6,7,4′-Trihydroxyflavanone Mitigates Methamphetamine-Induced Neurotoxicity in SH-SY5y Cells via Nrf2/heme Oxyganase-1 and PI3K/Akt/mTOR Signaling Pathways

Methamphetamine (METH) is a synthetic psychostimulant drug that has detrimental effects on the health of its users. Although it has been investigated as a cause of neurodegenerative disease due to its neurotoxicity, whether small molecules derived from natural products attenuate these side effects remains elusive. 6,7,4′-trihydroxyflavanone (THF) is a flavanone family that possesses various pharmacological activities, including anti-rheumatic, anti-ischemic, anti-inflammatory, anti-osteoclastogenic, and protective effects against METH-induced deactivation of T cells. However, little is known about whether THF protects neuronal cells from METH-induced neurotoxicity. Here, we investigated the protective effects of THF on neurotoxicity induced by METH exposure by enhancing the Nrf2/HO-1 and PI3K/Akt/mTOR signaling pathways in SH-SY5y cells. Treatment with THF did not lead to cytotoxicity, but attenuated METH-induced neurotoxicity by modulating the expression of apoptosis-related proteins, METH-induced oxidative stress, and PI3K/Akt/mTOR phosphorylation in METH-exposed SH-SY5y cells. Moreover, we found THF induced Nrf2 nuclear translocation and HO-1 expression. An inhibitor assay confirmed that the induction of HO-1 by THF attenuates METH-induced neurotoxicity. Therefore, we suggest that THF preserves neuronal cells from METH-induced neurotoxicity by upregulating HO-1 expression through the Nrf2 and PI3K/Akt/mTOR signaling pathways. Thus, THF has therapeutic potential for use in the treatment of METH-addicts suffering from neurodegenerative diseases.