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This Article Full Text Full Text (PDF) All Versions of this Article: 285/2/E318    most recent 00456.2002v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Ramos, M. P. Articles by Herrera, E. Search for Related Content PubMed PubMed Citation Articles by Ramos, M. P. Articles by Herrera, E.

Fat accumulation in the rat during early pregnancy is modulated by enhanced insulin responsiveness

Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, E-28668, Madrid, Spain

Submitted 22 October 2002 ; accepted in final form 4 April 2003

Insulin sensitivity has been implicated in the variation of fat accumulation in early gestation by as-yet-unknown mechanisms. In the present study, we analyzed the insulin sensitivity of lipolysis and lipogenesis in lumbar adipocytes from rats at 0, 7, 14, and 20 days of gestation. In adipocytes of 7-day pregnant rats, we found a twofold decrease in both -agonist (isoproterenol and BRL-37344)-stimulated lipolysis and ₃-adrenoceptor protein but not in lipolysis initiated by forskolin or isobutylmethylxanthine, suggesting a modification of the lipolytic pathway at the receptor level. Whereas adipocytes from 7-day pregnant rats showed a twofold increase in fatty acid synthesis from glucose, those from 20-day pregnant animals displayed a decreased lipogenic activity. Insulin responsiveness of the lipolytic and lipogenic pathways was analyzed by dose-response experiments, giving evidence for the involvement of improved insulin responsiveness in the enhanced lipogenic and reduced lipolytic activities of adipocytes in early pregnancy. In contrast, insulin resistance is responsible for lower antilipolytic and lipogenic actions of insulin in late pregnant animals. In conclusion, the present study shows that enhanced adipose tissue insulin responsiveness during early pregnancy contributes to maternal fat accumulation, whereas decreased insulin responsiveness during late gestation modulates fat breakdown.

adipose tissue; ₃-adrenoceptor; lipolysis; lipogenesis

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