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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Seasonal rhythmicity in the occurrence of acute depressive episodes and the therapeutic efficacy of light exposure suggest the possible involvement of the pineal gland or other biological oscillators in the pathophysiology of depressive illness. We have performed studies to clarify whether different light/dark (LD) cycle schedules may induce changes in the biochemical targets of antidepressants in the rat CNS. In particular, we have investigated the effect of short- (LD 8: 16) or long-day (LD 14:10) photoperiods on different biochemical parameters of serotonergic neurons. A significant increase in the density of [3H]imipramine ([3H]IMI) binding and in the Vmax of 5-[3H]hydroxytryptamine (5-[3H]HT) uptake was found in the hypothalamus of LD 8:16- with respect to LD 14:10-exposed rats, whereas no difference was found in the kinetic properties of postsynaptic 5-HT receptors and in 5-HT metabolism in the hypothalami and cerebral cortices of rats exposed to the two different photoperiods. A seasonal rhythm of [3H]IMI binding sites and 5-HT uptake seems to exist only in certain brain areas, such as the hypothalamus, because no differences were found in the cerebral cortex of LD 14:10- and LD 8:16-accustomed rats. [3H]IMI binding and 5-HT uptake were significantly increased in the hypothalamus of rats accustomed to a light/dark-inverted cycle (DL 10:14) and killed 6 h after the stopping of lighting in comparison to rats exposed to normal LD 14:10 cycles and killed 6 h after the beginning of lighting. Therefore, a circadian modification of the serotonergic presynaptic sites seems to be present and related to light/dark exposure. Because the existence of endogenous compounds able to modulate [3H]IMI binding and 5-HT uptake, other than 5-HT, has been postulated in the mammalian brain, the involvement of these substances in the periodic changes observed could be suggested.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of neurochemistry 74 (2000), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Depression has been treated pharmacologically for over three decades, but the views regarding the mechanism of action of antidepressant drugs have registered recently a major change. It was increasingly appreciated that adaptive changes in postreceptor signaling pathways, rather than primary action of drugs on monoamine transporters, metabolic enzymes, and receptors, are connected to therapeutic effect. For some of the various signaling pathways affected by antidepressant treatment, it was shown that protein phosphorylation, which represents an obligate step for most pathways, is markedly affected by long-term treatment. Changes were reported to be induced in the function of protein kinase C, cyclic AMP-dependent protein kinase, and calcium/calmodulin-dependent protein kinase. For two of these kinases (cyclic AMP- and calcium/calmodulin-dependent), the changes have been studied in isolated neuronal compartments (microtubules and presynaptic terminals). Antidepressant treatment activates the two kinases and increases the endogenous phosphorylation of selected substrates (microtubule-associated protein 2 and synaptotagmin). These modifications may be partly responsible for the changes induced by antidepressants in neurotransmission. The changes in protein phosphorylation induced by long-term antidepressant treatment may contribute to explain the therapeutic action of antidepressants and suggest new strategies of pharmacological intervention.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 30 (1978), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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