Protective Effect of Melatonin on Methamphetamine-Induced Apoptosis in Glioma Cell Line

Abstract

Methamphetamine (METH) is a highly addictive drug causing neurodegenerative diseases. METH has been known to be neurotoxic by inducing oxidative stress, free radical, and pro-inflammatory cytokines. Previous studies have shown that METH could induce neuron and glial cell death, especially inducing glial cell-mediated neurotoxicity that plays a critical role in stress-induced central nervous system damage. Therefore, the aim of the present study is to explore the mechanisms of METH-induced cell death in the glial cell. METH-induced glial cells death is mediated via mitochondrial damage pathway. METH activates the upregulation of the Bax, cytochrome c, cleavage caspase 9 and 3 proteins, and downregulation of Bcl-XL protein in cascade. Pretreatment with melatonin, a neurohormone secreted by the pineal gland, effectively reduced glial cell death. Moreover, melatonin increased the Bcl-XL/Bax ratio but reduced the level of cytochrome c, cleavage caspase 9 and 3 proteins. Therefore, these results demonstrated that melatonin could reduce the cytotoxic effect of METH by decreasing the mitochondrial death pathway activation in glial cells. This outcome suggests that melatonin might be beneficial as the neuroprotection in neurodegenerative diseases caused by METH or other pathogens.

Melatonin suppresses methamphetamine-triggered endoplasmic reticulum stress in C6 cells glioma cell lines

“…Our study demonstrated that melatonin protects glial cells against ER stress-induced cell death. Recent studies have demonstrated that METH is a neurotoxic drug that can induce neuronal (Ajjimaporn et al, 2005;Zhu et al, 2006;Deng et al, 2007) and glial cell death by several pathways, including oxidative stress (Riddle et al, 2006;Tocharus et al, 2008), mitochondrial dysfunction (Brown et al, 2005;Jumnongprakhon et al, 2014), excitotoxicity (Staszewski and Yamamoto, 2006;Ernst and Chang, 2008), inflammatory responses (Jumnongprakhon et al, 2015), and ER stress (Shah and Kumar, 2016). We have previously reported that exposure to METH causes an overproduction of ROS (Tocharus et al, 2010) that leads to oxidative stress.…”

“…Cells were pretreated with melatonin (1, 10, and 100 nM) for 2 hr in the presence or absence of METH (1.6 mM) for 9 hr as described in previous studies (Jumnongprakhon et al, 2014(Jumnongprakhon et al, , 2015. Cells were harvested, and the total RNA was isolated using TRIZOL reagent according to the manufacturer's protocol.…”

“…The cells were pretreated with melatonin at concentrations of 10, 100, and 500 nM for 2 hr prior to treatment with 1.6 mM METH (Jumnongprakhon et al, 2014(Jumnongprakhon et al, , 2015 for 9 hr or 12 hr and lysed in lysis buffer containing 1% NP-40, 1% sodium deoxycholate, 0.1% sodium dodecyl sulfate, 40 mM β-glycerophosphate, 50 mM sodium fluoride, 2 mM sodium orthovanadate and 1X protease inhibitors at 4°C for 15 min. The protein concentration was determined by using the Bradford protein assay (Bio-Rad Laboratories), and equal amounts of protein were electrophoresed in a 10-15% sodium dodecyl sulfate (SDS) polyacrylamide gel and then transferred to a polyvinylidene fluoride (PVDF) membrane (Immobilon-P, Millipore) at 400 mA for 30 min.…”

“…Recent studies have suggested that METH is a neurotoxic drug that can cause pathological changes and death in neuronal and glial cells (Thompson et al, 2004;Kitamura et al, 2007Kitamura et al, , 2010Takeichi et al, 2012). METH induces glial cell hyperactivity and death via many pathways, including apoptosis, oxidative stress, inflammation, interruption of mitochondrial function, and endoplasmic reticulum (ER)-stress responses (Tocharus et al, 2010;Jumnongprakhon et al, 2014Jumnongprakhon et al, , 2015Shah and Kumar, 2016). METH also induces neuronal apoptosis in the striatal neurons of mice by disturbing the function of the ER, leading to ER stress (Riddle et al, 2006;Deng et al, 2007;Jayanthi et al, 2014;Wongpayoon and Govitrapong, 2016).…”

“…Our previous studies suggested that melatonin is a neuroprotective agent that can down-regulate the expression of not only reactive oxygen species (ROS) and nitric oxide (NO) but also pro-inflammatory cytokines (Tocharus et al, 2008(Tocharus et al, , 2010. Moreover, melatonin also attenuates METH-induced glial cell death by decreasing the inflammatory responses and the mitochondrial death pathway (Jumnongprakhon et al, 2014(Jumnongprakhon et al, , 2015. Therefore, this study will investigate the effect of METH-mediated glial cell death through the ER stress pathway in glioma cell lines and further evaluate whether inhibition of the ER stress/UPR is an underlying mechanism of the anti-apoptotic effects of melatonin.…”