Investigation of the Effects of Curcumin on GLP1-R in Liver Tissue of Diabetic Rats

Abstract

The study aimed to examine the effect of curcumin, known for its antidiabetic properties, on the immunohistochemical localization and gene expression of glucagon-like peptide-1 receptor (GLP-1R) in the liver tissues of rats with experimental diabetic using reverse transcription polymerase chain reaction (RT-PCR). For this, 24 Sprague–Dawley rats were divided into four groups—control, sham, diabetic, and diabetic + curcumin groups. No administrations were performed for the control group, and 50 mg/kg streptozotocin was administered to the rats in the diabetic and diabetic + curcumin groups. After diabetes was established, 100 mg/kg curcumin was administered intraperitoneally to the diabetic + curcumin group rats for 21 days. In the sham group, intraperitoneal ethanol and isotonic sodium chloride solution were administered. Tissues sampled at the end of the experiment were examined histologically and immunohistochemically for GLP-1R localization, and RT-PCR was used to determine GLP-1R gene expression levels. In the histological examinations, a normal histological structure was observed in the tissue samples of the control and sham groups, whereas various degenerations such as sinusoidal wall enlargement and vacuolization in the hepatocytes were observed in the diabetic group. Furthermore, these degenerative findings were alleviated in the diabetic + curcumin group. In the immunohistochemical examinations, mostly the hepatocytes around the vena centralis, some endothelial, and some Kupffer cells were found to be positive for GLP-1R. The intensity of immunoreactivity was lower in the diabetic group and higher in the diabetic + curcumin group compared to the diabetes group. With regard to molecular analysis, there was no significant difference between the groups in terms of GLP-1R gene expression, but the mean expression level was higher in the diabetic + curcumin group. In conclusion, curcumin was seen to increase GLP-1R expression in the liver of the rats with diabetes. Since GLP-1R is one of the targets of diabetes treatment, curcumin can be used as a therapeutic agent for treating diabetes and alleviating its complications.