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Göteborgs universitets publikationer

Postreceptor events involved in the up-regulation of beta-adrenergic receptor mediated lipolysis by testosterone in rat white adipocytes.

Författare och institution:
X Xu (Wallenberglaboratoriet); G De Pergola (-); Peter S Eriksson (-); Michael Fu (Wallenberglaboratoriet); B Carlsson (-); S Yang (-); Staffan Edén (Institutionen för fysiologi och farmakologi, Avdelningen för fysiologi); Per Björntorp (Hjärt-kärlinstitutionen)
Publicerad i:
Endocrinology, 132 ( 4 ) s. 1651-7
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
In the previous studies we have shown that testosterone increases lipolytic responsiveness to catecholamines in rat white adipocytes, and that is associated with an up-regulation of beta-adrenergic receptor density. However, the postreceptor events involved in the testosterone induced enhancement of beta-adrenergic receptor activated lipolysis in these cells have not been adequately studied, and were therefore investigated in the present study. Male Sprague Dawley rats were divided into three groups: control, castrated, and castrated treated with testosterone. The beta-adrenergic receptor-mediated cAMP accumulation, measured with RIA after isoproterenol (a beta-adrenergic agonist) stimulation was decreased in castrated rats, and reversed by testosterone treatment, suggesting a testosterone effect at or proximal to adenylate cyclase. However, no differences between the groups were found in abundance of G alpha protein messenger RNAs (G alpha s, G alpha i-1, and G alpha i-2) as analyzed by Northern blot and a solution hybridization RNase protection assay, or in G protein mass measured with a quantitative enzyme-linked immunosorbent assay in fat cell membrane preparation. Lipolysis stimulated by N6-monobutyryl-cAMP was reduced in castrated rats and recovered by testosterone treatment, suggesting that components distal to the adenylate cyclase, i.e. protein kinase A (PKA) and/or hormone sensitive lipase (HSL) also are involved in testosterone regulation of lipolysis. In conclusion, these and previous results suggest that the testosterone-induced increase in lipolytic response to catecholamines in rat white adipocytes is mediated through several events including an increased beta-adrenergic receptor density, probably an increased adenylate cyclase activity and an increased protein kinase A/hormone sensitive lipase activity at the postreceptor level with apparent absence of effect on the expression of G-proteins.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Medicinska grundvetenskaper ->
Medicinska grundvetenskaper ->
Cell- och molekylärbiologi
Adenylate Cyclase, metabolism, Adipose Tissue, cytology, metabolism, Animals, Cells, Cultured, Cholesterol Esterase, metabolism, Enzyme-Linked Immunosorbent Assay, GTP-Binding Proteins, genetics, metabolism, Male, Orchiectomy, Protein Kinases, metabolism, RNA, Messenger, metabolism, Rats, Receptors, Adrenergic, beta, physiology, Testosterone, pharmacology, Up-Regulation, physiology
Postens nummer:
Posten skapad:
2007-10-31 21:18
Posten ändrad:
2011-01-20 09:59

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