Fig. 7

The expression of serotonergic receptor and transporter, oxytocin receptor, and vasopressin receptor genes is influenced by the use of MDMA and oxytocin receptor ligands. To unravel the mechanisms behind the behavioural effects, the changes in gene expression related to the serotonergic system, oxytocin and vasopressin receptors after exposure to MDMA, WAY-267464 and L-368,899 were studied. After the behavioural tests, the fish were euthanised, mRNA was isolated and a real-time PCR technique was utilised (a). The expression values between the reference sample and the test sample were converted to log2 (fold change, FC) and presented as a heat map (b). Our findings indicate that MDMA decreased the expression of the coding serotonin transporter (scl6a4), increased the expression of oxytocin receptors (oxtra and oxtrb) and dramatically reduced the expression of gene coding vasopressin receptor (avpr1aa). WAY-267464, oxytocin receptor agonists, increased expression of the gene coding the serotonin 5-HT1B receptor (htr1b) whereas reducing the gene coding the serotonin 5-HT2B (htr2b) and scl6a4. However, it had no effect on genes coding oxytocin receptors and vasopressin receptor. L-368,899, oxytocin receptor antagonist, increased expression of htr1b, scl6a4 and oxtra genes. The expression level of the oxtra gene was not assessed at the lowest MDMA dose of 0.5??M (indicated by the grey field). n?=?3, MDMA had no effect on the release of oxytocin. To determine whether MDMA led to the release of oxytocin in zebrafish, the ELISA test was conducted (c). According to the results, MDMA did not affect the oxytocin level in fish (d). Data were analysed using a one-way analysis of variance followed by Dunnett?s post hoc test, n?=?4. COI: compound of interest; FC: fold change.