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PubMed1994

Enkephalin-, thyrotropin-releasing hormone- and substance P-immunoreactive axonal innervation of the ventrolateral dendritic bundle in the cat sacral spinal cord: an ultrastructural study.

The distribution and synaptic arrangement of thyrotropin-releasing hormone-, substance P- and enkephalin-immunoreactive axonal boutons have been studied in the ventrolateral nucleus (Onuf's nucleus) of the upper sacral spinal cord segments in the cat. For this purpose, the peroxidase-antiperoxidase immunohistochemical technique was used. Immunoreactive axonal boutons were traced in complete series of sections in order to reveal synaptic contacts with the bundled dendrites of the ventrolateral nucleus. As judged from the cross-sectional diameter of the postsynaptic dendrites, the distribution of immunoreactive boutons was non-random. Enkephalin-immunoreactive axonal boutons, presumed to be mostly of segmental origin, displayed a rather restricted distribution to mainly (> 80%) medium-to-large dendrites. Thyrotropin-releasing hormone-immunoreactive boutons, that derive from supraspinal levels, were also found to impinge on medium-to-large dendrites (> 80%), indicating a proximal location within the dendritic trees. The skewness toward large postsynaptic dendrites was even more marked for thyrotropin-releasing hormone- than for enkephalin-immunoreactive boutons. Substance P-immunoreactive boutons, that are of either supraspinal or spinal origin, showed a more even distribution throughout the dendritic trees, including both thin distal branches and thick proximal dendrites. In view of the well-known fact that virtually all thyrotropin-releasing hormone-immunoreactive boutons in the ventral horn co-contain substance P (and serotonin) it was assumed that substance P-immunoreactive boutons in synaptic contact with the finest-calibre dendrites as well as most of those with a very proximal juxtasomatic location on the dendritic trees were of segmental origin, while those impinging on medium-to-large dendrites could be of either spinal or supraspinal origin. Fine-calibre dendrites (< 1 micron) represent about 25% of the dendritic branches in the ventrolateral nucleus, but receive, with the exception of substance P (8%), very little (< 3%) peptidergic or GABAergic (Ramírez-León and Ulfhake, 1993) input, although the degree of dendritic membrane covering by bouton profiles in the ventrolateral nucleus does not seem to vary much with the calibre of the postsynaptic dendrite (Ramírez-León and Ulfhake, 1993). Both substance P- and enkephalin-immunoreactive axonal boutons established synaptic contact with more than one dendrite. Furthermore, one and the same bouton could be found in contact with two dendrites that were coupled to each other by a dendro-dendritic contact of desmosomal or puncta adherentia type.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Multiple modes of action potential initiation and propagation in mitral cell primary dendrite.

The mitral cell primary dendrite plays an important role in transmitting distal olfactory nerve input from olfactory glomerulus to the soma-axon initial segment. To understand how dendritic active properties are involved in this transmission, we have combined dual soma and dendritic patch recordings with computational modeling to analyze action-potential initiation and propagation in the primary dendrite. In response to depolarizing current injection or distal olfactory nerve input, fast Na(+) action potentials were recorded along the entire length of the primary dendritic trunk. With weak-to-moderate olfactory nerve input, an action potential was initiated near the soma and then back-propagated into the primary dendrite. As olfactory nerve input increased, the initiation site suddenly shifted to the distal primary dendrite. Multi-compartmental modeling indicated that this abrupt shift of the spike-initiation site reflected an independent thresholding mechanism in the distal dendrite. When strong olfactory nerve excitation was paired with strong inhibition to the mitral cell basal secondary dendrites, a small fast prepotential was recorded at the soma, which indicated that an action potential was initiated in the distal primary dendrite but failed to propagate to the soma. As the inhibition became weaker, a "double-spike" was often observed at the dendritic recording site, corresponding to a single action potential at the soma. Simulation demonstrated that, in the course of forward propagation of the first dendritic spike, the action potential suddenly jumps from the middle of the dendrite to the axonal spike-initiation site, leaving the proximal part of primary dendrite unexcited by this initial dendritic spike. As Na(+) conductances in the proximal dendrite are not activated, they become available to support the back-propagation of the evoked somatic action potential to produce the second dendritic spike. In summary, the balance of spatially distributed excitatory and inhibitory inputs can dynamically switch the mitral cell firing among four different modes: axo-somatic initiation with back-propagation, dendritic initiation either with no forward propagation, forward propagation alone, or forward propagation followed by back-propagation.

Action Potentials↗
PubMed1997

Active dendrites reduce location-dependent variability of synaptic input trains.

We examined the hypothesis that dendritic voltage-gated channels can reduce the effect synaptic location has on somatic depolarization in response to patterns of short synaptic trains (referred to as location-dependent variability). Three computer models of a reconstructed hippocampal CA1 cell, each of increasing realism and complexity, were used. For each model, the goal was to identify the dendritic composition that best reduced the location-dependent variability. The first model was linear and a single parameter, dendritic membrane conductance (GDm, where Rm = 1/GDm), was varied. Surprisingly, a negative GDm minimized the location-dependent variability. Superposition of the synaptic inputs showed that, compared with passive dendrites, active dendrites increase the mean of the individual responses while decreasing the variance between synapses at different locations. Active dendrites compensate the three components of passive cable signal interference that increase with distance from the soma: the accumulation of charge on dendritic membrane capacitance, the escape of charge across synaptic and nonsynaptic dendritic membrane conductances, and the reduction in synaptic charge entry due to increased depolarization of dendrites located farther from the soma. We also found that the entire active dendritic tree contributes charge to any one active synapse. The second model contained an artificial voltage-dependent current (Iboost) added to passive apical dendrites. The optimal amount of Iboost that minimized location-dependent variability was found to be independent of the strength of individual synaptic inputs but inversely related to the synaptic duration. In the third model, realistic T-type Ca2+ and persistent Na+ channel models were added to passive dendrites and numerically fit to reproduce the effects of Iboost. Both realistic currents minimized synaptic variability. The densities for the realistic dendritic currents were not uniform but showed subtle variations and a slight reduction with distance from the soma. A heteroassociative memory network also was modeled to demonstrate the important relationship between location-dependent variability and memory recall performance. Compared with passive dendrites, active dendrites increased memory storage by reducing recall errors. These simulations demonstrate that active dendrites can minimize the cable properties of passive dendrites and enhance the soma's ability to determine the strength of the synaptic input. These models predict dendrites that minimize location-dependent variability will have an overall negative slope conductance I-V relationship that is tuned precisely.

Animals↗
PubMed2000

Differentiation of mitral cell dendrites in the developing main olfactory bulbs of normal and naris-occluded rats.

The morphological differentiation of mitral cell dendrites during embryonic and early postnatal development was examined in the main olfactory bulb of rats to determine a possible role of afferent activity in the development of the dendrites. Mitral cells and olfactory nerve fibers were labeled with 1,1'-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine perchlorate (DiI) and fluorescein-conjugated lectin (Ulex europeus agglutinin-I), respectively. Morphogenesis of mitral cell dendrites proceeded as previously described (Malun and Brunjes [1996] J. Comp. Neurol. 368:1-16); that is, undifferentiated dendrites with radial orientation were transformed into a single primary dendrite having a glomerular tuft and secondary dendrites extending tangentially into the external plexiform layer. Quantitative examinations in both pre- and postnatal rats revealed that the differentiation of primary dendrites, including tuft formation, increases in diameter and decreases in branching, started before birth, whereas differentiated secondary dendrites were only observed in postnatal animals. Mitral cells with more than two primary dendrites were found after embryonic day 21. The proportion of the mitral cells with differentiated dendrites increased postnatally. At postnatal day 10, almost all mitral cells had fully differentiated dendrites, and mitral cells with multiple primary dendrites were no longer seen. No significant change was found during development in the number of stem dendrites that arose directly from the cell body. Unilateral naris occlusion started on postnatal day 1 retarded differentiation of primary and secondary dendrites, and increased the proportion of mitral cells with multiple primary dendrites. These finding revealed that differentiation of mitral cell primary dendrites precedes that of secondary dendrites, and suggested that the differentiation of secondary dendrites proceeds in an activity-dependent manner.

Animals↗
PubMed1989

Sprouts emerging from the dendrites of axotomized lamprey central neurons have axonlike ultrastructure.

We have examined the dendritic and axonal ultrastructure of intact anterior bulbar reticulospinal neurons (ABCs) in the CNS of the larval sea lamprey and compared it with that of the dendrites and neuritic sprouts from ABCs examined 2 months following axotomy. Dendrites and axons of intact ABCs are distinguishable from one another by several ultrastructural criteria: (1) the predominance of microtubules in the dendritic cytoskeleton and neurofilaments in that of the axon, (2) the exclusively postsynaptic status of the dendrites versus the presynaptic status of the axon, and (3) the presence of polyribosomes and large numbers of mitochondria in the dendrites and their respective absence and scarcity in the axon. The ultrastructure of axonal sprouts evoked by axotomy of ABCs 1-1.5 mm from their somata ("intermediate axotomy") in many ways resembled that of intact axons. Axonal sprouts were presynaptic to other neurons, and their cytoskeletons consisted mainly of neurofilaments. They also exhibited some features not seen in either axons or dendrites, such as numerous clusters of small vesicles that were not associated with synapses and, in some cases, close associations with glial elements. We also examined sprouts emerging from the dendrites of ABCs following axotomy within 500 microns of their somata ("close axotomy") and found that such "dendritic" sprouts closely resembled axonal sprouts; they possessed neurofilament-dominated cytoskeletons, were presynaptic to other neurons, and were often associated with glial elements. The dendrites of ABCs undergoing dendritic sprouting retained their normal gross morphology but possessed a mixture of "axonal" and "dendritic" ultrastructural characteristics, exhibiting neurofilament-dominated cytoskeletons while remaining entirely postsynaptic to other neurons. However, there were significantly fewer synapses on the dendrites of axotomized cells than were found on the dendrites of intact ABCs. We conclude that sprouts evoked by axotomy are intrinsically axonal in character whether they originate from the axon stump or from the dendritic tree. Our results also suggest that the materials necessary for axonal regeneration may displace elements of the dendritic cytoskeleton as they are transported through the dendrites to the emerging "dendritic" sprouts following close axotomy.

Animals↗
PubMed1990

Differential growth and remodelling of ganglion cell dendrites in the postnatal rabbit retina.

The postnatal dendritic maturation of small field type 1 (SF1), medium field type 1 (MF1) and type 2 (MF2), and large field type 1 (alpha) ganglion cells in the rabbit retina was compared qualitatively and quantitatively. Dendritic tree structure was revealed by intracellular injection of the fluorescent dye Lucifer yellow, and the stained cells were then morphologically separated on the basis of some area, dendritic field size, total dendritic length, number of nodes, and mean internodal distance. Cells in the visual streak and an area inferior to the streak were sampled from retinae between birth and adulthood. The dendrites of all studied classes of rabbit ganglion cells were extensively covered by short spine-like appendages. As in cat retina, many dendritic spines disappeared by the end of the third postnatal week, at which stage the adult dendritic form could be recognised. However, there was differential loss in the number of spines from the dendrites of the four cell classes. In both the streak and inferior retina, adult SF1 cells had the same number of spines/dendritic unit length throughout postnatal life, whereas MF1 and MF2 ganglion cells lost at least half of their number of spines/unit dendritic length by maturity. Alpha ganglion cells lost virtually all their dendritic spines by adulthood. In both retinal locations, there were small changes in the number of nodes (dendritic branch points) of small field and medium field ganglion cells but alpha cells lost between 70 to 80% of their nodes by adulthood. The dendrites of ganglion cells with contrasting morphology thus undergo differential remodelling during postnatal maturation. The completion of the period of dendritic remodelling coincided with the first appearance of adult receptive field organisation, suggesting that structural remodelling, in particular that involving dendritic spines, may be associated with the development of the cell's synaptic circuitry. The dendrites of neighbouring postnatal ganglion cells in the rabbit retina also grow by different amounts; the increase in dendritic tree area, total dendritic length, and mean internodal distances of alpha cells exceeded that of small field and medium field cells in corresponding retinal positions. This implies that retinal dendrites elongate by active growth rather than by "passive stretching."

Aging↗
PubMed1986

The determination of dendrite morphology on lateral rectus motoneurons in cat.

Previously developed morphometric analysis of motoneurons (Ulfhake and Kellerth, '81, J. Comp. Neurol. 202: 571-583) was applied to lateral rectus motoneurons (LRMs). Total dendrite size was approximated from a single stem dendrite measurement. Fifteen dendrites from nine LRMs of the principal abducens nucleus intracellularly stained with HRP were morphometrically analyzed. The diameters and lengths along the extent of the dendrite were measured to calculate the surface area, volume, and combined length of the process. Linear correlation of stem dendrite diameter to these size parameters produced r values of .80, .84, and .61, respectively. Although the regression lines could be used to estimate dendrite size from the stem dendrite diameter, two morphologically distinct types were found among the 83 dendrites of the nine cells. Six dendrites differed from the other 77. Therefore, these six and a representative sample of the more common dendrite (nine) were included in the measurements. The rare dendrites consistently branched at about 40 micron from the soma into a rostrally and a caudally directed secondary dendrite. The secondary dendrites branched less and reduced more in diameter by tapering. Also, these dendrites exhibited a higher than expected total dendrite size to stem diameter ratio compared to "regular" dendrites. Statistical correlations of the stem diameter to surface area or volume within each dendrite type showed clear increases in r values from those of all 15. Significant differences were found between the size parameters of the two types. These qualitative and quantitative differences should be considered in accurate motoneuron size determinations in the abducens nucleus.

Animals↗
PubMed1995

Morphology of developing rat genioglossal motoneurons studied in vitro: relative changes in diameter and surface area of somata and dendrites.

This study describes the postnatal change in size of motoneurons in the hypoglossal nucleus that innervate the genioglossus muscle. Such anatomical information is essential for determining the cellular mechanisms responsible for the changes observed in the electrical properties of these motoneurons during postnatal development. The cells analyzed here are part of an earlier study (Núñez-Abades et al. [1994] J. Comp. Neurol. 339:401-420) where 40 genioglossal (GG) motoneurons from four age groups (1-2, 5-6, 13-15, and 19-30 postnatal days) were labeled by intracellular injection of neurobiotin in an in vitro slice preparation of the rat brainstem and their cellular morphology was reconstructed in three-dimensional space. The sequence of postnatal dendritic growth can be described in two phases. The first phase, between birth (1-2 days) and 13-15 days, was characterized by no change in either dendritic diameter (any branch order) or dendritic surface area of GG motoneurons. However, maturation of the dendritic tree produced more surface area at greater distances from the soma by redistributing existing membrane (retracting some terminal branches). During the second phase, between 13-15 days and 19-30 days, the dendritic surface area doubled as a result of an increase in the dendritic diameter across all branch orders and a generation of new terminal branches. In contrast to the growth exhibited by the dendrites, there was little discernible postnatal growth of somata. At all ages, dendrites of GG motoneurons show the largest amount of tapering in the first-and second-order dendrites. The calculated dendritic trunk parameter deviated from a value 1.0, indicating that the dendritic tree of developing GG motoneurons cannot be modeled accurately as an equivalent cylinder. However, the value of this parameter increased with age. Strong correlations were found between the diameter of the first-order dendrite and the dendritic surface area, dendritic volume, combined dendritic length, and, to a lesser extent, the number of terminal dendrites in GG motoneurons. Correlations were also found between somal and dendritic geometry but only when data were pooled across all age groups. These data support earlier studies on kitten phrenic motoneurons, which concluded that postnatal growth of motoneurons was not a continuous process. Based on the fact that there was no growth in the first 2 weeks, the changes in the membrane properties described during this phase of postnatal development (e.g., decrease in input resistance) cannot be attributed to increases in the total membrane surface area of these motoneurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Architecture of individual dendrites from intracellularly labeled thalamocortical projection neurons in the ventral posterolateral and ventral posteromedial nuclei of cat.

This study provides quantitative descriptions of individual dendrites from electrophysiologically characterized and intracellularly labeled thalamocortical projection (TCP) neurons of the cat ventrobasal complex. One hundred nine dendrites from six ventral posterolateral (VPL) neurons and six ventral posteromedial (VPM) neurons were examined. Measurement of several parameters showed that the individual dendrites were very similar to each other in overall architecture even though they varied greatly in total length and number of dendritic branches. The mean path distance (length from soma to a dendritic tip) was very similar for all dendrites in each group (VPL or VPM) regardless of the number of branches found along the path distance. However, VPL dendrites had a longer mean path distance (VPL = 206 +/- 36 microns; n = 51) than VPM dendrites (VPM = 182 +/- 29 microns; n = 58; P < 0.001). For all dendrites there was a strong correlation between the stem dendrite diameter and the dendritic length, which allows the estimation of dendritic length from dendrite diameter. Analysis of dendritic scaling shows that branches higher than first order do not follow Rall's 3/2 power rule, so these neurons cannot be modeled using the equivalent cylinder approximation. The data add to the qualitative descriptions of cat ventrobasal (VB) TCP dendrites currently available and provide a basis for future comparative, developmental, and plasticity studies. Analysis shows that many parameters of cat VB TCP dendrites fall within a narrow range, suggesting that, regardless of differences in length or superficial appearance, these dendrites share a stable underlying architecture.

Animals↗
PubMed1988

The pattern of dendritic development in the cerebral cortex of the rat.

The pattern of dendritic development of layer V pyramidal cells in the neocortex of the rat was studied using a variety of quantitative techniques in an attempt to determine what rules govern dendritic differentiation. Animals were sacrificed on postnatal days (P) 1, 3, 5, 7, 10, 15, 20, 25, 30 and 60, their brains impregnated with the rapid Golgi technique, and cells from the sensorimotor cortex examined for maximal apical and basilar dendritic field, number of dendritic branches at 20 micron intervals from the cell body, number of apical and basilar branch types (branching order), length of dendritic branch segments, and dendritic spine density. Primary dendrites are formed early in development, with no new ones formed after P7-10. Once a dendritic segment has bifurcated, all further development appears to occur at the tip, i.e. the trunk does not seem to undergo additional elongation, and new branches do not appear to form from the trunk. There is a plateau in dendritic differentiation close to the cell body after approximately P20; however, there is a continued increase in the length of terminal dendritic branches in the distal portions of the dendritic field into adulthood. During early development, dendrites bifurcate on reaching approximately 20-30 microns; however, during adulthood additional length is added to terminal dendrites without branching. Dendritic spines increase dramatically early in development, and then decline on proximal dendrites but continue to increase on terminal branches into adulthood. These results suggest that the terminal portion of the dendritic field remains plastic into adulthood, and that during development several general rules govern the pattern of dendritic differentiation.

Aging↗
PubMed2006

T-cadinol and calamenene induce dendritic cells from human monocytes and drive Th1 polarization.

T-cadinol and calamenene are sesquiterpenes isolated from the heartwood of Cryptomeria japonica and are pharmacologically active substances. Dendritic cells are pivotal in the initiation of adaptive immune responses and are recognized as key to the induction of immune responses to cancer. This study investigated the effects of T-cadinol and calamenene on the phenotypic and functional maturation of human monocyte-derived dendritic cells in vitro. Human monocytes were cultured with recombinant human granulocyte-macrophage colony-stimulation factor (GM-CSF) and recombinant human interleukin-4 (IL-4) for 6 days under standard conditions, followed by another 2 days in the presence of T-cadinol, calamenene, lipopolysaccharide (LPS), CT or nifedipine. Dendritic cells harvested on day 8 were examined using functional assays. The expression levels of CD1a, CD80, CD83, CD86 and HLA-DR on T-cadinol-primed dendritic cells or calamenene-primed dendritic cells were enhanced with a concomitant decrease in endocytic activity. T-cadinol-primed dendritic cells or calamenene-primed dendritic cells also enhanced the T cell stimulatory capacity in an allogeneic mixed lymphocyte reaction, as measured by T cell proliferation. Naïve T cells co-cultured with allogeneic T-cadinol-primed dendritic cells or calamenene-primed dendritic cells at 1:5 dendritic cells/T cell ratio turned into typical Th1 cells which produced large quantities of interferon-gamma (IFN-gamma) and released small amounts of IL-4 depending on IL-12 secretion. In contrast, naïve T cells co-cultured with CT-primed dendritic cells turned into Th2 cells. T-cadinol-primed dendritic cells and calamenene-primed dendritic cells expressed the chemokine receptor CCR7 and had a high migration to macrophage inflammatory protein (MIP-3beta). Intracellular Ca(2+) mobilization in T-cadinol-primed dendritic cells and calamenene-primed dendritic cells was induced by MIP-3beta. The differentiation and functional maturation of human monocyte-derived dendritic cells were not affected by nifedipine. These results suggest that T-cadinol and calamenene may be used in dendritic cells-based immunotherapy for cancer.

Antigens, Surface↗
PubMed1997

Dendritic changes of the pyramidal neurons in layer V of sensory-motor cortex of the rat brain during the postresuscitation period.

Experiments were performed on 40 Wistar rats. Total brain ischemia was induced by 10 min clamping of the cardiac blood vessels. The brains were examined in control rats, after 90 min and after 1, 3, 7, 30 and 90 days during the postresuscitation period. Histological sections were stained with the Golgi method. Morphometrical parameters, 12, of dendritic changes of the pyramidal neurons in layer V of sensory motor cortex (SMC) in rat brain were studied at different intervals of the postresuscitation period. Reduction of the dendrites of the pyramidal neurons due to the loss of the terminal branches of the oblique apical dendrites in layer III-IV was detected from the first day after ischemia. The maximal dendritic change was detected 3 and 7 days after ischemia. Decrease the volume of dendritic territory (54, 4%), the total dendritic length of the whole dendritic territory (56, 0%) and branching of dendrites, and decrease in the number of dendritic spines on apical dendrites in layers I-II (46, 1%) were the main changes during this period. Reduction of the total length of dendrites occurred mostly due to disappearance of the 2nd and 3rd order branches of the apical and basal dendrites. The change of dendrites neurons had returned to control levels after 30 days. By that time the diameter of the dendrites had increased, the varicosities on oblique apical and basal dendrites had disappeared, and the number of 2nd and 3rd order dendrites and of dendritic spines had increased.

Animals↗
PubMedDate not supplied

Postnatal dendritic development of Y-like geniculocortical relay neurons.

We describe the dendritic development of neurons in the dorsal lateral geniculate nucleus (LGNd) projecting to cortical area 18 in the postnatal cat. LGN neurons were identified by retrograde labeling from area 18 with fluorescent latex microspheres and injected in the fixed slice with Lucifer yellow (LY) and horseradish peroxidase (HRP) to visualize their dendritic arborizations. Both topological (measures of the patterns of dendritic branching and their territorial coverage) and metric parameters (measures of the quantitative parameters describing the size, length, extent and diameter of the dendritic arbors) were measured in three-dimensions for 25 LGN neurons in cats between 1 and 18 postnatal weeks. In addition, dendritic growth was compared to the changing dimensions of the LGNd. At all ages, neurons projecting to area 18 have large somata and radiate dendrites. From 1 to 18 weeks neurons increase in size--both soma area and the length of all dendritic segments double during this period. Intermediate and terminal dendritic segments show comparable growth until 5 weeks. However, only terminal segments continue to grow significantly from 5 until 18 weeks. Dendrites become straighter during development, the angle between daughter branches decreases and dendritic segment diameter increases, with terminal segments showing a greater increase relative to intermediate segments. The density of dendritic appendages increases transiently at 5 weeks and a differential redistribution occurs, so that by 18 weeks dendrites further from the soma have a greater density of appendages than those near the soma. Some dendritic relationships remain invariant during development--intermediate segments are always shorter, thicker and straighter than terminal segments. During these changes however, area 18 projecting neurons maintain a constant number of primary dendrites and have, on average, a constant branching pattern. The relative volume of the LGNd occupied by an area 18 projecting neuron increases 2.4-fold between 1 and 18 weeks as the dendrites grow with the result that the coverage of a given point of the LGNd by dendrites of area 18 projecting nearly doubles from 24 to 45 neurons per unit volume. This increased net dendritic overlap provides a substrate for enhanced numerical synaptic divergence of the Y-cell pathway from a point source in the retina to the visual cortex.

Aging↗
PubMed2006

Decreased number of circulating plasmacytoid dendritic cells in patients with atherosclerotic coronary artery disease.

BACKGROUND: Dendritic cells are potent antigen-presenting and immune modulating cells that have been implicated in the development of atherosclerosis. In human blood, two distinct lineages are distinguished: plasmacytoid dendritic cells and myeloid dendritic cells. Although dendritic cells have been described in atherosclerotic plaques, no information exists concerning circulating blood dendritic cells in atherosclerosis. This study aims to evaluate the number of circulating dendritic cells in patients with coronary artery disease. The relation with the extent of coronary artery disease, the clinical syndrome and with a marker of inflammation will be documented. METHODS: Patients with angiographically proven coronary artery disease (n=18) and age and sex-matched controls (n=18) were included. Myeloid dendritic cells and plasmacytoid dendritic cells were detected with the specific blood dendritic cell antigens, blood dendritic cell antigen-1 and blood dendritic cell antigen-2, respectively. RESULTS: Absolute and relative numbers of circulating plasmacytoid dendritic cells were significantly lower in patients with coronary artery disease (5722+/-601/ml and 0.08+/-0.01%) than in controls (12,640+/-1289/ml and 0.21+/-0.02%). Plasmacytoid dendritic cells were more decreased in patients with troponin-positive unstable coronary syndromes than in patients with low troponin values, and tended to be lower in more extensive coronary artery disease. Absolute myeloid dendritic cells numbers tended to be reduced in patients, whereas relative numbers were significantly decreased: 11,857+/-1895/ml versus 15,226+/-928/ml and 0.17+/-0.03% versus 0.26+/-0.01% in controls. CONCLUSIONS: The present study shows a significant decrease of circulating blood dendritic cell antigen-2 positive plasmacytoid dendritic cells in patients with coronary artery disease. The decrease tended to be more pronounced in unstable coronary syndromes and extensive coronary artery disease, suggesting a possible role of dendritic cells in plaque progression and rupture.

Adult↗
PubMed1981

Organization and development of brain stem auditory nuclei of the chicken: dendritic development in N. laminaris.

Nucleus laminaris (NL) is a third-order auditory nucleus in the avian brain stem which receives spatially segregated binaural inputs from the second-order nuclei magnocellularis. The examination of the development of dendritic structure in NL revealed a number of events: In the initial period of dendritic growth (E 8--9) there is no gradient of dendritic morphology or apparent size. Starting about E 9--10, there is a spatiotemporal gradient of proliferation of numerous fine dendritic processes, from rostromedial to caudolateral, corresponding with the morphological lamination of NL, and possibly with the onset of cell death. This is followed by a spatiotemporal gradient of the elimination of the overproliferated processes, from rostromedial to caudolateral possibly coinciding with the cessation of cell death. A result of the spatiotemporal gradients of dendritic process proliferation and elimination is a spatial gradient in the morphology (extension, branching) of the remaining "mature" dendrites. At E 15 there is only a slight spatial gradient of total dendritic size across NL; this gradient is larger at E 19, and by P 25 there is a 13-fold change in dendritic size from rostromedial to caudolateral. Regression analyses suggest the size gradient begins to form when NL activity becomes driven by cochlear activity, at about E 14. The progressive formation of the size gradient is largely the result of two factors: the growth of dendritic trees, and the loss or primary dendrites. The growth rate of the dendritic trees of NL cells was found to be very highly correlated with the intensities of the sound frequencies to which the cells respond. From E 15 to P 25 there is a 50% loss of the "mature" primary dendrites of NL neurons. The separate dorsal and ventral dendritic size gradients seen at E 15 realign to coincide at E 19, and the moderate correlation of dorsal and ventral dendritic sizes seen at E 15 and E 19 is significantly increased at P 25, indicating a developmental process of sharpening in the relationship of the dorsal and ventral dendritic organizations in the nucleus. The data suggest that a key element in the regulation of dendritic size and structure in n. laminaris may be the activity of the afferents to the cells.

Aging↗
PubMed1984

Dendritic caliber and the 3/2 power relationship of dentate granule cells.

A quantitative examination of granule cell dendritic caliber and knowledge of dendritic lengths allows assessment of the distribution of dendritic membrane and the 3/2 power relationship at branch points. This paper presents caliber data of Golgi-impregnated rat dentate gyrus. We used camera lucida drawings of the dendritic trees of 15 dorsal leaf and 15 ventral leaf granule cells to quantify mean dendritic caliber, dendritic taper, the 3/2 power relationship of parent and sibling dendritic diameters at branch points, and surface area. First-order dendrites vary substantially in diameter. However, the mean caliber of all other dendrites is uniform across the proximal two-thirds of the molecular layer for the dorsal and ventral leaves. The average diameter here is 1 micron. More distally, only mean ventral leaf dendritic caliber declines. Granule cell dendritic taper is due primarily to caliber decreases at branch points and not to a gradual decline in diameter across the length of a dendritic segment. Comparing the parent segment diameter raised to the 3/2 power with the sum of the 3/2 powers of the two sibling segment diameters reveals, for the dendritic tree located within the distal two-thirds of the molecular layer, the desired 3/2 power relationship for the dorsal and ventral leaves. More proximally, where first-, second-, and third-order dendrites branch sequentially across a 60-100-micron extent, a 3/2 power relationship is not obtained. For the average dorsal leaf granule cell, dendritic surface area (without spines) is 11,984 micron2. The ratio of dendritic to somatic surface area is 28:1. Discussion of these data includes their implications for electrotonic modeling of the dentate granule cell.

Animals↗
PubMed1989

Rapid changes in ultrastructure during deafferentation-induced dendritic atrophy.

This study describes qualitative and quantitative changes in dendritic ultrastructure during the rapid atrophy of nucleus laminaris (NL) dendrites following deafferentation. The dendrites of n. laminaris neurons in the chick auditory system are segregated into dorsal and ventral dendritic tufts, which receive spatially separated innervation from the ipsilateral and contralateral nucleus magnocellularis, respectively. We have previously shown that removing the input to the ventral side of NL results in the rapid atrophy of the ventral dendrites, whereas the nondeafferented dorsal dendrites of the same cells do not change in length. The ultrastructure of NL was examined in normal animals and after deafferentation. Changes in dendritic ultrastructure were not qualitatively apparent 4 hours after deafferentation. Between 12 and 48 hours the cytoplasm of the ventral dendrites became progressively more lucent, and a gap formed in the transition between the soma and ventral dendritic cytoplasm. Many of the dendrite tips, however, appeared normal even 2 days after deafferentation. Degeneration of dendrite plasma membrane was not visible until 2 days after deafferentation. On the other hand, quantitative measurements revealed a 30% decrease in microtubule density in the initial portion of the ventral dendrite by 4 hours, and a 50-60% decrease from 12 to 48 hours after deafferentation. Neurofilament density in the initial ventral dendrites decreased 50% by 12 hours, and 70% by 2 days after deafferentation. Many of the terminals of the severed afferents remained attached to the atrophying dendrite until 2 days after surgery, when they were in advanced stages of degeneration. Glia apparently were not involved in dendrite loss. The implications of these results on the role of cytoskeleton in the production and maintenance of dendritic shape are discussed.

Animals↗
PubMed1995

Dendritic reorganisation in the basal forebrain under degenerative conditions and its defects in Alzheimer's disease. II. Ageing, Korsakoff's disease, Parkinson's disease, and Alzheimer's disease.

Changes in the dendritic arborisation of Golgi-impregnated basal forebrain neurones with respect to size, shape, orientation, and topology of branching were quantitatively investigated in ageing, Alzheimer's disease (AD), Korsakoff's disease (KD), and Parkinson's disease (PD). A reorganisation of the whole dendritic tree characterized by an increase in both the total dendritic length and the degree of dendritic arborisation as well as by changes in the shape of the dendritic field was found during ageing, in KD, PD, and AD. Dendritic growth under these conditions was related to the extent of cell loss in basal forebrain nuclei. There appeared to be major differences, however, with respect to the overall pattern of dendritic reorganisation between AD on one side and ageing, KD, and PD on the other side. In both ageing and KD, dendritic growth was largely restricted to the terminal dendritic segments, resulting in an increase of the size of the dendritic field (pattern of "extensive growth") In AD, however, dendritic growth mainly resulted in an increase of the dendritic density within the dendritic field without being accompanied by an increase in the size of the volume occupied by the dendritic tree (pattern of "intensive growth"). In AD, aberrant growth processes were frequently observed in the perisomatic area or on distal dendritic segments of basal forebrain neurones of the reticular type. Neurones with aberrant growth profiles were typically located in the direct vicinity of deposits of beta/A4 amyloid. Perisomatic growth profiles were covered by the low-affinity receptor of nerve growth factor p75NGFR. Aberrant growth processes were not present in ageing, KD, and PD. On the basis of the present study, it is concluded that under certain degenerative conditions, reticular basal forebrain neurones undergo a compensatory reorganisation of their dendritic arborisation, a process that has become defective in AD, thereby converting a physiological signal into a cascade of events contributing to the pathology of the disease.

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