Acetaldehyde Excitation of Lateral Habenular Neurons via Multiple Cellular Mechanisms

In situ generation of copper(Ⅱ)/diethyldithiocarbamate complex through tannic acid/copper(Ⅱ) network coated hollow mesoporous silica for enhanced cancer chemodynamic therapy

The Cu2+ complex formed by the coordination of disulfiram (DSF) metabolite diethyldithiocarbamate (DTC), Cu(DTC)2, can effectively inhibit tumor growth. However, insufficient Cu2+ levels in the tumor microenvironment can impact tumor-suppressive effects of DTC. In this study, we proposed a Cu2+ and DSF tumor microenvironment-targeted delivery system. This system utilizes hollow mesoporous silica (HMSN) as a carrier, after loading with DSF, encases it using a complex of tannic acid (TA) and Cu2+ on the outer layer. In the slightly acidic tumor microenvironment, TA/Cu undergoes hydrolysis, releasing Cu2+ and DSF, which further form Cu(DTC)2 to inhibit tumor growth. Additionally, Cu2+ can engage in a Fenton-like reaction with H2O2 in the tumor microenvironment to form OH, therefore, chemodynamic therapy (CDT) and Cu(DTC)2 are used in combination for tumor therapy. In vivo tumor treatment results demonstrated that AHD@TA/Cu could accumulate at the tumor site, achieving a tumor inhibition rate of up to 77.6 %. This study offers a novel approach, circumventing the use of traditional chemotherapy drugs, and provides valuable insights into the development of in situ tumor drug therapies.

The classical D1 dopamine receptor antagonist SCH23390 is a functional sigma-1 receptor allosteric modulator

SCH23390 is a widely used D1 dopamine receptor (D1R) antagonist that also elicits some D1R-independent effects. We previously found that the benzazepine, SKF83959, an analog of SCH23390, produces positive allosteric modulation of the Sigma-1 receptor (Sig1R). SCH23390 does not bind to the orthodoxic site of Sig1R but enhances the binding of 3H (+)-pentazocine to Sig1R. In this study, we investigated whether SCH23390 functions as an allosteric modulator of Sig1R. We detected increased Sig1R dissociation from binding immunoglobulin protein (BiP) and translocation of Sig1R to the plasma membrane in response to SCH23390 in transfected HEK293T and SH-SY5Y cells, respectively. Activation of Sig1R by SCH23390 was further confirmed by inhibition of GSK3β activity in a time- and dose-dependent manner; this effect was blocked by pretreatment with the Sig1R antagonist, BD1047, and by knockdown of Sig1R. SCH23390 also inhibited GSK3β in wild-type mice but not in Sig1R knockout mice. Finally, we showed that SCH23390 allosterically modulated the effect of the Sig1R agonist SKF10047 on inhibition of GSK3β. This positive allosteric effect of SCH23390 was further confirmed via promotion of neuronal protection afforded by SKF10047 in primary cortical neurons challenged with MPP+. These results provide the first evidence that SCH23390 elicits functional allosteric modulation of Sig1R. Our findings not only reveal novel pharmacological effects of SCH23390 but also indicate a potential mechanism for SCH23390-mediated D1R-independent effects. Therefore, attention should be paid to these Sig1R-mediated effects when explaining pharmacological responses to SCH23390.

PEX5R/Trip8b-HCN2 channel regulating neuroinflammation involved in perioperative neurocognitive disorders

Background

Clinical and animal studies demonstrated that neuroinflammation from anesthesia (sevoflurane) is the main contributor to cause perioperative neurocognitive disorders (PND). Recently, it was reported that microglia respond to hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which was the target of sevoflurane. Whether HCN channels are involved in the induction of neuroinflammation after sevoflurane exposure is still unclear.

Results

Sevoflurane exposure had increased cognitive dysfunction and anxiety-like behaviors in rats. Rats inhaled with sevoflurane had activated microglia and increased neuroinflammation (IL-1β, IL-6, and TNF-α) in the hippocampus. RNA sequencing identified 132 DEGs (86 up-regulated and 46 down-regulated DEGs [differentially expressed genes]) in the hippocampus of PND rats. RNA-sequencing also uncovered that sevoflurane exposure down-regulates HCN2 expression. Pathway and process enrichment analysis suggests DEGs are mainly enriched in regulation of system process, positive regulation of glutamate secretion, secretion, regulation of synaptic transmission, regulation of nervous system process, behavior, negative regulation of sodium ion transport, and learning or memory. We validated that sevoflurane exposure can down-regulate the levels of PEX5R/Trip8b (an interaction partner and auxiliary subunit of HCN channels) and HCN1-4 channels in the hippocampus of PND rats. We used immunofluorescence staining to identify that HCN2 co-labels with neurons (Neun), astrocytes (GFAP), and microglia (iba1). We observed that the co-labeling of HCN2 with neurons or microglia decreased in the hippocampus and cortex after sevoflurane exposure. Blocking HCN2 by ZD7288 treatment further activated microglia and aggravated sevoflurane exposure-induced anxiety-like behavior, cognitive impairment, and neuroinflammation.

Conclusions

We concluded that sevoflurane exposure can induce an increased level of neuroinflammation, microglial activation, cognitive dysfunction, and anxiety-like behaviors in rats. HCN2 channel, as the target of sevoflurane action, mediates this process. HCN2 might be a target for the treatment and prevention of sevoflurane-induced PND.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00892-6.

Gene knockdown of HCN2 ion channels in the ventral tegmental area reduces ethanol consumption in alcohol preferring rats

Background: Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) ionic channels are known to play a key role in the control of neuron excitability and have been proposed as a molecular target of ethanol. Previous studies in rats have shown that gene-induced overexpression of the HCN2 channel in the ventral tegmental area (VTA) increases the rewarding effects of ethanol and its intake by the animals.Objective: The aim of this work was to study the effects of VTA HCN2 gene knockdown in the voluntary ethanol consumption of alcohol-preferring UChB rats.Methods: Two lentiviral vectors were generated; LV-siRNA-HCN2, coding for a siRNA that elicited >95% reduction of HCN2 protein levels in vitro, and a control vector coding for a scrambled siRNA sequence. Female UChB naïve rats (n = 14) were microinjected into the VTA with LV-siRNA-HCN2 or the scrambled control vector (n = 11). Four days after, animals were given a daily free access to 10% ethanol and water for 10 days.Results: Rats treated with the LV-siRNA-HCN2 vector showed a ~ 70% reduction (p < .001) in their ethanol preference and ethanol intake compared to control animals. No changes were observed in the total fluid intake of both groups. HCN2 levels in the VTA were measured by Western blot showing a reduction of 40% (p < .05) in the rats injected with LV-siRNA-HCN2, compared to control animals.Conclusion: These results show that knockdown of HCN2 ionic channels in the VTA of UChB rats markedly reduces their voluntary ethanol intake, supporting the idea that HCN2 channels may constitute a therapeutic target for alcohol use disorders.