Expression Of Leptin In Different Status Of Thyroid Function

PrefaceLeptin, the obese gene product, is secreted exclusively by adipo-cytes and is thought to act as a lipostatic signal that regulateds body weight homeostasis. The serum leptin levels are positively correlated with BMI, and relation between leptin and endocrinology and metabolism is very important. Recent reports suggest that leptin is a role for insulin, glucocorticoids, and sex hormones regulation. But the reports of serum leptin levels in different status of thyroid function are different, so we measured the levels of leptin in different status of thyroid function and investigated the relation between thyroid hormone levels and human serum immunoreactive leptin levels and insulin levels and triglycerides and cholesterol levels in different status of thyroid function.MaterialSpecimen source; We studied 35 hyperthyriod patients (11 males,24 females) , 33 hypothyriod patients(10 males,23 females) , and 20 euthyroid controls(6 males, 14 females) . According to serum thyroid hormone levels, 88 patients were divided into three groups. BMI is range from 18.5 to 25 kg/m2.ReagentThe DSL - 23100 Leptin Coated - Tube Immunoradiometric Assay kit. Diagnostic Systems Laboratoies, Inc, USA. Insuli,TSH,FT3 and FT4 immulite kit. DPC , USA. Triglycerides and Cholesterol Reagent. Shanghai Fenghui Medical Inc.MethodsSerum leptin concentrations were measured with an enzymatically amplified " two - step" sandwich - type immunoassay method. Insulin , TSH,FT3 and FT4 were determinded by chemiluminescent immunoas-says. Triglycerides were measured with GPO trinder method. Cholesterol were measured with enzymatic method. Body weight, height and body mass index were determined for each patients.Data were presented as means + S. D. The serum leptin,insulin, triglycerides cholesterol, TSH, FT3 and FT4 levels were compared a-mong the various groups using t - test and within each group by liner regression analysis.ResultsAge, body weight and BMI were similar in all three groups. The hyperthyriod group had significantly higher levels of FT3 and FT4 than the other groups. And TSH were significantly lower in this group. In contrast, the hypothyriod group tended to have lower levels of FT3 and FT4. And the hypothyriod group had significantly higher levels of TSH than other groups.The serum leptin concentrations levels were highly correlated with BMI in the three groups. It was generally significantly higher inwomen than in men with comparable BMI ranges in all the three groups. Serum leptin concentrations in the hyperthyriod group were no significant change with the normal group. Serum leptin concentrations in the hypothyriod group were significantly lower than those in the normal group. Serum insulin concentrations in the hyperthyriod and hypothyriod group were no significant change with the normal group. Serum triglycerides concentrations in the hyperthyriod group were no significant change with the normal group. Serum cholesterol concentrations in the hyperthyriod group were significantly lower than those in the normal group. And serum triglycerides concentrations in the hypothyriod were significantly higher thain those in the normal group. Serum cholesterol concentrations in the hypothyriod group were no significant change with the normal group.DiscussionLeptin, the obese gene product, is secreted exclusively by adipo-cytes. It acts on central neural networks and regulates energy metabolism according to reducing the expression of neuropeptideY in hypo-thalamus and keeps the relatively stabilization of body. It is validated that the serum leptin concentrations levels are highly correlated with BMI not only in hyperthyriod but in hypothyriod. The two way change of thyroid hormone can not transform the correlation.In this study, the levels of leptin were generally significantly higher in women than in men with comparable BMI ranges in all the three groups. The mechanisms may be ( 1) Testosterone reduces the level of leptin and the expression of ob gene in adipocytes. (2) The diff...