Distribution of three GnRHs in the brain and pituitary of the wild Japanese flounder Paralichthys olivaceus

ABSTRACT:   Wild adult maturing and immature female Japanese flounder Paralichthys olivaceus were collected in June 2004 and January 2005, respectively, to clarify a possible role of gonadotropin-releasing hormones (GnRHs) in reproduction. Levels of salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II) and sea bream GnRH (sbGnRH) in the brain and pituitary were examined by time-resolved fluoroimmunoassay. Three forms of GnRHs were detected in the discrete brain at various levels. In the pituitary of both maturing and immature fish, sbGnRH was abundant together with a pronounced amount of sGnRH, whereas cGnRH-II was almost below the detectable limit. In maturing fish, levels of sbGnRH were high in the telencephalon, hypothalamus and pituitary, while levels of sbGnRH of immature fish were very low in these regions. These results indicate that sbGnRH is mainly responsible for gonadotropin secretion, and that sbGnRH in the anterior part of the brain is associated with gonadal maturation in the Japanese flounder.     

Isolation of pituitary glycoprotein gonadotropins from the grass carp (Ctenopharyngodon idell)

Gonadotropins (GTH) were isolated from pituitary glands of grass carp and their properties investigated. Acetone-dried pituitaries were extracted with ammonium acetate-ethanol and were then passed through cation exchanger, anion exchanger, and gel filtration column. Two glycoprotein gonadotropins (DE I and DE II) were isolated of MW 56,000 and 53,000 daltons, respectively, as determined by gel filtration technique. Isoelectric points of the two GTHs also differed from each other. Sialic acid contents were 3.64% and 1.47% for DE I and DE II, respectively. Both GTH's stimulated, in a similar manner, testicular androgen and ovarian estradiol synthesisin vitro.     

Rat Ghrelin Stimulates GH Release and GH mRNA Expressionin the Pituitary of Orange-spotted Grouper, <Emphasis Type="BoldItalic">Epinephelus Coioides</Emphasis>

Ghrelin was recently demonstrated as an endogenous ligand of the growth hormone (GH) secretagogue receptor (GHS-R), which could promote the release of GH in mammal significantly. The present study conducted to determine whether ghrelin stimulate the release and synthesis of GH in orange-spotted grouper (Epinephelus coioides). Rat ghrelin was incubated with the pituitary fragments of grouper in static culture system. The culture medium was collected at 1, 6, 12, 18 and 24 h after incubation to detect the contents of GH by homologous radioimmunoassay. The level of GH mRNA in the pituitary fragments was measured by a sensitive chemiluminescent ribonuclease protection assay. The results showed that rat ghrelin not only stimulated the release of GH but also augmented the GH mRNA level in grouper. It suggested that the ghrelin-like peptide and the GHS-R involved in the regulation of GH synthesis and release in grouper. The present study would provide a better understanding of the regulatory mechanism of GH release in marine fish.     

Direct actions of serotonin on gonadotropin-II and growth hormone release from goldfish pituitary cells: interactions with gonadotropin-releasing hormone and dopamine and further evaluation of serotonin receptor specificity

In this study, the direct actions of serotonin (5HT) on gonadotropin (GTH)-II and growth hormone (GH) release in the goldfish were tested at the pituitary cell level. 5HT (10 nM - 10 µM) stimulated GTH-II but inhibited GH release from perifused goldfish pituitary cells in a dose-dependent manner. The minimal effective dose of 5HT tested to suppress basal GH secretion (10 nM) was 10-fold lower than that to stimulate GTH-II release (100 nM). The GTH-II releasing effect of 5HT was abolished by repeated 5HT treatment (10 µM) whereas the corresponding inhibition on GH release was unaffected. These results suggest that 5HT receptors on goldfish gonadotrophs and somatotrophs exhibit intrinsic differences in terms of sensitivity to stimulation and resistance to desensitization. Salmon GTH-releasing hormone (sGnRH, 100 nM) stimulated GTH-II and GH release from goldfish pituitary cells. The GTH-II releasing action of sGnRH was unaffected by simultaneous treatment of 5HT (1 µM). However, the corresponding GH response to sGnRH (100 nM) was inhibited. In the goldfish, dopamine is known to stimulate GH release through activation of pituitary D1 receptors. In the present study, the GH-releasing action of dopamine (1 µM) and the D1 agonist SKF38393 (1 µM) was significantly reduced by 5HT (1 µM). To examine the receptor specificity of 5HT action, the effects of 5HT1 and 5HT2 analogs on GTH-II and GH release were tested in goldfish pituitary cells. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) and 5HT2 agonist methyl 5HT (0.1 1µM) mimicked the GTH-II releasing effect of 5HT. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) also stimulated GH release but the 5HT2 agonist methyl 5HT (0.1 and 1µM) was inhibitory to basal GH secretion. In addition, 5HT (1µM) -stimulated GTH-II release was abolished by the 5HT1 antagonist methiothepin (10µM) and 5HT2 antagonist mianserin (10µM). Similarly, the inhibitory action of 5HT (1µM) on basal GH release was blocked by the 5HT2 antagonist mianserin (10µM). The 5HT1 antagonist methiothepin (10µM) was not effective in this regard. These results, taken together, indicate that 5HT exerts its regulatory actions on GTH-II and GH release in the goldfish directly at the pituitary cell level, probably through interactions with other regulators including sGnRH and dopamine. The GTH-II releasing action of 5HT is mediated through 5HT2 and possibly 5HT1 receptors. The inhibition of 5HT on basal GH release is mediated through 5HT2 receptors only. Apparently, 5HT1 receptors are not involved in this inhibitory action. In this study, a paradoxical stimulatory component of 5HT on GH release by activating 5HT1 receptors is also implicated.     

Ability of salmon growth hormone to accelerate somatic growth of juvenil abalone Haliotis discus hannai

ABSTRACT:   The ability of salmon growth hormone (sGH) to accelerate the somatic growth of juvenile abalone Haliotis discus hannai by immersion was examined. After immersion for one hour into a sGH-rich solution at a concentration of 30 mg/L, the sGH immunoreactivity in the body fluid of abalone was maximal after one day, and levels were still detectable at two days. No immunoreactivity was observed in the control group. Following immersion for one hour at one or two-week intervals for 120 weeks into the sGH-rich solution at 30 mg/L, the sGH-immersed abalone exhibited a significant increase in shell length and body weight. On the other hand, abalone immersed into a salmon prolactin (sPRL)-rich solution at 30 mg/L for one hour showed a lower increase in both shell length and body weight than the sGH-immersed abalone. No increases in shell length and body weight were observed in either the bovine serum albumin-immersed abalone or untreated controls. These results provide evidence that sGH can be transported from ambient water into the circulatory system of abalone, and can subsequently improve the somatic growth of juveniles.     

鸡胚发育过程中垂体促乳素的表达及其细胞的发育

利用免疫荧光标记方法研究了鸡胚发育过程中垂体促乳素(PRL)细胞的发生。结果表明，在鸡胚发育的第14.5天可观察到有少量PRL免疫荧光阳性细胞散在分布于腺垂体前叶。随着胚龄的增加，垂体PRL细胞的体积逐渐增大。细胞直径从第14.5天的6.83μm增加到第20.5天的11.24μm，胞核直径从4.27μm增加到5.99μm。PRL细胞占腺垂体细胞总数的百分比在胚胎发育的第14.5天为0.86％，第20.5天增加到18.85％，并且分布于整个腺垂体前叶。细胞多呈索状排列或团状分布。研究结果表明。鸡胚垂体催乳素细胞的增殖、分化和对PRL的分泌功能主要发生和建立于胚胎发育后期。     

初情期前母猪垂体细胞LH和FSH的释放及其对GnRH类似物的反应

利用垂体细胞单层培养模型研究了30，60，90，120和150日龄北京黑猪母猪垂体细胞LH和FSH的释放及其对LRH－A3反应能力。结果表明，猪垂体细胞LH和FSH释放对LRH－A3的反应呈S形剂量依赖型同线。LH基础释放量和LRH－A3刺激的最大释放量在不同日龄间没有显著差异，说明初情期前母猪垂体细胞已达最大LH释放和对GnRH反应的能力。FSH的基础释放量和LRH－A3刺激的最在释放量在30日龄与60日龄之间无差异，但90日龄以后垂体细胞FSH的释施量随日龄增大而降低，提出可能由于垂体在体内时受过抑制素的作用。     

经鼻小柱,鼻中隔,蝶窦入路行脑垂体瘤切除术

经鼻小柱、鼻中隔、蝶窦入路行鞍内肿瘤切除术６例的结果表明：经鼻小柱、鼻中隔、蝶窦入路不但可避免唇下入路的某些并发症，且手术疗效一致。指出磁共振成像在垂体微腺瘤的定位诊断与指导肿瘤切除中具有重要价值，倡导神经外科与鼻喉科密切合作。     

鸡胚胎腺垂体促甲状腺激素细胞的发生及其变化

应用免疫组织化学方法,对第3.5～20.5 d鸡胚腺垂体促甲状腺激素亚单位(TSH撸┫赴姆⑸⑹亢托翁植急浠媛山辛搜芯俊=峁允荆杭ε叻⒂牡?0.5 d,有少量TSH呦赴植加谙俅固迩耙叮赴派常伲舜螅患ε叻⒂牡?4.5 d以后,TSH呦赴灾黾樱≒ < 0.05),细胞体积增大,胞浆增多,细胞着色浓,分布于腺垂体前叶边缘区,少量分布于后叶背侧。研究结果证明,鸡胚腺垂体TSH呦赴⑸谂咛シ⒂闹衅冢幌赴脑鲋撤只谭⑸诩ε叻⒂闹泻笃冢籘SH的合成和分泌功能在胚胎发育的后期最旺盛。TSH呦赴植加谙俅固迩耙逗秃笠侗巢唷?     

保安湖鳜鱼脑垂体周年变化的组织学观察

对性成熟雌性鳜鱼的脑垂体进行了组织学研究。鳜鱼脑垂体由神经垂体和腺垂体两大部分组成。腺垂体分为前叶，间叶和过渡叶。间叶中含有嗜酸性细胞，嗜碱性细胞和嫌色细胞。其中嗜碱性细胞的形态和数量在年周期中有明显变化，并与生殖活动密切相关。