S Livi

Publications (2)7.18 Total impact

• Article: Methylamine-dependent release of nitric oxide and dopamine in the CNS modulates food intake in fasting rats.

  L Raimondi, C Alfarano, A Pacini, S Livi, C Ghelardini, G DeSiena, R Pirisino
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  ABSTRACT: Methylamine is an endogenous aliphatic amine exhibiting anorexigenic properties in mice. The aim of this work was to show whether methylamine also modifies feeding behaviour in rats and, if so, to identify the mediator(s) responsible for such effects. Microdialysis experiments with the probe inserted in the periventricular hypothalamic nucleus were carried out in 12 h starved, freely moving rats. Collected perfusate samples following methylamine injection (i.c.v.) were analysed for nitric oxide by chemiluminescence and for dopamine and 5-hydroxytryptamine content by HPLC. Kv1.6 potassium channel expression was reduced by antisense strategy and this decrease quantified by semi-quantitative RT-PCR analysis. Methylamine showed biphasic dose-related effects on rat feeding. At doses of 15-30 microg per rat, it was hyperphagic whereas higher doses (60-80 microg) were hypophagic. Methylamine stimulated central nitric oxide (+115% vs. basal) following hyperphagic and dopamine release (60% over basal values) at hypophagic doses, respectively. Treatment with L-N(G)-nitro-L-arginine-methyl ester (i.c.v. 2 microg 10 microl(-1)) or with alpha-methyl-p-tyrosine (i.p. 100 mg kg(-1)) before methylamine injection, reduced nitric oxide output and hyperphagia, or dopamine release and hypophagia respectively. Moreover, hypophagia and hyperphagia, as well as nitric oxide and dopamine release were significantly reduced by down-regulating brain Kv1.6 potassium channel expression. The effects of methylamine on feeding depend on the hypothalamic release of nitric oxide and dopamine as a result of interaction at the Kv1.6 channels. The study of methylamine levels in the CNS may provide new perspectives on the physiopathology of alimentary behaviour.
  British Journal of Pharmacology 05/2007; 150(8):1003-10. · 4.41 Impact Factor
• Article: The Ultraviolet Coronagraph Spectrometer for the solar and heliospheric observatory

  J. L. Kohl, R. Esser, L. D. Gardner, S. Habbal, P. S. Daigneau, E. F. Dennis, G. U. Nystrom, A. Panasyuk, J. C. Raymond, P. L. Smith, [......], J. G. Timothy, G. Gloeckler, A. Allegra, G. Basile, R. Brusa, B. Wood, O. H. W. Siegmund, W. Fowler, R. Fisher, M. Jhabvala
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  ABSTRACT: The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is composed of three reflecting telescopes with external and internal occultation and a spectrometer assembly consisting of two toric grating spectrometers and a visible light polarimeter. The purpose of the UVCS instrument is to provide a body of data that can be used to address a broad range of scientific questions regarding the nature of the solar corona and the generation of the solar wind. The primary scientific goals are the following: to locate and characterize the coronal source regions of the solar wind, to identify and understand the dominant physical processes that accelerate the solar wind, to understand how the coronal plasma is heated in solar wind acceleration regions, and to increase the knowledge of coronal phenomena that control the physical properties of the solar wind as determined byin situ measurements. To progress toward these goals, the UVCS will perform ultraviolet spectroscopy and visible polarimetry to be combined with plasma diagnostic analysis techniques to provide detailed empirical descriptions of the extended solar corona from the coronal base to a heliocentric height of 12 solar radii.
  Solar Physics 01/1995; 162(1):313-356. · 2.78 Impact Factor