Neuroprotective effects of sodium valproate on hippocampal cell and volume, and cognitive function in a rat model of focal cerebral ischemia

Anxiolytic and sedative effects of sodium valproate with different experimental paradigms in male and female rats

Valproic acid or sodium valproate is a widely used drug in the treatment of epilepsy, although it also appears to have anxiolytic and sedative properties derived from its agonistic action on the GABAergic system. To analyze these potential effects of the drug, we conducted three experiments with rats using procedures designed to assess anxiety in rodents. In the first experiment, with a fear conditioning procedure, three groups of male rats were included that received either 100 mg/kg or 300 mg/kg of valproate or an equivalent volume of saline solution. In Experiment 2, recording spontaneous activity in an open field, we compared the effects of valproic acid (300 mg/kg) on male and female rats. In the third experiment, we analyzed the effect of valproic acid using a novelty-induced hypophagia test and tested again for potential differences as a function of the sex of the animals. The results showed an anxiolytic effect restricted to the 300 mg/kg dose of the drug in Experiment 1. Such an effect was restricted to the female sample in Experiment 2, but in the third experiment affected both sexes. As for the sedative effect, it was observed in all experiments irrespective of the sex of the rats. These findings hold significant implications for the treatment of anxiety disorders since valproate may offer a novel therapeutic approach for anxiety-related conditions with distinct benefits and fewer side effects. However, clinical studies are needed to validate the translation of these findings from animal models to human patients.

Role of hippocampal and prefrontal cortical cholinergic transmission in combination therapy valproate and cannabidiol in memory consolidation in rats: involvement of CREB- BDNF signaling pathways

PURPOSE

Cognitive disorders are associated with valproate and drugs used to treat neuropsychological diseases. Cannabidiol (CBD) has beneficial effects on cognitive function. This study examined the effects of co-administration of CBD and valproate on memory consolidation, cholinergic transmission, and cyclic AMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway in the prefrontal cortex (PFC) and hippocampus (HPC).

METHODS

One-trial, step-through inhibitory test was used to evaluate memory consolidation in rats. The intra-CA1 injection of physostigmine and atropine was performed to assess the role of cholinergic transmission in this co-administration. Phosphorylated CREB (p-CREB)/CREB ratio and BDNF levels in the PFC and HPC were evaluated.

RESULTS

Post-training intraperitoneal (i.p.) valproate injection reduced memory consolidation; however, post-training co-administration of CBD with valproate ameliorated memory impairment induced by valproate. Post-training intra-CA1 injection of physostigmine at the ineffective doses in memory consolidation (0.5 and 1 µg/rat), plus injection of 10 mg/kg of CBD as an ineffective dose, improved memory loss induced by valproate, which was associated with BDNF and p-CREB level enhancement in the PFC and HPC. Conversely, post-training intra-CA1 injection of ineffective doses of atropine (1 and 2 µg/rat) reduced the positive effects of injection of CBD at a dose of 20 mg/kg on valproate-induced memory loss associated with BDNF and p-CREB level reduction in the PFC and HPC.

CONCLUSION

The results indicated a beneficial interplay between valproate and CBD in the process of memory consolidation, which probably creates this interaction through the BDNF-CREB signaling pathways in the cholinergic transmission of the PFC and HPC regions.

The combination treatment of hypothermia and intranasal insulin ameliorates the structural and functional changes in a rat model of traumatic brain injury

The present study aimed to investigate the combination effects of hypothermia (HT) and intranasal insulin (INS) on structural changes of the hippocampus and cognitive impairments in the traumatic brain injury (TBI) rat model. The rats were divided randomly into the following five groups (n = 10): Sham, TBI, TBI with HT treatment for 3 h (TBI + HT), TBI with INS (ten microliters of insulin) treatment daily for 7 days (TBI + INS), and TBI with combining HT and INS (TBI + HT + INS). At the end of the 7th day, the open field and the Morris water maze tests were done for evaluation of anxiety-like behavior and memory performance. Then, after sacrificing, the brain was removed for stereological study. TBI led to an increase in the total volume of hippocampal subfields CA1 and DG and a decrease in the total number of neurons and non-neuronal cells in both sub-regions, which was associated with anxiety-like behavior and memory impairment. Although, the combination of HT and INS prevented the increased hippocampal volume and cell loss and improved behavioral performances in the TBI group. Our study suggests that the combined treatment of HT and INS could prevent increased hippocampal volume and cell loss in CA1 and DG sub-regions and consequently improve anxiety-like behaviors and memory impairment following TBI.

The Function of Spag6 to Repair Brain Edema Damage After Cerebral Ischemic Stroke-reperfusion

Sperm associated antigen 6 (Spag6) is the PF16 homolog of Chlamydomonas and participates in the regulation of cilia movement. Studies have shown that Spag6 is expressed in the brain, and its loss will lead to cerebral edema caused by a defect in motor cilium function in ependymal cells. However, it has not been reported whether the limited or extensive cerebral edema resulting from ischemic strokes is related to the expression regulation of Spag6. Therefore, this study aimed to investigate the effect and related mechanism of Spag6 in alleviating Cerebral Ischemic stroke-reperfusion (CIS/R) damage. Our experimental results showed that Spag6 overexpression alleviated CIS/R-mediated motor cilia structural disorder, improved cerebral edema, inhibited nerve injuries in rats with cerebral ischemia, and alleviated synaptic and dendritic spinal injuries by regulating the expressions of synaptic-related proteins such as CaMKII, PSD95, and CREB. Based on significant changes in PI3K/AKT-mTOR signaling pathway activity after CIS/R determination, we determined that Spag6 regulates the abnormal expression of CIS/R-induced inflammatory factors NF-κB, NLRP3, IL-10, and the autophagy-related proteins Beclin-1, LC3, and P62 by activating the PI3K/AKT-mTOR signaling pathway. This inhibits inflammation and autophagy in the brain tissue. In summary, this study revealed that Spag6 alleviates brain edema damage after CIS/R by maintaining the structural function of the motor cilium, regulating the PI3K/AKT-mTOR signaling pathway, and inhibiting inflammation and autophagy reaction.

The impact of anesthetic drugs on hemodynamic parameters and neurological outcomes following temporal middle cerebral artery occlusion in rats

The induction of ischemic stroke in the experimental model requires general anesthesia. One of the factors that can be effective in the size of ischemic brain lesions and neurological outcomes is the type of anesthesia. So, the current study was designed to compare the impacts of the most important and widely used anesthetics including halothane, isoflurane, and chloral hydrate on the transient middle cerebral artery occlusion (MCAO) outcomes. Adult Male Sprague-Dawley rats were randomly divided into three groups as follows: (1) MCAO + halothane group, (2) MCAO + isoflurane group, and (3) MCAO + chloral hydrate group. After 24 h, the mortality rate, infarct size, tissue swelling, neurological function, hemodynamic, and arterial blood gas parameters were assessed. Our finding showed that 60 min MCAO rats anesthetized with chloral hydrate significantly increased mortality rate, infarct size, tissue swelling, and neurological deficits compared with halothane and isoflurane anesthetics after 24 h of MCAO. Also, chloral hydrate caused a significant decrease in mean arterial pressure and arterial pO2 compared to halothane and isoflurane anesthetics. On the basis of the current data, we concluded that chloral hydrate increased cerebral infarct volume and neurological outcomes and reduced hemodynamic and metabolic parameters compared with halothane and isoflurane-anesthetized rats temporal MCAO.

Neuroprotective Effects and Metabolomics Study of Protopanaxatriol (PPT) on Cerebral Ischemia/Reperfusion Injury In Vitro and In Vivo

Stroke, one of the leading causes of disability and death worldwide, is a severe neurological disease that threatens human life. Protopanaxatriol (PPT), panaxatriol-type saponin aglycone, is a rare saponin that exists in Panax ginseng and Panax Noto-ginseng. In this study, we established an oxygen-glucose deprivation (OGD)-PC12 cell model and middle cerebral artery occlusion/reperfusion (MCAO/R) model to evaluate the neuroprotective effects of PPT in vitro and in vivo. In addition, metabolomics analysis was performed on rat plasma and brain tissue samples to find relevant biomarkers and metabolic pathways. The results showed that PPT could significantly regulate the levels of LDH, MDA, SOD, TNF-α and IL-6 factors in OGD-PC12 cells in vitro. PPT can reduce the neurological deficit score and infarct volume of brain tissue in rats, restore the integrity of the blood-brain barrier, reduce pathological damage, and regulate TNF-α, IL-1β, IL-6, MDA, and SOD factors. In addition, the results of metabolomics found that PPT can regulate 19 biomarkers involving five metabolic pathways, including amino acid metabolism, arachidonic acid metabolism, sphingolipid metabolism, and glycerophospholipid metabolism. Thus, it could be inferred that PPT might serve as a novel natural agent for MCAO/R treatment.

Traditional and Innovative Anti-seizure Medications Targeting Key Physiopathological Mechanisms: Focus on Neurodevelopment and Neurodegeneration

Despite the wide range of compounds currently available to treat epilepsy, there is still no drug that directly tackles the physiopathological mechanisms underlying its development. Indeed, antiseizure medications attempt to prevent seizures but are inefficacious in counteracting or rescuing the physiopathological phenomena that underlie their onset and recurrence, and hence do not cure epilepsy. Classically, the altered excitation/inhibition balance is postulated as the mechanism underlying epileptogenesis and seizure generation. This oversimplification, however, does not account for deficits in homeostatic plasticity resulting from either insufficient or excessive compensatory mechanisms in response to a change in network activity. In this respect, both neurodevelopmental epilepsies and those associated with neurodegeneration may share common underlying mechanisms that still need to be fully elucidated. The understanding of these molecular mechanisms shed light on the identification of new classes of drugs able not only to suppress seizures, but also to present potential antiepileptogenic effects or "disease-modifying" properties.

Delta Opioid Peptide Targets Brain Microvascular Endothelial Cells Reducing Apoptosis to Relieve Hypoxia-Ischemic/Reperfusion Injury

Stroke is one of the leading causes of death. (D-ala2, D-leu5) enkephalin (DADLE) is a synthetic peptide and highly selective delta opioid receptor (δOR) agonist that has exhibited protective properties in ischemia. However, the specific target and mechanism are still unclear. The present study explores the expression of δOR on brain microvascular endothelial cells (BMECs) and whether DADLE could relieve I/R-induced injury by reducing apoptosis. A lateral ventricular injection of DADLE for pretreatment, the neurofunctional behavior score, and TTC staining, were used to evaluate the protective effect of DADLE. Immunofluorescence technology was used to label different types of cells with apoptosis-positive signals to test co-localization status. Primary cultured BMECs were separated and treated with DADLE, accompanied by OGD/R. The CCK-8 test was conducted to evaluate cell viability and TdT-mediated dUTP Nick-end Labelling (TUNEL) staining to test apoptosis levels. The levels of apoptosis-related proteins were analyzed by Western blotting. The co-localization results showed that BMECs, but not astrocytes, microglia, or neurons, presented mostly TUNEL-positive signals, especially in the Dentate gyrus (DG) area of the hippocampus. Either activation of δORs on rats' brains or primary BMECs mainly reduce cellular apoptosis and relieve the injury. Interference with the expression δOR could block this effect. DADLE also significantly increased levels of Bcl-2 and reduced levels of Bax. δOR's expressions can be detected on the BMECs, but not on the HEK293 cells, by Western blotting and IFC. Therefore, DADLE exerts a cytoprotective effect, primarily under hypoxia-ischemic injury/reperfusion conditions, by targeting BMECs to inhibit apoptosis.

Molecular mechanisms for the prevention and promoting the recovery from ischemic stroke by nutraceutical laminarin: A comparative transcriptomic approach

Stroke is the second leading cause of death and a major cause of disability worldwide. Ischemic stroke caused by atherosclerosis accounts for approximately 87% of all stroke cases. Ischemic stroke is a preventable disease; therefore, a better understanding of the molecular mechanisms underlying its pathogenesis and recovery processes could provide therapeutic targets for drug development and reduce the associated mortality rate. Laminarin, a polysaccharide, is a nutraceutical that can be found in brown algae. Accumulating evidence suggests that laminarin could reduce the detrimental effects of neuroinflammation on brain damage after stroke. However, the molecular mechanism underlying its beneficial effects remains largely unknown. In the present study, we used a middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomics to investigate the molecular targets and pathways involved in the beneficial effects of laminarin on ischemic stroke. Our results show the involvement of laminarin targets in biological processes related to blood circulation, oxygen supply, and anti-inflammatory responses in the normal brain. More importantly, laminarin treatment attenuated brain damage and neurodeficits caused by ischemic stroke. These beneficial effects are controlled by biological processes related to blood vessel development and brain cell death through the regulation of canonical pathways. Our study, for the first time, delineated the molecular mechanisms underlying the beneficial effects of laminarin on ischemic stroke prevention and recovery and provides novel therapeutic targets for drug development against ischemic stroke.