beta. -Adrenergic stimulation of brown adipocyte proliferation
- Laval Univ., Quebec City (Canada) Laboratoire de Thermoregulation et Metabolisme Energetique, Lyon (France)
The mechanisms of brown adipose tissue (BAT) growth were studied by quantitative photonic radioautography using tritiated thymidine to follow mitotic activity. To identify the nature of the adrenergic pathways mediating brown adipocyte proliferation and differentiation, the effects of cold exposure (4 days at 4{degree}C) on BAT growth were compared with those induced by treating rats at 25{degree}C with norepinephrine (a mixed agonist), isoproterenol (a {beta}-agonist), and phenylephrine (an {alpha}-agonist). Norepinephrine mimicked the effects of cold exposure, not only on the mitotic activity, but also on the distribution of the labeling among the various cellular types. Isoproterenol entirely reproduced the effects of norepinephrine both on the labeling index and on the cellular type labeling frequency. These results demonstrate that norepinephrine triggers a coordinated proliferation of brown adipocytes and endothelial cells in warm-exposed rats that is similar to that observed after cold exposure. They also suggest that cold exposure stimulates BAT growth by increasing the release of norepinephrine from sympathetic nerves and that the neurohormone activates mitoses in BAT precursor cells via {beta}-adrenergic pathways.
- OSTI ID:
- 6945415
- Journal Information:
- American Journal of Physiology; (USA), Vol. 254:1; ISSN 0002-9513
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ADIPOSE TISSUE
AUTORADIOGRAPHY
ADRENALINE
BIOLOGICAL EFFECTS
CELL PROLIFERATION
TEMPERATURE EFFECTS
SYMPATHOMIMETICS
CELL DIFFERENTIATION
MITOSIS
PHYSIOLOGY
RATS
THYMIDINE
TRITIUM COMPOUNDS
ADRENAL HORMONES
ANIMAL TISSUES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZINES
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL DIVISION
CONNECTIVE TISSUE
DRUGS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
MAMMALS
NEUROREGULATORS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RIBOSIDES
RODENTS
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques