Effect of histamine on corticosteroid secretion of isolated human and rat adrenocortical cells

Inflammation Research -     

Effects of somatostatin on basal and stimulated pancreatic secretion in conscious rat

The effects of somatostatin on pancreatic secretion were studied in conscious rats during diversion and recirculation of pancreatic juice. Pancreatic secretion was significantly inhibited by low doses (2 micrograms/kg/h) of somatostatin during diversion of pancreatic juice. The inhibitory effect was more marked on bicarbonate and protein output than on volume, while in bicarbonate and protein output a rebound effect was observed. These data suggest a combined inhibitory effect of somatostatin on endogenous CCK release and cholinergic mechanisms. During recirculation of pancreatic juice there was no rebound effect, thus only the inhibition of cholinergic mechanisms seems to be involved in the inhibitory effect of somatostatin. During recirculation, CCK-OP-stimulated bicarbonate and protein secretion was strongly inhibited by somatostatin. Even water secretion not stimulated by CCK-OP was significantly inhibited demonstrating a supplementary inhibitory effect on basal cholinergic mechanisms. Somatostatin decreased only slightly the synthetic secretin-stimulated water and bicarbonate secretion. The more effective inhibition of protein output was explained by an additive effect of somatostatin on basal cholinergic tone.     

Endocrine disruptors and rat adrenocortical function: studies on freshly dispersed and cultured cells

The effects of four endocrine disruptors: resveratrol, diphenylolpropane (bisphenol-A; BSP), benzophenone-3 (BP3) and silymarin on the secretory and proliferative activity of rat adrenocortical cells were investigated in vitro. Resveratrol and BP3 acutely increased basal corticosterone secretion from freshly dispersed adrenocortical cells, and resveratrol and BSP enhanced ACTH-stimulated cells. The 24-h exposure to resveratrol and BP3 increased basal corticosterone production from cultured adrenocortical cells, while ACTH-stimulated secretion was increased only by resveratrol. BSP was ineffective, while silymarin decreased basal, but not ACTH-stimulated secretion. The proliferative activity of the cultured adrenocortical cells was unaffected by the tested disruptors. In conclusion, the in vitro direct effect of endocrine disruptors on adrenocortical steroidogenesis displays a great variability, which seems to depend not only on their chemical nature, but also on their dose and the duration of the exposure of the studied cells.     

脂多糖刺激人血管内皮细胞分泌内皮素和肾上腺髓质素及其机制研究

目的:研究脂多糖(LPS)刺激人血管内皮细胞(HVEC)分泌内皮素-1(ET-1)与肾上腺髓质素(Adm)的机制。方法:在培养的HVEC上,用放射免疫法测定不同浓度LPS刺激HVEC分泌的ET-1与Adm,以及不同的细胞信号转导阻断剂对其分泌的影响。结果:LPS呈时间和浓度依赖性地增加HVEC分泌ET-1和Adm,ET-1/Adm比值与对照组比较无明显差异(P＞0.05)。在LPS刺激基础上,细胞外信号调节激酶(ERKs)抑制剂PD₀₉₈₀₅₉和P38蛋白激酶抑制剂SB₂₀₂₁₉₀可明显降低LPS刺激HVEC分泌ET-1(P＜0.01),仅SB₂₀₂₁₉₀显著降低Adm的分泌(P＜0.05),其余PKC抑制剂H₇,钙调素(CaM)抑制剂W₇,Ca²⁺阻断剂nicardipine,钙调神经磷酸酶(CaN)抑制剂环孢霉素(CsA)对LPS刺激HVEC分泌ET-1和Adm均无明显影响(P＞0.05)。结论:LPS刺激HVEC分泌ET-1可能与ERKs和P38两条途径有关,LPS刺激HVEC分泌Adm只与P38信号通路有关,两者均不取决于PKC、Ca²⁺、CaM、CaN依赖的信号通路。     

CXCL12对大鼠海马培养细胞GABA和乙酰胆碱分泌的影响及其机制

目的:观察CXCL12对体外培养的海马神经细胞神经递质γ-氨基丁酸(GABA)和乙酰胆碱分泌的影响,并探讨其受体机制。方法:通过免疫荧光组织化学染色方法观察CXCL12和其受体CXCR4在细胞内的定位;ELISA方法分别检测海马神经细胞在体外培养过程中CXCL12的分泌变化、CXCL12对海马神经细胞神经递质分泌的影响、以及用CXCR4阻断剂(AMD3100)阻断CXCR4后神经递质释放的变化。结果:CXCL12主要分布在海马神经细胞的细胞浆内,细胞膜上也有表达,其受体CXCR4主要表达在海马神经细胞的细胞膜上;在海马神经细胞体外培养过程中,随时间延长(1、3、5、7、10 d),CXCL12的分泌逐渐减少;采用50 ng/ml的CXCL12作用于海马神经细胞后,随着培养时间的延长,GABA和乙酰胆碱的分泌出现不同的变化,其中乙酰胆碱的分泌逐渐增加,而GABA的分泌则呈现一过性下降又短暂轻微升高的趋势;通过AMD3100阻断其受体CXCR4,则乙酰胆碱分泌减少,但GABA的分泌增加。结论:CXCL12通过CXCR4受体引起乙酰胆碱分泌增加,GABA分泌减少。这些现象表明CXCL12可以作为一种重要的神经生长因子刺激GABA和乙酰胆碱的分泌。     

肾上腺髓质素2对大鼠脑微血管内皮细胞增殖的影响

目的：研究肾上腺髓质素2（AM2）对大鼠脑微血管内皮细胞增殖的影响。 方法： 分离并培养SD大鼠脑微血管内皮细胞，经Ⅷ因子相关抗原的抗体鉴定和常规处理后，随机分为对照、AM2（10^-7 mol/L、10^-8 mol/L和10-9 mol/L）、ADM、ADM+AM2、10%胎牛血清和10％胎牛血清＋AM2 10-7 mol/L等8组，以［3H］-TdR掺入法测定MEC增殖反应。 结果： 10^-7-10^-9 mol/L各浓度AM2、ADM以及AM2和ADM合用对于静止状态的脑微血管内皮细胞［3H］-TdR掺入与对照组比较均无明显差异（均P>0.05）。10%胎牛血清刺激组脑微血管内皮细胞［3H］-TdR掺入比对照组高87.5%（P<0.05），10^-7mol/L AM2抑制胎牛血清诱导的脑微血管内皮细胞［3H］-TdR掺入增加（P<0.05）。 结论： AM2抑制血清诱导的脑微血管内皮细胞增殖。     

Effects of retinol and hepatocyte-conditioned medium on cultured rat hepatic stellate cells

Hepatic stellate cells (HSC) become activated in liver injury, proliferating and secreting components of connective tissue. Activated HSC lose their native retinol and fat storing capacity. Signals from hepatocytes and/or Kupffer cells injured (eg, by iron overload) may contribute to the so-called activated HSC phenotype. Primary rat HSC cultures were treated with retinol to determine if this could produce a quiescent cell for controlled in vitro studies of activation. Retinol resulted in suppressed DNA synthesis in proliferating HSC, a reorganization of actin filaments, and a return of fat storage. However, it did not suppress the expression of fibrogenic genes such as those for collagens type I and IV, and TGF-beta1. Furthermore, retinol-treated cells may increase expression of these genes in response to conditioned medium from hepatocyte cultures. The effect is especially apparent for collagen type I mRNA, and with conditioned medium from iron-loaded hepatocytes. Thus, retinol may be a two-edged sword in iron overload, potentially suppressing HSC proliferation on the one hand, and sensitizing a fibrogenic pattern of gene expression on the other. Factors influencing this balance merit further study.     

高浓度葡萄糖对大鼠肾小球系膜细胞增殖的影响

目的: 观察高糖环境对系膜细胞增殖的影响。方法: 用高浓度葡萄糖刺激系膜细胞, 采用MTT比色法观察系膜细胞的增殖情况。结果: 葡萄糖对系膜细胞的增殖效应呈现浓度和时间依赖性, 其中20 mmol/L的葡萄糖为最佳刺激增殖浓度, 反应最佳时点为48 h。10 mmol/L、20 mmol/L和30 mmol/L在72 h和96 h有抑制增殖作用。结论: 高糖在一定浓度和一定时段内有刺激大鼠系膜细胞增殖的效应, 随着时间的延长此效应消失。     

Leptin对缺氧诱导胎肺Ⅱ型上皮细胞凋亡的影响及机制

目的： 观察瘦素(LEP)对缺氧诱导胎鼠肺Ⅱ型上皮细胞（AECⅡ）凋亡的拮抗作用，并探讨其机制。方法： 采用改良免疫黏附法原代培养胎鼠AECⅡ细胞，并用SP-A免疫细胞化学法和透射电镜进行鉴定；用含5 mmol/L连二亚硫酸钠（Na₂S₂O₄）培养液培养AECⅡ细胞12 h建立缺氧诱导细胞凋亡模型，处理组含不同浓度LEP（100-1 600 μg/L）；噻唑兰（MTT）比色法检测细胞存活情况；流式细胞术分析细胞凋亡和细胞周期；蛋白质免疫印迹法（Western blotting）检测凋亡蛋白caspase 3的表达。结果： 采用免疫黏附法获得高纯度原代培养的AECⅡ细胞，免疫细胞化学法示SP-A阳性表达，电镜下可见细胞内特征性板层小体；5 mmol/L Na₂S₂O₄能诱导AECⅡ细胞凋亡和caspase 3活化，LEP（100-1 600 μg/L） 能减轻Na₂S₂O₄所致的细胞损伤，表现为AECⅡ存活率提高、增殖指数（PI）增高及凋亡峰下降、细胞形态恢复和caspase 3活化受抑制。结论： LEP可拮抗缺氧所致AECⅡ细胞凋亡，这可能与其促使细胞周期从G₁期进入S期及抑制凋亡蛋白caspase 3活化有关。     

Effects of beta-amyloid on rat neuromicrovascular endothelial cells cultured in vitro

Several studies have shown that beta-amyloid (beta A) deposits are associated with damage of cerebral vessels and that in Alzheimer's disease (AD) beta A peptides are cytotoxic for cerebral endothelial cells (ECs). However, little is known about the mechanisms underlying these effects of beta A peptides. Hence, we have investigated the effects of beta A(1-40) and beta A(1-42) on rat neuromicrovascular ECs (NECs) cultured in vitro. NECs were isolated, plated (1.5x10(4) cells/cm2) on collagen/fibronectin-coated Petri dishes and cultured in EC growth medium MV2. After 24 h of culture, NECs were incubated with beta A(1-40) and beta A(1-42) (10(-9) or 10(-7) M) and cultured for another 3, 24 or 48 h. Cell viability was assayed by either trypan blue exclusion or by measuring redox activity (MTS assay). Cell proliferation was assessed by measuring the incorporation of 5'-bromo-2'-deoxyuridine into DNA, cell apoptosis by TUNEL assay and cell necrosis by evaluating the release of lactate dehydrogenase. The morphology of cultured NECs was examined by transmission electron microscopy. Other NECs were plated (2.5x10(4) cells/cm2) on Matrigel coated-wells and incubated for 18 h in the presence or absence of beta A peptides for in vitro angiogenesis assay. Beta A peptides significantly decreased NEC viability and enhanced cell apoptosis and necrosis rates. NEC proliferation was not significantly affected. The effects were seen after an incubation period of 3 h (and also 24 h in the case of the redox activity) but not 48 h and beta A(1-42) was much more effective in its toxic effects than beta A(1-40). NECs incubated for 24 h with beta A peptides displayed ultrastructural signs of cell degeneration. beta A peptides prevented NECs cultured on Matrigel to form a capillary-like network and image analysis showed that the downloading of dimensional and topological parameters of the meshwork was significant only in the case of the incubation with beta A(1-42). Collectively our findings allow us to conclude that i) beta A peptides exert a marked toxic effect on cultured NECs, which conceivably reduces their in vitro angiogenic activity; ii) beta A(1-42) is the more toxic form, which could suggest its main role in the pathogenesis of cerebral vessel lesions in AD and iii) the maximum toxic action occurs after a short incubation period, which could be explained by assuming that beta A peptides are unable to accumulate in NECs due to their rapid degradation, thereby allowing NECs to fully recover within 48 h.     

Effects of preproglucagon-derived peptides and exendins on steroid-hormone secretion from dispersed adrenocortical cells of normal and streptozotocin-induced diabetic rats

Many lines of evidence have shown that preproglucagon-derived peptides affect steroid secretion from dispersed adrenocortical cells, and that streptozotocin (STZ)-induced experimental diabetes alters adrenocortical-cell function. Hence, we compared the effects of glucagon, glucagon-like peptide (GLP)-1 and GLP-2 on basal and ACTH-stimulated secretion of dispersed adrenocortical cells from normal and STZ-induced diabetic rats. We also examined the effects of exendins (EX) 3 and 4, because EX4 is known to be a potent and long-lasting agonist of GLP-1 receptors. STZ-induced diabetes moderately enhances basal and ACTH-stimulated secretion from dispersed zona glomerulosa (ZG) cells, without significantly affecting corticosterone production from dispersed zona fasciculata-reticularis (ZF/R) cells. In normoglycemic rats, glucagon increased basal aldosterone and corticosterone secretion from ZG and ZF/R cells, GLP-2 raised both basal and ACTH-stimulated aldosterone secretion and ACTH-stimulated corticosterone output, and EX4 increased basal corticosterone secretion. In contrast, glucagon, GLP-2 and EX4 did not elicit secretory responses from adrenocortical cells of diabetic rats. GLP-1 and EX3 did not alter secretion of dispersed adrenocortical cells of either normal or STZ-treated rats. Taken together, our findings indicate that preproglucagon-derived peptides enhance steroid secretion from adrenocortical cells of normal, but not STZ-induced diabetic rats. It is suggested that the prolonged exposure to low concentrations of insulin causes unresponsiveness of adrenocortical cells to glucagon, GLP-2 and EX4, which may contribute to the hyporeninemic hypoaldosteronism and alterations in glucocorticoid metabolism occurring in experimental diabetes.     

Effect of cholecystokinin octapeptide and vasoactive intestinal polypeptide on adrenocortical secretion in the rat

Intraperitoneal (i.p.) injection of C-terminal octapeptide of cholecystokinin (CCK-8) produced a dose-related increase in plasma corticosterone levels in intact rats, but not in vagotomized ones. Intracerebroventricular (i.c.v.) injection of CCK-8 was ineffective in stimulating the secretion of corticosterone, and in vitro experiment on ACTH release indicated that CCK-8 could not affect pituitary tissue directly. Since i.p. injection of non-sulfated CCK-8 failed to elevate plasma corticosterone levels, sulfated tyrosine residue in the CCK molecule is assumed to be indispensable for the stimulation of visceral organs. On the other hand, vasoactive intestinal polypeptide (VIP) was found to cause a dose-dependent increase in plasma corticosterone levels when administered centrally, but not after i.p. injection. However, VIP could not stimulate the release of ACTH from the pituitary tissue directly. The results suggest that VIP, but not CCK, stimulates the hypothalamic CRF neurons either directly or indirectly.