Decreased serum leptin and muscle oxidative enzyme activity with a dietary loss of intra-abdominal fat in rats

• Published in: The Journal of nutritional biochemistry 2004, Vol.15 (1), p.24-29
• Main Authors: Zou, Buhao, Suwa, Masataka, Nakano, Hiroshi, Higaki, Yasuki, Ito, Tatsumi, Katsuta, Shigeru, Kumagai, Shuzo
• Format: Article
• Language: English
• Subjects: 3-Hydroxyacyl CoA Dehydrogenases - metabolism; Abdomen; Adipose Tissue - anatomy & histology; Animals; Biological and medical sciences; Citrate (si)-Synthase - metabolism; Diet, Reducing; Energy restriction; Epididymis; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Hexokinase - metabolism; Intra-abdominal adipose; Leptin; Leptin - blood; Male; Muscle oxidative enzyme activity; Muscle, Skeletal - enzymology; Rats; Rats, Wistar; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0955-2863; 1873-4847
• DOI: 10.1016/j.jnutbio.2003.09.004

The purpose of the present study was to investigate the relationship among intra-abdominal adipose storage, adaptation in the serum leptin concentration and skeletal muscle enzyme activity after a 4-week energy restriction (ER). Thirty-one male Wistar rats were divided into 40% energy restricted ( n=24) or ad libitum-fed control (CL) rats ( n = 7). The energy-restricted rats were grouped into the most fat (MF, n=7), medium ( n 10) and the least fat (LF, n=7) by their intra-abdominal fat pads mass (epididymal, mesenteric, and perirenal) after ER. A superficial portion of M. gastrocnemius tissue obtained before and after the diet period were analyzed to determine the activities of hexokinase (HK), β-hydroxyacyl CoA dehydrogenase (β-HAD) and citrate synthase (CS). Blood samples were also collected for a serum leptin assay. At the baseline, no difference was found in either the leptin concentration or the enzyme activities among LF, MF and CL. The serum leptin concentration was positively correlated with the muscle activities of β-HAD and CS, while it negatively correlated with HK/β-HAD. After ER, the activities of HK, β-HAD and CS were all significantly lower in LF than in CL. Among the energy-restricted rats, the intra-abdominal fat pad weight, leptin concentration and the activities of β-HAD, CS, β-HAD/CS all significantly correlated with one another. The changes in leptin and the activity of β-HAD were also positively correlated. These findings indicate that parallel decreases in the serum leptin and skeletal muscle enzyme activities with the energy restriction-induced intra-abdominal adipose reduction, thus may suggest the leptin to have a regulative effect on the muscle enzyme activity during ER.