Fine structural studies of growth-hormone-releasing-factor (GRF)-immunoreactive neurons and their synaptic connections in the guinea pig arcuate nucleus

The fine structure of neurons containing human growth-hormone-releasing factor (hGRF) immunoreactivity located in the arcuate nucleus of the guinea pig was studied by means of the preembedding immunohistochemical technique. The perikaryon of labeled neurons was fusiform or ovoid; the nucleus was regular in shape and contained a prominent nucleolus. The main ultrastructural features of the hGRF-immunoreactive neurons were the presence of numerous labeled secretory granules (100-120 nm in diameter) and the abundance and the enlargement of the organelles involved in the synthesis of the peptides: a well-developed rough endoplasmic reticulum and a conspicuous Golgi apparatus. Synaptic inputs were observed on immunoreactive perikarya but, above all, on the labeled dendrites. The unstained presynaptic nerve endings most often contained only small clear vesicles and formed symmetrical contacts. In rare cases, the presynaptic terminals exhibited both small clear and large dense vesicles and constituted asymmetrical contacts. Immunoreactive nerve endings were also observed in this area: the synaptic boutons contained large, stained vesicles and small, unlabeled, clear vesicles. These axon terminals made synaptic contacts with unstained dendritic processes; the contacts were symmetrical. The results indicate that hGRF-immunoreactive neurons of the guinea pig arcuate nucleus present morphological features of neuroendocrine cells. Moreover, the presence of hGRF-labeled nerve endings in the arcuate nucleus itself suggests that a substance related to hGRF might be a neuromodulator, at least in this area.     

Luteinizing Hormone-Releasing Hormone Neurons which are R-etrogradely Labeled After Peripheral Fluoro-Gold Administration in the Male Ferret

This study identified luteinizing hormone-releasing hormone (LHRH)-producing neurons which have access to fenestrated capillaries in prepubertal male European ferrets. Fluoro-Gold was injected intraperitoneally to retrogradely label neurons with terminals outside the blood-brain barrier. LHRH neurons were identified by immunofluorescence using a secondary antibody tagged with tetramethylrhodamine isothiocyanate. Cell bodies which demonstrated both tetramethylrhodamine isothiocyanate and Fluoro-Gold fluorescence were defined as LHRH-producing neurons with axon terminals in regions containing fenestrated capillaries. The total number and neuroanatomical distribution of immunopositive (LHRH +) cells concurred with previous studies in the ferret in which cell bodies were diffusely distributed from rostral forebrain through caudal diencephalon, with approximately 70% of the LHRH + cell bodies located in retrochiasmatic hypothalamus. In the present study, an average of 59.8% of all LHRH+ neuronal perikarya also contained Fluoro-Gold. The majority of Fluoro-Gold filled LHRH+ neurons demonstrated only faint to moderate amounts of Fluoro-Gold when compared to other Fluoro-Gold filled neurosecretory neurons. This limited uptake of Fluoro-Gold may be due to a relative inactivity of LHRH neurons projecting outside the blood-brain barrier. Double-labeled LHRH + neurons were dispersed throughout the entire population of LHRH+ cell bodies and no apparent nuclear groups of double-labeled neurons were found. This observation suggests that the LHRH+ neurons responsible for neurosecretion into the median eminence coexist with the LHRH+ neurons responsible for intracerebral neurotransmission or neuromodulation. One distinguishable population of LHRH + neurons was consistently observed in all the brains. Only 26% of total LHRH+ perikarya within the caudal arcuate nucleus contained Fluoro-Gold, while at least 50% of LHRH+ neurons in other structures, including the rostral arcuate nucleus, contained Fluoro-Gold. Thus, in the prepubertal male ferret, the majority of LHRH cell bodies located in the caudal arcuate nucleus may be differentially regulated and/or involved in non-neuroendocrine functions.     

弓状核内微量注射5-羟色胺加强电针抑制胃运动

目的:探讨弓状核(ARC)内注射微量5-HT对电针足三里穴调节胃运动的影响.方法:采用霍耳效应原理慢性记录胃运动的变化.结果:通过ARC内埋植不锈钢插管注入2μ1生理盐水,不影响电针的抑制效应;而向ARC内注入5-HT1μg/2μ1时,则电针的抑制效应增强.结论:ARC内微量注射5-HT增强电针对胃的抑制,ARC内的5-HT可能参与电针对胃的抑制效应.     

Timing and completion of puberty in female mice depend on estrogen receptor alpha-signaling in kisspeptin neurons

Puberty onset is initiated by activation of neurons that secrete gonadotropin-releasing hormone (GnRH). The timing and progression of puberty may depend upon temporal coordination of two opposing central mechanisms--a restraint of GnRH secretion before puberty onset, followed by enhanced stimulation of GnRH release to complete reproductive maturation during puberty. Neuronal estrogen receptor α (ERα) has been implicated in both controls; however, the underlying neural circuits are not well understood. Here we test whether these mechanisms are mediated by neurons that express kisspeptin, a neuropeptide that modulates GnRH neurosecretion. Strikingly, conditional ablation of ERα in kisspeptin neurons results in a dramatic advancement of puberty onset in female mice. Furthermore, subsequent pubertal maturation is arrested in these animals, as they fail to acquire normal ovulatory cyclicity. We show that the temporal coordination of juvenile restraint and subsequent pubertal activation is likely mediated by ERα in two separate kisspeptin neuronal populations in the hypothalamus.     

Oestrogen-dependent tracing in the rat CNS after pseudorabies virus infection

This study examines the hypothesis that neuronal infectivity and the spreading of the pseudorabies virus (PRV) through the synapses in the central nervous system (CNS) are influenced by the oestrogen levels. The arcuate nucleus (ARC) and the subfornical organ (SFO) were chosen as models for analysis; the neurons in both structures possess oestrogen receptors and are mutually connected. A genetically engineered pseudorabies virus (Ba-DupLac) was used as a transneuronal tract tracer. This virus is taken up preferably by axon terminals, and transported very specifically through the synapses in a retrograde manner. Ba-DupLac was injected into the ARC of rats, followed by monitoring of the PRV-immunoreactivity (PRV-IR) in the SFO 72 h following inoculation. We found no PRV immunolabelling in the SFO of ovariectomized (OVX) rats, or in those OVX animals that received oestrogen shortly (4 h) before PRV infection (OVX + E 4 h). In contrast, in those OVX animals that received oestrogen 12 h before PRV infection (OVX + E 12 h), and also in intact control animals, PRV-IR was demonstrated in the SFO in all cases. Surprisingly, a reverse labelling was observed in the OVX rats; PRV-IR appeared in the pyriform cortex, whereas PRV-IR could not be detected in the control and OVX + E 12 h animals. As far as we are aware, this is the first study to demonstrate that transneuronal PRV labelling depends on the effects of oestrogen on certain CNS structures and connections.     

下丘脑弓状核参与左旋四氢巴马汀的镇痛作用(英文)

目的:研究弓状核在左旋四氢巴马汀(l-THP)镇痛效应中的作用,以阐明l-THP的镇痛作用机制。方法:应用辣根过氧化物酶(HRP)逆行追踪术追踪纹状体或伏膈核与PAG之间的纤维联系,HRP逆行追踪结合免疫组化观察投射神经元的性质,神经核团损毁和PAG核内注射药物观察对l-THP镇痛作用的影响。结果:纹状体或伏膈核通过弓状核或缰核间接与PAG联系,弓状核投射至PAG的神经元大部分是β内啡肽神经元。损毁弓状核后,l-THP的镇痛作用消失,而损毁缰核对l-THP的镇痛作用无明显影响。PAG核内注射纳洛酮能剂量依赖性翻转l-THP的镇痛作用。结论:弓状核的β内啡肽神经元在l-THP镇痛作用中起重要作用。     

动脉粥样硬化大鼠弓状核内β－内啡肽免疫反应阳性细胞的变化

用免疫细胞化学ＰＡＰ法和计算机图象分析技术，对动脉粥样硬化大鼠下丘脑弓状核β－内啡肽免疫反应阳性细胞的变化进行半定量研究。结果发现；动脉粥样硬化大鼠的下丘脑弓状核内β－ＥＮＤ阳性细胞数量增加，实验组和对照组在单位剖面弓状核内，阳性细胞数分别为２９．１±５．１和１５．５±４．２个。计算机图象分析其阳性细胞的积分光密度，实验组和对照组分别为０．１１４４６±０．０５１３和０．０８３３０±０．０４１６，经统计学处理，两组之间阳性细胞和ＩＯＤ都具有显著差异（Ｐ＜０．０５）。本文提示：下丘脑弓状核内β－ＥＮＤ样阳性神经元对动脉粥样硬化的形成和／或调控过程可能有一定影响。     

Dendritic arborization and axon trajectory of neurons in the hypothalamic arcuate nucleus of the rat--updated

Neurons in the hypothalamic arcuate nucleus (arcuate neurons) were traced on Golgi-impregnated sections. Dendrites of arcuate neurons showed characteristic orientation patterns. Dendrites along the lateral side follow the convex border of the nucleus by running parallel to the tanycyte processes. Neurons located in the ventrolateral portion of the nucleus have dendrites running parallel to the basal surface of the hypothalamus. Fine, beaded axons of arcuate neurons project mostly ventrally, and less frequently dorsally and dorsolaterally. Ventrally projecting axons converge towards the tuberoinfundibular sulcus which emerges into the ventral portion of the arcuate nucleus from below.     

Arcuate ligament vascular compression syndrome in infants and children

Background

Arcuate ligament vascular compression syndrome has not been described previously in the pediatric or pediatric surgical literature. However, it is mentioned in the literature of vascular and general surgery and in journals of radiology and orthopedics. In this review, the intraoperative pathological anatomy and the principles of treatment for 8 children will be presented.

Methods

The chart records and the anatomical sketches that were documented by the surgeon immediately after each procedure were analyzed retrospectively. In addition, preoperative courses and long-term follow-up (range, 3-18 years) were evaluated by a defined program.

Results

The diagnosis of celiac artery compression by an arcuate ligament was suspected in children presenting with a history of several years of recurrent acute abdominal pain associated with a typical arterial bruit in the midline of the epigastric region.

Conclusions

Other diseases with recurrent abdominal pain and an arterial bruit must be excluded before making the decision for an operative intervention. Duplex ultrasound and angiography are possibly helpful tools to establish the respective diagnosis, but in the patients of the present series, these techniques neither confirmed compression of the celiac axis nor demonstrated decreased perfusion of the superior mesenteric artery. However, as the clinical symptoms clearly announce the disease, these diagnostic measures are not mandatory.