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Changes of Noradrenergic Activity and Lipolysis in the Subcutaneous Abdominal Adipose Tissue of Hypo‐ and Hyperthyroid Patients: An In Vivo Microdialysis Study
Author(s) -
NEDVIDKOVA JARA,
HALUZIK MARTIN,
BARTAK VLADIMIR,
DOSTALOVA IVANA,
VLCEK PETR,
RACEK PAVEL,
TAUS MICHAL,
BEHANOVA MAGDALENA,
SVACINA STEPAN,
ALESCI SALVATORE,
PACAK KAREL
Publication year - 2004
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1296.067
Subject(s) - microdialysis , lipolysis , adipose tissue , subcutaneous adipose tissue , in vivo , subcutaneous tissue , subcutaneous fat , medicine , endocrinology , chemistry , pathology , biology , dopamine , microbiology and biotechnology
A bstract : Thyroid function plays an important role in the regulation of overall metabolic rate and lipid metabolism. However, it is uncertain whether thyroid hormones directly affect lipolysis in adipose tissue and to what extent those changes contribute to overall metabolic phenotype. Our study was designed, using the microdialysis technique, to determine basal and isoprenaline‐stimulated local lipolysis and to determine local concentrations of lipolysis‐regulating catecholamines in abdominal subcutaneous adipose tissue in 12 patients with hypothyroidism, 6 patients with hyperthyroidism, and 12 healthy control subjects. Plasma norepinephrine (NE) concentrations in hypothyroid subjects were significantly higher than in the control and hyperthyroid groups. In contrast, systemic, adipose NE levels in hypothyroid patients were decreased relative to controls. Hyperthyroidism, on the other hand, resulted in four‐fold higher adipose NE levels. Basal lipolysis measured by glycerol concentrations in adipose tissue was significantly attenuated in hypothyroid patients and markedly increased in hyperthyroid patients in comparison with the control group. In addition to differences in basal lipolysis, hypothyroidism resulted in attenuated, and hyperthyroidism in enhanced, lipolytic response to local stimulation with β 1,2 ‐adrenergic agonist isoprenaline. These results demonstrate that lipolysis in abdominal subcutaneous adipose tissue is strongly modulated by thyroid function. We suggest that thyroid hormones regulate lipolysis primarily by affecting local NE concentration and/or adrenergic postreceptor signaling.