GnRH类似物对大鼠回肠组织胰高血糖素释放的影响

目的 :研究促性腺激素释放激素 (GnRH)类似物 (阿拉瑞林 )对大鼠回肠L细胞释放胰高血糖素的影响。方法 :应用放射免疫分析法对体内和体外大鼠回肠进行观察。结果 :大鼠回肠灌注GnRH类似物后 ,血中及肠液中胰高血糖素的含量较对照组明显升高 ;体外孵育大鼠回肠组织后 ,在一定浓度范围内 ,孵育液中胰高血糖素含量随GnRH类似物浓度升高而升高 ;当浓度高于一定范围时 ,则随浓度升高而降低。GnRH类似物浓度为 1 .0× 1 0 - 4mol/L时孵育液中胰高血糖素含量是升高的。结论 :GnRH可能对大鼠回肠L细胞分泌胰高血糖素呈现双向调节作用。但是GnRH类似物为 1 .0× 1 0 - 4mol/L ,不论是体内还是体外 ,都可能对肠道分泌胰高血糖素表现促进作用     

卵泡刺激素对体外孵育大鼠下颌下腺分泌NGF和EGF的影响

目的 通过确定卵泡刺激素(FSH)与神经生长因子(NGF)或表皮生长因子(EGF)在大鼠下颌下腺的共定位关系,研究FSH在体外对大鼠下颌下腺组织分泌NGF和EGF的影响. 方法 采用邻片免疫组织化学共定化方法 ;体外孵育大鼠下颌下腺组织并给予不同浓度FSH,应用酶联免疫分析方法 检测上清液中NGF和EGF的含量. 结果 大鼠下颌下腺浆液性腺上皮细胞、颗粒曲管及大于颗粒曲管的导管上皮细胞均呈FSH、NGF及EGF免疫反应阳性,FSH与NGF或EGF有共存性;当FSH浓度大于10-5～10-6时,NGF或EGF分泌量随FSH浓度的递减而降低;当FSH浓度小于10-5～10-6时,NGF或EGF分泌量随FSH浓度的递减而升高. 结论 FSH在体外对NGF或EGF分泌具有相同的双向调节作用,FSH可能对下颌下腺内分泌具有调节功能.     

胰高血糖素放射免疫分析的临床应用(文献综述)

胰高血糖素（Glucagon）是由胰岛α细胞分泌的29个氨基酸组成的多肽,主要调节机体血糖浓度可使其升高。 一、胰高血糖素的生理作用:由于胰高血糖素的主要生理作用具有较强的促使血糖升高,其主要途径是激活肝细胞磷酸化酶,使肝糖元分解加速及促进氨基酸的脱氨基作用,使氨基酸转化为葡萄糖,加速糖元异生。胰高血糖素当激活心肌细胞磷酸化酶时,对于心肌内糖元可加速分解利用,使心肌收缩力可增强。 二、胰高血糖素分泌的调节:胰高血糖素分泌活动的生理调节与血糖浓度有密切关系,是调节胰高血糖素分泌的最重要的因素。当血糖浓度降低时可直接作用于胰岛α细胞,促使胰高血糖素分泌增加;相反,血糖增高时,则胰高血糖素分泌减少。胰高血糖素的分泌与胰岛素有密切关系,当血糖浓度增高时,胰岛β细胞分泌胰岛素增加,胰岛素可直接作用于胰岛α细胞抑制胰高血糖素分泌,使血糖浓度降低。胰高血糖素与胰岛素两者相互作用在调节血糖浓度维持动态平衡具有重要的作用。此外,生长激素、ACTH、皮质醇、α和β肾上腺素能受体刺激物等物质对胰高血糖素的分泌调节都具有作用。     

葡萄糖浓度与大鼠胰腺导管干细胞的诱导分化

背景：葡萄糖是胰腺导管干细胞分化的重要因素之一,与分化后胰岛素分泌细胞数量及分泌能力相关。 目的：对比不同浓度葡萄糖诱导下,胰腺导管干细胞分化后细胞的胰岛素分泌能力。 方法：使用胶原酶Ⅴ及Ficoll-400分离及纯化Wistar大鼠胰腺上皮细胞,获取胰腺导管干细胞,将干细胞分为10组,体外培养、增殖及分化形成胰岛素分泌细胞。各组在含有不同浓度葡萄糖的培养基中进行分化。采用免疫荧光染色法鉴定胰腺导管干细胞,光化学发光法检测分化出的胰岛素分泌细胞的胰岛素分泌量。 结果与结论：葡萄糖浓度为20.6,25.6,  30.6 mmol/L组细胞的刺激指数高于其他组(P < 0.05),但这3组两两比较差异无显著性意义(P > 0.05)。葡萄糖浓度为15.6,20.6,25.6 mmol/L组细胞胰岛素分泌量高于其他组(P < 0.05),但这3组两两比较差异无显著性意义(P > 0.05)。提示胰腺导管干细胞分化为胰岛素分泌细胞实验中,当分化时培养液所含葡萄糖浓度为20.6~25.6 mmol/L时,所得细胞胰岛素分泌能力最强。     

小儿单纯性营养不良胰腺内分泌功能研究

目的探讨单纯性营养不良（protein-energy malnutrition,PEM）患儿胰腺内分泌功能。方法采用放射免疫分析法测定空腹和摄入液体实验餐后60min时外周血胰岛素、胰高血糖素、生长抑素（SS）及血糖水平。结论与对照组比较,观察组空腹及餐后60min胰岛素、胰高血糖素、胰岛素以及胰高血糖素比值均明显降低,而SS水平则明显升高（P均〈0.01）。血糖水平则是餐前比较观察组明显降低（P均〈0.01）,餐后比较则明显升高（P均〈0.01）。与对照组相似,观察组患儿餐后与餐前比较,胰岛素、胰高血糖素、SS、胰岛素/胰高血糖素比值和血糖水平均明显升高（P均〈0.01）。结果PEM患儿存在着明显的胰腺内分泌紊乱,应引起重视。     

黄体生成素类似物对离体大鼠颌下腺细胞分泌神经生长因子的影响

目的:探讨黄体生成素(LH)类似物对离体大鼠颌下腺细胞分泌神经生长因子(NGF)的影响.方法:体外孵育大鼠颌下腺细胞并给予不同浓度的LH类似物,采用酶联免疫分析(ELISA)方法检测上清液中神经生长因子的含量.结果:当加入终浓度为10-6、10-4、10-2U/L的LH类似物孵育颌下腺细胞时,NGF的分泌量随着浓度的升高而逐渐增高;当LH类似物浓度为10-2、100、102 U/L时,NGF的分泌量随LH类似物浓度的递减而降低;同时随着时间的增加,NGF的分泌量也会增加,孵育8 h时达高峰,随后开始下降.结论:在体外LH类似物可双项调节大鼠颌下腺细胞分泌NGF的功能.     

β细胞素对胰腺干细胞转分化为胰岛样细胞团的影响

目的:探讨大鼠β细胞素在胰腺干细胞的增殖和转分化为胰岛细胞中的生物学作用.方法:分离并培养大鼠胰腺干细胞于CMRL1066和无血清DMEM/F12培养液中,不同浓度大鼠β细胞素处理后,双硫腙染色,放免法检测胰岛素分泌量.结果:在大鼠β细胞素浓度为20～30 mg/L时,大鼠胰腺干细胞转分化为胰岛样细胞团的数量明显高于对照组;其胰岛素分泌量明显高于对照组(P<0.01).结论:大鼠β细胞素具有促进胰腺干细胞转分化为胰岛β细胞并增强其胰岛素分泌的作用.     

大鼠骨髓间质干细胞体外诱导分化为胰岛素分泌细胞的实验研究

目的研究体外定向诱导大鼠骨髓间质干细胞（BMSCs）横向分化为胰岛素分泌细胞的可能性,并了解该细胞是否具备分泌胰岛素和胰高血糖素的功能.方法从健康成年大鼠骨髓中分离BMSCs,通过传代对细胞进行纯化和扩增.采用两期诱导方案,用诱导液1使BMSCs向巢蛋白（nestin）阳性的祖细胞分化;用诱导液2使nestin阳性的祖细胞向胰岛素分泌细胞分化.用双硫腙染色鉴定胰岛素分泌细胞团;免疫细胞化学法检测诱导前后nestin、胰岛素及胰高血糖素蛋白的表达;采用放射免疫分析法检测葡萄糖刺激后上清中胰岛素的量.结果BMSCs经第一期诱导5d可分化成nestin阳性的祖细胞,双硫腙染色阳性.免疫细胞化学显示,经两期,诱导后的细胞表达胰岛素、胰高血糖素等激素.放射免疫分析结果显示,诱导后的细胞团可以分泌胰岛素,糖反应性较弱.结论健康成年大鼠骨髓间质干细胞在体外可以被诱导分化为胰岛样细胞团,且具有可重复性.     

妊娠和高脂妊娠大鼠胰腺胰高血糖素的表达

目的:探讨在生理妊娠和高脂饮食诱导的病理妊娠状态下胰腺胰高血糖素的变化特点,同时观察2种妊娠状态葡萄糖耐量试验各点血糖和血清胰岛素的变化。方法:32只雌性SD大鼠随机分为对照组、高脂组、妊娠组和高脂妊娠组,高脂饲料喂养16周后,妊娠组大鼠进行配对受精,妊娠第14天,采用实时荧光定量PCR和免疫印迹法分别检测大鼠胰腺胰高血糖素原mRNA和胰高血糖素蛋白表达。结果:葡萄糖耐量试验结果显示各组大鼠的血糖最高点均在服糖后30min。对照组胰岛素分泌最高点在15min,而高脂组、妊娠组和高脂妊娠组胰岛素分泌高峰为30min。妊娠组空腹胰岛素高于对照组(P0.05),高脂妊娠组空腹胰岛素高于对照组(P0.01),同时胰岛素AUC也高于对照组(P0.05)。妊娠组胰腺胰高血糖素原mRNA相对表达量高于对照组1.46倍(P0.05),高脂妊娠组胰腺胰高血糖素原mRNA相对表达量高于对照组1.77倍(P0.01),高于高脂组1.54倍(P=0.01)。妊娠组胰高血糖素高于对照组2.57倍(P0.01),高脂妊娠组胰高血糖素高于对照组3.44倍(P0.01),高于高脂组2.9倍(P0.01)。结论:高脂和妊娠两种状态均导致胰岛素高峰分泌延迟,生理妊娠中期胰岛素抵抗以基础胰岛素增高为主,而高脂妊娠中期同时存在基础和糖负荷后高胰岛素血症和胰岛素抵抗。妊娠中期胰腺胰高血糖素增高可能是妊娠胰岛素抵抗增加的组成部分。     

曲古抑菌素A促进小鼠骨髓间充质干细胞分化为胰岛素分泌细胞

 目的： 观察曲古抑菌素A(TSA)诱导小鼠骨髓间充质干细胞分化为胰岛素分泌细胞的适宜浓度。方法: C57BL/6小鼠骨髓间充质干细胞系体外培养。实验分为5组：对照组（DMSO,A组)和TSA干预组（25 nmol/L,B组;50 nmol/L,C组;100 nmol/L,D组;200 nmol/L,E组）。各组分两阶段用相应的培养基培养10 d后进行检测。双硫腙染色鉴定各组的胰岛素分泌细胞,结果进行半定量分析。免疫荧光染色鉴定各组的胰岛素分泌,比较各组胰岛素平均荧光强度。酶联免疫吸附试验检测各组胰岛素分泌细胞胰岛素的分泌量。结果: TSA作用10 d能够诱导C57BL/6 小鼠骨髓间充质干细胞分化成为胰岛素分泌细胞并分泌胰岛素。 B组胰岛素染色阳性面积、阳性率、胰岛素染色积分吸光度以及胰岛素平均荧光强度显著高于其它干预组,差异有统计学意义（均P<0.05）。 随着各干预组TSA浓度的升高,胰岛素的分泌量减少。B组胰岛素含量显著高于其它干预组,差异有统计学意义（均P<0.05）。结论：TSA处理10 d能诱导C57BL/6 小鼠骨髓间充质干细胞分化成为胰岛素分泌细胞,并且25 nmol/L为TSA的适宜浓度。     

Gastrin releasing peptide stimulates the secretion of insulin, but not that of glucagon or somatostatin, from the isolated perfused dog pancreas

Gastrin releasing peptide (GRP) is an intrapancreatic peptide, but its physiological function is unknown. Previously, the peptide has been shown to increase plasma levels of insulin and glucagon in vivo in dogs, but no studies on the possible direct actions on islet hormone secretion from the dog pancreas have been undertaken. Therefore, we examined the effects of a 10-min perfusion of synthetic porcine GRP at four different dose rates over a wide range (0.1-50 nmol l-1) on the islet hormone release from the isolated dog pancreas (n = 5-6 in each group) at 5.5 mM glucose. We found that, at all four concentrations tested, GRP rapidly and markedly stimulated insulin secretion. The stimulation was, however, transient: the increased insulin secretion returned to basal levels within 7-8 min despite the ongoing GRP perfusion for 10 min. In contrast, GRP did not affect the pancreatic secretion of glucagon or somatostatin. We conclude that GRP stimulates insulin secretion by a direct pancreatic action without affecting the secretion of glucagon or somatostatin.     

Stimulation by calcium and barium of somatostatin release. Evidence for lower sensitivity of D- vis-à-vis B- and A-cells

To address the question whether a "second messenger" function of calcium differs between D-cells and other cells of the endocrine pancreas, we compared effects of calcium and barium (a calcium substitute) on somatostatin secretion to effects on insulin and glucagon secretion from the perfused pancreas of the rat. 6.5 mmol/l of calcium, when administered early during perfusion, failed to stimulate somatostatin release. 0.05 mmol/l of barium, when added to calcium-deprived media failed to affect somatostatin secretion while 0.5 induced a slight and 2.0 mmol/l a marked and sustained response. Barium-induced insulin release was left-shifted in relation to the somatostatin response, since 0.05 mmol/l of barium stimulated and 0.5 mmol/l evoked a near-maximal insulin response. All concentrations of barium evoked diphasic glucagon responses, i.e. a small (1 min) stimulation followed by sustained inhibition. Addition of 0.5 mmol/l of EGTA to calcium-deprived media abolished D- as well as B- and A-cell secretion. Reintroduction of 0.5-6.5 mmol/l of calcium stimulated somatostatin release; the secretory response was proportionate to the calcium concentration. In contrast, addition of calcium stimulated insulin and glucagon secretion maximally already at 0.5 mmol/l of calcium. We conclude that the D-cell is less sensitive than B- and A-cells to a regulatory effect on secretion exerted by extracellular calcium or barium.     

Inherent beta-cell dysfunction induced by transgenic expression of allogeneic major histocompatibility complex class I antigen in islet cells.

Insulin-dependent diabetes mellitus (IDDM) is generally believed to be an autoimmune disease resulting from T-cell dysfunction that produces beta-cell damage, but it is conceivable that some forms of IDDM are not immunologically mediated. The effect of the expression of a foreign transgenic MHC class I antigen (H-2Kb), restricted to pancreatic islet beta-cells, was tested in vitro and in nude (athymic) mice to determine whether beta-cell dysfunction was due to non-immune mechanisms. The models used clearly excluded immune involvement in beta-cell damage. Fetal pancreas from transgenic and littermate control mice was maintained in organ culture for up to 18 days and insulin secretion into the medium assessed. For the initial 3-4 days in vitro, fetal control and transgenic pancreas secreted similar amounts of insulin, but thereafter insulin secretion by the transgenic tissue decreased in comparison with the controls. When the cultured pancreas was transplanted into nude mice, the transgenic issue produced smaller grafts than the control pancreas, but there was wide variation in graft size. Expression of H-2Kb antigens in beta-cells of nude transgenic mice also resulted in early-onset diabetes. The insulin content in the pancreas of young H-2Kb transgenic euthymic mice, (previously shown not to have insulitis), was reduced but glucagon content was normal. The reduction in in vivo insulin production was similar chronologically to the reduced insulin production by transgenic islets in vitro. These data confirm the non-immune loss of beta-cell function in MHC-transgenic mice and they may be a model for atypical Type I diabetes.     

Secretory effects of cholecystokinins on the isolated perfused porcine pancreas

Three different molecular forms of cholecystokinin (CCK-39, -33, and -8) were used in concentrations from 10^-11 to 10^-8 mol/l to stimulate the endocrine and exocrine secretion from the isolated perfused porcine pancreas. During perfusion with a glucose concentration of 7.5 mmol/1 CCK-39 in the highest concentration increased the insulin secretion slightly. No significant effect was observed at lower glucose concentrations (5.0 and 3.5 mmol/l). CCK-33 and -8 did not stimulate the secretion of insulin significantly, and neither of the cholecystokinins increased the secretion of glucagon and bicarbonate. All three molecular forms stimulated the secretion of fluid and protein in concentrations above 10^-11 mol/l in a dose-dependent manner and with equal potency. We conclude that the effect of these three cholecystokinins on the endocrine pancreas is without physiological significance, whereas all three are sufficiently potent to play a role in the control of pancreatic protein secretion.     

Stimulation by calcium and barium of somatostatin release. Evidence for lower sensitivity of D- vis-à-vis B- and A-cells

To address the question whether a “second messenger” function of calcium differs between D-cells and other cells of the endocrine pancreas, we compared effects of calcium and barium (a calcium substitute) on somatostatin secretion to effects on insulin and glucagon secretion from the perfused pancreas of the rat. 6.5 mmol/l of calcium, when administered early during perfusion, failed to stimulate somatostatin release. 0.05 mmol/l of barium, when added to calcium-deprived media failed to affect somatostatin secretion while 0.5 induced a slight and 2.0 mmol/l a marked and sustained response. Barium-induced insulin release was left-shifted in relation to the somatostatin response, since 0.05 mmol/l of barium stimulated and 0.5 mmol/l evoked a near-maximal insulin response. All concentrations of barium evoked diphasic glucagon responses, i. e. a small (1 min) stimulation followed by sustained inhibition. Addition of 0.5 mmol/l of EGTA to calcium-deprived media abolished D- as well as B- and A-cell secretion. Reintroduction of 0.5–6.5 mmol/l of calcium stimulated somatostatin release; the secretory response was proportionate to the calcium concentration. In contrast, addition of calcium stimulated insulin and glucagon secretion maximally already at 0.5 mmol/l of calcium. We conclude that the D-cell is less sensitive than B- and A-cells to a regulatory effect on secretion exerted by extracellular calcium or barium.     

Effects of adrenergic blockade on the release of insulin,glucagon and somatostatin from the pancreas in response to splanchnic nerve stimulation in cats

The effects of α-,β- or α+β-adrenergic blockade on arterial plasma concentrations of insulin, glucagon and somatostatin in response to splanchnic nerve stimulation were studied in anesthetized cats. In control experiments splanchnic nerve stimulation caused a marked rise in plasma glucose and glucagon concentrations and a marked fall in insulin but somatostatin was unaffected. Pretreatment with phentolamine significantly increased basal plasma insulin concentration but the response pattern to splanchnic nerve stimulation was not altered. Propranolol attenuated both the glucose and insulin responses. Combined α-and β-blockade abolished the hyperglycemia and hypoinsulinemia induced by splanchnic nerve stimulation, whereas the rise in plasma glucagon was not affected. It is concluded that insulin release from the pancreas and glucose release from the liver is controlled by adrenergic mechanisms whereas pancreatic glucagon and somatostatin secretion is relatively insensitive to splanchnic nerve stimulation in cats.     

Nervous control of pancreatic endocrine secretion in pigs. III. The effect of acetylcholine on the pancreatic secretion of insulin and glucagon

We studied the effect of intraarterial administration of acetylcholine on insulin and glucagon secretion in anesthetized splanchnicotomized pigs and on insulin, glucagon, and pancreatic polypeptide secretion from the isolated perfused porcine pancreas and the isolated perfused duodeno-pancreatic block of pigs and dogs. In the pigs acetylcholine stimulated insulin and glucagon secretion in a glucose dependent manner similar to vagal stimulation; however, the response was completely resistant to hexamethonium and abolished by atropine. Acetylcholine stimulated insulin and pancreatic polypeptide secretion of the isolated perfused porcine pancreas, and inhibited glucagon secretion, whether the duodenum was present or not, whereas the glucagon secretion of the isolated perfused canine pancreas was stimulated by acetylcholine.     

Myelin basic protein stimulates insulin and glucagon secretion from rat pancreatic islets in vitro and in vivo.

The effect of myelin basic protein on insulin and glucagon secretion from rat pancreatic islets was studied in vivo and in vitro. The myelin basic proteins isolated from bovine, human and rat brains all stimulated insulin secretion in a similar fashion. In a static incubation of isolated pancreatic islets, myelin basic protein at doses of 15.6-250 micrograms in a 0.5-ml reaction volume (1.7 X 10(-6) to 2.7 X 10(-5) M) significantly stimulated hormone release. Maximal stimulation, obtained at the 250-micrograms dose, was 6.5-fold greater than control for insulin secretion and 6.7-fold greater than control for glucagon secretion. In the case of glucagon no saturation was observed, but saturation was obvious for insulin release at doses of myelin basic protein of 62.5-250 micrograms, larger doses causing permeabilization of the islet membranes as indicated by leakage of acid phosphatase. At a 100-micrograms dose the time course of insulin secretion induced by myelin basic protein indicated a fast initial release, and after the first 2 h only a little more insulin was released. At the lower doses of myelin basic protein (11 and 33 micrograms) the secretion rate was nearly constant after the first hour. Significant stimulation of glucagon release by myelin basic protein was seen after 60 min, the rate of release being roughly constant at 33- and 100-micrograms doses thereafter. At the 11-micrograms dose significant stimulation of hormone release was observed only after a 4-h incubation.(ABSTRACT TRUNCATED AT 250 WORDS)