Ameliorative effect of Tiron against paraquat-induced cerebral and pulmonary injury in rats: involvement of ferroptosis, TLR4/NF-κB and Nrf2/HO-1 signaling pathways

Paraquat (PQ) is a herbicide which is used indiscriminately specially in developing countries. The objective of our study is to evaluate the toxicity of PQ on cerebral and pulmonary tissues and the efficacy of Tiron in attenuating such toxicity through focusing in the involvement of Nrf2/HO-1 and TLR4/NF-κB signaling pathways. Rats were divided into 5 groups of 6 rats each: control, Tiron control (200 mg/kg), PQ (10 mg/kg), Tiron (100 mg/kg) + PQ, and Tiron (200 mg/kg) + PQ groups. Behavioural tests were performed before euthanasia. Subsequently, serum, brain, and lung samples were collected. Bronchoalveolar lavage (BAL) fluid and cell counting, serum iron and ferritin, oxidative stress biomarkers, histopathological examination along with immunohistochemical assessment of nuclear factor kappa B p65 subunit (NF-κB p65), nuclear factor erythroid 2-related factor 2 (Nrf2), and heme-oxygenase1(HO-1) were performed. Toll-like receptor 4 (TLR4), and interleukin 1beta (IL-1β) were also assessed. Tiron reversed PQ induced cerebral and pulmonary injury by enhancing motor activity confirmed by wire hanging and open field test (OFT), additionally, it decreased serum iron, total leucocytes count (TLC), monocytes and neutrophils count, 4-Hydroxynonenal (4-HNE), malondialdehyde (MDA), along with increased levels of serum ferritin, reduced glutathione (GSH), glutathione peroxidase 4 (GPX4), Nrf2, and total antioxidant capacity (TAC) in cerebral and pulmonary tissues beside improved histopathological alterations compared to PQ- administered group. Also, HO-1 was significantly increased along with a downregulation of TLR4, NF-κB p65, and IL-1β upon Tiron administration. Tiron mitigated PQ induced cerebral and pulmonary toxicity via restoration of ferroptosis balance, decreasing oxidative stress, and downregulation of inflammatory TLR4/ NF-κB pathway in a dose dependent manner.