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  • 2000-2004  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pindolol accelerates the clinical actions of selective serotonin reuptake inhibitors (SSRIs) in man, and modulates extracellular levels of monoamines in corticolimbic structures in rats. Herein, we examined its influence upon electrical activity of serotonergic, dopaminergic and adrenergic perikarya in the dorsal raphe nucleus (DRN), ventral tegmental area (VTA) and locus coeruleus (LC) of anaesthetized rats. In analogy to the serotonin1A (5-HT1A) agonist, 8-OH-DPAT (−100%), pindolol dose-dependently (0.063– 1.0 mg/kg) decreased (−70%) the firing rate of serotonergic neurons. The inhibitory action of pindolol was abolished by the selective 5-HT1A antagonist, WAY-100,635 (0.031 mg/kg). In contrast, 8-OH-DPAT (+26%) and pindolol (0.25–4.0 mg/kg, +60%) dose-dependently increased the firing rate of dopaminergic cells. Of 57 neurons recorded (pindolol, 2.0 mg/kg), 36 (63%) were excited, 11 (19%) were unaffected and 10 (18%) were inhibited. This variable influence could be attributed to regularly firing neurons in the parabrachial subdivision, inasmuch as all neurons in the paranigral subnucleus were excited. The facilitation of firing by pindolol was accompanied by an increase in burst firing throughout the VTA. Both the increases in burst firing and in firing rate were reversed by WAY-100,635 (0.031 mg/kg). Finally, the electrical activity of adrenergic neurons was dose-dependently enhanced by 8-OH-DPAT and pindolol (+99% and +83%, respectively). WAY-100,635 reversed this excitation and, itself, inhibited the activity of adrenergic neurons. In conclusion, via engagement of 5-HT1A receptors, pindolol inhibits serotonergic, and activates dopaminergic and adrenergic, neurons in anaesthetized rats. Such actions may contribute to its influence upon mood, both alone and in association with antidepressant agents.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mirtazapine displayed marked affinity for cloned, human α2A-adrenergic (AR) receptors at which it blocked noradrenaline (NA)-induced stimulation of guanosine-5′-O-(3-[35S]thio)-triphosphate ([35S]-GTPγS) binding. Similarly, mirtazapine showed high affinity for cloned, human serotonin (5-HT)2C receptors at which it abolished 5-HT-induced phosphoinositide generation. Alpha2-AR antagonist properties were revealed in vivo by blockade of UK-14,304-induced antinociception, while antagonist actions at 5-HT2C receptors were demonstrated by blockade of Ro 60 0175-induced penile erections and discriminative stimulus properties. Mirtazapine showed negligible affinity for 5-HT reuptake sites, in contrast to the selective 5-HT reuptake inhibitor, citalopram. In freely moving rats, in the dorsal hippocampus, frontal cortex (FCX), nucleus accumbens and striatum, citalopram increased dialysate levels of 5-HT, but not dopamine (DA) and NA. On the contrary, mirtazapine markedly elevated dialysate levels of NA and, in FCX, DA, whereas 5-HT was not affected. Citalopram inhibited the firing rate of serotonergic neurons in dorsal raphe nucleus, but not of dopaminergic neurons in the ventral tegmental area, nor adrenergic neurons in the locus coeruleus. Mirtazapine, in contrast, enhanced the firing rate of dopaminergic and adrenergic, but not serotonergic, neurons. Following 2 weeks administration, the facilitatory influence of mirtazapine upon dialysate levels of DA and NA versus 5-HT in FCX was maintained, and the influence of citalopram upon FCX levels of 5-HT versus DA and NA was also unchanged. Moreover, citalopram still inhibited, and mirtazapine still failed to influence, dorsal raphe serotonergic neurons. In conclusion, in contrast to citalopram, mirtazapine reinforces frontocortical dopaminergic and corticolimbic adrenergic, but not serotonergic, transmission. These actions reflect antagonist properties at α2A-AR and 5-HT2C receptors.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Acute as well as chronic sun exposure induces biologically damaging effects in skin including photoageing and cancer. Ultraviolet (UV)A radiation is involved in this process; it is therefore important that sunscreen products provide efficient and stable protection in this range of wavelengths.Objectives  This study based on in vitro approaches was performed to demonstrate that photostability is an essential requirement to protect against UVA-induced genetic and dermal alterations.Methods  The protection afforded by two sunscreen products, differing with regard to their photostability, was studied using biological markers related to the genotoxic or photoageing impact of UVA or simulated solar UV radiation (UV-SSR). Comet assay was used to assess direct DNA breakage, photo-oxidized purines and lomefloxacin-induced DNA breaks in nuclei of normal human keratinocytes in culture. In similar conditions, detection of p53 accumulation was performed. The use of reconstructed skin in vitro allowed us to use a three-dimensional model to analyse the dermal and epidermal damage induced by UVA or UV-SSR exposure. Abnormal morphological features of the tissue as well as fibroblast alterations and matrix metalloproteinase-1 release induced by UV exposure have been studied after topical application of products on the skin surface.Results  The results showed that the photostable product afforded better protection with regard to all the criteria studied, compared with the photounstable product.Conclusions  These data demonstrate that the loss of absorbing efficiency within the UVA wavelength domain due to photoinstability may have detrimental consequences on cell function and lead to impairments that have been implicated in genotoxic events as well as in the photoageing process.
    Type of Medium: Electronic Resource
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