摘要:

AbstractA number of different neuroactive substances have been found in striatal projection neurons and in fibers and terminals in their target areas, including substance P (SP), enkephalin (ENK), and dynorphin (DYN). In a preliminary report on birds and reptiles, we have suggested that SP and DYN are to a large extent found in the same striatal projection neurons and that ENK is found in a separate population of striatal projection neurons. In the present study, we have examined this issue in more detail in pigeons and turtles. Further, we have also explored this issue in rats to determine whether this is a phylogenetically conserved feature of basal ganglia organization.Simultaneous immunofluorescence double‐labeling procedures were employed to explore the colocalization of SP and DYN, SP and ENK, and ENK and DYN in striatal neurons and in striatal, nigral, and pallidal fibers in pigeons, turtles, and rats. To guard against possible cross‐reactivity of DYN and ENK antisera with each others' antigens, separate double‐label studies were carried out with several different antisera that were specific for DYN peptides (e.g., dynorphin A 1–17, dynorphin B, leumorphin) or ENK peptides (leucine‐enkephalin, metenkephalin‐arg6‐gly7‐leu8, methionine‐enkephalin‐arg6‐phe7). The results showed that SP and DYN co‐occur extensively in specific populations of striatal projection neurons, whereas ENK typically is present in different populations of striatal projection neurons. In pigeons, 95‐99% of all striatal neurons containing DYN were found to contain SP and vice versa. In contrast, only 1‐3% of the SP+ striatal neurons and no DYN neurons contained ENK. Similarly, in turtles, greater than 75% of the SP+ neurons were DYN+ and vice versa, whereas ENK was observed in fewer than 5% of the SP+ neurons and 2% of the DYN+ neurons. Finally, in rats, more than 70% of the SP+ neurons contained DYN and vice versa, but ENK was found in only 5% of the SP+ neurons and in none of the DYN+ perikarya. Fiber double‐labeling in the striatum and its target areas (the pallidum and substantia nigra) was also consonant with these observations in pigeons, turtles, and rats.These results, in conjunction with studies in cats by M.‐J. Besson, A. M. Graybiel, and B. Quinn (1986;Soc Neurosci. Abs. 12:876) strongly indicate that the co‐occurrence of SP and DYN in large numbers of striatonigral and striatopallidal projection neurons is a phylogenetically widespread, and therefore evolutionarily conserved, feature of basal ganglia organization. These populations of SP/DYN‐containing projection neurons appear to be distinct from those containing ENK. The evolutionarily conserved nature of such widespread SP/DYN co‐occurrence in striatal neurons that contain either of these peptides suggests that such co‐occurrence is an important functional characteristic of the basal ganglia. The precise significance of such co‐occurrence in terms of neurotransmission between these neurons and striatal target

ISSN:0092-7317    

DOI:10.1002/cne.902950302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe specific aim of this study was to search for morphological counterparts to the known antinociceptive effects of cholinomimetic drugs at the spinal cord level. For this, the light microscopic and ultrastructural distribution of choline acetyltransferase immunoreactivity was studied in laminae I‐III of the rat cervical spinal cord. Immunoreactivity was present in cell bodies in lamina III, and in dendrites and axons of all three laminae. Immunoreactive axonal varicosities were often presynaptic to the central varicosities of type II synaptic glomeruli in lamina II and lamina III, less often presynaptic to the central elements of type I glomeruli in lamina II, and often presynaptic to dendrites in both type I and type II glomeruli. In addition, immunoreactive dendrites were often postsynaptic to the central varicosities of glomeruli of all morphological types. These results indicate that (1) primary sensory fibers excite cholinergic interneurons; (2) the acetylcholine released by the axon terminals of these interneurons modulates both nociceptive and non‐nociceptive sensory information at the spinal cord level through both pre‐ and postsynaptic mechanisms. Furthermore, our results reinforce current ideas on reciprocal sensory interaction between thick and fine afferent f

ISSN:0092-7317    

DOI:10.1002/cne.902950303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe fibre organization of the monkey's optic tract was examined by implanting pellets of horseradish peroxidase into different locations within the tract, or into the superior colliculus and pretectum. Retinae were examined for the distribution, size, and morphological types of retrogradely labelled ganglion cells; optic tracts were examined for the distribution of anterogradely and retrogradely labelled axonal profiles; and lateral geniculate nuclei were examined for the distribution of anterogradely labelled processes within distinct geniculate laminae.Localized implants in the optic tract produced retrograde labelling of ganglion cells across wide regions of the retinal surface. The maximum density of labelled cells was always substantially less than the total ganglion cell density known to be present at those retinal loci. Distinct retinal ganglion cell types were labelled from differing regions within the optic tract: implants into the deep (dorsal) portion of the tract, far removed from the outer, pial, surface, retrogradely labelled predominantly Pβ retinal ganglion cells, whereas implants into the superficial (ventral), subpial, part of the tract retrogradely labelled primarily the other retinal ganglion cell types, i.e., the Pα, Pγ, and Pϵ cells.Withinany given class of axon, there is a mapping of the centroperipheral retinal axis across the deep‐to‐superficial dimension of the tract, but this retinotopy is extremely coarse. Anterograde labelling of axonal terminations within the lateral geniculate nucleus showed a corresponding specificity for distinct geniculate laminae, the deep implants labelling the parvocellular laminae, superficial implants labelling the magnocellular laminae. Implants into the visual centres of the midbrain produced retrograde axonal labelling rostral to the lateral geniculate nucleus only in the superficial part of the optic tract.These results demonstrate that the monkey's optic tract is not a simple topographic mapping of retinal eccenticity. Rather, the primary organizational principle is that of a segregation of functionally distinct optic axon classes. As fibre order in the mammalian optic tract is also a chronological index of axonal arrival during development, the present results provide specific predictions about the temporal order of ganglion call genesis and axonal addition within the visual pathway. They also provide an anatomical basis for the functionally selective visual impairments that may arise following local damage to the optic tract in

ISSN:0092-7317    

DOI:10.1002/cne.902950304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe representations of the two half‐retinae were examined in the monkey's optic tract. Intravitreal injections of tritiated amino acids were made to reveal the distributions of the crossed and uncrossed populations of optic axons, while localized implants of horseradish peroxidase (HRP) were made into different regions of the optic tract in order to examine the distributions and morphological types of retrogradely labelled cells at corresponding loci in the two half‐retinae.Crossed and uncrossed optic axons are intermingled throughout most of the optic tract, but uncrossed axons are very sparse or absent along both the deep and superficial extremes of the tract. Implants of HRP into the deeper regions of the tract demonstrate that the crossed and uncrossed optic axons of the Pβ retinal ganglion cells are slightly out of binocular registration, with the uncrossed map being shifted to a slightly superficial location relative to the crossed map. The optic axons for the remaining cell classes, revealed by implants of HRP into the superficial portion of the tract, are much more conspicuously out of binocular registration (in particular, the Pβ optic axons); but in their cases, the uncrossed optic axons are shifted to deeper locations relative to the crossed optic axons. Further evidence that these optic axon classes are markedly out of binocular registration comes from the two optic tracts of a bilaterally destriated monkey, in which most of the Pβ optic axons have undergone a transneuronal retrograde degeneration. Following a uni‐ocular injection of tritiated amino acids, the distributions of the remaining crossed and uncrossed axonal labelling occupied different positions within the tract rather than being intermingled, with the uncrossed optic axons situated deep to the majority of crossed optic axons.These results demonstrate that the optic chiasm does not combine binocularly corresponding optic axons of similar type. They also demonstrate that noncongruent field defects should be a common consequence of damage to the optic tract in humans.If the fibre order in the mammalian optic tract arises as a consequence of the sequence of axonal addition during development, then differences in the relative times of genesis for nasal and temporal members of any cell class, and/or differences in the relative pathlengths between the eye and two optic tracts, may produce the fibre ordering describe

ISSN:0092-7317    

DOI:10.1002/cne.902950305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractTo determine how saccade‐related areas in the brainstem address the saccade generator, we examined the afferents to the nucleus raphe interpositus. This region contains the omnipause neurons, which are pivotal in the generation of saccades. Horseradish peroxidase injected iontophoretically into the nucleus raphe interpositus retrogradely labeled a variety of brainstem nuclei. The greatest numbers of labeled neurons were in the paramedian pontomedullary reticular formation, in the nuclei reticularis gigantocellularis, and paragigantocellularis lateralis. Labeling was more modest but consistent in the interstitial nucleus of Cajal and the adjacent mesencephalic reticular formation, the middle gray of the superior colliculi, the region dorsolateral to the nucleus reticularis tegmenti pontis, and the medial vestibular nucleus. A few neurons were labeled around the habenulopeduncular tract and in the medial portion of the nucleus of the fields of Forel, in the nucleus reticularis medullaris ventralis, and in the spinal nucleus of the trigeminal nerve, the cochlear nucleus, and the superior olivary complex.The distribution and density of labeling suggest that omnipause neurons in the monkey are more intimately connected with other oculomotor structures than those in the cat. In addition, the rhombencephalic reticular afferents to the monkey omnipause neurons are more concentrated in their immediate vicinity than in the cat. The label consistently found dorsolateral to the nucleus reticularis tegmenti pontis may be a newly discovered link in saccade generatio

ISSN:0092-7317    

DOI:10.1002/cne.902950306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractVarious circumstances have brought about a dispute concerning the immunologically privileged status of the central nervous system (CNS). Using a transplantation paradigm, we have examined the cellular events associated with an experimentally induced focal assault on the CNS by the immune system. Chunks of embryonic mouse cortex were transplanted into neonatal rat brains and allowed to survive for 4 weeks. The adult rats then received a skin graft of donor origin to induce rejection of the transplanted tissue. Animals were sacrificed at various time points and examined histologically and immunocytochemically. Under these circumstances, the transplant is rejected via a first‐set rejection response, and astrocytes of donor origin appear to be the primary target of the host immune system. Expression of class I and class II major histocompatibility antigens is noted to correlate with lymphocytic invasion of the transplan

ISSN:0092-7317    

DOI:10.1002/cne.902950307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAnatomical studies of the Creel albino cat have demonstrated a pronounced atrophy of cells in the medial superior olive, a structure thought to be important for the detection of interaural time differences (ITDs). We looked for physiological abnormalities in the binaural interaction of cells in three albino cats by recording from single cells in the central nucleus of the inferior colliculus to ITDs of tones and noise. We found that the sensitivity to ITDs of tones and noise was somewhat diminished in the albino cats as compared to normally pigmented cats, though this deficit was only evident when a population of cells was examined. The range of sensitivity of individual cells for both tones and noise was the same in albinos and pigmented animals. Our anatomical measurements showed a smaller reduction in cross‐sectional area of cells in the medial superior olive than that reported earlier, and the cell bodies in the medial superior olive of the albinos were less elongated than in normal cat

ISSN:0092-7317    

DOI:10.1002/cne.902950308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have reconstructed from electron micrographs of a continuous series of thin sections the synaptic connections of the axonal arborizations of all the rod bipolar cells contained in a small region of the retina of the rabbit.We observed that all rod bipolars share the same pattern of connectivity and are probably functionally equivalent. As a rule, they do not contact ganglion cells. Their prevalent synaptic output is on narrow‐field, bistratified, and indoleamine‐accumulating amacrine cells. Their dominant inputs are the reciprocal synapses from the indoleamine‐accumulating amacrines, but they also receive a sizable number of synaptic contacts from other, non‐reciprocal, amacrine cells. The lateral spread of scotopic signals at the synapse between rod bipolars and narrow‐field, bistratified amacrines is small. Finally, in the rabbit, as in the cat, a narrow‐field, bistratified amacrine is inserted in series along the

ISSN:0092-7317    

DOI:10.1002/cne.902950309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution of two calcium‐binding proteins, parvalbumin (PV) and calbindin‐D 28K (CaBP), was studied by the peroxidase‐anti‐peroxidase immunohistochemical method at the light and electron microscopic level in the rat spinal cord and dorsal root ganglia. The possible coexistence of these two proteins was also investigated.PV‐positive neurons were revealed in all layers of the spinal cord, except lamina I, which was devoid of labelling. Most of the PV‐positive cells were found in the inner layer of lamina II, lamina III, internal basilar nucleus, central gray region, and at the dorsomedial and ventromedial aspects of the lateral motor column in the ventral horn. Neuronal processes intensely stained for PV sharply delineated inner lamina II. With the electron microscope most of them appeared to be dendrites, but vesicle containing profiles were also found in a smaller number. CaBP‐positive neurons appeared to be dispersed all over the spinal gray matter. The great majority of them were found in laminae I, II, IV; the central gray region; the intermediolateral nucleus; and in the ventral horn just medial to the lateral motor column. Laminae I and II were densely packed with CaBP‐positive punctate profiles that proved to be dendrites and axons in the electron microscope. A portion of labelled neurons in lamina IV and on the ventromedial aspect of the lateral motor column in the ventral horn disclosed both PV‐ and CaBP‐immunoreactivity.All of the funiculi of the spinal white matter contained a large number of fibres immunopositive for both PV and CaBP. The highest density of CaBP‐positive fibres was found in the dorsolateral funiculus, which was also densely packed with PV‐positive fibres. PV‐positive fibres were even more numerous in the dorsal part of the dorsal funiculus. The territory of the gracile funiculus in the brachial cord and that of the pyramidal tract in its whole extent were devoid of labelled fibres. In the thoracic cord, the dorsal nucleus of Clarke received a large number of PV‐positive fibres.Dorsal root ganglia displayed both PV‐ and CaBP‐immunopositivity. The cell diameter distribution histogram of PV‐positive neurons disclosed two peaks‐‐one at 35 μm and the other at 50 μm. CaBP‐positive cells in the dorsal root ganglia corresponded to subgroups of small and large neurons with mean diameters of 25 μm and 45 μm, respectively.On the basis of the location of perikarya and dendritic arborization patterns, PV‐ and CaBP‐positive cells are correlated with previously described and neurochemically or physiologically characterized neu

ISSN:0092-7317    

DOI:10.1002/cne.902950310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to examine the cholinergic innervation of the brainstem reticular formation in an effort to understand the potential role of cholinergic neurons in processes of sensory‐motor modulation and state control. The cholinergic cells and processes within the pontomedullary reticular formation were studied in the rat by application of peroxidase‐antiperoxidase immunohistochemistry with silver intensification for cholineacetyltransferase (ChAT). ChAT‐immunoreactive cells were located in the pontomesencephalic tegmentum within the laterodorsal and pedunculopontine tegmental (LDT and PPT) nuclei, where they numbered approximately 3,000 on each side and were scattered in the midline, medial, and lateral medullary reticular formation, where they numbered approximately 10,000 in total on each side. The cholinergic neurons within the reticular formation were commonly medium in size and gave rise to multiple dendrites that extended for considerable distances within the periventricular gray or the reticular formation, as is typical of other isodendritic reticular neurons. A prominent innervation of the entire pontomedullary reticular formation was evident by varicose ChAT‐immunoreactive fibers that often surrounded large noncholinergic reticular neurons in a typical perisomatic pattern of termination, suggesting a potent influence of the cholinergic innervation on pontomedullary reticular neurons.The contribution of the pontomesencephalic cholinergic neurons to the innervation of the medial medullary and lateral pontine reticular formation was studied by retrograde transport of horseradish peroxidase conjugated wheat germ agglutinin (WGA‐HRP) in combination with ChAT immunohistochemistry. A proportion of the cholinergic neurons within the laterodorsal tegmental nucleus (pars alpha) and the pedunculopontine tegmental nucleus were retrogradely labelled on the ipsilateral (10–15%) and contralateral (5–10%) sides from the medial medullary reticular formation, indicating a significant contribution to the cholinergic innervation of this region, which, however, also appeared to derive in part from intrinsic medullary cholinergic neurons. The major fiber system by which the medial medullary reticular formation was reached by the pontomesencephalic cholinergic neurons appeared to correspond to the lateral tegmentoreticular tract. Fibers passed from these cholinergic cells ventrally through the lateral pontine tegmentum, in the region of the subcoeruleus, where they also appeared to innervate by fibres en passage the noncholinergic neurons of the region. A significant proportion of the pontomesencephalic cholinergic neurons were retrogradely labelled from the lateral pontine tegmentum. The prominent innervation of the pontomedullary reticular formation by the pontomesencephalic cholinergic neurons provides a potential neuroanatomical substrate for the hypothesized role of cholinergic neurons in sensory‐motor modulation and state control, particularly the state of pa

ISSN:0092-7317    

DOI:10.1002/cne.902950311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY