Preliminary study on the relationship between cAMP level and gsp expression in cultured human pituitary somatotrophinomas

Growth hormone ( GH) releasing hormone( GHRH) is one of the main hypothalamic hormonewhich regulates the GH secretion depending on theadenylyl cyclase- c AMP- protein kinase A intracellularsignal transduction pathway[1] .GH- releasing peptide( His- D- Trp- Ala- D- Phe- Lys- NH2 ,GHRP- 6) is asynthetic hexapeptide able to strongly stimulate GHsecretion via protein kinase C transduction system[2 ] .Therefore,to gain further insight into the mecha-nisms of action of synthetical GHRP-…     

妊娠期雌二醇和催乳素与瘦素的关系

目的 研究妊娠期间性激素与瘦素水平之间的关系。方法 在180例不同孕周的妇女中,按孕周分为＜20周组,20－23周组,≥28周组,采用酶联免疫吸附法测定其外周血血清雌二醇（E2）和催乳素（PRL）,放射免疫法测定血清瘦素水平,分析这些激素之间的相互关系。结果 E2和PRL均随妊娠进展而逐步升高（P＜0．0001）,组间均有显著差异（P＜0．05）。各组瘦素水平均高于非妊娠组,但组间差异无显著性。瘦素水平与孕妇体重及体重指数显著相关（P0．01）,与PRL也呈相关（P＜0．05）,而与E2无明显相关。结论 PRL水平与妊娠期瘦素水平升高有一定关系。     

垂体腺瘤患者围术期促肾上腺皮质激素与皮质醇变化的研究

为观察垂体腺瘤患者围术期促肾上腺皮质激素 (ACTH)与皮质醇 (COR)的变化 ,选取 2 8例择期脑瘤切除患者 ,分为非垂体瘤组 (Ⅰ组 ,n =7)、生长激素 (GH)升高垂体瘤组 (Ⅱ组 ,n =9)和泌乳素升高垂体瘤组 (Ⅲ组 ,n =1 2 ) ,采用静吸复合全麻。抽取围术期不同阶段的静脉血标本 ,用放免法检测ACTH及COR。结果显示 ,术毕停麻醉2 0min时的ACTH和COR与入院后基础值相比差异显著 (P <0 .0 5) ,且Ⅱ、Ⅲ组与Ⅰ组间差异显著 (P <0 .0 5)。提示 :垂体腺瘤患者术毕时ACTH及COR水平明显高于术前 ,这不同于其他神经外科患者。     

大鼠肾上腺切除后垂体前叶GAP-43免疫阳性神经纤维的发芽过程

目的　阐明大鼠双侧肾上腺切除后垂体前叶生长相关蛋白 43(GAP- 43)免疫阳性神经纤维表达的量与术后时间点的关系 ,即轴突发芽的时间过程 .方法　免疫组织化学ABC法 .结果　大鼠双侧肾上腺切除术后第 4日垂体前叶GAP- 43阳性表达显著增多 ,第 2周有所下降 ,至第 4周基本降至正常水平 .结论　大鼠在双侧肾上腺切除后 ,垂体前叶出现肽能神经纤维发芽 ,并围绕在腺细胞周围 ,该发芽过程于术后 4～ 7d达到高峰 ,第 2周开始下降 ,第 4周基本结束     

Lactogen enhances Nb2 cell GTPase activity after 4 hours incubation

The lactogen receptor has been suggested to associate with one or more G proteins despite the absence of a 7-transmembrane spanning sequence. These studies were designed to determine whether lactogens acutely increase GTP binding to or GTPase activity in Nb2 cell membrane. Incubation of Nb2 cell membrane with either ovine PRL (10 ng/ml) or diluent for 0–1 h resulted in a decrease in total³⁵S-GTP binding to both with no difference in GTP binding between PRL- and diluent-treated membranes. There was also no change in³⁵S-GTP binding to Nb2 cell membrane incubated with increasing oPRL concentrations (0.001–100 ng/ml) for 60 min. α-³²P-GTP photoaffinity labelling was used to evaluate changes in GTP binding to specific G proteins. Photoaffinity labelling of α-³²P-GTP to no G protein was changed after preincubation with oPRL (10 ng/ml) for 0–60 min or with oPRL (0.01–10 ng/ml) for 60 min. Finally, it was determined whether oPRL had any acute effect on GTPase activity, as determined by release of³²Pi from γ-³²P-GTP. When Nb2 cell membrane was preincubated for 0–60 min with oPRL (10 ng/ml) or a range of oPRL concentrations (0–10 ng/ml), no change in GTPase activity was observed. However, when Nb2 cells were incubated with lactogen for 0–7 h, GTPase activity in equal quantities of Nb2 cell membrane prepared from those cells increased over time. Increased GTPase activity (64.9–74.4%;P<0.03 compared to 0 h) was observed after 4–7 h incubation with lactogen. In summary, addition of lactogen to Nb2 cell membrane did not acutely increase either GTP binding or GTPase activity. Yet when Nb2 cells were incubated with lactogen for 4 h prior to preparation of membrane, GTPase activity was significantly increased. This evidence, in addition to our previous results showing that 4 h incubation with lactogen increased G protein β subunit concentration and pertussis toxin-stimulated ADP-ribosylation of Gi, support a role for delayed lactogen modulation of one or more G proteins in the Nb2 cell, requiring at least 4 h for maximal effect.     

Comparison between nafarelin acetate andd-Trp6-LHRH for temporary pituitary suppression in in vitro fertilization (IVF) patients: A prospective crossover study

Purpose Nafarelin acetate is a new gonadotropin releasing (GnRH) agonist analogue with unique potency, intranasal administration, and convenient storage. Hence, nafarelin was considered as an alternative for temporary pituitary suppression in patients undergoing ovulation induction in IVF. A crossover treatment in a prospective study was performed including 40 women with bilateral obstructed tubes and normal ovarian function, treated in 80 ovulation induction cycles using the long protocol. Twenty patients used nafarelin acetate 600 g/daily in their first cycle and received d-Trp6-LHRH, 0.5 mg/daily, in their following cycle. The other 20 women used decapeptyl in their first cycle and received nafarelin in the second.Results Estradiol suppression was achieved by both d-Trp6-LHRH and nafarelin at equal time intervals. The average total number of ampoules (P=0.0005) and the length of administration of hMG required for ovarian stimulation (P=0.0002) and the time interval between GnRHa initiation to oocyte retrieval (P=0.04) was significantly lower in nafarelin cycles. The number and the distribution between large and small follicles as well as the average number of oocytes retrieved did not differ between the two GnRH analogues.Conclusion Our results demonstrate that nafarelin acetate is comparable to d-Trp6-LHRH for temporary pituitary suppression used for controlled ovarian stimulation in IVF patients. However, using nafarelin ovarian stimulation was achieved with fewer ampoules of hMG, administered for a shorter period of time, thus with a lesser cost.     

Immunohistochemical Heterogeneity Within Clinically Nonfunctioning Pituitary Adenomas

To investigate whether adenohypophysial hormone expression is heterogeneous within individual clinically nonfunctioning pituitary adenomas, immunohistochemical examinations were performed on tissues obtained by multiple sampling of 11 adenomas. Stained sections were assessed by morphometric image analysis as well as semiquantitative estimation under microscopy. All tumors except one were immunopositive for one or more gonadotropins. Results were divided into five grades based on the proportion of immunoreactive cells per section. Semiquantitative estimation showed only a one-grade difference among samples from the same tumor in four cases for FSHβ and in two cases for LHβ. These qualitative similarities between multiple samples were confirmed by morphometric image analysis. From the practical standpoint of making a diagnosis of nonfunctioning pituitary adenoma, it is not necessary to take into account immunohistochemical heterogeneity within an individual tumor, and immunohistochemical findings in a given sample obtained at surgery can be regarded as representative of the entire adenoma.     

原位PCR和免疫组化检测垂体腺癌P16基因

目的研究人垂体腺瘤P16基因的改变,同时探索原位PCR技术的适宜条件和结果确认,以及用于基因缺失检测的可行性。方法原位PCR和免疫组化技术。结界绝大部分间质细胞为P16蛋白免疫组化阴性,而一部分垂体肿瘤细胞呈P16阳性;针对P16基因的原位PCR信号则可见于垂体肿瘤细胞和间质细胞等各种细胞,即P16组化阴性的细胞同样表明有P16基因存在。结论原位PCR可以是P16基因研究的一种有效手段,提示垂体腺癌的P16基因改变形式可能主要是表达过度而不是基因缺失。     

Long-term enhancement of REM sleep by the pituitary adenylyl cyclase-activating polypeptide (PACAP) in the pontine reticular formation of the rat

In rats, rapid eye movement (REM) sleep can be elicited by microinjection of vasoactive intestinal polypeptide (VIP) into the oral pontine reticular nucleus (PnO). In the present study, we investigated whether this area could also be a REM-promoting target for a peptide closely related to VIP: the pituitary adenylyl cyclase-activating polypeptide (PACAP). When administered into the posterior part of the PnO, but not in nearby areas, of freely moving chronically implanted rats, PACAP-27 and PACAP-38 (0.3 and 3 pmol) induced a marked enhancement (60-85% over baseline) of REM sleep for 8 h that could be prevented by prior infusion of the antagonist PACAP-(6-27) (3 pmol) into the same site. Moreover, injections of PACAP into the centre of the posterior PnO resulted in REM sleep enhancement which could last for up to 11 consecutive days. Quantitative autoradiography using [125I]PACAP-27 revealed the presence in the PnO of specific binding sites with high affinity for PACAP-27 and PACAP-38 (IC50 = 2.4 and 3.2 nM, respectively), but very low affinity for VIP (IC50 > 1 microM). These data suggest that PACAP within the PnO may play a key role in REM sleep regulation, and provide evidence for long-term (several days) mechanisms involved in such a control. PAC1 receptors which have a much higher affinity for PACAP than for VIP might mediate this long-term action of PACAP on REM sleep.     

Sexually dimorphic expression of sst1 and sst2 somatostatin receptor subtypes in the arcuate nucleus and anterior pituitary of adult rats

The pattern of growth hormone (GH) secretion and rate of somatic growth are markedly sexually dimorphic, but the underlying neuroendocrine mechanisms are far from clear. In the present study, we tested the hypothesis that the sexual dimorphism of GH secretion may be due to gender-related differences in the transduction of somatostatin's actions in brain and/or pituitary. To accomplish this, we compared the distributional pattern and level of expression of two somatostatin receptor subtypes, sst1 and sst2, in the brain and pituitary of adult male and female rats by in-situ hybridization using 35S-labelled antisense riboprobes. In the brain, the hybridization pattern and labelling density of sst1 and sst2 mRNA-expressing cells, as revealed by computer-assisted image analysis, in areas including the cerebral cortex, medial habenula (MHb) and ventromedial hypothalamic nucleus (VMN), were similar in male and female rats. In contrast, there was a marked sex-related difference in sst1 expression in the arcuate nucleus of the hypothalamus; both the number and labelling density of sst1 mRNA-expressing cells were two- to threefold greater in males than in females and this significant increase was homogenous throughout the rostrocaudal extent of the nucleus. No gender-related differences in arcuate sst2 mRNA levels were found. At the level of the anterior pituitary, the labelling density of sst2 mRNA in males was significantly higher than that of females. No sex-related difference in pituitary sst1 mRNA was observed. These results demonstrate a sexual dimorphism in the expression of two somatostatin receptor subtypes, sst1 and sst2, at the level of the arcuate nucleus and anterior pituitary, respectively. Such dimorphism suggests a differential involvement of sst1 and sst2 in GH regulation with respect to gender, and may imply roles for sst2 and sst1 in transducing somatostatin's actions on pituitary somatotrophs and GH-releasing hormone-containing arcuate neurones, respectively, to generate the lower basal and higher GH pulse levels characteristic of the male rat.