促性腺激素释放激素信号转导研究进展

促性腺激素释放激素(gonadotropinreleasinghormone,GnRH)与垂体前叶细胞膜上特异的G蛋白偶联受体(Gproteincoupledreceptor,GPCR)结合,激活胞内一系列信号分子,最终使特定的基因表达,合成并分泌黄体生成素和卵泡刺激素。此外,GnRH脉冲频率的变化可影响胞内信号通路组件和下游基因反应的模式。促性腺激素基因自身结构的差异及各自启动子结构的不同,可部分解释GnRH受体下游基因反应的频率敏感性。     

人甲状腺促性腺激素释放激素及其受体的表达

目的　探讨人甲状腺中是否存在促性腺激素释放激素 (GnRH)及促性腺激素释放激素受体 (GnRH R)并细胞定位 ,试图从转录及翻译水平讨论人甲状腺可否合成GnRH及GnRH R ,为探讨GnRH可能影响甲状腺的功能提供形态学依据。　方法　采用免疫组织化学法和原位杂交技术。　结果　所测人正常甲状腺组织均呈较强的GnRH和GnRH R免疫反应阳性 ,甲状腺滤泡上皮细胞、滤泡旁细胞均为阳性细胞。免疫反应阳性物质主要分布在阳性细胞胞质内 ,胞核呈阴性。原位杂交结果同免疫组织化学染色基本一致 :甲状腺滤泡上皮细胞胞质和滤泡旁细胞胞质可检测到较强的GnRHmRNA及GnRH RmRNA阳性杂交信号。胞核均呈阴性 ,未检测到杂交信号。　结论　人甲状腺不仅表达GnRH和GnRH R ,而且可以自身合成GnRH和GnRH R。GnRH可能以自分泌的方式影响甲状腺的生理功能     

大鼠肝促性腺激素释放激素受体的定位研究

目的探讨大鼠肝是否表达促性腺激素释放激素(GnRH)受体,为GnRH能否参与肝代谢功能的调节提供形态学依据。方法采用兔抗GnRH的抗独特型抗体的免疫组织化学SABC法及地高辛标记探针的原位分子杂交法,对5例大鼠肝GnRH受体表达进行研究。结果大鼠肝细胞既呈GnRH受体阳性又有GnRH受体mRNA杂交信号。GnRH受体阳性物质和GnRH受体mRNA杂交信号物质均分布在大鼠肝细胞的细胞质,细胞核未检测到GnRH受体阳性物质及GnRH受体mRNA杂交信号。不同部位的肝细胞其GnRH受体免疫反应强度和GnRH受体mRNA杂交信号强度存在差别。结论大鼠肝细胞能表达GnRH受体,不同部位的肝细胞对GnRH受体表达水平存在差异。     

光照应激对SD大鼠胃促性腺激素释放激素受体表达的影响

目的 观察光照应激状态下SD大鼠胃内促性腺激素释放激素受体（GnRHR）的表达变化。 方法 建立SD大鼠光照应激模型(共64只,实验组与对照组各32只),24h持续光照,分别取光照1d、2d、3d、4d、1周、2周、3周、4周和相应对照组大鼠的胃,采用免疫组织化学、Western blotting和实时PCR法检测GnRHR在各时间段大鼠胃黏膜中的定位及蛋白和mRNA的表达变化。 结果 GnRHR阳性细胞广泛分布于大鼠胃底腺壁细胞中,在对照组和实验组中的定位无差异。实验组大鼠的GnRHR蛋白表达水平高于其相应的对照组。持续光照1～4周后,实验组与其对照组相比差异显著（P<0.05）;当持续光照2周时,GnRHR的表达至最高水平,与其对照组相比,差异极显著（P<0.01）。实验组大鼠胃GnRHR mRNA表达水平高于对照组,持续光照3～4周后,实验组大鼠胃GnRHR mRNA表达水平显著增加（P<0.05）。 结论 光照应激可以影响消化道内GnRHR的表达,提示GnRH通过其受体介导,对消化功能具有潜在的生理调节功能。GnRH除参与消化道正常生理功能外,可能还是一种参与应激反应的激素。     

电针对单纯性肥胖大鼠无排卵机制的影响

目的:探讨电针对食源性肥胖大鼠排卵机制的影响.方法:将刚断乳雌性SD大鼠分为2组,正常组喂以普通饲料,高能饲料组给予高能饲料,筛选出肥胖不孕大鼠.检测血清雌二醇(E2)、睾酮(T)、瘦素(leptin)、卵泡刺激素(FSH)、黄体生成素(LH)的水平;观察神经肽Y(NPY)及促性腺激素释放激素(GnRH)在下丘脑弓状核...     

哺乳期雌性大鼠下丘脑内促性腺激素释放激素神经元的免疫组织化学研究

采用免疫组织化学方法研究了产后授乳和中断授乳的雌性大鼠下丘脑内促性腺激素释放激素(GnRH)阳性神经元和神经纤维的密度和染色反应的变化.在哺乳的第3天,将半数母鼠的仔鼠去除,中断授乳后1～4天下丘脑内侧隔核、视前内侧区和Broca斜角带内的GnRH阳性神经元胞体的反应强度明显高于继续授乳组.在正中隆起和终板血管器的GnRH阳性纤维和终末的密度和染色强度也比授乳组明显增加.结果表明:中断授乳的母鼠下丘脑内GnRH分泌神经元激素的合成和释放功能均明施增强,而哺乳对下丘脑内GnRH神经元的合成和释放激素的功能有显著的抑制作用.     

妊娠与非妊娠大鼠子宫内膜促性腺激素释放激素及其受体的免疫组织化学研究

目的：研究促性腺激素释放激素（GnRH)及其受体在妊娠与非妊娠大鼠子宫内膜中的分布及相对含量,为了解促性腺激素释放激素对子宫内膜的可能功能提供依据。方法：免疫组织化学ABC法及图像分析技术。结果：非妊娠大鼠子宫内促性腺激素释放激素及促性腺激素释放激素受体阳性反应发生在内膜上皮、腺上皮及基质细胞。妊娠大鼠子宫内这二者阳性反应主要发生在内膜上皮及基蜕膜的蜕膜细胞,妊娠大鼠子宫上皮细胞中的促性腺激素释放激素及其受体的相对含量明显高于非妊娠大鼠子宫内膜。结论：妊娠与非妊娠大鼠子宫内膜均能表达促性腺激素释放激素及其受体。     

促性腺激素释放激素类似物对大鼠胃肠道5-羟色胺分泌的影响

目的 研究GnRH对胃肠道内5-HT分泌的影响。方法胃腔直接注射GnRH类似物阿拉瑞林(A1arelin GnRH—A)以模拟外分泌产生的GnRH，并以免疫组织化学、高压液相色谱电化学检测(HPLC-ECD)的方法对阿拉瑞林刺激后胃及十二指肠内5-HT免疫反应细胞、血清中5-HT含量进行检测。结果 胃腔内注射GnRH—A后，大鼠胃及十二指肠内5-HT免疫反应阳性细胞密度显著增多，但血清中5-HT含量显著减少。结论 外分泌的OnRH对于5-HT的释放起明显抑制作用，但对5-HT的合成可能不产生影响。     

乳腺浸润性导管癌中促性腺激素释放激素受体的表达及意义

目的 探讨促性腺激素释放激素受体(gonadotropin-releasing hormone,GnRHR)在乳腺浸润性导管癌中的表达及意义.方法 采用免疫组化方法 检测50例乳腺浸润性导管癌及18例正常乳腺组织中的GnRHR.结果 乳腺浸润性导管癌中GnRHR的阳性表达为68%(34/50).其中乳腺癌 G1组的阳性表达(92.3%,12/13)与G3组的阳性表达(46.2%,6/13)之间的差异有统计学意义(P<0.05).乳腺癌G3组的阳性表达和正常乳腺组织的阳性表达(94.4%,17/18)之间的差异有统计学意义(P<0.01).结论 大多数正常乳腺组织的GnRHR虽有表达,但呈弱阳性表达,而多数浸润性导管癌GnRHR则呈强阳性表达,提示乳腺组织的分化程度影响肿瘤组织内GnRHR的表达.     

电针上调食源性肥胖致不孕大鼠下丘脑弓状核内GnRH的表达

目的 探讨电针对食源性肥胖致不孕大鼠中枢性作用中,能否上调下丘脑弓状核GnRH的表达.方法 将100只刚断乳雌性SD大鼠随机分为2组:①正常组20只,喂以普通饲料;②高能饲料组80只,给予高能饲料,筛选出肥胖不孕大鼠22只,并将其随机分成两组,即对照组和电针组.检测血清雌二醇(E2)、睾酮(T)、瘦素(leptin) ...     

Pro-opiomelanocortin gene transfer to the nucleus of the solitary track but not arcuate nucleus ameliorates chronic diet-induced obesity

Short-term pharmacological melanocortin activation deters diet-induced obesity (DIO) effectively in rodents. However, whether central pro-opiomelanocortin (POMC) gene transfer targeted to the hypothalamus or hindbrain nucleus of the solitary track (NTS) can combat chronic dietary obesity has not been investigated. Four-weeks-old Sprague–Dawley rats were fed a high fat diet for 5 months, and then injected with either the POMC or control vector into the hypothalamus or NTS, and body weight and food intake recorded for 68 days. Insulin sensitivity, glucose metabolism and adrenal indicators of central sympathetic activation were measured, and voluntary wheel running (WR) assessed. Whereas the NTS POMC-treatment decreased cumulative food consumption and caused a sustained weight reduction over 68 days, the hypothalamic POMC-treatment did not alter cumulative food intake and produced weight loss only in the first 25 days. At death, only the NTS-POMC rats had a significant decrease in fat mass. They also displayed enhanced glucose tolerance, lowered fasting insulin and increased QUICK value, and elevated adrenal indicators of central sympathetic activation. Moreover, the NTS-POMC animals exhibited a near 20% increase in distance ran relative to the respective controls, but the ARC-POMC rats did not. In conclusion, POMC gene transfer to the NTS caused modest anorexia, persistent weight loss, improved insulin sensitivity, and increased propensity for WR in DIO rats. These metabolic improvements may involve stimulation of energy expenditure via centrally regulated sympathetic outflow. The similar POMC treatment in the hypothalamus had minimal long-term physiological or metabolic impact. Thus, melanocortin activation in the brainstem NTS region effectively ameliorates chronic dietary obesity whilst that in the hypothalamus fails to do so.     

隔核ghrelin对糖尿病胃动力障碍大鼠胃运动影响及下丘脑弓状核的潜在调控机制

 目的：研究隔核ghrelin对糖尿病(DM)大鼠胃运动的调控, 并探讨下丘脑弓状核与隔核间ghrelin通路对胃运动的调控机制。方法：链脲佐霉素腹腔注射制备DM大鼠模型;荧光免疫组化和real-time PCR方法检测DM大鼠隔核内ghrelin受体GHS-R1a表达变化;大鼠胃表面固定感应片在体记录胃运动并计算胃运动变化率;荧光金逆行示踪方法显示下丘脑弓状核和隔核间纤维联系,并采用中枢注射药物、核团损毁或电刺激等方法观察核团纤维联系对DM大鼠胃运动的调控作用。结果：（1） DM大鼠隔核GHS-R1a表达低于正常大鼠（P<0.05）,胃运动明显减弱,胃收缩幅度和频率显著降低（P<0.05）。（2）隔核注射ghrelin增强正常和DM大鼠胃运动（P<0.05）,且呈量效关系。（3） 荧光金在注射入隔核7 d后逆行至弓状核内神经元,其中部分神经元为ghrelin免疫阳性神经元;（4）正常大鼠体内,损毁隔核对胃运动和电刺激弓状核引起的胃运动变化无显著影响（P>0.05）;而对DM大鼠,损毁隔核减弱胃运动和电刺激弓状核后胃运动（P<0.05）。（5）隔核微量注射ghrelin受体阻断剂［D-Lys-3］-GHRP-6未显著改变正常大鼠电刺激弓状核后胃运动变化（P>0.05）,但可减弱DM大鼠电刺激弓状核引起的胃运动变化（P<0.05）。结论:隔核ghrelin和下丘脑弓状核-隔核间ghrelin通路在糖尿病大鼠胃运动调控中发挥重要作用。     

Estrogen stimulates neuronal plasticity in the deafferented hypothalamic arcuate nucleus in aged female rats

The hypothalamic arcuate nucleus (ARCN) was examined ultrastructurally 3 weeks after the complete deafferentation of the medial basal hypothalamus (MBH) with the island isolation technique in ovariectomized aged female rats (720-930 days of age). The mean numbers of axodendritic and axosomatic synapses in the ARCN decreased to about one-third of those in the intact controls. However, the treatment with estradiol benzoate (2 micrograms/day) during the 3 weeks following the day of brain surgery brought about a marked increase in the numbers of these synapses. The data suggest that the ARCN neurons of aged female rats still retain plasticity to react to deafferentation under influences of estrogen.     

Testosterone inhibition of tyrosine hydroxylase expression in the hypothalamic arcuate nucleus

Immunohistochemistry was used to detect tyrosine hydroxylase (TH)-containing neurons in the hypothalamic arcuate nucleus in male rats. Two weeks following castration, the number of TH-positive cells was significantly greater than in intact controls. The castration-responsive TH-positive cells were uniformly distributed throughout the mediolateral extent of the arcuate nucleus. Treatment with testosterone significantly suppressed the castration response, whereas neither estradiol nor 5 alpha-dihydrotestosterone were effective. The number of TH-positive arcuate neurons in the female was similar to that in the male. Ovariectomy did not affect the number of TH-positive neurons. These findings indicate that TH expression is tonically inhibited in the tuberoinfundibular dopaminergic system of the male rat by testosterone.     

Expression and colocalization patterns of calbindin-D28k,calretinin and parvalbumin in the rat hypothalamic arcuate nucleus

Calcium binding proteins (CaBPs) form a diverse group of molecules that function as signal transducers or as intracellular buffers of Ca²⁺ concentration. They have been extensively used to histochemically categorize cell types throughout the brain. One region which has not yet been characterized with regard to CaBP expression is the hypothalamic arcuate nucleus, which plays a vital role in neuroendocrine control and the central regulation of energy metabolism. Using in situ hybridization and immunofluorescence, we have investigated the cellular distribution of the three CaBPs, calbindin-D28k (CB), calretinin (CR) and parvalbumin (PV) in the rat arcuate nucleus. Both mRNA and immunoreactivity was detected in the arcuate nucleus for CB – located in the medial aspects – and CR – located ventrolaterally. No PV mRNA was detected in the arcuate nucleus. Immunofluorescence results for PV were ambiguous; while one antibody detected a group of cell somata, a different antibody failed to visualize any arcuate nucleus cell profiles. Using double-labeling, neither of the examined CaBPs were observed in cells immunoreactive for the signaling molecules agouti gene-related protein, tyrosine hydroxylase, neurotensin, growth hormone-releasing hormone, somatostatin, enkephalin, dynorphin or galanin. We did, however, observe CB- and CR-immunoreactivity, in two distinct populations of neurons immunoreactive for the melanocortin peptide α-melanocyte-stimulating hormone. These data identify distinct subpopulations of arcuate neurons defined by their expression of CaBPs and provide further support for differentiation between subpopulations of anorexigenic melanocortin neurons.