The α2δ-1/NMDA receptor complex is involved in brain injury after intracerebral hemorrhage in mice

Gabapentinoids for the treatment of stroke

ABSTRACT

Gabapentinoid drugs (pregabalin and gabapentin) have been successfully used in the treatment of neuropathic pain and in focal seizure prevention. Recent research has demonstrated their potent activities in modulating neurotransmitter release in neuronal tissue, oxidative stress, and inflammation, which matches the mechanism of action via voltage-gated calcium channels. In this review, we briefly elaborate on the medicinal history and ligand-binding sites of gabapentinoids. We systematically summarize the preclinical and clinical research on gabapentinoids in stroke, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, seizures after stroke, cortical spreading depolarization after stroke, pain after stroke, and nerve regeneration after stroke. This review also discusses the potential targets of gabapentinoids in stroke; however, the existing results are still uncertain regarding the effect of gabapentinoids on stroke and related diseases. Further preclinical and clinical trials are needed to test the therapeutic potential of gabapentinoids in stroke. Therefore, gabapentinoids have both opportunities and challenges in the treatment of stroke.

Ion Channel Dysregulation Following Intracerebral Hemorrhage

Injury to the brain after intracerebral hemorrhage (ICH) results from numerous complex cellular mechanisms. At present, effective therapy for ICH is limited and a better understanding of the mechanisms of brain injury is necessary to improve prognosis. There is increasing evidence that ion channel dysregulation occurs at multiple stages in primary and secondary brain injury following ICH. Ion channels such as TWIK-related K+ channel 1, sulfonylurea 1 transient receptor potential melastatin 4 and glutamate-gated channels affect ion homeostasis in ICH. They in turn participate in the formation of brain edema, disruption of the blood-brain barrier, and the generation of neurotoxicity. In this review, we summarize the interaction between ions and ion channels, the effects of ion channel dysregulation, and we discuss some therapeutics based on ion-channel modulation following ICH.

Cherry leaf decoction inhibits NMDAR expression and thereby ameliorates CUMS- induced depression-like behaviors through downregulation of α2δ-1

Depression is a complex and prevalent mental illness. Cherry leaf is a traditional Chinese herbal medicine, which has confirmed to exert a certain antidepressant effect, but its potential neural regulation mechanism is not clear. This paper aims to investigate the improved action of cherry leaf decoction (CLD) on chronic unpredictable mild stress (CUMS) rats and its potential neural regulation mechanism by verifying the role and function of NMDAR regulatory target α2δ-1 in depression due to CUMS. Male SD rats were subjected to random stressors persisting for 5 weeks to establish the CUMS depression rat model. CLD could effectively alleviate depression-like behaviors of CUMS rats in behavioral tests including sucrose preference test, forced swimming test, tail suspension test and open field test. After the administration of the CLD, the expression of corticotropic-releasing hormone (CRH) in the hypothalamus was inhibited. Moreover, the levels of CRH, adrenal cortical hormone (ACTH) and corticosterone (CORT) in serum also decreased significantly. CUMS upregulated the expressions of α2δ-1, N-methyl-d-aspartate receptor 1 (NR1), NR2A and NR2B, and enhanced the binding ability to of α2δ-1 and NR1, which were reversed by CLD. The results demonstrated that CLD could ameliorate depression-like behaviors due to CUMS, which was related to the fact that CLD down-regulated α2δ-1 level and interfered with α2δ-1 binding to NR1, thereby reducing NMDAR expression and ultimately inhibiting HPA axis activity.

Research progress and perspectives of N-methyl-D-aspartate receptor in myocardial and cerebral ischemia-reperfusion injury: A review

There is an urgent need to find common targets for precision therapy, as there are no effective preventive therapeutic measures for combined clinical heart-brain organ protection and common pathways associated with glutamate receptors are involved in heart-brain injury, but current glutamate receptor-related clinical trials have failed. Ischemia-reperfusion injury (IRI) is a common pathological condition that occurs in multiple organs, including the heart and brain, and can lead to severe morbidity and mortality. N-methyl-D-aspartate receptor (NMDAR), a type of ionotropic glutamate receptor, plays a crucial role in the pathogenesis of IRI. NMDAR activity is mainly regulated by endogenous activators, agonists, antagonists, and voltage-gated channels, and activation leads to excessive calcium influx, oxidative stress, mitochondrial dysfunction, inflammation, apoptosis, and necrosis in ischemic cells. In this review, we summarize current research advances regarding the role of NMDAR in myocardial and cerebral IRI and discuss potential therapeutic strategies to modulate NMDAR signaling to prevent and treat IRI.

Cigarette smoke triggers calcium overload in mouse hippocampal neurons via the ΔFOSB-CACNA2D1 axis to impair cognitive performance

A growing body of evidence shows that cigarette smoking impairs cognitive performance. The 'Calcium Hypothesis' theory of neuronopathies reveals a critical role of aberrant calcium signaling in compromised cognitive functions. However, the underlying implications of abnormalities in calcium signaling in the neurotoxicity induced by cigarette smoke (CS) have not yet been identified. CACNA2D1, an important auxiliary subunit involved in the composition of voltage-gated calcium channels (VGCCs), was reported to affect the calcium signaling in neurons by facilitating VGCCs-mediated Ca²⁺ influx. ΔFOSB, an alternatively-spliced product of the Fosb gene, is an activity-dependent transcription factor induced robustly in the brain in response to environmental stimuli such as CS. Interestingly, our preliminary bioinformatics analysis revealed a significant co-expression between ΔFOSB and CACNA2D1 in brain tissues of patients with neurodegenerative diseases characterized by progressive cognitive decline. Therefore, we hypothesized that the activation of the ΔFOSB-CACNA2D1 axis in response to CS exposure might cause dysregulation of calcium homeostasis in hippocampal neurons via VGCCs-mediated Ca²⁺ influx, thereby contributing to cognitive deficits. To this end, the present study established a CS-induced mouse model of hippocampus-dependent cognitive impairment, in which the activation of the ΔFOSB-CACNA2D1 axis accompanied by severe calcium overload was observed in the mouse hippocampal tissues. More importantly, ΔFOSB knockdown-/overexpression-mediated inactivation/activation of the ΔFOSB-CACNA2D1 axis interdicted/mimicked CS-induced dysregulation of calcium homeostasis followed by severe cellular damage in HT22 mouse hippocampal neurons. Mechanistically speaking, a further ChIP-qPCR assay confirmed the physical interaction between transcription factor ΔFOSB and the Cacna2d1 gene promoter, suggesting a direct transcriptional regulation of the Cacna2d1 gene by ΔFOSB. Overall, our current work aims to deliver a unique insight into the neurotoxic mechanisms induced by CS to explore potential targets for intervention.

Intracerebral Hemorrhage Models and Behavioral Tests in Rodents

Intracerebral hemorrhage (ICH) is one of the common types of stroke, which can cause neurological dysfunction. In preclinical ICH studies, researchers often established rodent models by donor/autologous whole blood or a collagenase injection. White matter injury (WMI) can result from primary and secondary injuries after ICH. WMI can lead to short- and long-term neurological impairment, and functional recovery can assess the effect of drug therapy after ICH. Therefore, researchers have devised various behavioral tests to assess dysfunction. This review compares the two ICH modeling methods in rodents and summarizes the pathological mechanisms underlying dysfunction after ICH. We also summarize the functions and characteristics of various behavioral methods, including sensation, motion, emotion, and cognition, to assist researchers in selecting the appropriate tests for preclinical ICH research.

The α2δ-1-NMDA receptor complex and its potential as a therapeutic target for ischemic stroke

N-methyl-_D-aspartate receptors (NMDARs) play a critical role in excitotoxicity caused by ischemic stroke, but NMDAR antagonists have failed to be translated into clinical practice for treating stroke patients. Recent studies suggest that targeting the specific protein-protein interactions that regulate NMDARs may be an effective strategy to reduce excitotoxicity associated with brain ischemia. α2δ-1 (encoded by the Cacna2d1 gene), previously known as a subunit of voltage-gated calcium channels, is a binding protein of gabapentinoids used clinically for treating chronic neuropathic pain and epilepsy. Recent studies indicate that α2δ-1 is an interacting protein of NMDARs and can promote synaptic trafficking and hyperactivity of NMDARs in neuropathic pain conditions. In this review, we highlight the newly identified roles of α2δ-1-mediated NMDAR activity in the gabapentinoid effects and NMDAR excitotoxicity during brain ischemia as well as targeting α2δ-1-bound NMDARs as a potential treatment for ischemic stroke.

Intracerebral hemorrhage alters α2δ1 and thrombospondin expression in rats

Calcium voltage-gated channel auxiliary subunit (α2δ1) is a non-essential subunit of the voltage-gated calcium channel complex and is ubiquitously expressed in a number of tissues, including the brain. Thrombospondin (TSP)1 and TSP2 are extracellular matrix proteins and belong to the multi-domain glycoprotein family of macromolecular oligomers. TSP1/2 and α2δ1 promote synapse formation and functional recovery following cerebral infarction. However, to the best of our knowledge, the expression levels of α2δ1 and TSP1/2 in brain tissues, and the effects of intracerebral hemorrhage (ICH) on these levels have not yet been elucidated. The present study established a rat model of hemorrhage induced by injecting collagenase IV into the striatum to determine the changes in α2δ1 and TSP1/2 expression following ICH. The protein expression levels of α2δ1 and TSP1 in the striatum after hemorrhage were significantly increased on day 5 and returned to baseline levels on day 21; however, the protein expression levels of TSP2 were decreased on day 5, whereas they increased on day 14, subsequently returning to baseline levels. In addition, using proteomics analysis of tissues from the sham group (saline injection) and at 24 h post-ICH, it was found that both α2δ1 and TSP1 interacted with neural EGFL like 2. Taken together, these findings suggested that the expression levels of α2δ1 and TSP1/2 were altered in brain tissues in response to ICH.

Serum calcium channel subunit α2δ-1 concentrations and outcomes in patients with acute spontaneous intracerebral hemorrhage

BACKGROUND

Voltage-gated calcium channel subunit α2δ-1 plays an important role in acute brain injury. We attempted to investigate whether serum α2δ-1 subunit concentrations are correlated with severity and prognosis following intracerebral hemorrhage (ICH).

METHODS

Serum α2δ-1 subunit concentrations were quantified in 103 ICH patients and 103 healthy controls. National Institutes of Health Stroke Scale (NIHSS) score and hematoma volume were estimated for assessing illness severity. Modified Rankin scale score of 3-6 at 90 days after stroke onset was defined as a worse outcome.

RESULTS

Serum α2δ-1 subunit concentrations were markedly higher in patients than in controls (median, 875.1 vs. 209.3 pg/ml). Serum α2δ-1 subunit concentrations of patients were tightly correlated with NIHSS score (r = 0.589) and hematoma volume (r = 0.594). Serum α2δ-1 subunit concentrations ≥ 875.1 pg/ml independently discriminated development of 90-day poor outcome with odds ratio of 5.228 (95% CI, 2.201-12.418) and area under the receiver operating characteristic curve of 0.794 (95% CI, 0.703-0.867). Serum α2δ-1 subunit concentrations > 973.4 pg/ml predicted 90-day poor outcome with 64.0% sensitivity and 90.6% specificity. The prognostic predictive ability of serum α2δ-1 concentrations was equivalent to those of NIHSS score and hematoma volume (both P > 0.05), and serum α2δ-1 concentrations also significantly improved the prognostic predictive capabilities of NIHSS score and hematoma volume (both P < 0.05).

CONCLUSIONS

Serum α2δ-1 subunit concentrations are intimately correlated with illness severity and are independently associated with poor 90-day outcome, substantializing serum α2δ-1 subunit as a potential prognostic biomarker for ICH.