Guidance of acetylcholinesterase-containing fibres by target tissue in co-cultured brain slices

Slices of various brain regions were prepared from newborn and from 7-day old rats and co-cultured in different combinations. In the majority of co-cultures of septal and hippocampal slices, acetylcholinesterase-positive fibres originating in the septal nuclei invaded the adjacent hippocampal slice. A similar pattern of hippocampal ingrowth by acetylcholinesterase-positive fibres occurred with slices prepared from the nucleus basalis of Meynert and from spinal cord. Septal neurones also projected to cortical slices, an effect which even occurred in the presence of their natural target tissue. In contrast to these massive projections to brain areas which in situ receive cholinergic inputs, no significant acetylcholinesterase-positive fibre ingrowth was observed in tissues which lack major cholinergic afferents in situ (hypothalamus, substantia nigra and cerebellum). These results indicate that under our culture conditions, acetylcholinesterase-positive fibres selectively invade cholinergic target areas. This effect is independent of the brain area from which the cholinergic neurones were derived.     

黄雀延髓层状核的传出纤维联系──HRP法研究

向４２只黄雀的延髓展状核加压注入或微电泳泳入ＨＲＰ后，在同侧的脑桥上橄榄核、对侧的脑桥外侧丘系腹核及中脑外侧核背侧部内见到密集的顺行标记终末或纤维；在双侧的延髓巨细胞核出现了大量的逆行标记细胞；在对侧的层状核内既有密集的标记终末又有一些标记细胞．结果表明：层状核的传出纤维投射到同侧上橄榄核，经外侧丘系走行至对侧的外侧丘系腹核和中脑外侧核背侧部，双侧的层状核之间也有交互投射。此外，层状核接受耳蜗亚核──双侧巨细胞核的传入投射．因此，层状核是听觉上行通路中的第二级中继站．     

Excitation of neuronal function in rabbit caudal ventrolateral medulla elevates plasma vasopressin

Injection of L-glutamate into the caudal ventrolateral medulla of the rabbit caused a dose-dependent increase in plasma vasopressin. Activity of the A1 noradrenergic cells within the caudal ventrolateral medulla appears to excite the vasopressin-secreting neuroendocrine cells within the hypothalamus.     

Medullary control of the pontine swallowing neurones in sheep

Summary The origin of the inputs from the medullary swallowing centre (dorsal region including the nucleus of the solitary tract, or ventral region corresponding to the reticular formation surrounding the nucleus ambigous) to the pontine swallowing neurones (PSNs) was studied in sheep anaesthetized with halothane.Out of 101 PSNs located in the posterior part of the trigeminal (Vth) motor nucleus, 46 were activated by stimulating either the dorsal (21 neurones) or the ventral (25 neurones) region of the ipsilateral medullary swallowing centre, 3–4 mm rostral from the obex. Thirty-one neurones out of the 46 were identified as a motoneurones supplying swallowing muscles (mylohyoïd, anterior body of digastric and medial pterygoïd). Their average activation latency through stimulation of the dorsal medullary region was about 1 ms longer than through stimulation of the ventral region (3.63 ms±0.81 versus 2.72 ms±0.32).To determine the origin of the medullary input to the PSNs, we tried to activate the medullary swallowing neurones (MSNs) antidromically through stimulating the posterior part of the Vth motor nucleus, which contains the swallowing motoneurones. Seventy-three MSNs were tested (25 located in the dorsal and 48 in the ventral region). None of the dorsal neurones tested could be antidromically activated by pontine stimulation: 15 ventral neurones showed a clear antidromic response (collision test) with an average latency of 2.5 ms±0.73. These neurones, which send their axons into the pons, were all located in the reticular formation, above the nucleus ambiguus, 3–4 mm rostral from the obex.These results suggest that MSNs in the ventral reticular formation connect the medullary swallowing centre to the Vth motor nucleus. They also suggest that during swallowing, inputs originating from the dorsal region of the medullary centre (interneurones programming the motor sequence) are relayed in the ventral region (reticular formation adjacent to the nucleus ambiguus) before reaching the PSNs.This work was supported, in part, by grants from CNRS (LA 205), INRA and M.R.I. (82 E 0685)     

Distribution of the largest neuron in mouse caudate-putamen nucleus: Its position in large-cell — Medium-cell clusters

Summary The position of the largest striatal neuron within territories delimited by medium-sized clustered neurons was charted in Nissl-stained sections through the mouse caudate-putamen nucleus. Medium-sized neuron somata occur in close proximity to this large cell at some point in the anteroposterior, mediolateral or dorsoventral extent of its soma. The size of the network of medium-sized neurons associated with the large cell may vary from two to 15 neurons. Even when this network is extensive, the large neuron is never completely surrounded. Most often, this cell also borders a fascicle of internal capsule fibers, and the entire cellular island may be aligned either parallel to or perpendicular to the orientation of these fibers. These findings suggest the hypothesis that cellular territories in the caudate-putamen nucleus have a very specific orientation in three dimensional space.     

The nuclei of origin of brain stem enkephalin and substance P projections to the rodent nucleus raphe magnus

The sites of origin of brain stem enkephalin and substance P projections to the rodent nucleus raphe magnus were studied utilizing the combined horseradish peroxidase retrograde transport-peroxidase-antiperoxidase immunohistochemical technique. Several brain stem areas were found to contain both enkephalin- and substance P-like immunoreactive double labeled neurons following injection of horseradish peroxidase into the raphe magnus. Nuclei providing both enkephalin and substance P inputs to the raphe magnus include the nucleus reticularis paragigantocellularis, the nucleus cuneiformis, the nucleus solitarius and the trigeminal subdivision of the lateral reticular nucleus. Enkephalin projections to the raphe magnus were also found to originate from the dorsal parabrachial nucleus, the nucleus reticularis gigantocellularis pars α and from an area which corresponds to the A5 group of Dahlström &; Fuxe. Additional neurons containing substance P-like immunoreactivity and horseradish peroxidase reaction product were identified in the superior central raphe nucleus and the nucleus pontis oralis. The midbrain periaqueductal gray contributes very few enkephalin and substance P fibers to the raphe magnus.The nucleus raphe magnus is a key structure in the intrinsic analgesia system and it has also been implicated in other diverse and non-nonciceptive functions. The present study identifies several brain stem sites which provide enkephalin and substance P input to this raphe nucleus. Several of these nuclei have been implicated in central analgesic mechanisms or in non-nociceptive autonomic functions. The present investigation raises the possibility that these brain stem regions may modulate neuronal activity in the raphe magnus via enkephalin or substance P projections and thus influence the involvement of the raphe magnus in both opiate related mechanisms of pain control and non-nociceptive functions.     

Synaptic responses of neurons in the parietal associative cortex of the cat to stimulation of the red nucleus

Acute experiments on anesthetized and immobilized cats using intracellular recording were used to study the responses of neurons in the parietal associative cortex to stimulation of the red nucleus. Efferent neurons of the parietal cortex were identified by antidromal activation on stimulation of the intrinsic nuclei of the pons and motor cortex. Oligo- and polysynaptic EPSP in response to stimulation of the red nucleus were seen. The results are discussed in the light of the morphological organization of the rubrothalamic and cerebellothalamocortical tracts. Laboratory for Central Nervous System Physiology (Director V. V. Fanardzhyan), L. A. Orbel' Institute of Physiology, Armenian National Academy of Sciences, Erevan. Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 81, No. 12, pp. 64–69, December, 1995.     

5-羟色胺免疫阳性纤维和终末在大鼠舌下神经伸、缩舌肌运动神经元的分布

5-羟色胺（5－HT）参与舌和面口部精细运动的调节。5－HT对舌下神经运动神经元功能的调控表现为兴奋性作用。本文首先采用免疫组化方法，在光镜下观察了大鼠舌下神经核内5－HT免疫阳性纤维的形态和分布特征。又进一步采用荧光逆行追踪结合固定脑片细胞内LuciferYellow染色和荧光免疫组织化学染色，通过共聚焦激光扫描显微镜观察了伸舌肌（颏舌肌、颏舌骨肌）和缩舌肌（茎突舌肌）运动神经元与5－HT免疫阳性纤维及其终末的解剖学关系。结果证明：舌下神经核有较丰富的5－HT阳性纤维，以尾侧段的背侧部和吻侧段的腹侧部较为密集；根据纤维及其膨体的形态特征，本文将此阳性纤维分为三种类型。5－HT免疫阳性膨体样纤维及其终末与舌下运动神经元的胞体、树突分枝和轴丘及轴突起始段形成紧密接触；这些接触多呈不均匀的簇状（由2～7个紧密接触点组成）分布。定量分析发现：在额舌肌神经元和茎突舌肌神经元，除少量分布在胞体（密度为3．4～6．7／1000μm2）外，主要分布在近段和中段树突分权处附近；但是在颏舌骨肌神经元则集中分布在跑体（密度为10．8～17．6／1000μm2）和近侧树突上。以上所见提示：5－HT对舌下神经核整体行为的调节在不同功能的亚核可能有所选择；5－HT调制舌下运动神经元兴奋性的方式可     

Cerebral ischemia induces transient intracellular redistribution and intranuclear translocation of the raf proto-oncogene product in hippocampal pyramidal cells

Summary In this report we describe changes in the intracellular redistribution of raf serine/threonine protein kinase (product of the raf proto-oncogene family) in hippocampal neurons following cerebral ischemia in Mongolian gerbils. For immunohistochemical localization studies polyclonal antisera specific for each of the A, B, and Raf-1 isotypes of raf, as well as a pan-raf antisera, were employed. Of these, only sera recognizing B-raf, as well as the general v-raf (raised against the conserved C-terminal region) were positive, indicating that B-raf is the major isotype in this neuronal region. Three different ischemie models were used (repeated 3 times for two min and single 5 or 15 min occlusions, of the common carotid arteries) to demonstrate that ischemie insult causes redistribution of raf protein kinase into the cell nucleus of hippocampal neurons. Increased amounts of raf protein in the nuclei of pyramidal cells following ischemia was confirmed by Western blot analysis of isolated nuclear fractionations. Moreover, an elevation in the level of nuclear raf protein also was detected in the contralateral (i.e. non-occluded hemisphere) neurons of CA1 and CA3 subfields 4 days after the ischemie insult indicating a possible transsynaptic increase in the amount of raf protein along with redistribution. The intranuclear translocation of the immunoreactive material started from the perinucleolar rim and with time extended throughout the nucleus. Enhanced levels and altered redistribution of the raf polypeptide in the nuclei of pyramidal cells of the CA3 subfleld appears to be reversible and returns to the normal level 12 days following the ischemic insult. In addition to triggering the above changes in the intracellular redistribution of raf, ischemie insult also caused an increase in the level of B-raf protein in reactive astrocytes.