The impact of diabetes mellitus on the serotonergic system in cardiomyopathy development

Abstract

The main objective of the study was to explore some of the intrinsic serotonergic system changes suffered during the development of diabetic cardiomyopathy (DCM). The diabetes mellitus model by streptozotocin (STZ) was used with their respective controls. Hearts were obtained at 7, 14 and 21 days after STZ to evaluate: tryptophan-5-hydroxylase (TPH) activity and serotonin (5-HT) concentration measured by high-resolution liquid chromatography. Besides, it was determined the expression of 5-HT_1B, 5-HT_2A, and 5-HT_2B receptors, as well as the serotonin transporter (SERT) expression by means of Western blot analyses. At day, 7, diabetic rats showed a remarkable decrease of activity and expression of the TPH1 and of the 5-HT concentration (P < 0.001), without any change on TPH2 expression. At day 14 it was also observed a decrease in the expression of SERT and 5-HT_2B receptors (P < 0.001), and an increase in 5-HT_2A receptors’ expression (P < 0.001). No changes were observed of 5-HT_1B expression. These results suggest that the observed alterations may play an important role in the development of the DCM, which is frequently observed in diabetic patients.