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PubMed1981

Sizes of soma and stem dendrites in intracellularly labelled alpha-motoneurones of the cat.

The morphology of identified hindlimb motoneurones was studied after intracellular labelling with Procion yellow (59 cells), Procion red (19 cells) or horseradish peroxidase (9 cells). With respect to the measurements performed, all three intracellular labels gave similar results. As judged by their axonal conduction velocity (62-117 m/sec) all included cells were alpha-motoneurones. The motoneuronal cell bodies had cross-sectional areas of 816-3732 sq. microns, corresponding to diameters of about 32-69 microns. On average each neurone had 12 (5-20) dendritic stems. For all cells together, the number of dendritic stems per neurone was not strongly correlated to soma diameter. In the whole material, the dendritic stem diameters varied between about 0.5 and 19 microns. Stem dendrites of 4-5 microns were common in all kinds of cells, whereas thicker dendritic stems were preferentially distributed to cells with larger somas. The maximum as well as the mean stem-dendrite diameter (d) per cell was clearly correlated to, and roughly proportional to, the diameter of the cell body. The sum of the cross-sectional areas of all the dendritic stems emanating from a cell ('sum of dendritic holes' = sigma pi d2/4) was roughly proportional to the volume of the soma. Quadriceps motoneurones had a markedly greater number of dendritic stems per cell (mean 16.9) than other kinds of hindlimb motoneurones studied (mean 11.5; includes motoneurones of the hamstring muscles, triceps surae and intrinsic foot muscles). The many quadruceps dendrites were, however, also relatively thin, and the average ratio between 'sum of dendritic holes' and soma volume was the same for quadriceps motoneurones as for the other cells.

Animals↗

PubMed1996

An improved isolation method for murine migratory cutaneous dendritic cells.

Dendritic cells are highly specialized accessory cells for the initiation of primary immune responses. They occur as trace populations in non-lymphoid and lymphoid organs. Therefore, the isolation and enrichment of primary dendritic cells is difficult and time-consuming. This applies also to dendritic cells from skin, i.e. epidermal Langerhans cells and dermal dendritic cells. Recently introduced skin organ cultures serve as a convenient source for primary cutaneous dendritic cells. We report here a refinement of such cultures in which cutaneous dendritic cells emigrate spontaneously into the culture medium. Murine ear skin is cultured for a total of 3 days in three sequential 24 h steps. This simple modification doubles or triples the yields of dendritic cells that can be obtained and up to 30,000 dendritic cells can be recovered from one ear half. This represents 50-70% (range 30-80%) of all viable cells. The cells are mature dendritic cells that possess potent T cell stimulatory function. Compared to the classical methods of preparing epidermal Langerhans cells by trypsinization this technique is easier and quicker; it does not require enzymes such as trypsin, and it yields similar numbers of mature dendritic cells. It should prove useful for further studies of dendritic cells of the skin.

Animals↗

PubMedDate not supplied

Dendritic architecture of ON-OFF direction-selective ganglion cells in the rabbit retina.

ON-OFF direction-selective ganglion cells in rabbit retina have bistratified dendritic arbors that are formed by contributions from three or four primary dendrites and their dependent branches (dendritic systems). Most dendritic systems contribute to both branching planes, but some are confined to a single plane. The way in which dendritic systems combine to form the branching planes varies from cell to cell, but the dendritic systems always produce a non-overlapping tiling of the planes having a distinctive mesh-like appearance. This mesh-like pattern appears to be produced primarily by a large number of branches that terminate close to the cell somata. Despite clear differences in the detailed construction of the dendritic arbors, quantitative morphological attributes vary primarily with overall size, and the variation is nearly isometric. We therefore regard these cells as isomorphic, in the sense that they have developed according to the same rather liberal rules for dendritic growth. More importantly, however, we have not found any morphological feature that is correlated with the cells' preferred response directions. We conclude that the distinctive dendritic architecture of these cells is related to general requirements for dense, uniform sampling from specific input arrays, and not direction-selectivity per se. The most important rules governing the branching pattern of the ON-OFF direction-selective cells may be related to territoriality, wherein dendrites, dendritic systems, and cells of the same type establish non-overlapping domains.

Animals↗

PubMed1987

Postnatal development of cell columns and their associated dendritic bundles in the lumbosacral spinal cord of the rat. I. The ventrolateral cell column.

The postnatal development of the ventrolateral dendrite bundle (LDB) in the rat lumbosacral cord was studied quantitatively with Golgi-Cox impregnation. At birth, motoneuronal perikarya and their dendrites were not fully developed, and had not begun to form bundles; varicose dendritic shafts radiated symmetrically from motoneurons. Dendrites contained numerous spines and growth cones. At 5 days, dendritic shafts began to arrange themselves longitudinally, and by 10 days of age, dendrite bundling was apparent. Dendritic growth and bundling appeared complete by two months of age. LDB formation was a dynamic process; rapid dendritic growth occurred in discrete phases with brief intervals of slower dendritic development between them. The mean number of secondary and tertiary dendrites, and the mean branch length of all orders progressively increased. Motoneurons of the LDB primarily innervate the pelvic musculature. Selective horizontal orientation of dendrites into discrete compact bundles suggests that the LDB may serve as a specialized receiving and integrating system for autonomic control over excretory and reproductive functions. It is interesting to note that in patients suffering from amyotrophic lateral sclerosis, motoneurons in the LDB are resistant to destruction. This finding suggests that motoneurons in the LDB may express unique features that protect them from certain disease processes. A better understanding of the developmental anatomical, physiological and biochemical properties of the LDB may provide insight into the treatment of patients with disease processes involving spinal cord and brainstem lower motoneurons.

Animals↗

PubMed1993

Changes in dendritic morphology of rat spinal motoneurons during development and after unilateral target deletion.

During normal development, motoneuron dendrites in the spinal nucleus of the bulbocavernosus (SNB) grow exuberantly to almost twice their adult length and then retract. In this study, we retrogradely labeled SNB motoneurons with cholera toxin B-conjugated horseradish peroxidase (BHRP) to examine the maturation of SNB dendritic arbors in more detail, particularly with regard to its spatial distribution and reorganization. The number and orientation of SNB motoneuron primary processes did not change over the first ten weeks of life. In contrast, total dendritic length, radial extent and arbor area increased significantly through the first four postnatal weeks and declined thereafter. The declines in length and extent were restricted to particular portions of the arbor, specifically the dorsal, ipsi- and contralateral projections. Estimates of the degree of overlap between the dendritic arbors from both sides of the SNB reflected these changes, with overlap initially increasing and then decreasing as the SNB established its adult dendritic morphology. To determine if dendritic interactions facilitated by this arbor overlap might be involved in regulating the normal retraction of SNB dendrites, we reduced SNB motoneuron numbers unilaterally by target muscle removal on the day of birth. Somal size, number and orientation of primary processes developed normally in unilateral muscle-extirpated animals. The dendritic morphology of surviving SNB motoneurons in unilateral muscle extirpated males was altered, with significant increases in dendritic length, extent and arbor area relative to those of normal males. These results indicate that substantial changes in dendritic organization of SNB motoneurons occur in normal development and may be influenced by interactions between dendrites from the two halves of the SNB.

Animals↗

PubMed1990

A quantitative study of dendrite complexity in selected areas of the human cerebral cortex.

This study seeks relationships between the degree of dendrite complexity of four areas of the human cerebral cortex and the type of function subserved by those areas. Quantitative studies of basilar dendrite patterns in the trunk and hand-finger receptive zones of areas 3 and 1, superior gyrus of the prefrontal cortex (area 9), and supramarginal gyrus (area 39) of the parietal lobe, in the left hemisphere of 10 subjects are reported. Measurements of dendrite complexity were based on the Sholl method of counting dendrite intersections with a series of superimposed concentric rings centered on the middle of the neuron soma. The data were analyzed graphically to show (1) characteristic dendrite profiles generated by cells in each of these areas, (2) comparisons between dendrite systems of two paired areas, i.e., trunk vs. hand-finger, and hand-finger vs. supramarginal, and (3) cumulative dendrite-ring intersection patterns for all areas studied. The data provided only partial support for our working hypothesis suggesting a relationship between complexity of the dendrite arbor and the nature of the computational tasks performed by the area. However, complexity of dendrite systems in the trunk area was found to be generally less than that of any other. In addition, there were suggestive associations between the complexity of dendrite systems of the hand-finger zone of the primary sensory receptive area and the nature of the work with which the individual had been associated during his/her working life. It proved more difficult to discern relationships between structure and function in the cortical associative areas. The study underlines the large degree of interindividual variation in dendrite structure and the need for much more extensive information about the life history of individuals who serve as subjects for this type of study.

Aged↗

PubMed2004

CD1c(+) immature myeloid dendritic cells are predominant in cord blood of healthy neonates.

It has been suggested lately that some types of antigen presenting cells-myeloid dendritic (DC-1) cells can differentiate the immune response towards Th1 type immunity, whereas lymphoid cells (DC-2) can stimulate Th2 type immunity. It has been observed that neonates are deficient in Th1 response. The purpose of our study was to estimate the proportions of immature myeloid (CD1c(+)) and lymphoid (BDCA-2(+), BDCA-4(+)) dendritic cells and the CD1c(+):BDCA-2(+) cell ratio in cord blood of healthy neonates in comparison with dendritic cells of healthy adults. Thirty healthy neonates born from normal pregnancies and 30 healthy adults were included in the study. The dendritic cells were isolated from cord and peripheral blood, stained with anti-CD1c, anti-BDCA-2, anti-BDCA-4, anti-CD123 and anti-CD19 monoclonal antibodies and estimated using flow cytometry. The percentage of CD1c(+) dendritic cells in cord blood of healthy newborns did not differ significantly when compared to those in peripheral blood of healthy adults. The percentages of cord blood BDCA-2(+) and BDCA-4(+) dendritic cells of neonates were significantly lower when compared to lymphoid dendritic cells in peripheral blood of adults. The CD1c(+):BDCA-2(+) ratio was significantly higher in cord blood of neonates in comparison with CD1c(+):BDCA-2(+) ratio in adult's blood. Myeloid and lymphoid dendritic cells may be involved in the immune regulation during fetal development. Immature myeloid dendritic cells are predominant in cord blood of healthy neonates. Immature lymphoid dendritic cells are not the major population of dendritic cells in cord blood.

Adult↗

PubMed1997

Cocultured, but not isolated, cortical explants display normal dendritic development: a long-term quantitative study.

Dendritic growth has been studied in long-term organotypic neonatal rat occipital neocortex grown either apart as isolated explants or in tandem as cocultures. Quantitative light microscopic measurement of dendritic and axonal branching patterns within the cortical slice was accomplished using rapid Golgi stained materials. In both isolates and cocultures the overall cellular organization of the slice was maintained over 4 weeks in vitro with morphologically distinguishable pyramidal and nonpyramidal neurons located within the same layers and with the same orientations as observed in situ. Long-term increases in the total length of basal dendrites, apical dendrite and axons were observed only in cocultures and were similar to growth patterns reported for in situ materials. Dendritic growth was mainly due to elongation of terminal dendritic segments. Surprisingly, isolated explants showed no long-term increases in total (basal) dendrites, apical dendrites or axons with time in vitro. A transient decrease in the number of basal dendritic segments and increase in terminal segment lengths at the end of the first week in vitro, however, was observed in nonpyramidal neurons. It is hypothesized that (i) afferent inputs and/or efferent targets develop only in cocultures and provide a crucial conditions for the continued growth of dendritic/axonal arborization for neocortical neurons in vitro, (ii) intrinsic interconnectivity within isolated explants is not sufficient to maintain long-term growth of neuritic arbors, and (iii) remodelling of dendritic arbors within isolated explants occurs at the same time as these explants are showing noticeable increases in the level of spontaneous bioelectric activity, which suggests that dendritic growth and network formation may be function dependent.

Animals↗

PubMed2000

Roles of ion channels in EPSP integration at neuronal dendrites.

Many different kinds of voltage-gated ion channels (Na+ channels, K+ channels, Ca2+ channels) exist at neuronal dendrites. Integration of dendritic electric signals (excitatory postsynaptic potentials (EPSPs), inhibitory postsynaptic potentials (IPSPs) and action potentials) and/or non-electric signals (Ca2+ and second messengers) occurs in restricted dendritic compartments consisting of spines and adjacent fine dendrites. Voltage-gated ion channels at neuronal dendrites play crucial roles in the integration of dendritic signals. Dendritic signals, in turn, play important roles in the modulation of local dendritic physiological functions (e.g. input-specific synaptic plasticity, long-term potentiation (LTP) and long term depression (LTD)). A combined experimental and theoretical approach is a good way to clarify the biophysical behaviors of dendritic ion channels. Analyses of dendritic ion channels can open the door to a new wave of discoveries about EPSP integration at neuronal dendrites.

Animals↗

PubMed2002

Dendritic morphology of callosal and ipsilateral projection neurons in monkey prefrontal cortex.

Subpopulations of cortical pyramidal neurons have been distinguished based on the projection target of their principal axons or by their dendritic morphology. In this study, we sought to test the hypothesis that pyramidal neurons in monkey prefrontal cortex that furnish callosal or ipsilateral projections have distinctive dendritic morphologies. Retrogradely-labeled, Fast Blue-containing callosal and ipsilateral neurons were intracellularly filled with Lucifer Yellow, immunoconverted, and reconstructed. Quantitative measurements of the size and complexity of the dendritic arbor, including total dendritic length, horizontal extent, number of branch points, maximum branch order, and number of segments, as well as spine density, were made. In general, callosal neurons had larger and more complex dendritic arbors for both apical and basilar dendritic trees than did ipsilateral neurons. The greatest difference was in total dendritic length; the apical and basilar trees of callosal neurons were 34 and 25% longer, respectively. In addition, spine density was also significantly greater on the apical and basilar dendrites of callosal neurons. These findings could not be explained by differences in somal size or completeness of dendritic filling between callosal and ipsilateral neurons. Our observations support the hypothesis that callosal and ipsilateral neurons differ on a number of measures of dendritic size and complexity. Furthermore, these findings imply that these two subpopulations of pyramidal cells differ in the number and perhaps types of excitatory inputs that they receive. Finally, differences in the dendritic morphology of callosal and ipsilateral neurons have implications for understanding the functional attributes of these two populations of cells, as well as for the characterization of pyramidal neurons in human disease states.

Amidines↗

PubMed2003

Dendrite-associated opioid-binding cell adhesion molecule localizes at neurosecretory granules in the hypothalamic magnocellular neurons.

Opioid-binding cell adhesion molecule (OBCAM) is a member of the immunoglobulin superfamily containing limbic system-associated membrane protein (IgLON) subgroup of glycosylphosphatidylinositol-anchored immunoglobulin cell adhesion molecules. We have previously found that OBCAM is localized preferentially to dendrites compared with somata and terminals of hypothalamic vasopressin-secreting magnocellular neurons. This localization indicates that OBCAM is one of the dendrite-associated cell adhesion molecules. In the present study, we further characterized the localization and the sorting mechanism, and activity-dependent changes of this molecule in vasopressin-secreting magnocellular dendrites. Confocal microscopic observation revealed the preferential localization of OBCAM at the neurosecretory granules in the vasopressin-positive dendrites. Electron microscopic observation using chromogen-intensified and gold-conjugated methods also demonstrated the OBCAM labeling at most of the neurosecretory granules within the dendrites, while the labeling within the somata was observed at only a few neurosecretory granules. I.c.v. colchicine administration resulted in the disappearance of OBCAM immunoreactivity from the dendrites and in its concomitant accumulation at the somata, suggesting that OBCAM is synthesized at the somata and transported to the dendrites by dendrite-associated neurosecretory granules. During the postnatal development, OBCAM immunoreactivity targeted to vasopressin-positive dendrites became clear from at least 3 weeks after birth, although it appeared at only a few somata 2 weeks after birth. Phosphatidylinositol specific phospholipase C treatment of the membrane fraction of the supraoptic homogenate solubilized OBCAM. Kilon, another IgLON member, was also shown to localize at the neurosecretory granules of vasopressin-positive dendrites via the glycosylphosphatidylinositol anchor. High K(+)-stimulation appeared to cause the diffusion of OBCAM-labeled gold particles from neurosecretory granules together with the exocytosis. These findings indicate that OBCAM is synthesized within the somata, attached to vasopressin neurosecretory granules via the glycosylphosphatidylinositol anchor, and transported to the dendrites. Moreover, the subcellular localization of OBCAM is changed in an activity-dependent manner.

Animals↗

PubMed1998

Increased numbers of CD68 antigen positive dendritic epidermal cells and upregulation of CLA (cutaneous lymphocyte-associated antigen) expression on these cells in various skin diseases.

CD68 is a myelomonocytic marker identified in human dermal macrophages. Although the existence of CD68 + dendritic epidermal cells has been reported, their characteristics have not been well elucidated. Cutaneous lymphocyte-associated antigen (CLA) is a homing receptor of cutaneous inflammatory T cells. Our recent report suggested that CLA was a homing molecule of CD1a+ Langerhans cells (LC) in the skin. In the present study we tested whether CD68 and CLA+ dendritic epidermal cells were present in skin specimens of normal skin and diseased skin such as lichen planus (LP), psoriasis vulgaris (PS), discoid lupus erythematosus (DLE), basal cell epithelioma (BCE), squamous cell carcinoma (SCC), irritated seborrheic keratosis (iSK), and Bowen's disease (BD). CD68+ dendritic epidermal cells were identified in normal skin and consisted of half the population of CD1a+ LC. These data indicate that CD68+ dendritic epidermal cells constitute a subpopulation of CD1a+ LC. CLA was expressed on a small percentage of CD68+ dendritic epidermal cells in normal skin. A remarkably increased number of CD68+ dendritic epidermal cells and upregulation of CLA on CD68+ dendritic epidermal cells were observed in diseased skin. The percentage of CLA+ cells among all CD68+ dendritic epidermal cells was less than that of CLA+ cells among all CD1a+ LC in diseased skin. The percentage of CLA+ cells among all CD68+ dendritic dermal cells was much less than that of CLA+ cells among all CD1a+ dendritic dermal cells. In normal skin, the epidermis showed minimal expression of monocyte chemoattractant protein (MCP)-1 and TGF-beta2, and no expression of TGF-beta1. In diseased skin, the epidermis showed elevated, but still moderate immunoreactivity for MCP-1. Slightly enhanced immunoreactivity for TGF-beta2, but not for TGF-beta1, was observed in the epidermis of diseased skin. Increased epidermal MCP-1 immunohistochemical staining was associated with the increased number of CD68 dendritic epidermal cells. These data suggest the possibility that MCP-1 secretion from the epidermis can affect the migration of CD68; Cutaneous lymphocyte-associated antigen; Monocyte chemoattractant protein-1; TAF-beta.

Antigens, CD↗

PubMed1998

Immunophenotypic analysis of the aortic aneurysm wall suggests that vascular dendritic cells are involved in immune responses.

OBJECTIVE: Inflammatory infiltrates similar to those in atherosclerotic plaques are prominent in the abdominal aortic aneurysm wall. Antigen presenting vascular dendritic cells are present in both early and advanced atherosclerotic lesions but their possible participation in abdominal aortic aneurysms has not been previously examined. This study reports the presence of vascular dendritic cells in abdominal aortic aneurysms and their participation in immune responses. METHODS: Samples of the anterior wall were collected from 18 atherosclerotic infrarenal abdominal aortic aneurysms ranging in diameter from 5-8 cm. All the patients were operated upon electively and no ruptured or rapidly expanding abdominal aortic aneurysms were included. Specimens were immediately frozen or fixed in 10% buffered formalin. Vascular dendritic cells were identified with anti-CD1a or with S-100. T cells and T cell subpopulations were identified with anti-CD3, anti-CD4 and anti-CD8. B cells were studied with anti-CD20. Analyses were carried out in sets of consecutive parallel sections immunostained with these antibodies and double immunostaining included different combinations of antigens such as CD1a/CD3, S-100/CD4, S-100/CD8. RESULTS: Most inflammatory infiltrates were found in the adventitia. These infiltrates contained B cells (CD20+) and T cells (CD3+) with their CD4+ and CD3+ cell subpopulations. In the aneurysm wall, CD1a+/S-100+ cells exhibiting dendritic appearance were detected and double immunostaining demonstrated that these vascular dendritic cells contained different lymphocyte populations including CD3+, CD4+, CD8+ and CD20+ cells. In some inflammatory infiltrates, B cells (CD20+) represented the predominant cell population (60-80%). Double immunostaining demonstrated that, in these infiltrates, vascular dendritic cells contacted CD20+ cells. CONCLUSIONS: Vascular dendritic cells are involved in immune reactions in the aneurysm wall, and this process mostly occurs in the adventitia. Vascular dendritic cells contact both T cells and B cells, suggesting that these vascular dendritic cells differ from other dendritic cells, subtypes of which associate with T cells (Langerhans cells, interdigitating cells) and B cells (follicular dendritic cells).

Aorta↗

PubMedDate not supplied

Development of dendritic trees of rabbit retinal alpha ganglion cells: relation to differential retinal growth.

To provide a quantitative description of the postnatal development of dendritic trees in alpha ganglion cells of the rabbit retina, these cells were stained either by intracellular injection of Lucifer yellow or by application of the lipophilic dye DiI. This was done at three developmental stages: postnatal day (P) 8/9, P 16/17, and in adults. For different retinal locations we quantified the alpha cell dendritic field area, the number of dendritic branch points, and the average dendritic length between branch points. According to the alpha cell location, the data were collected in three groups representing the retinal center, midperiphery, and far periphery, respectively. The data were then correlated with the postnatal retinal expansion which is known to differ among the above topographic regions of the retinae (Reichenbach et al., 1993). Our results show that the growth of alpha ganglion cell dendrites is not proportional to, but significantly exceeds, that of the local retinal tissue. Between P 8/9 and adulthood, the area of central alpha cells increases almost six-fold from 26,000 to 144,000 microns 2 (retinal expansion: 2.2-fold), and that of peripheral cells more than 15-fold from 35,000 to 556,000 microns 2 (retinal expansion: four-fold). During this period, the coverage factor of alpha cell dendritic fields increases about three-fold, and reaches adult levels of about 3 (retinal center) and 2.2 (periphery), respectively. The number of dendritic branch points remains nearly constant, and the distance between them increases by a factor close to the square root of the factor by which the dendritic field area grows. Thus, it appears that, from the second postnatal week on, dendritic trees of rabbit alpha ganglion cells increase by intense "interstitial growth," rather than by outgrowth of (new) dendritic branches. This growth pattern is different from that of some other rabbit retinal ganglion cell types, and of alpha ganglion cells of the cat retina, whose dendritic trees expand at a rate equal to or less than that of the surrounding retinal tissue. The consequences for synaptic contacts with bipolar and amacrine cells are discussed; they suggest a high degree of synaptic plasticity during normal postnatal retinal growth.

Animals↗

PubMed2001

Chronological ageing and photoageing of dendritic cells.

Ageing involves the whole organism, including the immune system. Age-dependent alterations of immune functions are located in both the adaptive and innate parts of the immune system. The most important cell type of the innate immune system are the dendritic cells, because their capacity to induce primary immune responses via professional antigen presentation is crucial for the initiation of the adaptive immune response. Evidence exists that dendritic cells of the systemic immune system, represented by lymph-node and blood-derived dendritic cells, as well as of local immunity, represented by Langerhans cells of the skin, participate in ageing processes. In animal models of older mice, dendritic cells of lymph nodes show degenerative characteristics with decreased adhesion molecule expression, less dendrite formation, and reduced antigen trapping capacity, which together imply disruption of functional activity. In contrast, dendritic cells generated from peripheral blood of elderly people were not impaired in their capacity to induce T-cell responses. Together, these findings indicate that in old individuals in vivo dendritic cells of the systemic immune system are reduced in their functional capacity to stimulate immune responses, whereas in vitro generated dendritic cells are fully functional, and therefore might be used in therapeutic approaches to treat age-associated malfunctions of the immune system. Thus far, only morphological descriptions about age-associated changes of dendritic cells (in particular the Langerhans cells) of the skin exist. In the skin, effects of naturally occurring ageing have to be differentiated from UV-radiation-induced ageing processes. The hallmark of Langerhans cell changes in natural as well as UV-induced skin ageing is their reduction in cell number within the epidermis. In addition, they show an atrophic morphology with less dendrites, and less Birbeck granules. It is assumed that these morphological changes are associated with loss of dendritic cell functions, and that this contributes to age-associated development of skin cancer. Therapeutic strategies against natural and UV-induced skin ageing should include a reduction of these changes of Langerhans cells in order to strengthen the immunological functions of the body's outer surface.

Animals↗

PubMed2000

Protein kinase C activity modulates dendritic differentiation of rat Purkinje cells in cerebellar slice cultures.

The molecular mechanisms underlying dendritic differentiation in neurons are currently poorly understood. We used slice cultures from rat cerebellum of postnatal day 8 to investigate the effect of protein kinase C (PKC) activity on dendritic development of Purkinje cells. After 12 days in culture under control conditions, Purkinje cells had developed a typical dendritic tree consisting of a few long primary dendrites with shorter side branches. Following treatment with the PKC agonist, phorbol-12-myristate-13-acetate (PMA), the dendritic tree area was strongly reduced to 32% of control and primary dendrites were short with only a few side branches. Delayed addition of PMA after 6 days resulted in a retraction of existing dendrites, whereas discontinuation of PMA treatment after 6 days resulted in a recovery of the dendritic tree to almost control values. In the presence of the PKC inhibitor, 2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl)maleimide (GF109203X), the dendritic tree area was increased to 158% of control with much more ramified branches after 12 days. The overall morphology of the cultures and the survival of Purkinje cells were unaffected by PKC modulators. Our data show that increased activity of PKC inhibits, and reduced activity of PKC promotes dendritic growth. This suggests that PKC activity is a critical regulator of dendritic growth and differentiation in cerebellar Purkinje cells.

Animals↗

PubMed2003

p38 Mitogen-activated protein kinase and extracellular signal-regulated kinases play distinct roles in the activation of dendritic cells by two representative haptens, NiCl2 and 2,4-dinitrochlorobenzene.

Previous studies have demonstrated that haptens induce several phenotypic and functional changes of dendritic cells in vivo as well as in vitro. Although recently, the crucial role of p38 mitogen-activated protein kinase has been reported in the activation of dendritic cells by haptens, the signal transduction elements involved in each phenotypic and functional changes that occur in the activation of dendritic cells by haptens remain unknown. Therefore, we examined the role of mitogen-activated protein kinases and nuclear factor-kappaB in the signal transduction of dendritic cells stimulated with two representative haptens, i.e., NiCl2 and 2,4-dinitrochlorobenzene. Human monocyte-derived dendritic cells stimulated with 2,4-dinitrochlorobenzene induced the phosphorylation of p38 and stress-activated protein kinase/c-jun N-terminal kinases, whereas NiCl2 induced that of p44/42 extracellular signal-regulated kinases, p38, and stress-activated protein kinase/c-jun N-terminal kinases. In addition, NiCl2 phosphorylated inhibitor kappaB and activated nuclear factor-kappaB. In contrast, primary irritants, e.g., benzalkonium chloride, or sodium lauryl sulfate, did not activate these signal transduction pathways. By using specific inhibitors for extracellular signal-regulated kinases and p38 pathways, PD98059 and SB203580, respectively, we demonstrated that the augmentation of CD86, HLA-DR, and CD83, and the production of interleukin-8 along with its increased mRNA expression by monocyte-derived dendritic cells stimulated with 2,4-dinitrochlorobenzene, and the augmentation of CD83 and the interleukin-12 p40 production by monocyte-derived dendritic cells stimulated with NiCl2, were suppressed by SB203580, whereas PD98059 suppressed the production of interleukin-1beta and tumor necrosis factor-alpha, together with their increased mRNA expression by monocyte-derived dendritic cells treated with NiCl2. On the other hand, in spite of the activation of nuclear factor-kappaB by monocyte-derived dendritic cells stimulated with NiCl2, nuclear factor-kappaB inhibitor did not significantly affect the phenotypic and functional changes in the activation of monocyte-derived dendritic cells. These data indicate that NiCl2 and 2,4-dinitrochlorobenzene stimulate different signal transduction pathways in monocyte-derived dendritic cells, and subsequently induce different phenotypic and functional changes in them.

Antigens, CD↗

PubMed2006

Dendritic compartmentalization of chloride cotransporters underlies directional responses of starburst amacrine cells in retina.

The mechanisms in the retina that generate light responses selective for the direction of image motion remain unresolved. Recent evidence indicates that directionally selective light responses occur first in the retina in the dendrites of an interneuron, i.e., the starburst amacrine cell, and that these responses are highly sensitive to the activity of Na-K-2Cl (NKCC) and K-Cl (KCC), two types of chloride cotransporter that determine whether the neurotransmitter GABA depolarizes or hyperpolarizes neurons, respectively. We show here that selective blockade of the NKCC2 and KCC2 cotransporters located on starburst dendrites consistently hyperpolarized and depolarized the starburst cells, respectively, and greatly reduced or eliminated their directionally selective light responses. By mapping NKCC2 and KCC2 antibody staining on these dendrites, we further show that NKCC2 and KCC2 are preferentially located in the proximal and distal dendritic compartments, respectively. Finally, measurements of the GABA reversal potential in different starburst dendritic compartments indicate that the GABA reversal potential at the distal dendrite is more hyperpolarized than at the proximal dendrite due to KCC2 activity. These results thus demonstrate that the differential distribution of NKCC2 on the proximal dendrites and KCC2 on the distal dendrites of starburst cells results in a GABA-evoked depolarization and hyperpolarization at the NKCC2 and KCC2 compartments, respectively, and underlies the directionally selective light responses of the dendrites. The functional compartmentalization of interneuron dendrites may be an important means by which the nervous system encodes complex information at the subcellular level.

Amacrine Cells↗