Chronic psycho-environmental stress can induce neurological dysfunction due to an increase in cortisol levels. It is possible that some food supplements could attenuate its negative impact, such as avocado oil (AO), which is rich in fatty acids with beneficial effects on the brain. This hypothesis was tested by an in vitro model using undifferentiated neuroblastoma cells (SH-SY5Y) exposed to hydrocortisone (HC), an active cortisol molecule with and without AO-supplementation. Cortisol can induce oxidative stress, apoptosis events, and a lowering effect on brain-derived neurotrophic factor (BDNF), a neurogenic molecule. As AO protective effects on HC-exposed cells could involve these routes, some markers of these routes were compared among neuroblastoma cultures. In the first assay, the range concentrations of HC exposure that trigger cell mortality and range AO-concentrations that could revert the HC effect. AO at all concentrations tested (2-30 µg/ml) did not present a cytotoxic effect on SH-SY5Y cells, whereas HC at 0.3-10 ng/ml had a dose-dependent cytotoxic effect on these cells. From these results, HC at 10 ng/ml and AO at 5 µg/ml were chosen for mechanistic analysis. AO was able to decrease the oxidative molecules; however, both AO-and HC-induced differential and varied gene expression modulation of these enzymes. AO partially reverted the protein and gene expression of apoptotic markers that were higher in HC-exposed cells. AO also increases the BDNF levels, which are lower HC-exposed cultures. The results indicate that AO could be a beneficial supplement in situations where cortisol levels are elevated, including chronic psycho-environmental stress. Practical applications Psychological chronic stress that induces high cortisol exposure has been linked to premature aging and decreased healthy life expectancy. Neurobiological models involving cortisol have suggested a neurotoxic effect of this molecule, increasing the risk of psychiatric and other CNTDs. This effect can have a high impact mainly in How to cite this article: Motta JR, Jung IEDC, Azzolin VF, et al. Avocado oil (Persea americana) protects SH-SY5Y cells against cytotoxicity triggered by cortisol by the modulation of BDNF, oxidative stress, and apoptosis molecules.