Schinus terebinthifolia leaf lectin (SteLL) attenuates immobility and anxiogenic behavior in mice through modulation of monoaminergic signaling

Lectins are proteins that exhibit various biological and pharmacological potentials. These proteins contain at least one carbohydrate-binding domain in their structure, enabling specific and reversible binding to carbohydrates. Despite their known properties, there is limited knowledge about the effects of lectins on the Central Nervous System. Schinus terebinthifolia leaf lectin (SteLL) is a glycosylated protein extracted from S. terebinthifolia leaves with the ability to bind chitin. The aim of the present work is to evaluate the effects of SteLL on mouse models of anxiety and depression-like symptoms and to explore whether monoaminergic signaling and the carbohydrate-binding domain (CRD) play a role in the lectin's activity. When administered at a dose of 4mg/kg intraperitoneally (i.p.), SteLL significantly reduced the number of hearings and the time spent in the open arms, while diminishing the immobility time of animals in the tail suspension test. The anti-immobility effect, but not the anxiolytic effect, was found to be dependent on the CRD, as prior incubation with casein (an inhibitor of SteLL CRD) blocked the activity. Additionally, the efficacy of SteLL in the elevated plus maze and in the immobility test was reversed by pretreatment with pharmacological antagonists of the α2-adrenoceptor, 5-HT2A/2C serotonin receptor, and the D1 dopamine receptor. In a subacute evaluation, the anti-immobility effect of SteLL persisted after seven days of treatment. Overall, our results suggest that the anxiolytic and anti-immobility effects of SteLL are dependent on the monoaminergic signaling cascade, and the CRD is crucial for the lectin's anti-immobility efficacy.