摘要:

AbstractA double‐label strategy was used to determine the distribution and central projections of primary afferent neurons that innervate the periodontium and muscles of mastication in cats. Central injections of either Fast Blue (FB) or a mixture of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) and HRP were made into one of three cytoarchitectonically distinct regions of the spinal trigeminal nucleus. These regions included the subnucleus oralis (Vo), the subnucleus interpolaris (Vi), and the medullary dorsal horn (MDH). In each case, injections were also made into the periodontium of the ipsilateral mandibular teeth or into the ipsilateral masseter muscle. FB injections preceded the peroxidase injections by at least 48 hours and total survival time ranged from 72 to 96 hours. Animals were perfused with phosphate‐buffered paraformaldehyde (4%; pH 7.2). Serial frozen sections were made through the brainstem and trigeminal ganglion. Tetramethylbenzidine was used as a chromagen to demonstrate HRP and sections were viewed with brightfield and epifluorescent illumination. Cells containing peripherally injected tracer were observed in the lateral portion of the ganglion and in the mesencephalic nucleus (Vmes). Double‐labeled ganglion cells were observed in most cats that received periodontal injections in combination with central injections in the dorsal part of spinal trigeminal nucleus regardless of the rostrocaudal level of the central injection. In the animals that received intramuscular injections, double‐labeled ganglion cells were observed only in the animals that received central injections caudal to the Vo. Double‐labeled Vmes perikarya were observed in cats that received either intramuscular or periodontal injections in combination with central injections into the MDH and Vo but not in animals that received injections into the Vi. These results demonstrate that ganglion cell periodontal afferents project to the three major rostrocaudal subdivisions of the spinal trigeminal nucleus while ganglion cell muscle afferents have more limited central projections to caudal regions of the nucleus. Masseter and periodontal Vmes afferents also project to the spinal trigeminal nucleus‐specifically, to the Vo and MDH. These findings are consistent with physiological observations regarding the role of periodontal and masseteric afferents in oral and facial reflexes and someth

ISSN:0092-7317    

DOI:10.1002/cne.902790302

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe globus pallidus of 20 monkeys ranging in age from newborn to 4 months was examined in Golgi‐impregnated material and ultrastructurally. There was no discernible difference between the lateral and medial segments of the structure. At the light microscope level, all neuronal types described in the adult are found at birth. The most common, the large fusifom cell, shows initial signs of immaturity such as blunt protrusions and dendritic dilations at bifurcation points, as well as growth cones, filopodia, and filiform processes. These features become more rare with age, and by 4 months, the neurons appear fully mature save for the terminal dendritic arborizations which are still underdeveloped. From the earliest ages examined, the large globular cells and the interneurons are more mature than the previous type. The afferent radial fibers of striatal origin are observed from birth, but they are grouped in bundles only after 8 weeks. The density of their climbing branches increases over time, reaching a mature appearance by 16 weeks. Afferents entering from the ventral surface do not yet show clusters of varicosities at 2 weeks. At the latter age, plexuses of fine beaded fibers are already seen covering large extensions of the nucleus.The fine structure correlates well with the Golgi material. The basic features of the neuropil are present at birth, albeit with immature characteristics such as the incomplete covering of the dendrites with axonal boutons and the low level of myelination of the radial fibers. Growth cones and profiles with signs of degeneration are observed during the first month. In the early ages examined, most dendrites show large varicosities and protrusions, some of which are spinelike and can be postsynaptic to multiple terminals. The other dendritic type, with only an occasional axodendritic synapse, is also seen from birth and increases in size as a function of time. The type I axonal boutons, of probable striatal origin, are quite immature at birth, and their characteristic interdigitations are seen only after the first week. The type II, III, IV, and V boutons appear mature at all ages examined but crest synapses formed by the type III terminals are observed in the later stages of the study. Finally, postsynaptic vesicle‐containing profiles are present at 4 weeks, but triadic synaptic arrangements are formed only by 16 weeks.Results indicate the occurrence of progressive changes in neuronal and neuropil morphology of both segments of the primate globus pallidus in the first 4 postnatal months and suggest that this structure matures earlier than the neostriatum, probably as a reflection of its diencephalic ori

ISSN:0092-7317    

DOI:10.1002/cne.902790303

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have shown previously that rubral axons can grow caudal to a lesion of their pathway at thoracic levels of the spinal cord in the developing opossum,Didelphis virginiana.In the present report we expand on that observation and present evidence which suggests that the critical period for plasticity of the rubrospinal tract ends earlier at cervical than at thoracic levels. In addition, we show that most rubrospinal neurons die as a result of axotomy during early stages of the critical period. The opossum was chosen for study because the development of its rubrospinal tract occurs after birth.In one set of experiments the area containing the rubrospinal tract was lesioned at cervical or thoracic levels and after 30 days or more, retrograde transport techniques were used to determine if rubral axons had grown caudal to the lesion. When the lesions were made at rostral cervical levels between estimated postnatal day 26 and maturity, neurons could not be labeled in the contralateral red nucleus by injections of retrograde markers ipsilateral to the lesion and caudal to it. We were not able to obtain adequate survival after cervical lesions made prior to estimated postnatal day 26. When the lesions were made at mid to caudal thoracic levels between estimated postnatal days 19 and 26, neurons could be labeled in the contralateral red nucleus. When comparable lesions were made at estimated postnatal day 40, there was usually a decrease in the number of labeled neurons, and when they were made at estimated postnatal day 54, none was labeled. In selected cases, operated at estimated postnatal day 19, cell counts provided evidence for loss of neurons in the red nucleus contralateral to the lesion.In orthograde transport experiments performed on animals with thoracic lesions of the rubrospinal tract made between estimated postnatal days 18 and 33, rubral axons could be labeled caudal to the lesion, and they seemed to take the most direct route around it. Although they sometimes assumed abnormal positions caudal to the lesion, rubral axons appeared to reach areas of the gray matter appropriate to them. When lesions were made at estimated postnatal day 54 or in older animals, labeled axons could be traced to the lesion site but not caudal to it.In still other experiments rubrospinal neurons were labeled by caudal thoracic or rostral lumbar injections of Fast Blue at estimated postnatal day 26 and 3–4 days later the injected animals were subjected to a lesion of the rubrospinal tract three segments rostral to the injection and ipsilateral to it. They were killed 30–34 days after the lesion so that the red nucleus contralateral to it could be examined for labeled neurons. The results showed that only a few rubrospinal neurons survived axotomy, suggesting that the growth of new axons around the lesion is a major factor in plastic

ISSN:0092-7317    

DOI:10.1002/cne.902790304

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractNeurons in the lateral superior olive are optimally excited by stimulation of the ipsilateral ear, as are those in the inferior colliculus by stimulation of the contralateral ear. This reversal of ear dominance may result, in part, from distinct crossed excitatory and uncrossed inhibitory pathways ascending from the lateral superior olive. To explore this possibility, immunoreactivity for two putative inhibitory neurotransmitters, glycine and GABA, was examined in projection neurons that retrogradely transported horseradish peroxidase from the cat inferior colliculus.The results suggest that the projection from the lateral superior olive can be segregated, immunocytochemically, into three components: (1) a crossed, glycine‐negative (−) projection; (2) an uncrossed, glycine‐positive (+) projection; and (3) an uncrossed, glycine(−) projection. Additional evidence suggests that the terminal fields of the two uncrossed projections may distribute differently within the inferior colliculus. Glycine(+) or glycine(−) projection neurons, crossed or uncrossed, do not differ in the size, shape, or location of their somata. However, most glycine(−) neurons are heavily encrusted with glycine(+) endings; glycine(+) neurons have 40–60% fewer of these endings. Glycine(−) neurons located in the lateral limb have fewer glycine(+) perisomatic endings than those in the medial limb. Few projection neurons are GABA(+), and GABA(+) perisomatic endings are rare in the lateral superior olive.Thus, there is a heavy uncrossed projection from the cat lateral superior olive to the inferior colliculus that may be glycinergic and inhibitory. Furthermore, there is a bilateral projection that is not glycinergic or GABAergic, which may be excitatory. The potential contribution of these pathways to contralateral ear dominance in the inferior collicul

ISSN:0092-7317    

DOI:10.1002/cne.902790305

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe coexistence of cholecystokinin‐ and tyrosine hydroxylase‐like immunoreactivities within neurons of the rat ventral mesencephalon was analyzed by using an indirect immunofluorescence technique for the simultaneous demonstration of two antigens in the same tissue section. A high degree of colocalization was observed in the substantia nigra pars compacta, in which 80–90% of all labeled neurons at rostral and up to 70% at intermediate levels contained both cholecystokinin and tyrosine hydroxylase. At caudal levels, the incidence of colocalization declined to approximately 30–50%. All of the immunoreactive perikarya in the substantia nigra pars lateralis were labeled with both substances. Other areas of the ventral midbrain that exhibited a moderate proportion of neurons immunoreactive for both cholecystokinin and tyrosine hydroxylase included the ventral tegmental area, interfascicular nucleus, and rostral and caudal linear nuclei. In addition, coexistence was occasionally observed within neurons of the central and ventral periaqueductal gray matter, supramammillary region, peripeduncular region, retrorubral field, and, extremely rarely, within the substantia nigra pars reticulata. Cell bodies containing tyrosine hydroxylase‐like immunoreactivity (indicative of dopamine) usually outnumbered those containing the peptide except in the supramammillary region and in the ventral periaqueductal gray matter, where the cholecystokinin perikarya were present in higher numbers.The double‐labeling colocalization technique was combined with fluorescence retrograde tracing to determine some of the forebrain projections of these neurons. Ventral midbrain neurons containing both cholecystokinin and tyrosine hydroxylase were found to project to the caudate‐putamen, nucleus accumbens, prefrontal cortex, and amygdala. These projections originated from neurons located predominantly in the substantia nigra pars compacta and the ventral tegmental area. Thus, cholecystokinin occurs within the well‐known dopaminergic nigrostriatal pathway in the rat. Overall, these results demonstrate that a significant proportion of the dopamine neurons giving rise to the ascending mesotelencephalic projections also contain the peptide

ISSN:0092-7317    

DOI:10.1002/cne.902790306

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe purpose of the present study was to analyze the distribution of cholecystokininlike‐immunoreactive (CCK‐I) neurons within the rat ventral mesencephalon which project to several forebrain areas. The peroxidase‐antiperoxidase immunocytochemical technique was used to examine the anatomical localization of CCK‐I within the ventral midbrain and in the following forebrain regions: caudate‐putamen, nucleus accumbens, olfactory tubercle, bed nucleus of the stria terminalis, septum, amygdala, and prefrontal, anterior cingulate, and piriform cortices. CCK‐I perikarya were distributed throughout the substantia nigra, ventral tegmental area, and several midline raphe nuclei to a greater extent than previously reported, particularly in the substantia nigra pars compacta. Terminallike immunoreactivity for CCK was observed in all of the above forebrain sites. In addition, infrequent CCK‐I cell bodies were localized in the caudate‐putamen, nucleus accumbens, olfactory tubercle, septum, and bed nucleus of the stria terminalis.To analyze forebrain projections of the ventral midbrain CCK‐I neurons, indirect immunofluorescence was combined with fluorescence retrograde tracing. CCK‐I neurons of the substantia nigra and/or ventral tegmental area were found to project, to varying extents, to all of the above CCK‐I forebrain terminal fields. The nucleus accumbens, olfactory tubercle, and septal and prefrontal cortical projections arose primarily from CCK‐I perikarya in the ventral tegmental area whereas the projections to the caudateputamen and anterior cingulate cortex arose predominantly from immunoreactive neurons in the substantia nigra pars compacta. The amygdala received innervation mainly from CCK‐I cell bodies located in the substantia nigra pars lateralis. CCK‐I afferents to the bed nucleus of the stria terminalis and piriform cortex originated from perikarya distributed approximately equally across the ventral tegmental area and substantia nigra pars compacta. The general topography of CCK‐I forebrain innervation observed in this study is similar to that previously reported for the ascending dopaminergic projections from ventral mesencephalic neurons. CCK‐I neurons of the midline raphe nuclei were found to provide relatively minor afferents to the caudate‐putamen, bed nucleus of the stria terminalis, septum, and prefrontal cortex and more substantial projections to the amygdala.The results of this study demonstrate that CCK‐I neurons of the ventral midbrain supply a much broader innervation of forebrain regions than previously appreciated. Moreover, these data suggest that ventral mesencephalic CCK projections encompass the full range of the well‐known dopaminergic masolimbic. mesostriatal, and mesocortial projections. Thus, CCK may play a significant role in th

ISSN:0092-7317    

DOI:10.1002/cne.902790307

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have investigated developmental alterations in the tonotopic projection of the gerbil lateral superior olive. Single neurons were characterized in the frequency domain and the recording site marked with fast green. Transverse tissue sections from the auditory brainstem of each animal were visualized with a video‐equipped microscope, and the image was digitized for subsequent alignment. The three‐dimensional display indicated little variation in the rostrocaudal axis, allowing us to collapse the data into a two‐dimensional tonotopic map. The tonotopic map was found to change with age such that the characterstic frequency of neurons in a given anatomical location became successively higher during development. These results are consistent with the hypothesis that the place code gradually shifts in the developing co

ISSN:0092-7317    

DOI:10.1002/cne.902790308

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe regional distribution of the three opioid peptide neuronal systems‐proopiomelanocortin (POMC), proenkephalin A, and proenkephalin B‐was investigated in the lower brainstem of Japanese monkeys (Macaca fuscata) by immunocytochemical techniques. Antiserum to β‐endorphin/β‐lipotropin, [Met]‐enkephalin‐Arg6‐Gly7‐Leu8, and human leumorphin were used to identify the POMC and the proenkephalin A and B systems, respectively. POMC‐related immunoreactive material was not found in the neuronal perikarya in the lower brainstem; reactive fibers and apparent terminals were distributed in the substantia nigra, lemniscus lateralis, midbrain central gray, the nucleus raphes, nucleus parabrachialis lateralis, ventral area of the spinal trigeminal nerve, nucleus tractus solitarii, and in the reticular formation throughout the lower brainstem. Proenkephalin A‐related immunoreactive neuronal perikarya were detected in the central gray, reticular formation, nucleus raphes, trapezoid body, nucleus parabrachialis lateralis and medialis, nucleus spinalis nervi trigemini, nucleus dorsalis nervi vagi, and in the nucleus tractus solitarii. Densely packed immunoreactive fibers were widely distributed in the substantia nigra, nucleus interpeduncularis, nucleus raphes, superior colliculus, periaqueductal central gray, nucleus parabrachialis lateralis and medialis, locus coeruleus, trapezoid body, nuclei cochleares, nucleus spinalis nervi trigemini, tractus spinalis nervi trigemini, nucleus tractus solitarii, nucleus dorsalis nervi vagi, nucleus gracilis, nucleus cuneatus, nucleus cuneatus accessorius, and in the reticular formation throughout the lower brainstem. Neuronal perikarya containing immunoreactive material related to proenkephalin B were found in the periaqueductal central gray, nucleus parabrachialis lateralis and medialis, nucleus tractus solitarii, and nucleus spinalis nervi trigemini. In addition, immunoreactive fibers were detected in the ventral tegmental area, substantia nigra, nucleus parabrachialis lateralis and medialis, nucleus vestibularis lateralis and medialis, and in some areas of the reticular formation. These anatomical findings demonstrate that these three opioid peptide neuronal systems are widely but uniquely distributed in the lower br

ISSN:0092-7317    

DOI:10.1002/cne.902790309

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe topography of the projections from the reticular nucleus of the thalamus (RT) to the intralaminar and medial thalamic nuclei were studied in the cat by the method of retrograde transport of horseradish peroxidase (HRP). Single small injections of the enzyme were made in the different intralaminar nuclei‐mediodorsal, ventromedial, midline, and habenular‐and in anterior group nuclei. The location and density of the neuronal labeling in the different parts of the RT were studied in each case.Our results show that 1) after injections located in all the nuclei here studied, a consistent number of labeled neurons were found in the RT, except for the injections in the lateral habenula and the anterior thalamic nuclear complex, both of which did not label neurons in the RT. 2) Among the other thalamic nuclei here studied, the most medially situated receive less numerous RT projections than those most laterally located. 3) Injections in all the nuclei studied gave rise to a cellular labeling in the anterior sectors of the RT, except for the anterior nuclear group and the lateral habenula. The projections from the rostral pole of the RT were topographically mediolaterally organized. 4) The anterodorsal part of the pregeniculate sector of the RT projects upon the large‐called part of the lateral central nucleus and to a lesser extent upon the paracentral, centromedian, and ventromedial nuclei, the anterior part of the lateral central nucleus, and the lateral band of the mediodorsal nucleus. The posterodorsal part of the RT pregeniculate sector only projects to the large‐celled part of the lateral central nucleus. The dorsal portion of the posteroventral part of the RT pregeniculate sector also projects upon the large‐celled part of the lateral central nucleus; its ventral portion projects to the ventromedial nucleus, the posterior part of the paracentral nucleus, the lateral band of the mediodorsal nucleus, and the centromedian nucleus. 5) The infrageniculate sector of the RT projects to the posterior part of the ventromedial nucleus. A weaker projection to the large‐celled part of the lateral central nucleus, the centromedian nucleus, and the lateral band of the mediodorsal nucleus was also observed. 6) The ventral lateral geniculate nucleus projects upon the large‐celled part of the lateral central nucleus, the lateral band of the mediodorsal nucleus, and the ventromedial nucleus.All these findings suggest an important modulatory action of the RT on the activity of the thalamic nuclei co

ISSN:0092-7317    

DOI:10.1002/cne.902790310

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe aim of this study was to describe the localization of cholinergic and GABAergic neurons and terminals in the amygdaloid nuclei of the rat. Double immunolabeling was performed to study cholinergic‐GABAergic synaptic interconnections.Cholinergic elements were labeled by using a monoclonal antibody to choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme. Antibodies against glutamate decarboxylase (GAD), the GABA‐ synthesizing enzyme, were employed to identify GABAergic perikarya and terminals. The tissue sites of the antibody bindings were detected by using either Sternberger's peroxidase‐antiperoxidase (PAP) method or a biotinylated secondary antibody and avidinated ferritin. These two contrasting immunolabels allowed us to study GABAergic‐cholinergic interconnections at the electron microscopic level.Our study revealed a characteristic distribution of GABAergic and cholinergic elements in the various amygdaloid nuclei: 1) Large, ChATimmunopositive cells with heavily labeled dendrites were observed in the anterior amygdaloid area and in the lateral and medial zones of the central nucleus. These cells seem to constitute the intraamygdaloid extension of the magnocellular basal nucleus. Their dendrites invaded other amygdaloid nuclei, in particular the intercalated nuclei, the lateral olfactory tract nucleus, and the central zone of the central nucleus. These ChAT‐immunoreactive dendrites formed synaptic contacts with GAD‐positive terminals. GABAergic terminals probably thus exert an inhibitory amygdaloid influence onto cholinergic neurons of the magnocellular basal nucleus. 2) Two amygdaloid nuclei‐the basal dorsal nucleus and the lateral olfactory tract nucleus‐contained a dense network of ChAT‐immunoreactive fibers and terminals, but they also contained numerous GAD‐positive perikarya. Double‐immunolabeling experiments revealed cholinergic terminals forming synaptic contacts on GAD‐immunopositive cell bodies, dendritic shafts, and spines. 3) The central and medial nucleus seem to be the main target of GABAergic fibers to the amygdala. Both nuclei contained a dense plexus of GAD‐immunoreactive terminals that may arise, at least in part, from the GABAergic neurons in the basal dorsal nucleus. Inhibition of the centromedial “excitatory” region through intraamygdaloid GABAergic connections may reduce excitatory amygdaloid influence on

ISSN:0092-7317    

DOI:10.1002/cne.902790311

出版商:Alan R. Liss, Inc.    

年代:1989

数据来源: WILEY