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  • 1
    Electronic Resource
    Electronic Resource
    Redox modulation of synaptic responses and plasticity in rat CA1 hippocampal neurons (1997)
    Springer
    Experimental brain research 113 (1997), S. 343-352 
    Details
    ISSN: 1432-1106
    Keywords: Memory ; Glutamate receptors ; GABA receptors ; Modulatory sites of NMDA receptors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of redox reagents on excitatory and inhibitory synaptic responses as well as on the bidirectional plasticity of α-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA) andN-methyl-d-aspartate (NMDA) receptor-mediated synaptic responses were studied in CA1 pyramidal neurons in rat hippocampal slices. The oxidizing agent 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB, 200 μM) did not affect AMPA, GABAA or GABAB receptor-mediated synaptic responses or the activation of presynaptic metabotropic receptors. However, DTNB irreversibly decreased (by approximately 50%) currents evoked by focal application of NMDA. DTNB also decreased the NMDA component of the EPSC. The reversal potential of NMDA currents and the Mg2+ block were not modified. In the presence of physiological concentrations of Mg2+ (1.3 mM), DTNB did not affect the NMDA receptor-dependent induction of long-term potentiation (LTP) or long-term depression (LTD) expressed by AMPA receptors. In contrast, DTNB fully prevented LTP and LTD induced and expressed by NMDA receptors. Plasticity of NMDA receptor-mediated synaptic responses could be reinstated by the reducing agenttris-(2-carboxyethyl) phosphine (TCEP, 200 μM). These results suggest that persistent, bidirectional changes in synaptic currents mediated by NMDA receptors cannot be evoked when these receptors are in an oxidized state, whereas NMDA-dependent LTP and LTD are still expressed by AMPA receptors. Our observations raise the possibility of developing therapeutic agents that would prevent persistent excitotoxic enhancement of NMDA receptor-mediated events without blocking long-term modifications of AMPA receptor-mediated synaptic responses, thought to underlie memory processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450332
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Insecticidal defenses of Piperaceae from the neotropics (1995)
    Springer
    Journal of chemical ecology 21 (1995), S. 801-814 
    Details
    ISSN: 1573-1561
    Keywords: Piperaceae ; botanical insecticide ; isobutyl amides ; lignans ; dillapiol ; conocarpan ; piperlonguminine ; European corn borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Insecticidal and growth-reducing properties of extracts of 14 species of American neotropical Piperaceae were investigated by inclusion in diets of a polyphagous lepidopteran, the European corn borer,Ostrinia nubilalis. Nutritional indices suggested most extracts acted by postdigestive toxicity.Piper aduncum, P. tuberculatum, andP. decurrens were among the most active species and were subjected to bioassay-guided isolation of the active components. Dillapiol was isolated from the active fraction ofP. aduncum, piperlonguminine was isolated fromP. tuberculatum, and a novel neolignan fromP. decurrens. The results support other studies on Asian and AfricanPiper species, which suggest that lignans and isobutyl amides are the active defence compounds in this family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02033462
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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