| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; and 2Department of Biochemistry, Nutrition Research Center, Wake Forest University Health Sciences, Winston-Salem, North Carolina
Submitted 23 September 2005 ; accepted in final form 13 April 2006
In vitro, leptin secretion is regulated at the level of mRNA translation by the rapamycin-sensitive mammalian target of rapamycin (mTOR) and its agonist leucine (Leu). Studies were conducted on meal-trained rats to evaluate the potential physiological relevance of these in vitro findings and the role of Leu in affecting rises in plasma leptin observed after a meal. In the first study, we correlated changes in plasma insulin and Leu to mTOR-signaling pathway activation and plasma leptin at different times during meal feeding. Rapid rises in plasma insulin and Leu, along with mTOR signaling (phosphorylation of eIF4G, S6K1, rpS6, and 4E-BP1) in adipose tissue were observed during the 3-h meal and declined thereafter. Plasma leptin rose more slowly, peaking at 3 h, and was inhibited by rapamycin (0.75 mg/kg) pretreatment. In another experiment, oral Leu or norleucine was provided instead of a meal. Leu and norleucine stimulated a rise in plasma leptin; however, the magnitude was less than the response to a complete meal. In a third study, rats were provided a meal that lacked Leu, branched-chain amino acids, or all amino acids. Stimulation of leptin secretion was reduced 
40% in animals provided the Leu-deficient meal. Further reductions were not observed by removing the other amino acids. Thus Leu appears to regulate most of the effects of dietary amino acids on the postprandial rise in plasma leptin but is responsible only for part of the leptin response to meal feeding.
protein synthesis; translation initiation; obesity; rats; meal feeding; meal trained
This article has been cited by other articles:
|
|
 |
|
  M.-J. Lee and S. K. Fried Integration of hormonal and nutrient signals that regulate leptin synthesis and secretion Am J Physiol Endocrinol Metab, June 1, 2009; 296(6): E1230 - E1238. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Avruch, X. Long, S. Ortiz-Vega, J. Rapley, A. Papageorgiou, and N. Dai Amino acid regulation of TOR complex 1 Am J Physiol Endocrinol Metab, April 1, 2009; 296(4): E592 - E602. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Nairizi, P. She, T. C. Vary, and C. J. Lynch Leucine Supplementation of Drinking Water Does Not Alter Susceptibility to Diet-Induced Obesity in Mice J. Nutr., April 1, 2009; 139(4): 715 - 719. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. R. Ropelle, J. R. Pauli, M. F. A. Fernandes, S. A. Rocco, R. M. Marin, J. Morari, K. K. Souza, M. M. Dias, M. C. Gomes-Marcondes, J. A.R. Gontijo, et al. A Central Role for Neuronal AMP-Activated Protein Kinase (AMPK) and Mammalian Target of Rapamycin (mTOR) in High-Protein Diet-Induced Weight Loss Diabetes, March 1, 2008; 57(3): 594 - 605. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. She, C. Van Horn, T. Reid, S. M. Hutson, R. N. Cooney, and C. J. Lynch Obesity-related elevations in plasma leucine are associated with alterations in enzymes involved in branched-chain amino acid metabolism Am J Physiol Endocrinol Metab, December 1, 2007; 293(6): E1552 - E1563. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.-J. Lee, Y. Wang, M. R. Ricci, S. Sullivan, C. D. Russell, and S. K. Fried Acute and chronic regulation of leptin synthesis, storage, and secretion by insulin and dexamethasone in human adipose tissue Am J Physiol Endocrinol Metab, March 1, 2007; 292(3): E858 - E864. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
