Increased OB gene expression leads to elevated plasma leptin concetrations in patients with chronic primary hyperinsulinemia
| Autor: | D. Zorretta, E. Maroccia, A. Buongiorno, Guido Tamburrano, Fabrizio Barbetti, Andrea Giaccari, Monica D’Adamo, Frida Leonetti, Paolo Sbraccia |
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| Jazyk: | angličtina |
| Rok vydání: | 1998 |
| Předmět: |
Adult
Blood Glucose Leptin Male medicine.medical_specialty Endocrinology Diabetes and Metabolism medicine.medical_treatment Gene Expression Adipose tissue Peptide hormone Biology Polymerase Chain Reaction Settore MED/13 - Endocrinologia Hyperinsulinism Internal medicine Internal Medicine medicine Hyperinsulinemia Humans Insulin Obesity RNA Messenger Insulinoma Pancreatic hormone digestive oral and skin physiology Proteins RNA-Directed DNA Polymerase Fasting Middle Aged medicine.disease Pancreatic Neoplasms Endocrinology Adipose Tissue Female hormones hormone substitutes and hormone antagonists |
| Popis: | Leptin, a hormone secreted by adipocytes, decreases food intake and increases energy expenditure. The role of insulin in the regulation of leptin secretion is poorly understood and is still a topic of debate. Insulin increases leptin mRNA synthesis in rodents, but in humans, the available data are discordant. To investigate the role of chronic hyperinsulinemia in the regulation of plasma leptin concentrations, we studied 13 patients with surgically confirmed insulinoma before and after tumor removal, along with 15 healthy control subjects matched for sex, age, and BMI. Immunoreactive plasma leptin levels were measured by radioimmunoassay; leptin mRNA levels were also determined by reverse transcription-competitive polymerase chain reaction in a subgroup of six patients with insulinoma and six control subjects. All determinations were made with subjects in the fasting state. Plasma leptin concentrations correlated positively with leptin mRNA levels (r = 0.880, P < 0.001). Leptin levels, both plasma protein and mRNA, were significantly higher in the insulinoma patients than in the control subjects (plasma protein: 17.5 +/- 3.6 vs. 2.9 +/- 0.4 ng/ml, respectively, P < 0.001; mRNA: 0.98 +/- 0.33 vs. 0.19 +/- 0.064 amol/microg RNA, respectively, P < 0.05), and they correlated positively with fasting plasma insulin levels in the patients with insulinoma (plasma protein: r = 0.686, P < 0.01; mRNA: 0.796, P < 0.05). Finally, removal of the insulin-secreting tumor was followed by the normalization of plasma leptin levels. In summary, in patients with insulinoma, 1) plasma leptin levels and leptin mRNA are elevated; 2) a direct relationship exists between leptin, both circulating protein and mRNA, and insulin concentrations; and 3) plasma leptin returns to normal levels after tumor removal. These data, therefore, support a role for insulin in the chronic regulation of leptin gene expression. |
| Databáze: | OpenAIRE |
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