title: Characteristics of metabolic changes in adipocytes of growing rats.
abstract: Adipocytes, cells of white fat tissue, store energy in the form of lipids and have also endocrine functions. Disturbances in adipocyte metabolism lead to decreased or excessive fat tissue accumulation and are associated with numerous diseases. Pathologic alterations in adipose tissue are known to develop with age, however, changes in young, growing subjects are poorly elucidated. In the present study, glucose transport and metabolism, hyperpolarization of the inner mitochondrial membrane and the lipolytic activity were compared in the epididymal adipocytes of 8-week-old and 16-week-old rats. It was demonstrated that glucose conversion to lipids, glucose transport and oxidation was decreased in the adipocytes of the older animals. These effects were accompanied by increase in lactate release and by decrease in hyperpolarization of the mitochondrial membrane. Lipolytic response to epinephrine was increased (at lower concentrations of the hormone) or reduced (at higher concentration) in the adipocytes of the older rats. However, induction of lipolysis by the direct activation of protein kinase A induced similar response. It was also demonstrated that inhibition of phosphodiesterase 3B or adenosine A1 receptor blocking caused lower lipolysis in the cells of the older rats. Moreover, antilipolytic action of insulin was impaired in the adipocytes of these rats, probably due to changes in the initial steps of the insulin signaling pathway. However, the use of the pharmacologic inhibitor of protein kinase A instead of insulin resulted in similar antilipolysis in both groups of cells. These results show that, in spite of relatively small age difference, substantial changes in adipose tissue metabolism develop in these animals. Decreased response to insulin action seems to be particularly relevant finding.
authors.affiliation: Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland.
authors.forename: Kinga
authors.initials: K
authors.lastname: Gwóźdź
authors.affiliation: Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szkudelski
authors.affiliation: Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Wolynska 35, 60-637 Poznan, Poland. Electronic address: katewa@poczta.onet.eu.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szkudelska
mesh_terms: D058916:Adenosine A1 Receptor Antagonists / Q000494:pharmacology; D017667:Adipocytes / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D004837:Epinephrine / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D008066:Lipolysis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D058987:Phosphodiesterase 3 Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D058916:Adenosine A1 Receptor Antagonists; D058987:Phosphodiesterase 3 Inhibitors; D005947:Glucose; D004837:Epinephrine
keywords: Adipocytes; Growing rats; Metabolism