棉酚对大鼠下丘脑视上核、室旁核和弓状核影响的组织学和组织化学观察

本文应用组织学和组织化学方法,观察了喂饲棉酚(30mg/kg/d×5周及30 mg/kg/d×5周+60mg/kg/周×5周)的成年雄性大鼠下丘脑视上核、室旁核和弓状核神经元的一般形态结构,以及反映神经分泌功能的形态学指标。结果表明,饲药5及10周,上述三个核团神经分泌细胞的光镜形态学,未见明显变化;根据细胞核体积测量、尼氏体和神经分泌物质含量,硫胺素焦磷酸酶和酸性磷酸酶活性的半定量测定,三核团神经分泌活性无显著改变,仅用药5周时,室旁核尼氏体含量增加。这说明抗生育有效剂量棉酚,对大鼠下丘脑没有明显的直接作用;室旁核分泌活性一度增强,可能是大细胞性神经分泌系统,对棉酚引起机体内环境某些改变的生理性调节反应。     

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.     

N-氨基-D-门冬氨酸诱导大鼠下丘脑视上核、室旁核和弓状核内c-fos基因表达

实验用foS蛋白免疫组织化学方法,研究了中枢神经系统兴奋性介质N-氨基-D-门冬氨酸诱导大鼠下丘脑内c-fos的表达.N-氨基-D-门冬氨酸注射大鼠皮下后,观察了fos阳性细胞在下丘脑内开始出现与消失的时程相关以及在下丘脑内的分布.结果表明:给N-氨基-D-门冬氨酸后30分开始出现fos阳性细胞,1～2小时达高峰,4～8小时消失.fos阳性细胞主要分布于视上核、室旁核和弓状核,视上核和室旁核中fos阳性细胞分别占细胞总数的57.8%和63.6%,在弓状核中占细胞总数的60.6%.     

切除两侧肾上腺对大鼠下丘脑加压素、催产素神经元的影响

为了进一步确定加压素(VP)在应激反应中的作用,我们应用免疫组化和免疫电镜观察了切除两侧肾上腺对大鼠下丘脑室旁核和视上核的神经内分泌细胞的影响,发现下丘脑室旁核VP神经元处于功能亢进状态,其合成、储存和分泌VP的功能均亢进,而视上核的加压素(VP)神经元以及室旁核和视上核的催产素(OT)神经元的功能状态均无明显改变,提示室旁核的VP神经元可能是参与下丘脑—垂体—肾上腺这一应激反应轴调节的重要因素。     

不同禁水时间老龄大鼠下丘脑大细胞分泌神经元的免疫电镜观察

电镜观察了不同禁水时间老龄大鼠下丘脑视上核和室旁核分泌神经元，即加压素和催产素神经元及胶质细胞的超微结构变化，结果显示，禁水6与12h后，上述两核团中的分泌神经元胞体增大，胞质中粗面内质网（RER）排列紧密且规则，高尔基（Golgi)器的未成熟分泌颗粒及神经分泌颗粒增多，轴突内神经分泌颗粒少见，胶质细胞成份减少，突起回缩；相邻两神经元胞膜直接接触，质膜并列现象及突触增多，而在禁水24h后，神经元胞体内的神经分泌颗粒有减少，轴突中的神经分泌颗粒却增多并聚集成膨大区域，以上结果提示老龄大鼠视上核和室旁核的分泌神经元在禁水时其合成激素的功能是活跃的，而且催产素神经元的结构变化与加压素神经元结构变化是相似的，胶质细胞的结构变化为神经元质膜并列及突触的形式提供了有利条件。     

大鼠视上核神经分泌细胞的衰老形态变化

本文选用青年(3个月)、成年(10—12个月)和老年(28—30个月)雄性Wistar大鼠,对其下丘脑视上核神经分泌细胞分别作了光镜和电镜观察与测定。结果表明:老年大鼠视上核前部的神经分泌细胞密度与细胞核体积明显低于青年和成年大鼠,提示老年大鼠视上核有神经元消失和细胞活性降低的表现;神经分泌细胞核周质内的醛复红阳性颗粒未测出三个年龄组大鼠间的差异,含醛复红阳性颗粒的胞突在老年时却显示增粗和膨大;老年动物神经分泌细胞超微结构的主要变化为神经分泌颗粒和脂褐素增加,尤以后者为甚。老年大鼠少数神经分泌细胞还表现有粗面内质网和核蛋白体减少,排列紊乱,池囊扩张和脱颗粒,高尔基复合体池囊变窄或扩张,胞质和胞突内有自噬体样物质出现等衰老改变;多数细胞胞质内的其他结构同青年和成年大鼠者相似。此外。老年大鼠视上核神经毡结构中有多层膜包绕胞突,终末和突触等的鞘样结构出现增多。本研究表明大鼠衰老时视上核神经分泌细胞活性降低。     

老年大鼠禁水时室旁核加压素样神经元免疫电镜观察

用免疫细胞化学ＰＡＰ法对禁水老年大鼠室旁核加压素样神经元的超微结构进行了观察研究。结果显示实验老年大鼠室旁核加太素样神经元蛋白质的合成功能活跃，表现为粗面内质网丰富，高尔基复合体发达，胞质内神经分泌颗料增多；随着禁水时间的延长，胞质中神经分泌颗粒渐减少，轴突内神经分泌颗粒增多，并聚集成膨大区域。此外，部分神经元胞体间的细胞间隙变窄，甚至有胞膜并例。此外还对上述结果对禁水时老年大鼠室旁核加压素样神经     

强啡肽B免疫反应阳性神经元在大鼠下丘脑的分布及与精氨酸加压素的共存

实验应用免疫细胞化学 PAP法显示了强啡肽 B免疫活性阳性神经元在大鼠下丘脑形态特征和分布特点。结果表明 :强啡肽 B正常条件下免疫活性阳性神经元仅在下丘脑的视上核、室旁核、环核、附属神经分泌核和室管膜。正中隆起处有强啡肽 B免疫活性阳性纤维分布。侧脑室注射秋水仙素后在下丘脑视前区、前区、室周核、前连合核、交叉上核、交叉后核、弓状核、背侧区、背内侧核、穹隆周核、下丘脑外侧区、腹内侧核、室周大细胞区等核区显示了强啡肽 B免疫活性阳性神经元。双标记免疫组织化学方法还显示强啡肽 B与精氨酸加压素主要共存于下丘脑室旁核 ,次为视上核 ,附属神经分泌核和下丘脑外侧区     

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。     

大鼠垂体后叶中神经降压素阳性神经纤维的起源

向垂体后叶注射WGA-HRP,进行逆行追踪并与免疫组织化学相结合研究了大鼠垂体后叶中神经降压素(NT)能神经纤维的起源。投射到垂体后叶的NT免疫阳性神经元胞体主要位于下丘脑室旁核小细胞部、室周区,环状核、室旁核大细胞亚核内侧部、视上核背侧部、穹窿后核及下丘脑前区、外侧区。弓状核内未见任何双标记神经元,从而否定了Goedert等用损毁的方法得出的大鼠垂体后叶中NT阳性神经纤维起源于弓状核的结论。一些室周双标记神经元位于室管膜内,距第三脑室腔很近,常挤在室管膜细胞之间。提示这些神元在监测脑脊液的化学变化,调节垂体后叶分泌方面起一定的作用。     

下丘脑强啡肽A1-13神经元及纤维的分布特征:免疫细胞化学观察

应用免疫细胞化学PAP法和DAB氧化产物金银加强法显示了大鼠下丘脑强啡肽A1-13神经元及纤维的分布特征。结果:除以往作者显示过的视上核、室旁核、环核、附属神经内分泌核和弓状核外,我们首次在下丘脑视前区、前区、室周核、前连合核、室周大细胞区、交叉上核、交叉后核、前侧区、背内侧核和外侧区显示了强啡肽A1-13神经元及纤维。     

针刺“足三里”穴下丘脑血管加压素(Vp)样细胞的形态学变化——免疫组织化学法

采用免疫组化PAP技术,在电针大鼠“足三里”穴位后,观察丘脑下部Vp样神经元的变化。发现视上核与室旁核Vp样大神经元数目增多、胞体胀大,并伸出细长突起。室旁核少数串珠状神经纤维可插入第三脑室壁的细胞之间。在视交叉上核腹内侧Vp小神经元密集,而背外侧反应阳性神经元较少。视上核与室旁核间的神经元岛的细胞体积增大、轴索变长伸向视上区。该区的串珠状纤维集合成束达正中隆起的外层。以上实验结果提示,电针“足三里”可促进下丘脑有关核团Vp样物质的合成与分泌。     

Expression of provasopressin gene during ontogeny in the hypothalamus of developing mice.

We investigated the ontogeny of provasopressin gene expression in neurosecretory neurons of the supraoptic and paraventricular nuclei of developing mice by semi-quantitative in situ hybridization and immunohistochemical techniques in combination with stereometry of vasopressin-immunoreactive neurons. Provasopressin mRNA was detected in paraffin sections using a mixture of radiolabeled synthetic oligonucleotide probes complementary to the mRNA loci encoding vasopressin (2-9) and vasopressin neurophysin (1-8). Vasopressin immunoreactivity was located with a polyclonal anti-vasopressin antiserum and a monoclonal anti-vasopressin-neurophysin antibody either with or without enhancing technique for the diaminobenzidine reaction. Autoradiographic hybridization signals that indicate the localization of provasopressin mRNA were first detected on embryonic day 15 in the supraoptic nucleus and embryonic day 18 in the paraventricular nucleus. Vasopressin immunoreactivity was first found in the median eminence on embryonic day 14, and then in the supraoptic and paraventricular nuclei on embryonic days 15 and 16, respectively. The provasopressin mRNA levels were markedly increased in both the supraoptic and the paraventricular nuclei just after birth. The immunoreactivity of vasopressin neurons was drastically decreased in both nuclei on postnatal days 1 and 2, suggesting marked vasopressin release in the neonates. Cross-sectional areas of vasopressin-immunoreactive somata and their cell nuclei gradually increased in both the supraoptic and the paraventricular nuclei during the perinatal period by day 5, and then attained adult size between days 10 and 20. During this phase, the level of provasopressin mRNA remained low compared with that in the adult magnocellular neurosecretory cells. These results indicate that the expression of provasopressin gene is markedly increased in both the supraoptic and the paraventricular nuclei soon after birth. Secretory activity of vasopressin neurons is elevated in neonatal mice. Vasopressin may have an important osmoregulatory role in neonatal mice undergoing drastic changes in water metabolism following birth.     

一氧化氮合酶在自发性高血压大鼠视上核及室旁核的分布

目的：探讨自发性高血压大鼠视上核及室旁核内一氧化氮合酶阳性神经元的改变。方法：用ＮＡＤＰＨ－ｄｉ－ａｐｈｏｒａｅ组织化学方法,观察和比较了一氧化氮合酶在自发性高血压大鼠和正常对照大鼠视上核和室旁核的分布间下观察下捕脑视上核及室旁核的一氧化氮合酶阳性细胞形态、分布并进行计数。用图像分析仪测其灰度显差异。视上核及室旁核内的一氧化氮合酶阳性细胞灰度值在高血压组均明显高于对照组。提示这两上核内一氧化氮合酶     

Electrophysiology of supraoptico-paraventricular nucleus connections in the rat

Summary In an attempt to clarify the mechanisms involved during synchronous discharge of magnocellular neurosecretory cells of the supraoptic and paraventricular nuclei, extracellular action potentials were recorded from 149 single units located in the rat paraventricular nucleus. Responses of the cells to stimulation of the ipsilateral supraoptic nucleus were recorded and it was observed that 7% of paraventricular nucleus neurones could be antidromically identified as projecting to the supraoptic nucleus. Excitatory responses were recorded from 40% of cells tested and were probably mediated by an interneurone population. Inhibitory responses were recorded from 37% of the cells and may have been mediated by direct projections from the supraoptic nucleus. No differences in responses were recorded from cells identified as projecting to the median eminence or neurohypophysis as compared with the rest of the population tested. However, more of the phasically firing putative vasopressin-secreting cells, (58%) were excited than were continuously active cells (38%). Delivery of short trains of high-frequency stimulation induced bursts of discharge from 93% of cells so tested, regardless of response to single shock stimulation. These burst discharges showed a late onset as compared with responses following single shock stimulation. The results suggest that a complex of intra- and internuclear interactions serve to regulate the neurosecretory activity of magnocellular cells within the supraoptic and paraventricular nuclei.     

Partial co-existence of NADPH-diaphorase and acetylcholinesterase in the hypothalamic magnocellular secretory nuclei of the rat

Co-localization of NADPH-diaphorase (ND) and acetylcholinesterase (AChE) activities were explored in the magnocellular secretory nuclei of the rat hypothalamus by means of a double histochemical staining of the same sections. Partial co-existence was found in all the nuclei studied (paraventricular, supraoptic, fornicals and circular nuclei). No particular location of the neurons expressing both markers was found, although in the paraventricular nucleus all of them (ND+, AChE+ and neurons expressing both markers) were preferentially located in the magnocellular subdivisions whereas in the parvicellular ones only some neurons belonging to all three types were detected, mainly located in the periventricular and medial subdivisions. The lowest degree of co-existence was found at the level of the main magnocellular nuclei (supraoptic and paraventricular) when compared with the accessory magnocellular nuclei, especially the posterior fornical and the circular nuclei. These results extend previous data on the chemical nature of the neurons producing nitric oxide in the neurosecretory nuclei and the possible functional role of this atypical messenger in the hypothalamus.     

Changes in the Metabolic Activity of Neurons in the Anterior Hypothalamic Nuclei in Rats during Hyperthermia,Fever, and Hypothermia

Histochemical methods were used to detect differently directed changes in the metabolic activity of neurons in the anterior hypothalamic nuclei in rats during hyperthermia, fever, and hypothermia. Hyperthermia induced by high temperatures was associated with increases in the activities of enzymes involved in energy metabolism, with increases in RNA contents in neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus of the rat, which is evidence for increases in metabolic activity in the neurons of these nuclei. Endotoxin-induced fever was accompanied by decreases in the metabolic activity of neurons in the median preoptic nucleus, while activity in neurons of the supraoptic and paraventricular nuclei showed no significant change. The development of hypothermia induced by low temperatures was characterized by decreases in the metabolic activity of neurons in the supraoptic, paraventricular, and median preoptic nuclei of the anterior hypothalamus. It is suggested that the differently directed changes in metabolic activity in the neurons of the anterior hypothalamus in hyperthermia, fever, and hypothermia are associated with their roles in the central mechanisms of thermoregulation (median preoptic nucleus) and neurosecretory processes (supraoptic and paraventricular nuclei).