Serotoninergic control of the activity and expression of glial GABA transporters in the rat cerebellum

OBJECTIVE: The purpose of the study was to compare staff versus patient perceptions of the causes and emotional impact of verbal and physical aggression on a psychiatric inpatient unit, and the corrective measures each group would endorse. METHODS: Fifty-four patients and 32 nursing staff members responded to similar questions about physical and verbal aggression. They also reported their emotional responses to aggression and steps they would endorse to reduce aggression at the medical center. Data was analyzed by chi-square tests for proportion comparisons between groups. RESULTS: "Verbal Abuse" was viewed an important contributor to physical aggression. Staff stressed patient substance abuse and violent lifestyles. Patients focused on the use of involuntary procedures and cultural differences between patients and staff. CONCLUSIONS: Patients endorsed more restrictive safety measures as long as the measures such as metal detectors and searches were applied to staff and visitors, as well as patients. Patients requested more input into decision-making processes through patient-staff workgroups.     

Effect of kainate on the membrane conductance of hilar glial precursor cells recorded in the perforated-patch configuration

OBJECTIVE: To determine discontinuation effects of ipsapirone, a novel azapirone and partial 5-HTIA agonist that has anxiolytic effects clinically and has not caused dependence or withdrawal symptoms in animals, and to compare these effects with those of the benzodiazepine lorazepam, owing to concern about dependence or withdrawal symptoms following use of these drugs. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: Outpatient and inpatient treatment. PARTICIPANTS: Sixty-five healthy male volunteers who had experience with sedative-hypnotics or anxiolytics and did not meet DSM-III-R criteria for abuse or dependence. INTERVENTIONS: Participants were randomized to receive ipsapirone 15 mg per day (n = 17), ipsapirone 22.5 mg per day (n = 16), lorazepam 3 mg per day (n = 16), or placebo (n = 16) as outpatients for 36 days (treatment) followed by single-blind placebo as inpatients for 3 days and as outpatients for 6 days (withdrawal). OUTCOME MEASURES: Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Scale (HAM-D), Spielberger State Anxiety Scale, Sleep Quality Questionnaire, General Symptom Checklist, self-rated intoxication, Clinical Institute Withdrawal Assessment--Benzodiazepines (CIWA-Benzo), psychomotor testing and urine drug screen. RESULTS: Only 45 subjects completed the study; discontinuation rates did not significantly differ among treatment groups. At day 39, fewer and less severe symptoms (e.g., insomnia and fatigue) were found on the CIWA-Benzo scale after treatment with ipsapirone or placebo than after treatment with lorazepam (p < 0.05). Subjects reported longer sleep latency and poorer sleep quality after receiving lorazepam than after receiving ipsapirone or placebo. Scores on the HAM-D, Spielberger State Anxiety and HAM-A scales did not change from baseline. CONCLUSIONS: Withdrawal symptoms were detected after discontinuation of therapeutic doses of lorazepam. Significantly fewer symptoms were observed after withdrawal from anxiolytic doses of ipsapirone.     

Identification of acutely isolated cells from developing rat cerebellum

Immunocytochemical staining was used to identify nerve and glial cells from postnatal rat cerebelli in situ and following tissue dissociation. Purkinje cells were identified using antibodies for the calcium-binding proteins calbindin and PEP19. Purkinje cells isolated during the second postnatal week were 15-20 microns in diameter and relatively abundant and displayed thin perisomatic processes. These features were used to identify Purkinje cells with scanning electron microscopy, which revealed extensive membrane infoldings. Golgi and nuclear cells were identified using antibodies against rat-303 antigen. Pale, nuclear, and Purkinje cells were identified using antibodies for rat-302 antigen. Although staining for rat-302 and rat-303 was weak during the second postnatal week, we were able to identify Golgi and pale cells even after tissue dissociation. Isolated Golgi cells were 8-10 microns in diameter and fewer in number than Purkinje cells and did not counterstain with calbindin antibodies. Isolated pale cells were 8-10 microns in diameter, rare, and resistant to calbindin antibodies. Isolated neurons from cerebellar nuclei were not located with either 302 or 303 staining, suggesting that they remained in the tissue. Golgi-Bergmann cells and astrocytes were identified using antibodies for glial fibrillary acidic protein. Isolated glial cells were 12-15 microns in diameter, more numerous than Purkinje cells, and unstained with calbindin antibodies. With phase-contrast optics, glial cells appeared flatter than neuronal cell types and had acentric nuclei. These results demonstrate that specific cell types in developing rat cerebellum can be identified after acute isolation, which should facilitate analysis of their endogenous properties.     

Endothelin-1 inhibits the adipose differentiation of cultured human adipocyte precursor cells

To investigate whether the T cell defective capacity to proliferate observed in systemic lupus erythematosus (SLE) T cells is a possible consequence of an intrinsic T cell disorder, the integrity of the accessory activation pathway mediated through CD26 antigen in SLE T cells was studied. Hyporesponsiveness of peripheral blood mononuclear cells (PBMC) from SLE to PHA and CD26 Mab was observed and no differences were found when the responsiveness of highly purified T cells to IL-2, IL-2 plus CD26 Mab, phorbol 12-myristate 13-acetate (PMA), or when PMA plus CD26 Mab was analyzed. Findings suggest that signals induced by triggering CD26 are not intrinsically altered in SLE T cells. However, some alteration of the regulatory involvement of monocytes or B cell over T cell function may be involved.     

The growth of the dendritic trees of Purkinje cells in the cerebellum of the rat

The growth of Purkinje cell dendritic trees in the cerebellum of the rat was studied over the first 50 days of life, using the technique of network analysis and the Golgi-Cox impregnation method. Our findings showed that a growth spurt occurred from the 10th to 30th day post partum (pp) and involved the production of a massive number of branches of fairly constant length. Growth of the tree occurred firstly in the lateral domain, so that by 15 days pp most trees were of adult width. Thereafter, increases in height occurred until 30 days pp. Associated with this change in direction of growth, from the mainly transverse to the vertical plane, was a deviation from the normal random pattern of branching of the tree, but this was reestablished when reorientation was complete, and growth in the vertical plane underway. The lengths of proximal segments increased once they had become established, but distal branches probably maintained a constant length. The above results, together with changes in segment length, trichotomy, branching probability, and growth cone morphology during development have been discussed in relation to current concepts of dendritic growth.     

Development and function of embryonic central nervous system glial cells in Drosophila

Each abdominal neuromere of a Drosophila embryo contains about 60 glial cells [Kl?mbt C, Goodman CS (1991): Glia 4:205-213; Ito et al. (1995): Roux's Arch Dev Biol, 204:284-307]. Among these, the midline and longitudinal glia are described to some detail. The midline glia are located dorsally in the nerve cord ensheathing the two segmental commissures. They are required for the proper establishment of commissures. The longitudinal glia, the A and B glia, and the segment boundary cells (SBC) are covering the longitudinal connectives. The longitudinal glia prefigure longitudinal axon paths and appear capable of regulating the expression of neuronal antigens. In the following we summarize the knowledge on the function of these glial cells.     

Nitric oxide precursor arginine and S-nitrosoglutathione in synaptic and glial function

In the last few years, there has been an important increase in interest in nitric oxide (NO) as an intercellular messenger, and its putative role in numerous CNS functions is being continually updated. Arginine, the nitric oxide precursor, has been found in our laboratory to be released following stimulation of the white matter in the cerebellum and of sensory afferents in the thalamus. Since arginine is localized in glial cells while the nitric oxide synthesizing enzyme is localized in different cells (predominantly in neurons), these findings may represent a transfer of arginine from glia to neurons in order to supply the nitric oxide synthase with its substrate. The mechanism underlying this glial-neuronal interaction seems to involve the activation of excitatory amino acid receptors present on glial cells. Our results speak for an intense crosstalk between neurons and glia (activation of glial receptors by neurotransmitter released from neurons) and between glia and neurons (supply of the nitric precursor arginine from glia to neurons). The form in which NO is released from cells has been much debated. The chemical identity of the endothelial-derived relaxing factor in particular is still a matter of dispute, the major contender being NO. and a S-nitrosothiol compound. Based on the strong reactivity of NO for thiols and on the presence of cysteine and glutathione at the mM level intracellularly and microM level extracellularly, we have investigated whether S-nitrosothiols, i.e. S-nitrosoglutathione, may be the potential "package" form in which NO could be stored. We demonstrated, with HPLC coupled to mass spectrometry techniques, the presence of endogenous nitrosoglutathione in rat brain tissue. This packaging of NO in the form of nitrosothiols might serve to facilitate its transfer, prolong its life, and target its delivery to specific effectors. That could confer a specificity of action to the widely diffusable messenger NO, may determine the range of effectiveness of NO and mitigate its adverse cytotoxic effects.     

Purification and characterization of adult oligodendrocyte precursor cells from the rat optic nerve

Oligodendrocyte precursor cells (OPCs) persist in substantial numbers in the adult brain in a quiescent state suggesting that they may provide a source of new oligodendrocytes after injury. To determine whether adult OPCs have the capacity to divide rapidly, we have developed a method to highly purify OPCs from adult optic nerve and have directly compared their properties with their perinatal counterparts. When cultured in platelet-derived growth factor (PDGF), an astrocyte-derived mitogen, perinatal OPCs divided approximately once per day, whereas adult OPCs divided only once every 3 or 4 d. The proliferation rate of adult OPCs was not increased by addition of fibroblast growth factor (FGF) or of the neuregulin glial growth factor 2 (GGF2), two mitogens that are normally produced by retinal ganglion cells. cAMP elevation has been shown previously to be essential for Schwann cells to survive and divide in response to GGF2 and other mitogens. Similarly we found that when cAMP levels were elevated, GGF2 alone was sufficient to induce perinatal OPCs to divide slowly, approximately once every 4 d, but adult OPCs still did not divide. When PDGF was combined with GGF2 and cAMP elevation, however, the adult OPCs began to divide rapidly. These findings indicate that adult OPCs are intrinsically different than perinatal OPCs. They are not senescent cells, however, because they retain the capacity to divide rapidly. Thus, after demyelinating injuries, enhanced axonal release of GGF2 or a related neuregulin might collaborate with astrocyte-derived PDGF to induce rapid division of adult OPCs.     

Changes in ion channel expression during in vitro differentiation of trout oligodendrocyte precursor cells

A prospective study of conduct disorder (CD) was conducted using 4 annual structured diagnostic interviews of 171 clinic-referred boys, their parents, and their teachers. Only about half of the 65 boys who met criteria for CD in Year 1 met criteria again during the next year, but 88% met criteria for CD again at least once during the next 3 years. For most boys with CD, the number of symptoms fluctuated above and below the diagnostic threshold from year to year but remained relatively high. Lower socioeconomic status, parental antisocial personality disorder (APD), and attention-deficit hyperactivity disorder were significant correlates of CD in Year 1, but the interaction of parental APD and the boy's verbal intelligence predicted the persistence of CD symptoms over time (i.e., only boys without a parent with APD and with above-average verbal intelligence clearly improved).     

Parallel induction of nitric oxide and tetrahydrobiopterin synthesis by cytokines in rat glial cells

Activation of monocyte-derived macrophages with cytokines leads to the induction of nitric oxide synthase. Much less is known about the effects of cytokines on microglia, resident brain macrophages, or on astrocytes. In this study, we compared the induction by lipopolysaccharide, interferon-gamma, and tumor necrosis factor-alpha of nitric oxide production and synthesis of tetrahydrobiopterin, the required cofactor for nitric oxide synthase, in microglia and peritoneal macrophages. Activation of microglia induced parallel increases in nitric oxide and intracellular tetrahydrobiopterin levels, although induction of the latter appears to be somewhat more sensitive to diverse stimulators. As with macrophages, inducible nitric oxide production in microglia was blocked by inhibitors of tetrahydrobiopterin biosynthesis. Interleukin-2, an important component of the neuroimmunomodulatory system, was only a weak activator of microglia by itself but potently synergized with interferon-gamma to stimulate production of both nitric oxide and tetrahydrobiopterin. Astrocytes were also activated by lipopolysaccharide and combinations of cytokines but showed a somewhat different pattern of responses than microglia. Biopterin synthesis was increased to higher levels in astrocytes than in microglia, but maximal induction of nitric oxide production required higher concentrations of cytokines than microglia and the response was much lower. These results suggest that tetrahydrobiopterin synthesis in glial cells is a potential target for therapeutic intervention in acute CNS infections whose pathology may be mediated by overproduction of nitric oxide.     

Endothelin enhances lipopolysaccharide-induced expression of inducible nitric oxide synthase in rat glial cells

Lipopolysaccharide is known to stimulate production of nitrite via expression of inducible nitric oxide (NO) synthase in not only macrophages but also glial cells. We found that in glial cell cultures lipopolysaccharide-stimulated inducible NO synthase expression and nitrite accumulation were synergistically enhanced by pretreatment with endothelin, whereas endothelin itself did not induce these responses. Pretreatment with endothelin-1, endothelin-3, and the selective endothelin type B (ETB) receptor agonist IRL 1620 caused the same effect with similar potencies, suggesting that the synergism was mediated via the endothelin ETB receptor. A protein kinase C inhibitor, calphostin C, suppressed endothelin-3-enhanced inducible NO synthase expression. Pretreatment with either endothelin-3 or phorbol ester enhanced lipopolysaccharide-induced production of tumor necrosis factor-alpha (TNF-alpha). Simultaneous addition of TNF-alpha increased lipopolysaccharide-stimulated inducible NO synthase expression. These results suggest that the increase in inducible NO synthase expression by endothelin was due to the elevated TNF-alpha production via protein kinase C. Our findings present the possibility that endothelin is implicated in neurotoxicity via enhancement of inducible NO synthase expression.     

Effects of styrene exposure on middle latency auditory evoked potentials and glial cells in rat

The demand for health care and social welfare services for the elderly has increased and in Japan, there is a need in the social system to improve the quality of life, especially for those who are disabled. This article directs attention to bed-ridden elderly persons from the standpoint of social problems attending economic development and population changes based on data from Japan, the United States, Sweden, and OECD countries. Compared to the United States, there are more bed-ridden elderly in Japan, and inadequate public resources for caring. Physicians, nurses, care workers, and rehabilitation specialists such as physiotherapist and occupational therapist per 1000 aged sixty-five or over are 89.5 in Japan while 237.4 in Sweden. Japan has the fewest such health and welfare personnel among developed countries. Even with increases in such personnel through the New Gold Plan, future increase in aged population would off-set the effect and the problem of providing care for the elderly remains.     

The use of transplanted glial cells to reconstruct glial environments in the CNS

Transplantation studies have demonstrated that glia-depleted areas of the CNS can be reconstituted by the introduction of cultured cells. Thus, the influx of Schwann cells into glia-free areas of demyelination in the spinal cord can be prevented by the combined introduction of astrocytes and cells of the O-2A lineage. Although Schwann cell invasion of areas of demyelination is associated with destruction of astrocytes, the transplantation of rat tissue culture astrocytes ("type-1") alone cannot suppress this invasion, indicating a role for cells of the O-2A lineage in reconstruction of glial environments. By transplanting different glial cell preparations and manipulating lesions so as to prevent meningeal cell and Schwann cell proliferation it is possible to demonstrate that the behaviour of tissue culture astrocytes ("type-1") and astrocytes derived from O-2A progenitor cells ("type-2") is different. In the presence of meningeal cells, tissue culture astrocytes clump together to form cords of cells. In contrast, type-2 astrocytes spread throughout glia-free areas in a manner unaffected by the presence of meningeal cells or Schwann cells. Thus, progenitor-derived astrocytes show a greater ability to fill glia-free areas than tissue culture astrocytes. Similarly, when introduced into infarcted white matter in the spinal cord, progenitor-derived astrocytes fill the malacic area more effectively than tissue culture astrocytes, although axons do not regenerate into the reconstituted area.     

Transcellular retrograde labeling of radial glial cells with WGA-HRP and DiI in neonatal rat and hamster

Topographically distinct populations of radial glial cells in the diencephalon and mesencephalon of neonatal rats and hamsters were transcellularly labeled with wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and with the lipophilic tracer DiI. A comparison of the histological distribution of the two tracers is suggestive of two different mechanisms of transcellular labeling. Intraocular injections of WGA-HRP resulted in the uptake of exogenously applied WGA-HRP by retinal ganglion cells, followed by anterograde axonal transport and exocytosis within the optic target nuclei. In addition to the transneuronal labeling, which is typical of such injections, we observed the transcellular labeling of the processes and somata of radial glial cells that were topographically associated with the terminal fields of the labeled axons. Similar transcellular labeling of radial glial cells associated with the axon terminal fields of the colliculogeniculate projection to the medial geniculate nucleus was observed following injections of WGA-HRP in the inferior colliculus. The transcellular labeling within the radial glial cells was discontinuous and somatopetally concentrated, indicating the existence of a retrograde active transport mechanism within the radial glial processes subsequent to its uptake following release of tracer from axons. This type of labeling can be referred to as transcellular retrograde glioplasmic transport. In contrast, DiI was used as a tracer through its capacity to diffuse within the plasmalemma. Topographically distinct populations of radial glial cells were transcellularly labeled following placements of DiI in the retina, inferior colliculus, or dorsal thalamus of fixed brains. The radial processes of labeled radial glial cells consistently extended into regions that also contained labeled axons. It is likely that the transcellular radial glial labeling with DiI occurred via transmembranous diffusion. These data indicate that a close structural and functional relation exists between axons and glial cells in the developing brain.     

Membrane-fusions and cytoplasmic bridges in the cells of the developing cerebellum

In the developing cerebellum of the neonate rats membrane-fusions and cytoplasmic bridges between cells were observed. These membrane-fusions were characterized by the presence of loops of membrane and cytoplasmic bridges between the two limits of the membrane-fusions. They were found between Purkinje cells, Purkinje cells and the migratory cells, mitotically potent cells of the external granular layer, and differentiating granule cells of the internal granular layer. The membrane-fusions were found to be a transient developmental phenomenon. Issues pertaining to the universality of membrane-fusions, their significance in the induction for cell differentiation, and the problem of fixation artifacts are discussed.     

Calcium signalling in glial cells

Glial cells respond to a variety of external stimuli such as neurotransmitters, hormones or even mechanical stress by generating complex changes in the cytoplasmic Ca2+ concentration. This Ca2+ signal is controlled by an interplay of different mechanisms including plasmalemmal and intracellular Ca2+ channels, Ca2+ transporters and cytoplasmic Ca2+ buffers. In astrocytes, the Ca2+ signal can travel as waves within the syncytium spreading via gap junctions which might be regarded as a possible means for interglial communication. Ca2+ signalling is also an important medium for neurone-glia interaction: neuronal activity can trigger Ca2+ signals in glial cells and, in turn, there is evidence that glial Ca2+ signals can elicit responses in neurones. While glial cells are not equipped with the proper channels to generate action potentials, Ca2+ signalling could be the instrument by which these cells integrate and propagate signals in the CNS.