Inhibition of GSDMD-dependent pyroptosis decreased methamphetamine self-administration in rats.

It is widely believed that the activation of the central dopamine (DA) system is crucial to the rewarding effects of methamphetamine (METH) and to the behavioral outcomes of METH use disorder. It was reported that METH exposure induced gasdermin D (GSDMD)-dependent pyroptosis in rats. The membrane pore formation caused by METH-induced pyroptosis may also contribute to the overflow of DA into the extracellular space and subsequently increase the DA levels in the brain. The present study firstly investigated whether the membrane pore information induced by GSDMD-dependent pyroptosis was associated with the increased DA levels in the ventral tegmental area (VAT) and nucleus accumbens (NAc) of rats self-administering METH and SY-SH5Y cells treated by METH. Subsequently, the effect of pore formation blockade or genetic inhibition of GSDMD on the reinforcing and motivational effect of METH was determined in rats, using the animal model of METH self-administration (SA). METH exposure significantly increased the activity of NLRP1/Cas-1/GSDMD pathway and the presence of pyroptosis, accompanied by the significantly increased DA levels in VTA and NAc. Moreover, intraperitoneal injections of disulfiram (DSF) or microinjection of rAAV-shGSDMD into VTA/NAc significantly reduced the reinforcing and motivational effect of METH, accompanied by the decreased level of DA in VTA and NAc. The results provided novel evidence that METH-induced pyroptosis could increase DA release in VTA and NAc via the NLRP1/Cas-1/GSDMD pathway. Additionally, membrane pores or GSDMD blockade could significantly reduce the reinforcing and motivational effect of METH. In conclusion, blocking GSDMD and membrane pore formation could be a promising potential target for the development of agents to treat METH use disorder.

The neuroprotective effect of LCZ696 on methamphetamine-induced cognitive impairment in mice.

OBJECTIVE: Methamphetamine (METH) exposure commonly causes cognitive impairment. An angiotensin II receptor/neprilysin inhibitor (ARNI), LCZ696 has been demonstrated to inhibit inflammation, oxidative stress and apoptosis. The present study was designed to examine the effect of LCZ696 on METH-induced cognitive impairment and the underlying mechanism. METHODS: Following daily treatment of either saline or METH (5 mg/kg) for 5 consecutive days, the cognitive function was tested using the Y-maze and the Novel Object Recognition (NOR) in Experiment 1. In Experiment 2, mice were initially treated with saline or LCZ696 (60 mg/kg) for 9 consecutive days, followed by LCZ696, METH or saline for 5 days. Cognitive testing was carried out as Experiment 1. In Experiment 3, SH-SY5Y cells were treated with either METH (2.5 Mm) or ddH2O for 12 h. The apoptosis and reactive oxygen species (ROS) level of SH-SY5Y were examined. In Experiment 4, SH-SY5Y cells were pretreated with either ddH2O or LCZ696 (70um) for 30 min, followed by ddH2O or METH treatment for 12 h. Nrf2 and HO-1 protein expression was examined in the ventral tegemental area (VTA) of all the animals and SH-SY5Y cells. RESULTS: LCZ696 significantly improved METH-induced cognitive impairment, in conjunction with decreased apoptosis and ROS levels in VTA of METH-treated mice and SH-SY5Y cells. METH significantly decreased Nrf2 and HO-1 protein expression in VTA of mice and SH-SY5Y cells, which was reversed by LCZ696 treatment. CONCLUSION: LCZ696 yields a neuroprotective effect against METH-induced cognitive dysfunction via the Nrf2/HO-1 signaling pathway.

EGCG attenuates METH self-administration and reinstatement of METH seeking in mice.

Methamphetamine (METH) use disorder is a chronic, relapsing disorder and involves frequent failures of self-control of drug seeking and taking. Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenolic compounds of green tea, which has shown great therapeutic effectiveness in neurological disorders. However, it is still unknown whether and how EGCG affects METH seeking behaviour. Here, we show nanostructured EGCG/ascorbic acid nanoparticles (EGCG/AA NPs) dose-dependently reduced METH self-administration (SA) under fixed-ratio 1 (FR1) and progressive ratio (PR) reinforcement schedules in mice and shifted METH dose-response curves downward. Furthermore, EGCG/AA NPs decreased drug- and cue-induced METH seeking. In addition, we found that METH SA led to a decrease in inhibitory postsynaptic currents (IPSCs) and increase in the AMPAR/NMDAR ratio and excitation/inhibition (E/I) ratio in ex vivo midbrain slices from ventral tegmental area (VTA) dopamine neurons. EGCG/AA NPs enhanced Gamma-aminobutyric acid (GABA)ergic inhibition and normalized the E/I ratio. EGCG restored the balance between excitation and inhibition in VTA dopamine neurons, which may contribute to the attenuation of METH SA. These findings indicate that EGCG is a promising pharmacotherapy for METH use disorder.