大鼠下丘脑弓状核神经元的衰老性变化

选用青、中年和老年雄性大鼠各１０只，用形态计量学和体视学方法定量分析弓状核神经元年龄性变化。结果发现在老年大鼠弓状核，部分暗型和亮型神经元内粗面内质网排列紊乱、缩短和双层膜间隔增宽，线粒体嵴断裂、肿胀和空泡化，溶酶体，微管和颗粒小泡数减少；与青、中年组比较神经元数分别丢失３７％和２７％，核仁平均体积缩小３０％左右；     

大鼠下丘脑弓状核神经元的神经支配

用ＨＲＰ逆行追踪和免疫细胞化学与电镜结合法研究了下丘脑弓状核神经元的神经支配。结果表明，室旁核向弓状核投射的神经元中，有一部分为催产素免疫反应阳性，一部分为后叶加压素免疫反应阳性，视上核也有部分ＯＴ免疫反应阳性神经元发出纤维投射至弓状核。将零乱毒素Ｂ亚单位结合ＨＲＰ注入第三脑室后，可见弓状核内有逆行标记细胞，电镜观察发现弓状核内的脑啡肽免疫反应阳性的树突接受ＨＲＰ反应阳性的触液神经元的轴突形成突触     

Ghrelin对糖尿病大鼠下丘脑弓状核胃牵张敏感神经元放电活动及胃运动的调控

 目的：观察链脲佐菌素(STZ)所致糖尿病（DM）大鼠下丘脑弓状核（Arc）胃牵张（GD）敏感神经元放电活动及胃运动改变,探讨ghrelin对DM大鼠下丘脑Arc GD敏感神经元放电活动和胃运动的影响。方法：采用STZ腹腔注射诱导DM大鼠模型;通过细胞外记录神经元单位放电和在体胃运动方法,观察ghrelin及其受体阻断剂［D-Lys3］-GHRP-6对DM大鼠下丘脑Arc GD敏感神经元自发放电活动和胃运动的影响;应用real-time PCR和荧光免疫组化方法,探讨DM大鼠Arc内ghrelin受体（GHS-R1a）mRNA及其免疫阳性物的表达。结果：在正常大鼠Arc记录到的98个GD敏感神经元中,64.3%为GD兴奋性（GD-E）神经元,35.7%为GD抑制性（GD-I）神经元。在63个GD-E神经元中,Arc微量注射ghrelin可使其中73.0%神经元兴奋,其放电频率与生理盐水组比较显著增加（P<0.05）;而在35个GD-I神经元中,Arc微量注射ghrelin可抑制其中60.0%神经元,放电频率显著降低（P<0.01）;ghrelin改变GD神经元放电效应可被ghrelin 受体阻断剂［D-Lys3］-GHRP-6阻断（P<0.05）;在DM大鼠,Arc记录到的66个GD敏感神经元中有56.1%为GD-E神经元,43.9%为GD-I神经元。Arc注射ghrelin可兴奋其中35.1%GD-E神经元,放电频率与生理盐水比较显著增加（P<0.05）;而在29个GD-I神经元中,ghrelin可抑制其中21个神经元（72.4%）,放电频率显著降低（P<0.01）。与正常大鼠比较,DM大鼠Arc GD敏感神经元中的GD-E和GD-I比例无显著改变（P>0.05）,但ghrelin使GD-E神经元兴奋的比率明显降低（P<0.05）,放电频率平均增加率也显著下降（P<0.05）;但ghrelin使GD-I 神经元抑制比率和放电频率平均减少率均无显著改变（P>0.05）。在体胃运动研究结果显示,Arc微量注射ghrelin,可显著促进正常和DM大鼠胃运动,且呈显著量效关系（P<0.05,P<0.01）,但ghrelin对正常大鼠的促胃运动作用显著强于其对DM大鼠的作用（P<0.05）,［D-Lys3］-GHRP-6可完全阻断ghrelin该作用。Real-time PCR研究结果显示,DM大鼠下丘脑Arc GHS-R1a mRNA表达较正常大鼠明显减少（P<0.05）;免疫荧光研究进一步证实DM大鼠下丘脑Arc GHS-R1a 免疫阳性物表达较正常大鼠明显减少（P<0.05）。结论：下丘脑Arc ghrelin参与DM大鼠GD敏感神经元自发放电活动,并参与胃运动的调控,该效应可能是通过作用于ghrelin受体而实现的。     

大鼠下丘脑弓状核年龄性变化的电镜观察

电镜观察大鼠下丘脑弓状核超微结构的年龄变化。结果发现:衰老大鼠弓状核的年龄变化主要发生在弓状核中的暗细胞神经元,出现粗面内质网退化变短,排列失序;高尔基氏器缩小;多聚核蛋白体和神经内分泌物质明显减少。特别引人注目的是在部分暗细胞中出现由双层膜缠绕形成的膜性涡旋体结构。此外,在神经毯出现突触结构异常。突触厚度变薄、间断不连续;神经胶质细胞突起增多,并可进一步形成包绕树突、轴突终末、甚至突触的多层膜环绕的髓鞘样结构。上述研究结果提示,下丘脑弓状核超微结构的年龄性变化是导致神经内分泌系统衰老的主要原因之一。     

复方甲地孕酮微囊注射液对大鼠下丘脑弓状核超微结构的影响

用不同剂量的复方甲地孕酮微囊针剂注射大鼠，观察其下丘脑弓状核超微结构变化，结果显示：实验组有部暗细胞的粗面内质网及高尔基器囊扩大，囊内有低电子密度絮状物，神经分泌颗粒增多，部分亮细胞质内参与分泌颗合成的细胞器减少；０．４ｍｌ组次级溶酶体数量和弓状核细胞体上含颗粒囊泡的轴体突触数目均增加，该两项分别与对照组比较，差异有显著性（Ｐ值均＜０．０１）。     

STZ和alloxan联合使用复制实验性糖尿病大鼠模型

糖尿病（ｄｉａｂｅｔｅｓｍｅｌｌｉｌｕｓ,ＤＭ）是一种慢性进行性内分泌代谢性疾病。为了弄清该病病因,尽快筛选出有效药物,需要一种成本低,复制成功率较高的ＤＭ模型。为此,本实验联合应用链脲佐菌素（ｓｔｒｅｐｔｏｚｏｔｏｃｉｎ,ＳＴＺ）和四氧嘧啶（ａｌｌｏｘａｎ）复制ＤＭ大鼠模型,成功率达８２－６％,且成本低。现将结果报道如下。材　料　与　方　法一、仪器、材料：（一）仪器：①ｐＨ－２ｃ酸碱计：上海华侨仪表厂;②日产７１５０型全自动生化分析仪;③γ免疫计数器：西安２６２厂（ＦＪ－２００８Ｇ）。　　…     

实验性糖尿病大鼠心肌超微结构观察

实验性糖尿病大鼠心肌超微结构观察南京军区南京总医院（南京２１０００２）施志明钱晓明周晓军章俐陈云吴振国糖尿病心肌病是糖尿病主要并发症，也是糖尿病致死的原因之一。本实验对链脲佐菌素（ｓｔｒｅｐｔｏｚｏｔｏｃｉｎ，ＳＴＺ）诱导的实验性糖尿病大鼠心肌超微...     

Ⅰ型糖尿病大鼠模型制备经验

目的探讨Ⅰ型糖尿病大鼠模型制作方法和注意事项。方法一次性大剂量注射链脲佐菌素（STZ）诱导Ⅰ型糖尿病大鼠模型。结果一般情况观察：大鼠多饮、多食、多尿、消瘦明显。体重：实验组在1、2、4、8、12周和对照组同期组比较有显著差异（P〈0.05）;实验组内1、2、4、8、12周两两比较有显著差异（P〈0.05）。尾静脉血糖：实验组在1、2、4、8、12周和对照组同期组比较有显著差异（P〈0.05）;实验组诱导前与1、2、4、8、12周比有显著差异（P〈0.05）。结论通过腹腔一次大剂量注射STZ（55mg/kg）可以严重损伤胰岛,引起与Ⅰ型糖尿病相似的症状。     

大鼠下丘脑弓状核神经胶质细胞的年龄性变化

对青年、中年和老年大鼠下丘脑弓状核进行细胞计数和电镜观察显示;老年大鼠神经元数显著减少而神经胶质细胞数增加,胶质细胞与神经元呈卫星化状态增多,表面下复合器形成增加;星形胶质细胞、少突胶质细胞和小胶质细胞不同程度增生且部分发生异常改变:胞浆内脂褐素显著增加,体积增大,线粒体和粗面内质网变性和出现致密体等,胶质细胞突起伸长增多常包绕一些变性终未形成髓鞘样结构,上述结果表明;老年大鼠弓状核胶质细胞在数量、形态和结构上已发生增龄性变化,这可能是老年下丘脑神经内分泌功能紊乱的形态学基础之一.     

老年大鼠下丘脑视上核和弓状核的超微结构变化

观察老年大鼠下丘脑视上核腹侧大细胞神经元和弓状核神经元的超微结构,结果显示:老年大鼠视上核腹侧血管加压素(VP)神经元的胞体较成年鼠大,胞质结构比较致密,内含许多核糖体颗粒,粗面内质网分散成小泡状,神经分泌颗粒增多,溶酶体、线粒体、高尔基氏复合体数量都较多.而弓状核内的暗细胞和亮细胞的核糖体减少,高尔基氏复合体和线粒体都变化,还有少数神经元固缩,细胞质内胞器明显减少,呈现变性现象.结果提示:老年期下丘脑视上核VP神经元机能增强;而弓状核内两种细胞都显示机能减弱的征象.老年时下丘脑各核团神经元的这种不协调性变化,可能是动物衰老的一种重要表现.     

Degeneration of dopaminergic neurons triggers an expression of individual enzymes of dopamine synthesis in non-dopaminergic neurons of the arcuate nucleus in adult rats

Non-dopaminergic neurons expressing individual complementary enzymes dopamine (DA) synthesis were shown to produce DA in cooperation [Ugrumov, M., Melnikova, V., Ershov, P., Balan, I., Calas A., 2002. Tyrosine hydroxylase- and/or aromatic L-amino acid decarboxylase-expressing neurons in the rat arcuate nucleus: ontogenesis and functional significance. Psychoneuroendocrinology 27, 533-548; Ugrumov, M.V., Melnikova, V.I., Lavrentyeva, A.V., Kudrin, V.S., Rayevsky, K.S., 2004. Dopamine synthesis by non-dopaminergic neurons expressing individual complementary enzymes of the dopamine synthetic pathway in the arcuate nucleus of fetal rats. Neuroscience 124, 629-635]. This study was aimed at testing our hypothesis that the cooperative synthesis of DA in non-dopaminergic neurons is an adaptive reaction under functional insufficiency of the dopaminergic system. Functional insufficiency of the tuberoinfundibular dopaminergic system was provoked by 6-OHDA-induced degeneration of dopaminergic neurons in the arcuate nucleus in adult rats. Bienzymatic (dopaminergic) neurons and monoenzymatic neurons expressing tyrosine hydroxylase (TH) or aromatic L-amino acid decarboxylase (AADC) were detected with a double-immunofluorescent technique on cryostat sections. The 6-OHDA-induced degeneration of dopaminergic neurons was accompanied by a significant increase of the number of monoenzymatic TH neurons and AADC neurons that appears to support our hypothesis. The reaction of bienzymatic and monoenzymatic neuron populations to the 6-OHDA administration occurred to be region-specific. The former disappeared in the dorsomedial region of the arcuate nucleus while the latter increased in the ventrolateral region. Thus, degeneration of dopaminergic neurons in the arcuate nucleus of adult rats is accompanied by the expression of individual enzymes of DA synthesis in non-dopaminergic neurons that may be an adaptive reaction.     

糖尿病大鼠孤束核的形态学变化

目的:探讨糖尿病对大鼠孤束核形态学的影响。方法:建立糖尿病大鼠模型,用多聚甲醛原位灌注固定后,取其孤束核部位,分别在光镜和电镜下观察其形态学变化。结果:与对照组相比,糖尿病大鼠孤束核部位神经元细胞排列紊乱,胞质密度降低,部分神经元线粒体出现空泡状改变、嵴断裂,并有髓鞘分裂现象。结论:糖尿病可导致大鼠孤束核部位神经元的形态学改变。     

大鼠丘脑前核神经元内γ-氨基丁酸及其受体的表达

目的:探讨大鼠丘脑前核内γ-氨基丁酸(GABA)及其GABAA受体(GABAARα1和β2subunits)的表达,从形态学角度为系统研究丘脑前核的功能提供依据。方法:分别采用包埋后胶体金免疫电镜技术和原位杂交检测丘脑前核内GABA及GABAARα1和β2mRNA的表达。结果:(1)在丘脑前核,GABAARα1和GABAARβ2阳性神经元分布较密集,细胞形态较一致。空白对照切片为阴性,未见GABAARα1和GABAARβ2mRNA表达阳性神经元。(2)GABA胶体金免疫反应切片上,GABA胶体金颗粒浓重标记GrayⅡ型轴突终末,而树突、神经元、胶质细胞及背景标记极少。GABA能阳性轴突终末与中小型树突形成对称性轴-树突触,也与神经元胞体形成对称性轴-体突触。结论:提示在丘脑前核能够合成GABAARα1和GABAARβ2,且GABA能轴突终末与神经元的树突或胞体形成对称性突触。     

Tachykinin-induced changes in β-endorphin gene expression in the rat arcuate nucleus

Previous neuroanatomical data have indicated the presence of synaptic connections between tachykinergic terminals and proopiomelanocortin (POMC) neurons in the arcuate nucleus. Consequently, tachykinins may regulate the activity of POMC neurons. To evaluate the functional signification of this regulation, the effect of intracerebroventricular injections of neurokinin A (NKA) on POMC mRNA levels was studied by using in situ hybridization. Repeated injection of NKA (40 μg/animal per day during 3 days) induced a 48% increase in POMC mRNA expression as compared to NaCl injected control animals. In conclusion the results of this study show an excitatory effect of tachykinin on POMC neurons and suggest a direct and/or indirect excitatory control of POMC neuronal activity by endogenous tachykinins.     

The role of dopamine in the control of neuropeptide Y neurons in the rat arcuate nucleus

In order to determine the role of dopamine (DA) on neuropeptide Y (NPY) neurons in the arcuate nucleus of the rat hypothalamus, we evaluated the effects of alpha-methylparatyrosine (alpha-MPT), an inhibitor of catecholamines biosynthesis, and haloperidol, a dopaminergic antagonist, on NPY immunoreactive neurons. The two drugs used produced in the arcuate nucleus the appearance of a large number of NPY-containing neuronal bodies which are normally absent in control animals. The density of stained fibers were not significantly modified. These results suggest that DA can exert some negative regulation of NPY neurons activity in the arcuate nucleus.     

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。     

N-甲基-D-天冬氨酸受体在大鼠丘脑前核和扣带后回的表达

目的探讨大鼠丘脑前核和扣带后回内N-甲基-D-天冬氨酸受体NMDAR2A,NMDAR2B及NMDAR1(NR2A.NR2B及NR1)mRNA的表达,从形态学角度为系统研究丘脑前核的功能提供了依据。方法应用原位杂交方法检测丘脑前核及扣带后回内NR2A,NR2B以及NR1 mRNA的表达。结果原位杂交阳性反应产物为棕黄色,主要分布在神经元核周围胞浆中,胞核基本不着色。在丘脑前核,阳性神经元分布较密集,细胞形态较一致。扣带后回皮质阳性神经元在在大脑皮质不同部位分布有差异,分子层染色最弱,外颗粒层密集分布且染色增强,余四层较外颗粒层松散,染色细胞减少。结论 NR2A,NR2B以及NR1广泛分布在丘脑前核和扣带后回。     

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.     

5-HT3 receptors control dopamine release in the nucleus accumbens of freely moving rats

ICS 205-930, a selective and potent 5-HT3 receptor antagonist applied either systemically, or locally into the ventral tegmental area, antagonized the stimulation of dopamine release in the nucleus accumbens, induced by the subcutaneous administration of morphine. These findings, obtained by the use of brain microdialysis in awake freely-moving rats, demonstrate in vivo a functional role of 5-HT3 receptors in the brain. Since stimulation of dopamine release in the nucleus accumbens is a prerequisite for the expression of the rewarding properties of morphine, its suppression by ICS 205-930 suggests a possible application of 5-HT3 receptor antagonists in the treatment of addiction.