Background:

Cardiomyocytes synthesize, utilize and reuptake serotonin, which is involved in the paracrine and autocrine modulation of heart activity and in the pathophysiology of some cardiovascular diseases.

Objective:

To determine the expression of tryptophan-5-hydroxylase (TPH) 1 and 2, serotonin transporter protein (SERT) and serotonergic receptors in hearts with dilated cardiomyopathy (DCM) compared to controls.

Method:

A comparative study was performed in six tissue blocks of the left ventricular free wall (LVWL) and inter-ventricular septum from patients who died of DCM and six who died of no cardiovascular diseases (controls). Five slices from each block were obtained to determine the expression of TPH1 and TPH2, SERT and serotonergic receptors with antibodies specific for immunofluorescence. Immunofluorescence was analyzed by Student’s t-test, accepting a significance level of p < 0.05.

Results:

An increase in TPH1, TPH2, 5-HT2A and 5-HT2B receptors expression were observed in dilated structures compared to controls (p < 0.05). For dilated inter-ventricular septum, the 5-HT4 receptor increased its expression (p < 0.05), and SERT in PLVI compared to controls (p < 0.05).

Conclusions:

These results suggest that the increases observed in the expression of TPH, SERT, and serotonergic receptors in hearts with DCM compared to controls could play an important role in the pathophysiology of MCD in humans