The regulation of ob gene expression in abdominal subcutaneous adipose tissue was investigated using a reverse transcription-competitive PCR method to quantify the mRNA level of leptin. Leptin mRNA level was highly correlated with the body mass index of 26 subjects (12 lean, 7 non-insulin-dependent diabetic, and 7 obese patients). The effect of fasting on ob gene expression was investigated in ...

Cytokines, such as tumor necrosis factor (TNF) and interleukin-6, may contribute to the anorexia and cachexia of infection, cancer, and AIDS. The present study tests the hypothesis that endotoxin alters the expression of two key fat cell proteins, leptin and β3-adrenergic receptor (β3-AR), through a mechanism involving TNF-α. Increasing doses of Escherichia coli endotoxin (lipopolysaccharide, L...

Leptin biosynthesis in adipose cells in vivo is increased by food intake and decreased by food deprivation. However, the mechanism that couples leptin production to food intake remains unknown. We found that addition of leucine to isolated rat adipocytes significantly increased leptin production by these cells, suggesting that postprandial leptin levels may be directly regulated by dietary leuc...

Leptin controls feeding behavior and insulin secretion from pancreatic beta-cells. Insulin stimulates the production of leptin, thereby establishing an adipoinsular axis. Earlier we identified leptin receptors on pancreatic beta-cells and showed leptin-mediated inhibition of insulin secretion by activation of ATP-sensitive potassium channels. Here we examine transcriptional effects of leptin on...

Leptin is known as a cytokine mostly produced by fat cells and implicated in regulation of energy metabolism and food intake but has also been shown to be involved in many physiological mechanisms such as tissue metabolism and cell differentiation and proliferation. In particular, leptin influences the development of mammary gland. Although leptin expression in mammary gland has been studied in...

In addition to its well-known role as an adipostat in adult mammals, leptin has diverse physiological and developmental actions in vertebrates. Leptin has been shown to promote development of hypothalamic circuits and to induce mitosis in different brain areas of mammals. We investigated the ontogeny of leptin mRNA, leptin actions on cell proliferation in the brain, and gene expression in the p...

To examine the functional role of CRH in the regulation of energy homeostasis by leptin, we measured the effects of the CRH antagonist, alpha-helical CRH 8-41 (alphaCRH) on a number of factors affected by leptin activity. These included food intake, body weight, hypothalamic c-fos-like immunoreactivity (c-FLI), weight and histological characterization of white adipose tissue, and mRNA expressio...

BACKGROUND A marked elevation of serum leptin is observed soon after the start of peritoneal dialysis (PD), suggesting that leptin production may be stimulated by this treatment. Glucose metabolism is the major factor regulating leptin. The current study was designed to test if glucose-based PD fluids might regulate leptin production in vitro. METHODS 3T3-L1 adipocytes were exposed to a 50:50...

Protein tyrosine phosphatase 1B (PTP1B) contributes to leptin resistance by inhibiting intracellular leptin receptor signaling. Mice with whole body or neuron-specific deletion of PTP1B are hypersensitive to leptin and resistant to diet-induced obesity. Here we report a significant increase in PTP1B protein levels in the mediobasal hypothalamus (P = 0.003) and a concomitant reduction in leptin ...

Plasma leptin and ob gene mRNA levels were increased in mice following bacterial peritonitis, and blocking an endogenous tumor necrosis factor alpha (TNF-alpha) response blunted the increase. However, plasma leptin concentrations did not correlate with the associated anorexia. We conclude that leptin expression is under partial regulatory control of TNF-alpha in peritonitis, but the anorexia is...