Dysregulation of iron homeostasis and methamphetamine reward behaviors in Clk1-deficient mice

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.

Impact of miR-29c-3p in the Nucleus Accumbens on Methamphetamine-Induced Behavioral Sensitization and Neuroplasticity-Related Proteins

Methamphetamine (METH) abuse inflicts both physical and psychological harm. While our previous research has established the regulatory role of miR-29c-3p in behavior sensitization, the underlying mechanisms and target genes remain incompletely understood. In this study, we employed the isobaric tags for relative and absolute quantitation (iTRAQ) technique in conjunction with Ingenuity pathway analysis (IPA) to probe the putative molecular mechanisms of METH sensitization through miR-29c-3p inhibition. Through a microinjection of AAV-anti-miR-29c-3p into the nucleus accumbens (NAc) of mice, we observed the attenuation of METH-induced locomotor effects. Subsequent iTRAQ analysis identified 70 differentially expressed proteins (DEPs), with 22 up-regulated potential target proteins identified through miR-29c-3p target gene prediction and IPA analysis. Our focus extended to the number of neuronal branches, the excitatory synapse count, and locomotion-related pathways. Notably, GPR37, NPC1, and IREB2 emerged as potential target molecules for miR-29c-3p regulation, suggesting their involvement in the modulation of METH sensitization. Quantitative PCR confirmed the METH-induced aberrant expression of Gpr37, Npc1, and Ireb2 in the NAc of mice. Specifically, the over-expression of miR-29c-3p led to a significant reduction in the mRNA level of Gpr37, while the inhibition of miR-29c-3p resulted in a significant increase in the mRNA level of Gpr37, consistent with the regulatory principle of miRNAs modulating target gene expression. This suggests that miR-29c-3p potentially influences METH sensitization through its regulation of neuroplasticity. Our research indicates that miR-29c-3p plays a crucial role in regulating METH-induced sensitization, and it identified the potential molecular of miR-29c-3p in regulating METH-induced sensitization.

Iron chelation prevents nigrostriatal neurodegeneration in a chronic methamphetamine mice model

Methamphetamine (METH) has been established to selectively target and impair dopaminergic neurons through multiple pathways. Ferroptosis is a unique form of non-apoptotic cell death driven by cellular iron accumulation-induced lipid peroxidation. Nonetheless, it remains unclear whether METH can induce ferroptosis. In the present study, we sought to assess alterations in iron levels after chronic METH exposure and reveal the modulatory role of iron on METH-induced pathologies. Importantly, we demonstrated that METH increased iron deposition in the nigrostriatal system, including the substantia nigra (SN) and caudate putamen (CPu). Moreover, decreases in GPx4 levels, increases in lipid peroxidation products, and pathological alterations were observed in the nigrostriatal system as a consequence of chronic METH exposure. The iron chelator deferiprone not only alleviated nigrostriatal iron deposition, dopaminergic cell death, and lipid peroxidation, but alsoattenuated the decreases in GPx4 induced by METH. These findings suggest an alleviation of ferroptosis in dopaminergic neurons. In addition, we found that the ferroptosis inhibitor liproxstatin-1 attenuated METH-induced dopaminergic degeneration in the nigrostriatal system. Our findings corroborated that METH might induce dopaminergic neurodegeneration through iron-dependent ferroptosis. Interestingly, reducing iron levels or inhibiting ferroptosis may alleviate METH-induced dopaminergic neurodegeneration.

Hypoxia-inducible factor upregulation by roxadustat attenuates drug reward by altering brain iron homoeostasis

Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the upregulation of Hypoxia-inducible factor-1α (HIF-1α) expression by roxadustat (Rox), a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α, administered either systemically or locally into selected brain regions, suppressed morphine (Mor)-induced conditioned place preference (CPP). A similar effect was observed with methamphetamine (METH). Moreover, Rox also inhibited the expression of both established and reinstated Mor-CPP and promoted the extinction of Mor-CPP. Additionally, the elevation of HIF-1α enhanced hepcidin/ferroportin 1 (FPN1)-mediated iron efflux and resulted in cellular iron deficiency, which led to the functional accumulation of the dopamine transporter (DAT) in plasma membranes due to iron deficiency-impaired ubiquitin degradation. Notably, iron-deficient mice generated via a low iron diet mimicked the effect of Rox on the prevention of Mor- or METH-CPP formation, without affecting other types of memory. These data reveal a novel mechanism for HIF-1α and iron involvement in substance use disorder, which may represent a potential novel therapeutic strategy for the treatment of drug abuse. The findings also repurpose Rox by suggesting a potential new indication for the treatment of substance use disorder.

Role of microglial metabolic reprogramming in Parkinson's disease

Parkinson's disease (PD) is a common age-related neurodegenerative disorder characterized by damage to nigrostriatal dopaminergic neurons. Key pathogenic mechanisms underlying PD include alpha-synuclein misfolding and aggregation, impaired protein clearance, mitochondrial dysfunction, oxidative stress, and neuroinflammation. However, to date, no study has confirmed the specific pathogenesis of PD. Similarly, current PD treatment methods still have shortcomings. Although some emerging therapies have proved effective for PD, the specific mechanism still needs further clarification. Metabolic reprogramming, a term first proposed by Warburg, is applied to the metabolic energy characteristics of tumor cells. Microglia have similar metabolic characteristics. Pro-inflammatory M1 type and anti-inflammatory M2 type are the two types of activated microglia, which exhibit different metabolic patterns in glucose, lipid, amino acid, and iron metabolism. Additionally, mitochondrial dysfunction may be involved in microglial metabolic reprogramming by activating various signaling mechanisms. Functional changes in microglia resulting from metabolic reprogramming can cause changes in the brain microenvironment, thus playing an important role in neuroinflammation or tissue repair. The involvement of microglial metabolic reprogramming in PD pathogenesis has been confirmed. Neuroinflammation and dopaminergic neuronal death can effectively be reduced by inhibiting certain metabolic pathways in M1 microglia or reverting M1 cells to the M2 phenotype. This review summarizes the relationship between microglial metabolic reprogramming and PD and provides strategies for PD treatment.