https://www.scienced...27858461400061X
Moreover, the combination of high concentrations of racemic fluoxetine with an inactive concentration of tranylcypromine or LSD potentiates the behavioral effects of fluoxetine, without altering bottom-dwelling in the case of tranylcypromine (Stewart et al., 2013). Thus, in zebrafish, serotonin toxicity would be characterized by surfacing behavior and decreased freezing, a behavioral profile that was also observed by intraperitoneal injection (Maximino et al., 2013b). In this case, SSRIs and MAOis would not produce an ‘anxiolytic’ effect in the NTT (Maximino et al., 2012) but rather these alterations would be symptoms of serotonin toxicity. Some complications arise from this thesis, as in at least two cases low, but not higher doses/concentrations, of fluoxetine decrease bottom-dwelling and freezing (Iturriaga-Vásquez et al., 2012, Maximino et al., 2013b). Moreover, at 2.5 mg/kg (the dose which also increases scototaxis; Maximino et al., 2013b), fluoxetine increases extracellular serotonin levels by only ~ 50% (Maximino, 2014), a value much smaller than that observed after developmental deprenyl exposure (Sallinen et al., 2009) and after co-treatment of rodents with fluoxetine and tranylcypromine (Shioda et al., 2004). These results argue against the hypothesis of serotonin toxicity at low fluoxetine doses, but do not necessarily discard it at higher fluoxetine doses, or by the combination of fluoxetine with other serotonergic drugs (Stewart et al., 2013)
