Cannabidiol prevents methamphetamine-induced neurotoxicity by modulating dopamine receptor D1-mediated calcium-dependent phosphorylation of methyl-CpG-binding protein 2

Mitochondrial Calcium Uniporter (MCU)-Mediated Calcium Overload in Psychoactive Drug Neurotoxicity: From Pathogenesis to Therapeutic Targets

With rapid societal changes and increasing stress levels, the abuse of psychoactive substances has emerged as a global health crisis. Studies indicate that the mitochondrial calcium uniporter (MCU) plays a pivotal role in neurotoxic damage induced by psychoactive substances. As the primary channel for mitochondrial Ca2+ uptake, MCU dysfunction can lead to Ca2+ overload, oxidative stress, and apoptosis, representing a crucial mechanism underlying neurotoxic damage. Psychoactive substances such as 3,4-Methylenedioxymethamphetamine (MDMA), cocaine, and morphine influence MCU function through multiple pathways, resulting in excessive Ca2+ accumulation and mitochondrial dysfunction, ultimately leading to neuronal injury. Although MCU inhibitors have demonstrated potential in alleviating Ca2+ overload and improving neural function in preliminary studies, their selectivity and long-term safety require further evaluation. Future research should explore the precise regulatory mechanisms of MCU in neurotoxic damage induced by psychoactive substances and develop more effective targeted therapeutic strategies.

Apelin Receptor Homodimerisation Inhibits Hippocampal Neuronal Autophagy via G Protein-Dependent Signalling in Vascular Dementia

Vascular dementia (VD), a progressive vascular cognitive impairment, is characterised by the presence of cerebral hypoperfusion, increased blood-brain barrier permeability, and white matter lesions. Although current treatment strategies primarily focus on risk factors such as hypertension, diabetes, and heart disease, efficient and targeted therapies are lacking and the underlying mechanisms of VD remain unclear. We previously discovered that Apelin receptors (APJ), which are G protein-coupled receptors (GPCRs), can homodimerize and generate signals that are distinct from those of APJ monomers in VD rats. Apelin-13 reduces the level of APJ homodimers and leads to the proliferation of endogenous neural stem cells in the hippocampal dentate gyrus area, suggesting that it has a neuroprotective role. In this study, we established a rat and cellular oxygen-glucose deprivation/reoxygenation VD model to investigate the impact of APJ homodimerisation on autophagy. We found that APJ homodimers protect against VD by inhibiting autophagy through the Gαq and PI3K/Akt/mTOR pathways upon Gαi signalling, both in vivo and in vitro. This discovery provides a promising therapeutic target for chronic cerebral ischaemia-reperfusion diseases and an experimental foundation for the development of drugs that target APJ homodimers.

Methamphetamine inhibits huntingtin-associated protein 1-mediated tyrosine receptor kinase B endocytosis resulting the neuroprotective dysfunction of brain-derived neurotrophic factor

Methamphetamine (METH), a synthetic stimulant, has seen an escalating abuse situation globally over the past decade. Although the molecular mechanism underlying METH-induced neurotoxicity has been explored, the dysfunction of brain-derived neurotrophic factor (BDNF) neuroprotection in the context of METH neurotoxicity remains insufficiently understood. Our previous studies have found that METH induced neurotoxicity and BDNF expression in rat primary neurons, necessitating further research into this paradox. Specifically, BDNF-dependent tyrosine receptor kinase B (TrkB) endocytosis was crucial for BDNF to confer neuroprotection in neurons. Therefore, we investigated the effect and molecular mechanism of METH on TrkB endocytosis. This work attempted to explain the potential reasons why BDNF did not exert neuroprotection in the context of METH exposure. In the current study, excessive apoptosis, elevated BDNF and reduced huntingtin-associated protein 1 (HAP1) expression were observed in the hippocampus of METH users. METH also induced cell degeneration, cytotoxicity, and BDNF expression and release in HT-22 cells in both a concentration- (0.25, 0.5, 1, 2, and 4 mM) and time-dependent manner (3, 6, 12, 24, and 48 h). Furthermore, following 24 h of exposure to METH (2 mM), apoptosis, impaired TrkB endocytosis, and reduced HAP1 expression were evident in HT-22 cells and organotypic hippocampal slices from mice. Notably, overexpression of HAP1 attenuated METH-induced cell degeneration, cytotoxicity, apoptosis, and TrkB endocytosis disruption in HT-22 cells. These findings suggest that HAP1 is a key molecule in the disruption of BDNF-mediated neuroprotective signaling by METH, and that targeting HAP1-mediated TrkB endocytosis may represent a promising therapeutic avenue for METH-induced neurotoxicity.

The role of D1-like dopamine receptors within the ventral tegmental area in the cannabidiol's inhibitory effects on the methamphetamine-induced conditioned place preference in rats

Cannabidiol (CBD) is a non-psychoactive drug extracted from marijuana. It is well established that CBD attenuates the reinforcing effects of drugs of abuse, although its mechanism of action is not fully understood. The current study tries to clarify the role of D1-like dopamine receptors (D1R) in the ventral tegmental area (VTA) in the inhibitory effects of the CBD on the acquisition and expression of methamphetamine (METH)-conditioned place preference (CPP). In the CPP training, adult male Wistar rats were conditioned with subcutaneous administration of METH (1 mg/kg) for five days. Three groups of animals were treated with multiple doses of SCH23390 (as a D1R antagonist; 0.25, 1, and 4 μg/0.3 μl saline) in the VTA, respectively, before intracerebroventricular (ICV) injection of CBD (10 μg/5 μl DMSO) in the acquisition phase. In the second experiment of the study, rats received SCH23390 in the VTA before ICV administration of CBD (50 μg/5 μl DMSO) in the expression of METH CPP. Here, the current study demonstrated that CBD inhibits the acquisition and expression of METH CPP, while microinjection of D1R antagonists (1 and 4 μg) into the VTA significantly reduced CBD's suppressive effect on the acquisition and expression of METH place preference. Furthermore, this research demonstrated that either SCH23390 or CBD alone does not lead to place preference in the CPP paradigm. Based on these data, this study suggests that pharmacological manipulations of D1R may alter the CBD's effect on METH-conditioned preference.