Pineapple (Ananas comosus) Ameliorates Depressant-like Behaviors in Rats Induced by Lipopolysaccharide

Abstract

Lipopolysaccharide (LPS) injection can lead to depression and mood disorders by reducing tryptophan availability through increased activity of the enzyme indoleamine 2,3-dioxygenase. Tryptophan, sourced from fruits such as pineapple (Ananas cosmosus), is vital for the body, especially the serotonergic system. This study aims to assess how pineapple pulp (PP) counters LPS-induced depressive behaviors in male Wistar rats. The experiment involved force-feeding PP for 28 days before LPS injection (0.5 mg/kg intraperitoneal [i.p.]) in 30 male Wistar rats, divided into five groups. Groups I (normal) and II (LPS control) received 15 ml aquadest/kg/day. Test Groups III, IV, and V were given varied doses of PP; low dose (3.75 ml/kg/day), medium dose (7.5 ml/kg/day), and high dose (15 ml/kg/day). At the study's end, rats underwent the open field test (OFT) and the tail suspension test (TST). In addition, blood and brain samples were analyzed for neuroendocrine markers related to depression. LPS triggers depressive symptoms, as evidenced by increased immobility time in the TST and altered behaviors indicative of anxiety in the OFT, especially in groups not receiving PP. This is followed by decreased serotonin levels in both plasma and brain when compared to groups given PP. In addition, higher corticosterone levels were observed in the LPS group than in the PP-treated group. Administering PP at 7.5 ml/kg/day for 28 days can alleviate the depressive effects induced by LPS injection. PP may have antidepressant properties, potentially by mitigating behaviors leading to depressive symptoms.