A study on changes of serum leptin and its expression in CAPD animal model

Choi, Jae Young; Yu, Soo Jeong; Oh, Dong Jin; Yu, Suk Hee

Abstract

BACKGROUND: The ob gene product leptin is thought to be an adipostatic hormone through the regulation of food intake and energy expenditure. There are many reports that serum leptin concentration was increased in CRF patients, especially CAPD patients. Increased body fat mass, decreased residual renal function, active inflammation, hyperinsulinemia and intraperitoneal hyperglycemia all are suggested to influence serum leptin concentration in CAPD patients. In order to investigate the pathogenic mechanism of increased serum leptin concentration in CAPD patients, we observed the changes of serum leptin concentration, leptin expression in the mesenteric and epididymal fat tissue in CAPD animal model. METHOD: 10 CAPD animal models (Sprague-Dawley rat, male) were enrolled in this study. Serum leptin concentration was measured by RIA before start of CAPD (baseline data), 7 days after start of CAPD. Simultaneously, mesenteric and epididymal fat tissues were extracted for analysis of ob gene expression. Ob mRNA expression was measured by northern blot assay. The changes of serum insulin concentration, serum lactate concentration, fasting blood sugar and urine volume were measured.
RESULTS
Leptin expression in the mesenteric fat tissue was significantly increased 7 days after start of CAPD (0.19+/-0.03, 0.46+/-0.22, p<0.05). On the contrary, serum leptin concentration and leptin expression in the epididymal fat tissue were decreased 7 days after start of CAPD. Significant increase of serum insulin concentration and urine volume were observed during the study period.
CONCLUSION
In these results, hyperleptinemia in CAPD patients may be associated with glucose uptake into the mesenteric fat tissue and decreased residual renal function. Therefore, a study of the changes of serum leptin concentration and leptin expression in fat tissue will be needed in nephrecomized CAPD animal model.