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  • 1995-1999  (3)
  • 1940-1944
  • Haloperidol  (2)
  • ESSF biogeoclimatic zone  (1)
  • 1
    Electronic Resource
    Electronic Resource
    GM1 ganglioside administration partially counteracts the morphological changes associated with haloperidol treatment within the dorsal striatum of the rat (1995)
    Springer
    Psychopharmacology 121 (1995), S. 461-469 
    Details
    ISSN: 1432-2072
    Keywords: GM1 ; Haloperidol ; Glutamate synapses ; Perforated PSD ; Striatum ; Dopamine receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Haloperidol, a typical antipsychotic drug, causes an increase in the mean percentage of synapses within the striatum containing a discontinuous, or perforated, postsynaptic density (PSD) following 1 month of treatment (Meshul et al. 1994). This effect is not observed with the atypical antipsychotic drug, clozapine, following subchronic administration (Meshul et al. 1992a). This morphological change is also associated with an increase in the density of dopamine D2 receptors. The synapses containing the perforated PSD are asymmetrical and the nerve terminals contain the neurotransmitter, glutamate, as demonstrated by immunocytochemistry. We have also shown that subchronic treatment with haloperidol (0.5 mg/kg per day, 30 days) results in a decrease in the density of glutamate immunoreactivity within asymmetric nerve terminals associated with perforated and non-perforated PSDs (Meshul and Tan 1994). This could be due to an increase in glutamate release, perhaps due to activation of corticostriatal synapses. Agnati et al. (1983a) reported that administration of GM1 ganglioside blocks the increase in dopamine D2 receptors following haloperidol treatment. GM1 has also been shown to attenuate the release of glutamate (Nicoletti et al. 1989). In order to determine if similar treatment with ganglioside could block the haloperidol-induced ultrastructural changes noted above, rats were coadministered GM1 (10 mg/kg per day) and haloperidol (0.5 mg/kg per day) for 30 days. We report that GM1 blocked the haloperidol-induced increase in striatal asymmetric synapses containing a perforated PSD, but had no effect on the increase in dopamine D2 receptors or the decrease in nerve terminal glutamate immunoreactivity. GM1, either alone or co-administered with haloperidol, also caused a small, but significant, increase in the density of all asymmetric synapses within the striatum. It is possible that the effect of GM1 in attenuating the haloperidol-induced change in glutamate synapses with perforated PSDs is primarily postsynaptic, since GM1 did not block the change in density of glutamate immunoreactivity within asymmetric nerve terminals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246494
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Correlation of vacuous chewing movements with morphological changes in rats following 1-year treatment with haloperidol (1996)
    Springer
    Psychopharmacology 125 (1996), S. 238-247 
    Details
    ISSN: 1432-2072
    Keywords: Haloperidol ; Vacuous chewing movements ; Glutamate synapses ; Perforated postsynaptic density ; Striatum ; Tardive dyskinesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Long-term treatment with the typical antipsychotic drug, haloperidol, can lead to a sometimes irreversible motor disorder, tardive dyskinesia (TD). It has been hypothesized that increased release of glutamate due to prolonged neuroleptic drug treatment may result in an excitotoxic lesion in specific neuronal populations within the basal ganglia, leading to TD. We reported that treatment with haloperidol for 1 month results in an increase in the mean percentage of striatal asymmetric synapses containing a perforated postsynaptic density (PSD) and that these synapses are glutamatergic. Using quantitative immunocytochemistry, we found that depending on how long the animals had been off haloperidol following subchronic (30d) treatment, there was either a decrease (1 day off) or increase (3–4 days off) in the density of glutamate immunolabeling within the presynaptic terminals of synapses with perforated PSDs. Using a rat model for TD, animals in the current study were treated for 1 year with haloperidol and spontaneous oral dyskinesias (i.e. vacuous chewing movements, VCMs) were recorded. In these long-term treated animals we wanted to determine if there was a correlation between glutamate function, as measured by changes in synapses with perforated PSDs and the density of nerve terminal glutamate immunoreactivity, and VCM behavior. In drug treated rats which demonstrated either a high or low rate of VCMs, there was a significant increase in the mean percentage of asymmetric synapses in the dorsolateral striatum with perforated PSDs in both haloperidol-treated groups compared to vehicle-treated rats. There was a small but significant increase in the density of glutamate immunolabeling within striatal nerve terminals of the high VCM group compared to the low VCM group. There was, however, no difference in the density of glutamate immunolabeling between the high VCM group compared to the vehicle-treated animals. One reason for this lack of difference was partially due to a significant increase in nerve terminal area within the high VCM group compared to either the low VCM- or vehicle-treated groups. The larger nerve terminal size in the high VCM group may be due to a small but sustained increase in glutamate neurotransmitter release with the ability of the terminal to maintain its supply of glutamate, while the terminals in the low VCM group showed evidence of glutamate depletion. This finding would be consistent with the hypothesis that increased glutamatergic activity may be associated with TD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247334
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Planted conifer seedling growth under two soil thermal regimes in high-elevation forest openings in interior British Columbia (1997)
    Springer
    New forests 14 (1997), S. 63-82 
    Details
    ISSN: 1573-5095
    Keywords: Engelmann spruce ; ESSF biogeoclimatic zone ; forest regeneration ; lodgepole pine ; root growth ; soil temperature ; spruce-fir forests ; subalpine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field trial was conducted investigating the single season growth response of 1+0 313 PSB Engelmann spruce (Picea engelmannii Parry ex Engelm.) and lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings planted into two different soil thermal regimes at three high-elevation locations spanning 200 km in the Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zone in the Cariboo Mountains of central British Columbia. Temperature treatments represented the extremes of soil temperature commonly found in high-elevation clear-cuts. A warm soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 18 to 25 °C at −10 cm) consisting of a bare mineral soil hummock (average dimensions of 100 cm × 100 cm × 40 cm) was contrasted with a cool soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 10 to 13 °C at −10 cm) comprised of organic forest floor overlying mineral soil. By the end of the growing season, seedlings of both species planted into the warm treatment generally exhibited greater root, stem, foliage, and total seedling biomass than cool treatment seedlings. Measurements of root growth at 30, 60, and 90 days after planting showed that total root number and total root length were consistently greater for warm treatment seedlings than for cool treatment seedlings. Root growth was greater from the bottom rather than from the side of the root plug for all seedlings. These results suggest that the effect of low soil temperatures on outplanted styroblock conifer seedlings is pronounced and may be limiting growth performance in high-elevation plantations in British Columbia. We recommend silvicultural treatments that secure natural regeneration, ensure that warmer microsites are always planted, and utilize seedling stocktypes able to make rapid lateral root growth into warmer surface organic horizons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006592705104
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    Paper (German National Licenses)
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