Fig. 1

Experimental design scheme. During the study, 3-week-old zebrafish were treated with the tested drugs and then subjected to behavioural procedures to assess their anxiety and social behaviours. Following the behavioural tests, the fish were euthanised and their tissues were used for molecular studies to evaluate changes in gene expression, including serotonergic receptors and transporter, oxytocin receptors and vasopressin receptor genes, the oxytocin level as well as alterations in the ERK1/2 and AKT signalling pathways. Zebrafish were treated with a compound of interest (COI) for 60?min and then behavioural tests were performed (a). To evaluate anxiety behaviour in fish, the novel environment exploration test, which is based on thigmotaxis ? a natural tendency of fish to stay close to the periphery of a new environment, was performed. During the procedure, the first 6?min were designated as a light period, followed by 4?min of darkness. The findings indicate that the transition from light to dark did not affect the distance untreated fish moved. (b) To determine whether fish exhibit a preference for light or dark conditions, a light?dark preference test was conducted. The test utilised a chamber with two zones, one light and one dark, and lasted for 8?min. The findings indicate that the untreated control fish did not display a preference for either zone (c). To evaluate social behaviour in fish, a three-chambered setup with fish present as social stimuli was applied. In the tested arena, there were two distinguishable zones: the social zone, located in front of the chamber containing familiar fish stimulus, and the non-social zone, located in front of the empty chamber. The first 15?min of the experiment was for the acclimation phase without the stimulus fish, followed by 15?min of the social cue phase with the stimulus fish present. The findings indicate that fish tend to exhibit a preference for conspecifics (d). Data were analysed using t-test (b, d). Mann?Whitney test was used for datasets that failed normality testing or had significantly different variances (c). The confidence limit of *p?