作用后TRPC6蛋白的表达。CCK-8法检测TRPC6阻断剂对PDGF 诱导ASMCs增殖的作用。结果：细胞免疫荧光显示：TRPC6广泛存在于气道平滑肌细胞。CCK-8法检测细胞的增殖发现,20 μg/L PDGF作用后 ASMCs发生增殖 (P<0.05);PDGF与TRPC6阻断剂SKF96365共同作用于ASMCs,ASMCs的增殖较单独使用PDGF组减弱 (P<0.05),且减弱的程度具有剂量及时间依赖性。Real-time PCR结果显示：PDGF分别作用于ASMCs 12 h、24 h和48 h后,TRPC6 mRNA表达与相应的对照组比较明显升高 (P<0.05)。Western blotting检测结果显示：PDGF分别作用ASMCs 24 h和48 h后,TRPC6蛋白表达与相应的对照组比较明显升高 (P<0.05)。结论：TRPC6参与了PDGF诱导ASMCs增殖的过程,PDGF促进ASMCs增殖可能与其上调TRPC6 mRNA和蛋白表达相关。     

转染isl1基因促进骨髓间充质干细胞向心肌样细胞分化

目的: Isli蛋白在心脏发生和多能心脏祖细胞分化调节中发挥着重要作用, 本文旨在探寻转染 isl1 基因是否能提高骨髓间充质干细胞(BMSCs)向心肌样细胞分化的能力。方法: 利用携带 isl1 基因的慢病毒(LVS- isl1)感染人骨髓间充质干细胞, 通过Puromycin筛选获得稳定细胞株,并对其进行RT-PCR和Western blotting鉴定。以共培养为基础, 用real-time PCR、Western blotting以及免疫荧光法检测Isl1蛋白的心肌诱导能力。结果: RT-PCR和Western blotting表明成功获得稳定细胞株BMSC- isl1, real time-PCR结果显示BMSC- isl1组较之BMSCs组和BMSC-vehicle组GATA 结合蛋白4、NK2转录因子5、肌细胞增强因子2C和兰尼碱受体2的表达量分别提高了2.3、2.7、2.6和3.2倍;Western blotting以及免疫荧光法结果均提示BMSC- isl1 组内心肌肌钙蛋白T、心肌肌钙蛋白I和α-辅肌动蛋白的表达均比BMSCs组和BMSC-vehicle组要高。结论: 转染isl基因的BMSCs不仅可以稳定表达Isli蛋白, 而且在微环境共培养条件下, 可以提高BMSCs向心肌细胞分化的能力。     

小环肽C*HSDGIC*对中波紫外线诱导的视网膜色素人上皮细胞凋亡的影响

目的: 探讨垂体腺苷酸环化酶激活多肽 (PACAP) 的衍生物小环肽C^*HSDGIC^*(CHC)对中波紫外线(UVB)诱导的人视网膜色素上皮(RPE)细胞凋亡的影响。方法:Western blotting检测人RPE细胞PACAP 1型受体(PAC1受体)表达;RPE细胞接受0.2 J/cm² UVB照射,随后实验组给予含不同浓度CHC的无血清培养基培养,对照组给予无血清培养基培养;CCK-8法检测CHC对RPE细胞活性的影响;流式细胞术Annexin-V/PI双染检测RPE细胞凋亡情况,JC-1染色检测线粒体膜电位。结果:Western blotting显示RPE细胞表达PAC1受体,CCK-8法显示CHC促细胞活性的最佳浓度为100 μmol/L,细胞活性比对照组增加(34.23±3.39)%(P<0.05),抗凋亡最佳浓度也为100 μmol/L,细胞活性比对照组增加(20.10±1.48)%(P<0.05)。流式细胞仪分析显示,100 μmol/L CHC能使UVB照射后凋亡细胞比例下降 (5.63±1.49)%,线粒体去极化细胞比例下降(5.2±0.5)% (P<0.05)。结论:人RPE细胞存在PAC1受体,小环肽C^*HSDGIC^*对人RPE细胞有促进活性和拮抗凋亡的作用。     

白藜芦醇对视网膜色素上皮细胞增殖的影响

 目的:探讨白藜芦醇（resveratrol,Res）对视网膜色素上皮细胞增殖的影响,并初步探讨其作用机制。方法:用0、50、100、150、200和300 μmol/L Res作用于ARPE-19细胞24、48 和72 h后,CCK-8法检测Res对ARPE-19细胞增殖的影响,0、100、150和200 μmol/L Res作用ARPE-19细胞48 h,PI单染流式细胞术检测细胞周期,Annexin V-FITC/PI双染流式细胞术检测细胞凋亡,免疫荧光化学法检测PCNA蛋白表达,实时荧光定量PCR（real-time PCR）法检测PCNA、P21和P27的mRNA表达水平。结果:CCK-8 结果显示,Res抑制ARPE-19细胞增殖,呈时间和剂量依赖性;流式细胞术显示,Res使S期细胞百分比显著上升且各组凋亡率没有区别;免疫荧光显示, Res抑制PCNA蛋白表达,荧光减弱;real-time PCR显示, Res浓度依赖性地抑制PCNA的mRNA表达,而诱导表达P21和P27的mRNA。结论: Res能抑制ARPE-19细胞的增殖,使细胞阻滞在S期,其机制可能与白藜芦醇诱导P21与P27的mRNA表达、抑制PCNA的mRNA表达有关。     

雌激素受体2对前列腺癌细胞系PC-3M增殖的影响

目的： 构建带有人雌激素受体2（ESR2）全长cDNA的重组质粒pcDNA3.1-hERβ,转染人前列腺癌PC-3M细胞株,观察ESR2对细胞增殖能力的影响。 方法：RT-PCR方法从人正常卵巢组织中获取ESR2全长cDNA,利用基因重组技术与真核表达载体pcDNA3.1连接,构建重组质粒pcDNA3.1-hERβ;瞬时转染前列腺癌PC-3M细胞株,应用细胞计数、MTT法及流式细胞术检测细胞增殖能力的改变;半定量RT-PCR法及Western blotting法分别检测增殖相关基因cyclinD1和 P21Cip1 mRNA及蛋白表达。 结果：DNA测序结果显示扩增的ESR2序列与GenBank（NM_001437）所公布的序列完全一致。重组质粒pcDNA3.1-hERβ瞬时转染人PC-3M细胞48 h后,与质粒对照组相比：RT-PCR法及Western blotting法显示,ESR2基因在mRNA水平和蛋白水平的表达均明显增加;细胞计数及MTT结果发现,细胞数目减少,细胞增殖活性下降（P<0.01）;流式细胞实验显示,G0/G1期细胞比例增加（P<0.05）,S期及G2/M期细胞比例减少（P<0.05）;RT-PCR及Western blotting结果还发现cyclinD1的表达减弱,而P21Cip1的表达增强。 结论：成功构建pcDNA3.1-hERβ重组质粒;带有ESR2全长基因的重组质粒转染PC-3M细胞后,细胞的增殖活性受到抑制;RSR2可能通过影响细胞增殖相关基因cyclinD1和 P21Cip1的表达抑制细胞的增殖。     

17β-雌二醇对紧密连接蛋白claudin-6表达及乳腺癌MCF-7细胞生物学行为的影响

目的 研究雌激素调控紧密连接蛋白claudin-6表达和对乳腺癌细胞MCF-7细胞生物学行为的影响.方法 用17β-雌二醇(17β-E2)作用MCF-7细胞后,采用RT-PCR和免疫细胞化学法分析claudin-6表达与17β-E2的浓度和时间效应关系;采用Cell Counting Kit-8(CCK-8)检测17β-E2对MCF-7细胞增殖的影响;采用细胞划痕法检测17β-E2对MCF-7细胞迁移能力的影响.结果 RT-PCR结果显示,17β-E2能够诱导MCF-7细胞表达claudin-6,其诱导表达具有浓度和时间依赖性,其最佳浓度和时间分别为5 nmol/L和24 h;细胞免疫荧光法检测显示,17β-E2组claudin-6主要表达于细胞膜;CCK-8结果显示,5 nmol/L 17β-E2作用24 h可明显抑制MCF-7细胞的生长(P<0.05);细胞划痕实验显示,5 nmol/L 17β-E2作用24 h具有抑制MCF-7细胞迁移的趋势,但差异无统计学意义.结论 17β-E2可以调控claudin-6表达,并具有抑制MCF-7细胞的增殖和迁移的作用.推测17β-E2调控claudin-6表达可能在影响MCF-7细胞生物学行为的过程中发挥一定作用.     

配对相关同源框1基因敲减促进脐带间充质干细胞增殖和多能性

目的:研究基因敲减配对相关同源框1(prrx1)的表达对脐带间充质干细胞(UMSCs)增殖能力和多能性的影响。方法:胚胎干细胞-多能成体祖细胞-间充质干细胞(ESCs-MAPCs-MSCs)全基因组芯片筛选不同干细胞中差异表达的mRNA,针对所选基因特定序列构建prrx1-siRNA,转入UMSCs,real-time PCR验证干扰效率,检测增殖相关基因ki67,多能性相关基因oct4、sox2、nanog,上皮相关基因cdh1、epcam的表达,免疫荧光实验检测ki67蛋白表达。结果:干扰prrx1基因能明显促进增殖相关标志物ki67表达,促进多能性相关基因oct4、sox2、nanog的表达,促进上皮相关基因cdh1、epcam的表达,但不能使细胞发生形态上的改变。结论:下调MSCs中的相对高表达的prrx1基因表达,可促进UMSCs增殖能力与多能性。     

转铁蛋白受体基因对神经干细胞体外增殖和分化的影响研究

目的研究转铁蛋白受体基因(TfR)对神经干细胞(NSCs)体外增殖和分化的影响。方法分别将转铁蛋白受体基因神经干细胞(TfR-NSCs)和正常神经干细胞加入神经干细胞分化液分化7 d后,免疫荧光观察细胞分化及分别计算两种细胞胶质细胞和神经元细胞的分化率;CCK-8法检测其细胞在1 d、2 d、3 d时的A值来观察细胞增殖能力。结果转铁蛋白受体基因神经干细胞和正常神经干细胞均可分化成神经元和胶质细胞,且二者分化率未见明显差异(P0.05);转基因神经干细胞的增殖能力未受抑制(P0.05)。结论转铁蛋白受体基因神经干细胞的增殖分化未受明显影响,为下一步转铁蛋白受体转基因神经干细胞的应用提供支持。     

The PACAP-type I receptor agonist maxadilan from sand fly saliva protects mice against lethal endotoxemia by a mechanism partially dependent on IL-10

Sand fly saliva contains maxadilan, a peptide that causes vasodilation and modifies the secretion of pro-inflammatory cytokines by macrophages. We show that 1 to 10 μg maxadilan protected BALB/c mice against a lethal dose of LPS. Maxadilan reduced serum levels of TNF-α by approximately tenfold, while it caused a threefold increase in IL-6 and IL-10. The protective effect of maxadilan is partially dependent on its ability to induce IL-10 production since maxadilan did not prevent death from endotoxic shock in IL-10^−/- mice. Finally, maxadilan is a selective agonist of the pituitary adenylate cyclase-activating peptide (PACAP) type I receptor, and we found that the natural ligand of this receptor (PACAP 38) also protected mice against lethal endotoxemia. These results indicate that activation of the PACAP type I receptor may contribute to the control of systemic inflammation by a mechanism that is partially dependent on IL-10.     

PACAP modulation of the colon–inferior mesenteric ganglion reflex in the guinea pig

We investigated the effect of pituitary adenylate cyclase activating peptide (PACAP) on the colon–inferior mesenteric ganglion (IMG) reflex loop in vitro . PACAP27 and PACAP38 applied to the IMG caused a prolonged depolarization and intense generation of fast EPSPs and action potentials in IMG neurones. Activation of PACAP-preferring receptors (PAC1-Rs) with the selective agonist maxadilan or vasoactive intestinal peptide (VIP)/PACAP (VPAC) receptors with VIP produced similar effects whereas prior incubation of the IMG with selective PAC1-R antagonists PACAP6-38 and M65 inhibited the effects of PACAP. Colonic distension evoked a slow EPSP in IMG neurones that was reduced in amplitude by prolonged superfusion of the IMG with either PACAP27, maxidilan, PACAP6-38, M65 or VIP. Activation of IMG neurones by PACAP27 or maxadilan resulted in an inhibition of ongoing spontaneous colonic contractions. PACAP-LI was detected in nerve trunks attached to the IMG and in varicosities surrounding IMG neurones. Cell bodies with PACAP-LI were present in lumbar 2–3 dorsal root ganglia and in colonic myenteric ganglia. Colonic distension evoked release of PACAP peptides in the IMG as measured by radioimmunoassay. Volume reconstructed images showed that a majority of PACAP-LI, VIP-LI and VAChT-LI nerve endings making putative synaptic contact onto IMG neurones and a majority of putative receptor sites containing PAC1-R-LI and nAChR-LI on the neurones were distributed along secondary and tertiary dendrites. These results suggest involvement of a PACAP-ergic pathway, operated through PAC1-Rs, in controlling the colon–IMG reflex.     

Is Gulf War Syndrome an autoimmune disorder of endogenous neuropeptides, exogenous sandfly maxadilan and molecular mimicry?

Gulf War Syndrome (GWS) remains a contentious diagnosis with conflicting laboratory investigation and lack of a biologically plausible aetiology. This paper discusses the potential role of maxadilan, a potent sandfly vasoactive peptide, in causing autoimmune responses in susceptible individuals through possible molecular mimicry with pituitary adenylate cyclase activating polypeptide (PACAP) and the PAC1R receptor. Gulf War Syndrome may share some causative pathology with Chronic Fatigue Syndrome (CFS), a disorder characterised by prolonged fatigue and debility mostly associated with post-infection sequelae although ongoing infection is unproven. Immunological aberration associated with an expanding group of vasoactive neuropeptides in the context of molecular mimicry and inappropriate immunological memory has been recently raised as possible cause of CFS. Vasoactive neuropeptides act as hormones, neurotransmitters, immune modulators and neurotrophes. They are readily catalysed to small peptide fragments. They and their binding sites are immunogenic and are known to be associated with a range of autoimmune conditions. Maxadilan, while not sharing substantial sequence homology with PACAP is a known agonist of the PACAP specific receptor (PAC1R) and therefore emulates these functions. Moreover a specific amino acid sequence peptide deletion within maxadilan converts it to a PACAP receptor antagonist raising the possibility of this substance provoking a CFS like response in humans exposed to it. This paper describes a biologically plausible mechanism for the development of a GWS-like chronic fatigue state based on loss of immunological tolerance to the vasoactive neuropeptide PACAP or its receptor following bites of the sandfly Phlebotomus papatasi and injection of the vasodilator peptide maxadilan. Exacerbation of this autoimmune response as a consequence of recent or simultaneous multiple vaccination exposures deserves further investigation. While the possible association between the relatively recently discovered vasoactive neuropeptides and chronic fatigue conditions has only recently been reported in the literature, this paper explores links for further research into GWS and CFS.     

Reduction of lipopolysaccharide-induced neurotoxicity in mixed cortical neuron/glia cultures by femtomolar concentrations of pituitary adenylate cyclase-activating polypeptide.

Stimulation of murine primary mixed cortical neuron/glia cultures with lipopolysaccharide, an endotoxin, was used as a model for inflammatory disorders of the central nervous system. Lipopolysaccharide (20 microg/ml) increased the secretion of lactate dehydrogenase, a marker for cell injury, and nitric oxide into the culture medium. The lipopolysaccharide-induced release of lactate dehydrogenase into the culture medium was reduced by pituitary adenylate cyclase-activating polypeptide (PACAP) at 10(-14)-10(-12) M. The 27- and 38-amino-acid forms of PACAP were equipotent and their dose-response curves were U-shaped. PACAP6-38, a specific type I PACAP receptor antagonist, blocked the reduction by PACAP38 of the lipopolysaccharide-induced release of lactate dehydrogenase. The lipopolysaccharide-induced secretion of nitric oxide into the culture medium was reduced by PACAP at 10(-14)-10(-12) M and 10(-8)-10(-6) M. The 27- and 38-amino-acid forms of PACAP were equipotent. PACAP6-38 blocked the reduction of the lipopolysaccharide-induced secretion of nitric oxide by PACAP38 at 10(-12) M, but not at 10(-8) M. Vasoactive intestinal polypeptide reduced the lipopolysaccharide-induced release of lactate dehydrogenase into the culture medium at 10(-14)-10(-12) M, but these concentrations of vasoactive intestinal polypeptide had no effect on the lipopolysaccharide-induced secretion of nitric oxide. PACAP6-38 did not effect the reduction of the lipopolysaccharide-induced release of lactate dehydrogenase into the culture medium by 10(-12) M vasoactive intestinal polypeptide. These results indicate that stimulation of type I PACAP receptors by femtomolar concentrations of PACAP can prevent neuron death in a model for inflammatory disorders of the CNS. These results suggest that PACAP is also an extraordinarily potent inhibitor of some microglial functions.     

Pituitary adenylate cyclase-activating polypeptide inhibits transforming growth factor-beta1-induced apoptosis in a human pituitary adenoma cell line

Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from hypothalamic tissues based on its ability to stimulate cAMP production in cultured anterior pituitary cells. Recent studies have suggested a functional role for PACAP in the apoptosis of brain cells. However, the role of PACAP in regulating apoptosis in human pituitary adenomas has not previously been examined. Analysis of the cultured human pituitary adenoma cell line HP75, which expresses all three major PACAP receptors, showed that both PACAP-38 and PACAP-27 inhibited TGF-beta1-induced apoptosis. Treatment with the PACAP receptor antagonists PACAP 6-38 (PACAP type I receptor antagonist) and (p-chloro-D-Phe(6), Leu(17))-VIP (PACAP type II receptor antagonist) blocked the effects of PACAP-38 on the inhibition of transforming growth factor-beta1 (TGF-beta1)-induced apoptosis, confirming the specificity of the role of PACAP. Treatment with forskolin but not phorbol 12-myristate 13-acetate (PMA) also inhibited TGF-beta1-induced apoptosis. TGF-beta1 treatment was associated with an increase in mitogen-activated protein kinase (MAP kinase) when analyzed by Western blotting, but PACAP inhibition of TGF-beta1-induced apoptosis was not associated with activation of MAP kinase. Immunocytochemical analysis of the cell cycle cyclin-dependent kinase inhibitor p27 showed that treatment with TGF-beta1, forskolin, PMA, and PACAP increased p27 expression in cultured HP75 cells. These results indicate that PACAP is a highly specific inhibitor of TGF-beta1-induced apoptosis in the HP75 human pituitary adenoma cell line and that PACAP, TGF-beta1, forskolin, and PMA all stimulate expression of the TGF-beta-regulated cell cycle protein p27 in the HP75 human pituitary adenoma cell line. The HP75 cell line can be used as a model to study the regulation of apoptosis in human pituitary cells.     

Endocannabinoids contribute to metabotropic glutamate receptor-mediated inhibition of GABA release onto hippocampal CA3 pyramidal neurons in an isolated neuron/bouton preparation

Retrograde synaptic signaling by endogenous cannabinoids (endocannabinoids) is a recently discovered form of neuromodulation in various brain regions. In hippocampus, it is well known that endocannabinoids suppress presynaptic inhibitory neurotransmitter release in CA1 region. However, endocannabinoid signaling in CA3 region remains to be examined. Here we investigated whether presynaptic inhibition can be caused by activation of postsynaptic group I metabotropic glutamate receptors (mGluRs) and following presynaptic cannabinoid receptor type 1 (CB1 receptor) using mechanically dissociated rat hippocampal CA3 pyramidal neurons with adherent functional synaptic boutons. Application of group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) reversibly suppressed spontaneous inhibitory postsynaptic currents (IPSCs). In the presence of tetrodotoxin (TTX), frequency of miniature IPSCs was significantly reduced by DHPG, while there were no significant changes in minimum quantal size and sensitivity of postsynaptic GABA_A receptors to the GABA_A receptor agonist muscimol, indicating that this suppression was caused by a decrease in GABA release from presynaptic nerve terminals. Application of CB1 synthetic agonist WIN55212-2 (mesylate(R)-(+)-[2,3-dihydro-5-methyl-3-[4-morpholino)methyl]pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl](1-naphthyl)methanone) or endocannabinoid 2-arachidonoylglycerol also suppressed the spontaneous IPSC. The inhibitory effect of DHPG on spontaneous IPSCs was abolished by SR-141716 (5-(4-chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide), a CB1 receptor antagonist. Furthermore, postsynaptic application of GDP-βS blocked the DHPG-induced inhibition of spontaneous IPSCs, indicating the involvement of endcannabinoid-mediated retrograde synaptic signaling. These results provide solid evidence for retrograde signaling from postsynaptic group I mGluRs to presynaptic CB1 receptors, which induces presynaptic inhibition of GABA release in rat hippocampal CA3 region.     

Role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the action of ginsenoside Rh2 against beta-amyloid-induced inhibition of rat brain astrocytes

Ginsenoside, the active principles in Panax ginseng root, has been demonstrated to show neurotrophic and neuroprotective actions for prevention of neuron degeneration. Deposition of β-amyloid peptide (Aβ) causes neurotoxicity through the formation of plaques in brains with Alzheimer's disease. Pituitary adenylate cyclase-activating polypeptide (PACAP) is introduced as a neurotrophic factor to promote cell survival. However, effect of Rh2, one of ginsenosides, on PACAP expression induced by Aβ remains unclear. In the present study, we found that Rh2 stimulates PACAP gene expression and cell proliferation in type I rat brain astrocytes (RBA1) cells and both effects were not modified by the estrogen antagonists (MPP or ICI 182780). Also, Rh2 ameliorates the RBA1 growth inhibition of Aβ. Moreover, blockade of PACAP receptor PAC1 using PACAP (6-38) inhibits all the actions of Rh2. These results suggest that Rh2 can induce an increase of PACAP to activate PAC1, but not estrogen receptor, and thereby leads to attenuate Aβ-induced toxicity. Thus, ginseng seems useful in the prevention of dementia.     

Retrograde signaling changes the venue of postsynaptic inhibition in rat substantia nigra

Both endocannabinoids through cannabinoid receptor type I (CB1) receptors and dopamine through dopamine receptor type D1 receptors modulate postsynaptic inhibition in substantia nigra by changing GABA release from striatonigral terminals. By recording from visually identified pars compacta and pars reticulata neurons we searched for a possible co-release and interaction of endocannabinoids and dopamine. Depolarization of a neuron in pars reticulata or in pars compacta transiently suppressed evoked synaptic currents which were blocked by GABA(A) receptor antagonists (inhibitory postsynaptic currents [IPSCs]). This depolarization-induced suppression of inhibition (DSI) was abrogated by the cannabinoid CB1 receptor antagonist AM251 (1 microM). A correlation existed between the degree of DSI and the degree of reduction of evoked IPSCs by the CB1 receptor agonist WIN55,212-2 (1 microM). The cholinergic receptor agonist carbachol (0.5-5 microM) enhanced DSI, but suppression of spontaneous IPSCs was barely detectable pointing to the existence of GABA release sites without CB1 receptors. In dopamine, but not in GABAergic neurons DSI was enhanced by the dopamine D1 receptor antagonist SCH23390 (3-10 microM). Both the antagonist for CB1 receptors and the antagonist for dopamine D1 receptors enhanced or reduced, respectively, the amplitudes of evoked IPSCs. This tonic influence persisted if the receptor for the other ligand was blocked. We conclude that endocannabinoids and dopamine can be co-released. Retrograde signaling through endocannabinoids and dopamine changes inhibition independently from each other. Activation of dopamine D1 receptors emphasizes extrinsic inhibition and activation of CB1 receptors promotes intrinsic inhibition.     

PAC1 receptors in chick cerebral cortex: characterization by binding of pituitary adenylate cyclase-activating polypeptide, [125I]-PACAP27

In this study we characterized receptors for pituitary adenylate cyclase-activating polypeptide (PACAP) in chick cerebral cortex by in vitro binding technique, using [125I]-PACAP27 as a ligand. The specific binding of [125I]-PACAP27 to chick cerebral cortical membranes was found to be rapid, stable, saturable, and of high affinity. Scatchard analysis suggested binding to a single class of receptor binding sites with high affinity (K(d)=0.41+/-0.08 nM) and high capacity (B(max)=457+/-35 fmol/mg protein). The relative rank order of potency of the tested peptides to inhibit [125I]-PACAP27 binding to chick cerebrum was: PACAP38 approximately PACAP27>PACAP6-27 approximately PACAP6-38 > chicken VIP > mammalian VIP > secretin (inactive). It is concluded that the cerebral cortex of chick, in addition to VPAC recognition sites, contains a large population of PAC(1)-type receptor binding sites.