Study of leptin gene expression changes in streptozotocin-induced diabetic rats

ABSTRACT

Leptin, a peptide hormone, is the product of [ob] Gene. Leptin regulate body weight and composition through reducing appetite and energy expenditure in rodents and humans. The aim of this study was to evaluate differences in expression of Leptin Gene in different tissues of streptozotocin induced diabetic rats. 40 Sprague Dawely rat were selected. Intra peritoneal injection was carried out in 20 rats and another 20 rats were used as control. After injection of 60mg/kg Streptozotocin, animals were transformed into diabetic. Glucose was measured by glucose oxidase method. Leptin and insulin were measure by commercially available immunoassay kits. After one week treatment, different tissues including adipose tissues, Spleen, epidydimis, and Liver of both control and experimental animals were dissected. For investigation of any changes of the Leptin gene expression in different tissues, RNA was extracted using Trizol method. By using RT-PCR technique, Leptin cDNA and beta-actin cDNA as internal control were constructed and PCR was carried out. The RT-PCR products were detected on 2% agarose gel using electrophoresis. Mean serum levels of Leptin was 5.23 +/- 0.45 ng/ml before injection of streptozotocin and markedly decreased in STZ induced diabetic rats to 0.79 +/- 0.25 ng/ml. This decrease was statistically significant [P<0.05]. There was a direct and significant correlation between leptin and insulin in streptozotocin-induced diabetic rats [r=0.37, P<0.05] while, this was reverse in control rats [r= -0.28, P<0.05]. Using RT-PCR method, Leptin gene expression in different tissues including fat epidydimis, liver, and spleen showed that the intensity of leptin band with 452 bp was decreased in diabetic rats in comparison to normal rats. Actin Gene expression was identified in PCR products having 403 bp and the intensity was constant in both groups. The reduction rates of [ob] mRNA in fat epidydimis tissue in STZ diabetic rats was remarkable in comparison to Spleen and Liver. It is speculated that Leptin gene could be under regulation of insulin dependent mechanism in diabetic rats and by modulating Leptin gene expression in diabetic patients, it may be useful in clinical practices