垂体生长激素分泌瘤细胞有关生长抑素调节的受体和受体后…

为了解生长抑素在人垂体生长激素分泌瘤发病中的作用，在２５例肢端肥大症患者体外培养的垂体瘤细胞观察了ＳＲＩＦ激动剂，抑制性鸟苷酸调节蛋白拮抗剂百日咳毒素和钙离子载体Ａ２３１８７对ＧＨ分泌的影响，以及ＳＭＳ对细胞内ｃＡＭＰ水平的抑制作用。     

生长激素释放激素和生长抑素对垂体生长激素细胞的作用

早在六十年代,人们已觉察到下丘脑对垂体前叶生长激素(GH)的分泌有兴奋性和抑制性两种作用,但直到1973和1982年,美国的Guillemin及其同事才分别将生长抑素(SS)和生长激素释放激素(GHRH)分离、提纯,并阐明其结构。从此,GHRH和SS对垂体GH细胞调节的研究进入到细胞水平以至分子水平,这些研究大大推动了内分泌生理学和病理生理学的发展。现就最近几年关于GHRH和SS对垂体GH细胞的生理作用及细胞内机制作一简要综述。     

磁场对实验性AMI大鼠血浆cAMP、cGMP和血清Mg~(2 )含量变化的影响

本实验将大鼠随机分为五组：空白对照组、磁作用对照组、ＡＭＩ组、ＡＭＩ药物（心得安）治疗组、ＡＭＩ磁场治疗组。分别采用放射免疫方法和原子分光光度法测定各组大鼠血浆ｃＡＭＰ、ｃＧＭＰ和血清Ｍｇ２＋含量。结果表明：ＡＭＩ磁场治疗组血浆ｃＡＭＰ、ｃＧＭＰ含量及ｃＡＭＰ／ｃＧＡＰ比值均明显低于ＡＭＩ组（Ｐ＜０．０５）,与药物治疗组近似,略高于空白对照组、磁作用对照组,空白对照组略高于磁使用对照组,磁作用对照组最低,两组间无显著差异（Ｐ＞０．０５）。ＡＭＩ磁场治疗组血清Ｍｇ２＋含量明显高于ＡＭＩ组（Ｐ＜０．０５）,与药物治疗组近似,略低于空白对照组、磁作用对照组,空白对照组和磁作用对照组最高,两组间无显著差异（Ｐ＞０．０５）。提示：磁场对动物实验性ＡＭＩ心肌具有一定的保护作用。     

金黄地鼠精子发生及附睾成熟过程中Ca~（2＋）的分布规律

应用焦锑酸钾原位沉淀法对金黄地鼠精子发生及附睾成熟过程中Ｃａ２＋的分布变化规律进行了系统的研究。在睾丸的曲细精管中，支持细胞和生精细胞的细胞核和细胞质有钙沉淀颗粒分布。在支持细胞、精原细胞、精母细胞、高尔基体期和顶体期精子细胞的胞质中钙沉淀主要分布于线粒体和内质网。支持细胞核仁的无定形部分、核仁相随染色质和核质中有大量的钙沉淀颗粒。在精原细胞、精母细胞、高尔基体期的精子细胞核中钙沉淀主要分布于浓缩的染色质周围及其内部，而分散的染色质中则少见钙沉淀。在顶体期的精子细胞核内钙沉淀主要分布于核膜上，核质中偶见Ｃａ２＋沉淀。成熟期的精子细胞钙沉淀颗粒分布于顶体外膜和顶体内膜的内侧，顶体内膜上有钙沉淀集中分布。在附睾中钙沉淀分布于精子顶体区的质膜内外两侧和顶体外膜外侧，精子尾部线粒体外膜和基质中也有钙沉淀分布。     

低水平辐射对大鼠血浆和某些腺体中cAMP和cGMP水平的影响

本研究分二批进行,第一批用成年雄性大鼠每天接受X射线全身照射50mGy/次和100mGy/次,剂量率为15mGy/分,6次/周,共照5周(30次),累积剂量分别为1.5Gy和3.0Gy。受照大鼠睾丸重量在停照后4周内呈持续性减轻,以照射剂量大,停照时间长者,减轻最明显(相当于对照43.9%)。睾丸中cAMP含量于停照后1周升高,以100mGy组明显(P<0.01),停照后2周仍显著高于对照(P<0.05),停照后4周回降到正常较低水平。而血浆和肾上腺中cAMP和胸上腺中cGMP含量无明显变化。第二批实验动物条件与第一批相同,每天接受16.3mGy,~(60)Coγ射线全身照射,剂量率为45.3pGy/分,6次/周,每次照射6小时,在照射6、10、14、18、22周,累积剂量分别为0.59、0.98、1.37、1.76、2.15Gy时与相应对照组比较,垂体、睾丸中cAMP含量及睾丸重量无显著差别,证实慢性小剂量全身照射对睾丸组织的损伤主要取决于剂量率大小,剂量率愈大损伤愈明显。     

654－2对大鼠心肌缺血再灌注损伤的保护作用

本实验采用离体大鼠Ｌａｎｇｅｎｄｏｒｆｆ灌流模型，观察了６５４－２对灌流液中Ｃａ￣（２＋）浓度变化所致心肌缺血再灌注损伤的保护作用。结果表明：６５４－２对缺血前（６５４－２在预灌时给予）及再灌时（６５４－２在再灌时给予）Ｃａ￣（２＋）浓度变化所致的心肌损伤均有明显的保护作用。推测这种保护作用可能是通过其稳膜及Ｃａ￣（２＋）调节作用而实现的。     

组织中Ca~（2＋）－ATP酶的图像分析仪测定法

在Ｃａ（２＋）－ＡＴＰ酶含量的测定中，我们尝试用图像分析仪测定组织中Ｃａ（２＋）－ＡＴＰ的含量，并将其结果与显微分光光度法进行了比较。表明两种方法的结果一致（Ｐ＞０．０５），而图像分析仪法操作简便、快速、准确，是测定组织中Ｃａ（２＋）－ＡＴＰ酶含量较理想的方法。我们应用该法测定了晕厥心肌中Ｃａ（２＋）－ＡＴＰ酶含量，缺血组织中Ｃａ（２＋）－ＡＴＰ含量明显低于对照组（Ｐ＜０．０１）。     

3’-甲基-二甲基偶氮苯喂饲大鼠肝卵圆细胞体外 转化过程中胞浆游离钙浓度及cAMP含量的变化

目的和方法：为了解SD大鼠肝卵圆细胞体外转化过程中胞浆游离钙及cAMP含量的变化。用荧光探针标记法检测胞浆游离钙浓度。以放射免疫法检测cAMP含量。结果：从喂饲3'-甲基-N，N-二甲基-4-氨基偶氯苯（3’-Me－DAB）大鼠分离到的卵圆细胞，体外生长至30代时发生转化，生长速度加快。80％的转化卵圆细胞为异倍体，并能在软琼脂中呈克隆性生长。尽管细胞在转化过程中未见表皮生长因子受体含量改变，但细胞游离钙升高和cAMP水平明显降低，反映细胞传导系统发生了改变。结论：这种细胞第二信使物质的改变使细胞保持恶性转化表型并能不断生长。     

抗CD4抗体不同地调节CD4，45RO~＋和CD4，45RA~＋T细胞的辅助性功能及TCR／CD3调节的Ca￣（2＋）信号

观察了抗ＣＤ４抗体（ａｎｔｉ－ＣＤ４）在体外对ＣＤ４Ｔ淋巴细胞亚群ＣＤ４，４５ＲＡ￣＋和ＣＤ４，４５ＲＯ￣＋Ｔ细胞的辅助性功能及Ｔ细胞受体调节的细胞内Ｃａ￣（２＋）信号的影响。ａｎｔｉ－ＣＤ４主要是通过影响Ｔ－Ｂ淋巴细胞相互作用早期而影响ＣＤ４，４５ＲＯ￣＋Ｔ细胞的辅助性功能；ａｎｔｉ－ＣＤ４对ＴＣＲ／ＣＤ３调节的Ｔ细胞增殖反应的抑制是由于抑制了细胞内Ｃａ￣（２＋）信号的传导，并且与ＣＤ４５的分子结构密切相关。     

多聚Clq诱导免疫细胞的Ca~（2＋）动员

多聚Ｃｌｑ与人Ｔ细胞系Ｊｕｒｋａｔ、Ｂ细胞系Ｒａｎ和Ｍφ系Ｕ９３７细胞表面ＣｌｑＲ相互作用，诱导４５Ｃａ２＋跨膜快速内流，刺激［Ｃａ２＋］ｉ迅速增高，前者可为质膜Ｃａ２＋通道阻滞剂Ｖｅｒａｐａｍｉｌ所阻断，后者能被胞外Ｃａ２＋络合剂ＥＧＴＡ部分抑制，被蛋白酪氨酸激酶（ＰＴＫ）抑制剂Ｇｅｎｉｓｔｅｉｎ完全消除。资料表明，Ｃｌｑ／ＣｌｑＲ系统介导的信号转导机制涉及内Ｃａ２＋和外Ｃａ２＋两者的动员，且与ＰＴＫ有关。     

In situ hybridization for different mRNA in GH-secreting and in inactive pituitary adenomas

In a series of 40 pituitary adenomas in acromegaly all tumors showed mRNA for GH by in situ hybridization (ISH). The signals were mostly very strong and found in more than 80% of adenoma cells by using frozen sections. In paraffin sections the number of positive cells and the intensity of signals are lower. Prolactin mRNA was found in 87% of adenomas. In 27% more than 80% of cells were marked. beta-HCGmRNA (with 90% hormology for LH-mRNA) was demonstrable in very sparse cells of 25% of adenomas. Comparing ISH with immunohistology (IH) we found a correlation between signals and hormone content in 100% of adenomas for GH, in 60% for Prolactin and in 10% for Gonadotropins. In 18% Prolactin mRNA but not the hormone was demonstrable and in 5% Prolactin was immunostained but no hybridization signals were detected. In a series of 40 clinically inactive adenomas sparse cells of three tumors expressed GHmRNA and two of these contained also the hormone, whereas in one adenoma GH but not GHmRNA was demonstrable. Prolactin mRNA was found in 8 adenomas. 7 of these also contained the hormone. In two cases Prolactin but not Prolactin mRNA was present. Beta-HCG(LH)mRNA and the respective hormones were shown in very sparse cells of 6 adenomas, whereas only beta-HCG(LH)-mRNA was found in 8 cases. The significance of the findings is discussed.     

Mapping of somatostatin receptor types in GH or/and PRL producing pituitary adenomas

BACKGROUND: Somatostatin is a tetradecapeptide exerting inhibitory action on endocrine and exocrine cell secretion and proliferation. Somatostatin receptors (SST) are widely expressed in various neoplasms including endocrine tumours. Using immunohistochemistry, the expression of SST(1), SST(2A), SST(2B), SST(3), SST(4), and SST(5) was studied in tissue microarrays (TMAs), using a series of 90 human pituitary adenomas producing growth hormone and/or prolactin, including 30 of each somatotroph, lactotroph, and mixed somatotroph/lactotroph adenoma type. METHODS: For immunohistochemistry, the standard avidin biotin complex method enhanced by tyramide was used, using polyclonal antisera for all SST types. A four point scoring system was used to assess the membranous immunopositivity. RESULTS: All SST types were positive in all tumour types, showing varying immunoreactivity scores. SST(5) and SST(2A) were the predominant receptors, showing strong expression in high frequency in all three adenoma types. Strong expression of SST(1) was higher in lactotroph adenomas than in other tumour types. CONCLUSIONS: The immunohistochemical results of SST expression are in agreement with most findings of previous molecular studies. The fact that SST(2A) expression is predominant suggests that pharmaceutical octapeptide somatostatin analogues may act through this receptor, while the role of SST(2B) may be merely synergistic.     

Response of thyrotropin-secreting pituitary adenomas to a long-acting somatostatin analogue

Thyrotropin-secreting pituitary adenomas are aggressive, invasive tumors that respond poorly to available surgical and medical treatments. Inappropriate release of thyrotropin by these tumors can result in hyperthyroidism. We treated five patients who had thyrotropin-secreting pituitary adenomas with the long-acting somatostatin analogue SMS 201-995, which was administered by subcutaneous injection in doses of 50 to 100 micrograms every 8 to 12 hours. Serum levels of thyrotropin were dramatically reduced by treatment in four of the five patients, and levels of another tumor marker, the alpha-subunit of thyrotropin, were reduced in all five. In two patients with hyperthyroidism due to production of excess thyrotropin by the tumor, treatment with the somatostatin analogue resulted in a sustained euthyroid state. One patient who was treated for more than 16 months had a persistent reduction in serum levels of thyrotropin and iodothyronines. We conclude that SMS 201-995 is an effective means of controlling hypersecretion of thyrotropin and the associated hyperthyroidism due to thyrotropin-secreting pituitary tumors.     

Glucocorticoid receptor expression in nontumorous human pituitaries and pituitary adenomas

Glucocorticoids have multiple actions, including a suppressive feedback effect on pituitary corticotrophs via the glucocorticoid receptor (GR). By immunocytochemistry, we studied GR expression in 86 surgically removed various pituitary adenoma types. Ten cases contained nontumorous pituitary fragments, which were suitable for immunocytochemical investigation. In addition, 30 autopsy-obtained pituitaries, 10 of them containing incidental microadenomas, were examined as well. Using a polyclonal GR antibody, the streptavidin-biotin-peroxidase complex method revealed nuclear and/or cytoplasmic GR immunoreactivity in many nontumorous corticotrophs and other adenohypophysial cell types and in S-100 protein immunopositive stellate cells. Cellular localization was confirmed by double immunostaining. Pars intermedia corticotrophs, posterior lobe axons, Herring bodies, and pituicytes as well as several endothelial cells lining the capillaries were also immunopositive. GR immunoreactivity was also demonstrated in many GH, PRL, ACTH, TSH, FSH, LH α-subunit producing adenomas, null cell adenomas, and oncocytomas. The extent and degree of immunostaining varied considerably from case to case. Suppressed corticotrophs showing the Crooke’s hyaline change due to glucocorticoid excess were present in the nontumorous pituitaries of patients with Cushing’s disease and in those treated with pharmacologic doses of glucocorticoids. Many suppressed nontumorous corticotrophs exhibited only weak or no GR immunopositivity, indicating GR downregulation accompanied by cellular injury. Study of autopsy obtained pituitaries for GR yielded inconclusive results indicating that autopsy obtained adenohypophyses are not suitable for the immunocytochemical investigation of GR.     

垂体生长激素腺瘤对生长抑素类似物的耐药机制研究进展

生长抑素类似物能抑制垂体生长激素细胞对生长激素的分泌及相关肿瘤细胞的增殖,是目前垂体生长激素腺瘤临床治疗的首选药物.但部分患者因耐药而影响疗效,其耐药机制涉及生长抑素受体、受体下游信号传导通路、组织病理和细胞黏附分子等因素.     

Androgen receptor in pituitary adenomas of the gonadotroph cell complex

Although androgen receptors have been identified in normal gonadotroph and somatotroph cells of the pituitary, immunohistochemical studies have failed to reveal these receptors in pituitary adenomas so far. Using a monoclonal antibody to androgen receptor in our series of 60 adenomas of the gonadotroph cell complex (20 FSH/LH cell adenomas, 20 null cell adenomas, 20 oncocytic adenomas), only one null cell adenoma showed strong nuclear immunostaining. All the other antibodies were completely negative. The significance of this finding in correlation with clinical data is still unclear, although it may be associated with more rapid tumor growth. In paraadenomous tissue, some normal gonadotrophs expressed the androgen receptor.     

Detection of gonadotropin-releasing hormone receptor in normal human pituitary cells and pituitary adenomas using immunohistochemistry

Gonadotropin-releasing hormone (GnRH), which is a well-known regulator of gonadotroph function, has recently been considered to be a paracrine factor involved in the control of somatotroph, lactotroph, and corticotroph cells. GnRH action is initiated by binding to a specific cell surface receptor, the gonadotropin-releasing hormone receptor (GnRHR), which is expressed by follicle-stimulating hormone/luteinizing hormone (FSH/LH) cells. Using in situ hybridization techniques, GnRHR messenger ribonucleic acid (mRNA) has recently been detected in normal human anterior pituitary gland and in various pituitary adenomas, including FSH/LH-cell, growth hormone (GH)-cell, adrenocorticotropic hormone (ACTH)-cell, and null-cell adenomas. However, immunohistochemical studies indicating the specific cell distribution of GnRHR in normal pituitary cells have never been reported. The aim of the present investigation was to evaluate the immunohistochemical expression of GnRHR in different types of normal pituitary cells and related tumors. Using double-label immunohistochemical techniques on formalin-fixed and paraffin-embedded tissues and specific antibodies directed against pituitary hormones and GnRHR, we found GnRHR immunoreactivity not only in FSH/LH cells, but also in GH- and thyroid-stimulating hormone (TSH) cells. GnRHR was detected in FSH/LH-cell, GH-cell, mixed GH- and prolactin (PRL)-cell, and α-subunit (α-SU)/null-cell adenomas. The findings of this study suggest that the interaction between GnRH and GnRHR may play a role in paracrine/autocrine regulation of different types of normal pituitary cells and pituitary adenomas. Received: 24 January 2000 / Accepted: 12 April 2000     

Effects of somatostatin on somatotroph adenomas of the human pituitary: An in vitro functional and morphological study

The effects of somatostatin or the somatostatin analog SMS 201–995 were studied on 4 densely granulated somatotroph adenomas and 4 sparsely granulated somatotroph adenomas in vitro. Release of growth hormone (GH) into culture media during incubation with somatostatin or SMS 201 -995 were measured by radioimmunoassay, and light-microscopical and ultrastructural morphometric parameters were compared with those of cultured control somatotroph adenoma cells of the same tumor. In all tumors except for 1 densely granulated somatotroph adenoma, somatostatin or SMS 201–995 decreased GH release into culture media in 24- and 2-hour incubations. After 48-hour incubation with somatostatin or SMS 201–995, there was no change in cell size or secretory granule diameter. One densely granulated adenoma showed decreased cytoplasmic volume density (CVD) of Golgi apparatus and secretory granules, and a sparsely granulated adenoma had reduced CVD of endoplasmic reticulum. All the tumors that responded with decreased GH release exhibited increased CVD of lysosomes after incubation with somatostatin or SMS 201–995. These results indicate that both densely and sparsely granulated somatotroph adenomas respond to somatostatin inhibition and, furthermore, that inhibition of hormone release is associated with accumulation of lysosomes, suggesting lysosomal degradation of stored hormone. Hospital 20 Nov. (ISSSTE) Coyoacan y Felix Cuevas, Colonia del Valle and (Dept Patologia) y Hospital de Especialidades (C.M.N., IMSS) Cuauhtemoc y Dr. Marquez, Mexico City (IF).