Reduced numbers of somatostatin receptors in the cerebral cortex in Alzheimer's disease

Somatostatin receptor concentrations were measured in patients with Alzheimer's disease and controls. In the frontal cortex (Brodmann areas 6, 9, and 10) and temporal cortex (Brodmann area 21), the concentrations of somatostatin in receptors in the patients were reduced to approximately 50 percent of control values. A 40 percent reduction was seen in the hippocampus, while no significant changes were found in the cingulate cortex, postcentral gyrus, temporal pole, and superior temporal gyrus. Scatchard analysis showed a reduction in receptor number rather than a change in affinity. Somatostatin-like immunoreactivity was significantly reduced in both the frontal and temporal cortex. Somatostatin-like immunoreactivity was linearly related to somatostatin-receptor binding in the cortices of Alzheimer's patients. These findings may reflect degeneration of postsynaptic neurons or cortical afferents in the patients' cerebral cortices. Alternatively, decreased somatostatin-like immunoreactivity in Alzheimer's disease might indicate increased release of somatostatin and down regulation of postsynaptic receptors.     

Circulating somatostatin acts on the islets of Langerhans by way of a somatostatin-poor compartment

Somatostatin perfused in canine pancreases at 10 to 20 picograms per milliliter or 10 to 20 percent of the pancreatic vein somatostatin concentration inhibited insulin and glucagon secretion. This suggests that the high local concentration of endogenous somatostatin is not in contact with somatostatin receptors of the islets. The integrity of this separation may determine the sensitivity of islet cells to circulating somatostatin.     

Two types of somatostatin receptors differentiated by cyclic somatostatin analogs

Somatostatin receptors in rat brain, pituitary, and pancreas were labeled with two radioiodinated analogs of somatostatins 14 and 28. Two cyclic analogs of somatostatin, SMS201-995 and cyclo(Ala-Cys-Phe-D-Trp-Lys-Thr-Cys), showed biphasic displacement of binding to somatostatin receptors by these radioligands. In contrast, all other somatostatin analogs, including somatostatin-14, competed for the receptor sites with monophasic displacement of radioligand receptor binding. Thus two types of somatostatin receptors were identified. It was found that the pituitary and pancreas have predominantly one type of somatostatin receptor whereas the brain has both, and that different regions of the brain have various proportions of the two types. These findings suggest methods to characterize other types of somatostatin receptors subserving somatostatin's diverse physiological functions, including a potential role in cognitive function and extrapyramidal motor system control.     

Depolarization- and ionophore-induced release of octacosa somatostatin from stalk median eminence synaptosomes

Species of somatostatin of higher molecular weight were present in the nerve terminals (synaptosomes) of ovine stalk median eminences and were released by depolarizing stimuli. One of these species was identified as the biologically active molecule octacosa somatostatin. Octacosa somatostatin appears therefore to be secreted into the hypothalamic-hypophyseal system, supporting the concept of a role for this peptide in regulating pituitary hormone secretion.     

Gonadotroph-specific expression of metallothionein fusion genes in pituitaries of transgenic mice

Transgenic mice expressing a metallothionein-somatostatin fusion gene contain high concentrations of somatostatin in the anterior pituitary gland, a tissue that does not normally produce somatostatin. Immunoreactive somatostatin within the anterior pituitaries was found exclusively within gonadotrophs. Similarly, a metallothionein-human growth-hormone fusion gene was also expressed selectively in gonadotrophs. It is proposed that sequences common to the two fusion genes are responsible for the gonadotroph-specific expression.     

泌乳晚期大鼠乳腺生长抑素基因的表达

利用大鼠生长抑素基因设计引物,对泌乳晚期SD大鼠的乳腺组织生长抑素基因进行RT-PCR检测,PCR产物与pMD-19T载体连接后转化JM109感受态细胞,筛选阳性克隆、测序.结果发现在泌乳晚期大鼠乳腺中有生长抑素基因的表达.     

Somatostatin augments the M-current in hippocampal neurons

Immunocytochemical and electrophysiological evidence suggests that somatostatin may be a transmitter in the hippocampus. To characterize the ionic mechanisms underlying somatostatin effects, voltage-clamp and current-clamp studies on single CA1 pyramidal neurons in the hippocampal slice preparation were performed. Both somatostatin-28 and somatostatin-14 elicited a steady outward current and selectively augmented the noninactivating, voltage-dependent outward potassium current known as the M-current. Since the muscarinic cholinergic agonists carbachol and muscarine antagonized this current, these results suggest a reciprocal regulation of the M-current by somatostatin and acetylcholine.     

日粮添加半胱胺对淮南麻鸭生长性能和血液中生长抑素水平的影响

研究旨在观察在日粮中添加不同剂量半胱胺对淮南麻鸭生长性能及血液中生长抑素水平的影响.选用1日龄淮南麻鸭200羽,随机分成4组,每组5个重复,每个重复10羽.从8日龄开始,分别在基础日粮中添加半胱胺0（对照组）、100、200、400 mg· kg-1（试验组）,连续饲喂28 d.结果表明,与对照组相比,添加半胱胺组的麻鸭试验末体重和日增重均显著提高（P＜0.05）,其中添加半胱胺200 mg· kg-1组麻鸭生长指标最佳;添加半胱胺组的麻鸭血液中生长抑素水平均显著降低（P＜0.05）,其中添加200 mg· kg-1剂量组麻鸭血液中生长抑素水平值最低.试验结果表明,日粮中适当添加半胱胺制剂可以促进淮南麻鸭生长发育,且其机制与降低血液中生长抑素浓度有关.     

Paradoxical elevation of growth hormone by intraventricular somatostatin: possible ultrashort-loop feedback

Somatostatin, the growth hormone-inhibiting factor, when microinjected into the third ventricle of the rat brain, paradoxically induced the release of growth hormone. A pituitary site of action having been ruled out, this result supports the concept that exogenous somatostatin within the hypothalamus acts either to suppress the release of somatostatin from somatostatin-containing neurons, possibly via an ultrashort-loop feedback mechanism, or to augment release of hypothalamic growth hormone-releasing factor, thereby inducing a release of growth hormone. Injection of somatostatin into the third ventricle also decreased plasma concentrations of luteinizing hormone, follicle-stimulating hormone, and thyroid-stimulating hormone, probably by inhibiting the release of luteinizing hormone-releasing factor and thyrotropin-releasing factor.     

生长抑素主动和被动免疫及基因免疫研究进展

生长抑素(somatostatin,SS)是下丘脑释放的14肽激素,在动物体内具有广泛的抑制作用,特别是对生长及免疫反应具有明显的影响,通过耗竭或免疫中和体内的SS水平相应提高生长激素(GH)等水平促进动物生长。文中简要介绍了生长抑素主动和被动免疫的研究进展及基因免疫的作用机理、特点及增强基因免疫的途径;阐述了生长抑素基因疫苗的研究和应用发展前景。     

基因佐剂CpGDNA对生长抑素DNA疫苗pES/2SS的作用

 【目的】探讨CpGDNA对生长抑素DNA疫苗免疫小鼠免疫效果的影响。【方法】生长抑素质粒pES/2SS分别与CpG-ODN、pE-CpG、细菌DNA、脂质体配合免疫小鼠，疫苗剂量为20μg/只，佐剂等量混合，2周后加强免疫。【结果】雌性小鼠免疫后4、6周，疫苗组平均增重显著高于对照组(P<0.05)。CpGDNA和DNA疫苗联合免疫后SS抗体P/N值、IgG2a/IgG1、脾细胞活性、GH和IGF-I均比单一使用DNA疫苗的高(P<0.05)。免疫后4周，P/N值以pES/2SS + CpGODN组最高，SI值以pES/2SS+ CpG-ODN组最高。CpGDNA佐剂组GH从第2周开始升高，至第6周达高峰，显著高于pES/2SS组（P<0.01），CpG-ODN组GH高水平持续时间最长，至免疫后8周，仍显著高于pES/2SS组（P<0.01）。CpGDNA组IGF-I值显著高于pES/2SS疫苗组（P<0.05）。【结论】生长抑素基因免疫小鼠可以产生SS抗体，而含CpGDNA序列的核酸佐剂及脂质体粗品，可以增强生长抑素基因疫苗的效果。     

鸡抗病促生长剂的试验研究

采用ＤＮＡ重组技术和蚀斑技术获得融合基因的重组病毒，制备了鸡生长抑制因子（ＳＳ）免疫原，与鸡传染性ＩＢＤ、ＮＤ免疫原共同高免健康产蛋鸡，使其卵黄中产生高效价的抗鸡ＳＳ、ＩＢＤ、ＮＤ抗体，利用含高效价的卵黄制成鸡抗病促生长剂。实验结果表明，该制剂对人工感染的ＩＢＤ鸡治愈率为９７．５％，预防保护率９８．４％；对流行区自然感染的ＩＢＤ鸡治愈率９６％，预防保护率９７％。对健康肉仔鸡应用，可使其育成出栏时间提前３天，每只平均比对照增重１３５．７ｇ；饲料转化率提高８．３７％。     

Receptors for dopamine and somatostatin: formation of hetero-oligomers with enhanced functional activity

Somatostatin and dopamine are two major neurotransmitter systems that share a number of structural and functional characteristics. Somatostatin receptors and dopamine receptors are colocalized in neuronal subgroups, and somatostatin is involved in modulating dopamine-mediated control of motor activity. However, the molecular basis for such interaction between the two systems is unclear. Here, we show that dopamine receptor D2R and somatostatin receptor SSTR5 interact physically through hetero-oligomerization to create a novel receptor with enhanced functional activity. Our results provide evidence that receptors from different G protein (heterotrimeric guanine nucleotide binding protein)-coupled receptor families interact through oligomerization. Such direct intramembrane association defines a new level of molecular crosstalk between related G protein-coupled receptor subfamilies.     

Pulsatile growth hormone secretion: suppression by hypothalamic ventromedial lesions and by long-acting somatostatin

Sequential blood samples, obtained from freely behaving, nonstressed male rats, showed a pulsatile pattern of growth hormone secretion with a mean interval between peaks of 68 minutes. The bursts of secretion were blocked by lesions of the hypothalamic ventromedial nuclei and by administration of a longacting preparation of synthetic somatostatin.     

Growth hormone-releasing factor: direct effects on growth hormone, glucose, and behavior via the brain

Intracerebroventricular administration of human pancreatic growth hormone-releasing factor caused a dose-dependent inhibition of growth hormone secretion, elevated plasma glucose concentrations, and produced marked behavioral and motor effects. Immunoneutralization with antiserum to somatostatin did not reverse the suppression of growth hormone. These findings suggest that hypothalamic growth hormone-releasing factor may regulate its own neurosecretion through an "ultrashort-loop" negative feedback mechanism and may have important neurotransmitter and neuromodulatory functions in the brain.     

仔猪海马结构及其周围皮质内生长抑素mRNA的分布

用原位杂交组织化学法研究了５头仔猪海马结构及其周围皮质内生长抑素ｍＲＮＡ的分布。结果表明生长抑素ｍＲＮＡ主要分布于海马的始层和齿状回的多形层，偶见于海马的辐射层和锥体细胞层，此外，在内溴区和海马旁回内也见到标记细胞，主要位于深层。     

高钙与高蛋白日粮诱发鸡痛风的尿液临床病理学研究

将120羽35日龄伊沙蛋鸡随机均分为对照组、高钙组、高蛋白组和高钙高蛋白组,进行30d的饲养试验。50日龄时测定分析鸡的尿液和尿沉渣。结果表明：高钙高蛋白组鸡发生了典型的内脏型痛风;与对照组和高蛋白组相比,高钙组和高钙高蛋白组鸡尿量显著增加,尿液pH值升高,尿液中钙、钠、钾和镁相对含量和24h尿钠总量显著降低;高钙组和高钙高蛋白组鸡尿液中尿酸、钙、无机磷、钾和镁的24h总量和高蛋白组尿液无机磷的相对含量以及尿酸和无机磷的24h总量显著高于对照组;对照组和高蛋白组鸡尿沉渣以球状晶体居多;高钙组鸡尿沉渣中以针状晶体较多;高钙高蛋白组鸡尿沉渣中针状及球状晶体含量相当。与对照组相比,高钙组尿沉渣中钙、磷含量升高,而钾、钠和镁含量均下降;高蛋白组和高钙高蛋白组尿沉渣中磷含量升高,而钙、钾和钠含量均下降。     

老年人尿路感染76例临床分析

目的分析老年性尿路感染的特性及临床特点.方法对老年性尿路感染各项指标进行综合分析.结果老年人的生理特点有其特殊性,老年人尿路感染常呈现反复发作,缠绵难愈的特点,因此成为临床常见的难治疾病.结论老年人尿路感染症状复杂,易误诊、漏诊,常产生耐药性而不易诊治,应引起临床医师的重视.     

七彩山鸡胃肠道生长抑素细胞的免疫组织化学定位

[目的]应用生长抑素（somatostatin,SS）抗血清研究七彩山鸡（Phasianus colchicas）胃肠道SS免疫活性细胞的分布密度和形态,并探讨其分布型的成因及细胞形态与功能的关系。[方法]采用免疫组织化学方法进行试验。[结果]SS细胞在腺胃及十二指肠以下都有分布。在回肠分布密度最高,空肠和十二指肠较高,盲肠和腺胃次之,直肠很少。SS细胞的型态多样,呈圆形、椭圆形、锥体形等,主要分布于胃肠固有膜、黏膜上皮细胞之间、黏膜上皮细胞基部、腺泡上皮细胞之间。[结论]七彩山鸡胃肠道SS细胞分布型的形成与各部位消化功能有关,根据形态,认为七彩山鸡胃肠道SS细胞具有内、外分泌两种功能。