Influence of the dopaminergic system, CREB, and transcription factor-κB on cocaine neurotoxicity

Amniotic LPS-Induced Apoptosis in the Fetal Brain Is Suppressed by Vaginal LPS Preconditioning but Is Promoted by Continuous Ischemic Reperfusion

Chorioamnionitis (CAM) is an increasingly common disease affecting pregnant women which derives from bacterial vaginosis. In different clinical cases, it has been shown that CAM can cause multiple risk factors for fetal brain damage, such as infection, and intra-uterine asphyxia. However, the molecular mechanism remains unknown. In this study, we established a novel CAM mouse model by exposing pregnant mice to a combination of three risk factors: vaginal lipopolysaccharides (LPS), amniotic LPS, and ischemic reperfusion. We found amniotic LPS caused Parkinson's disease-like fetal brain damage, in a dose and time-dependent manner. Moreover, the mechanism of this fetal brain damage is apoptosis induced by amniotic LPS but it was inhibited by being pretreated with a vaginal LPS challenge before amniotic LPS injection. In contrast, amniotic LPS with continuous ischemic reperfusion caused a higher level of apoptotic cell death than amniotic LPS alone. In particular, a potential neuroprotective biomarker phosphorylation (p)-CREB (ser133) appeared in only vaginal LPS preconditioned before amniotic LPS, whereas ischemic reperfusion triggered IKK phosphorylation after amniotic LPS. Despite the need for many future investigations, this study also discussed a developed understanding of the molecular mechanism of how these phenotypes occurred.

IκBα is required for full transcriptional induction of some NFκB-regulated genes in response to TNF in MCF-7 cells

Inflammatory stimuli triggers the degradation of three inhibitory κB (IκB) proteins, allowing for nuclear translocation of nuclear factor-κB (NFκB) for transcriptional induction of its target genes. Of these three, IκBα is a well-known negative feedback regulator that limits the duration of NFκB activity. We sought to determine whether IκBα's role in enabling or limiting NFκB activation is important for tumor necrosis factor (TNF)-induced gene expression in human breast cancer cells (MCF-7). Contrary to our expectations, many more TNF-response genes showed reduced induction than enhanced induction in IκBα knockdown cells. Mathematical modeling was used to investigate the underlying mechanism. We found that the reduced activation of some NFκB target genes in IκBα-deficient cells could be explained by the incoherent feedforward loop (IFFL) model. In addition, for a subset of genes, prolonged NFκB activity due to loss of negative feedback control did not prolong their transient activation; this implied a multi-state transcription cycle control of gene induction. Genes encoding key inflammation-related transcription factors, such as JUNB and KLF10, were found to be best represented by a model that contained both the IFFL and the transcription cycle motif. Our analysis sheds light on the regulatory strategies that safeguard inflammatory gene expression from overproduction and repositions the function of IκBα not only as a negative feedback regulator of NFκB but also as an enabler of NFκB-regulated stimulus-responsive inflammatory gene expression. This study indicates the complex involvement of IκBα in the inflammatory response to TNF that is induced by radiation therapy in breast cancer.

Single Low Dose of Cocaine-Structural Brain Injury Without Metabolic and Behavioral Changes

Chronic cocaine use has been shown to lead to neurotoxicity in rodents and humans, being associated with high morbidity and mortality rates. However, recreational use, which may lead to addictive behavior, is often neglected. This occurs, in part, due to the belief that exposure to low doses of cocaine comes with no brain damage risk. Cocaine addicts have shown glucose metabolism changes related to dopamine brain activity and reduced volume of striatal gray matter. This work aims to evaluate the morphological brain changes underlying metabolic and locomotor behavioral outcome, in response to a single low dose of cocaine in a pre-clinical study. In this context, a Balb-c mouse model has been chosen, and animals were injected with a single dose of cocaine (0.5 mg/kg). Control animals were injected with saline. A behavioral test, positron emission tomography (PET) imaging, and anatomopathological studies were conducted with this low dose of cocaine, to study functional, metabolic, and morphological brain changes, respectively. Animals exposed to this cocaine dose showed similar open field activity and brain metabolic activity as compared with controls. However, histological analysis showed alterations in the prefrontal cortex and hippocampus of mice exposed to cocaine. For the first time, it has been demonstrated that a single low dose of cocaine, which can cause no locomotor behavioral and brain metabolic changes, can induce structural damage. These brain changes must always be considered regardless of the dosage used. It is essential to alert the population even against the consumption of low doses of cocaine.

The anticonvulsant effects of cannabidiol in experimental models of epileptic seizures: From behavior and mechanisms to clinical insights

Epilepsy is a neurological disorder characterized by the presence of seizures and neuropsychiatric comorbidities. Despite the number of antiepileptic drugs, one-third of patients did not have their seizures under control, leading to pharmacoresistance epilepsy. Cannabis sativa has been used since ancient times in Medicine for the treatment of many diseases, including convulsive seizures. In this context, Cannabidiol (CBD), a non-psychoactive phytocannabinoid present in Cannabis, has been a promising compound for treating epilepsies due to its anticonvulsant properties in animal models and humans, especially in pharmacoresistant patients. In this review, we summarize evidence of the CBD anticonvulsant activities present in a great diversity of animal models. Special attention was given to behavioral CBD effects and its translation to human epilepsies. CBD anticonvulsant effects are associated with a great variety of mechanisms of action such as endocannabinoid and calcium signaling. CBD has shown effectiveness in the clinical scenario for epilepsies, but its effects on epilepsy-related comorbidities are scarce even in basic research. More detailed and complex behavioral evaluation about CBD effects on seizures and epilepsy-related comorbidities are required.

Cannabidiol, a Cannabis sativa constituent, inhibits cocaine-induced seizures in mice: Possible role of the mTOR pathway and reduction in glutamate release

Cannabidiol (CBD), a major non-psychotomimetic constituent of Cannabis sativa, has therapeutic potential for certain psychiatric and neurological disorders. Studies in laboratory animals and limited human trials indicate that CBD has anticonvulsant and neuroprotective properties. Its effects against cocaine neurotoxicity, however, have remained unclear. Thus, the present study tested the hypothesis that CBD protects against cocaine-induced seizures and investigated the underlying mechanisms. CBD (30 mg/kg) pre-treatment increased the latency and reduced the duration of cocaine (75 mg/kg)-induced seizures in mice. The CB1 receptor antagonist, AM251 (1 and 3mg/kg), and the CB2 receptor antagonist, AM630 (2 and 4 mg/kg), failed to reverse this protective effect, suggesting that alternative mechanisms are involved. Synaptosome studies with the hippocampus of drug-treated animals revealed that cocaine increases glutamate release, whereas CBD induces the opposite effect. Finally, the protective effect of this cannabinoid against cocaine-induced seizure was reversed by rapamycin (1 and 5mg/kg), an inhibitor of the mammalian target of rapamycin (mTOR) intracellular pathway. In conclusion, CBD protects against seizures in a model of cocaine intoxication. These effects possibly occur through activation of mTOR with subsequent reduction in glutamate release. CBD should be further investigated as a strategy for alleviating psychostimulant toxicity.

Cocaine Causes Apoptotic Death in Rat Mesencephalon and Striatum Primary Cultures

To study cocaine's toxic effects in vitro, we have used primary mesencephalic and striatal cultures from rat embryonic brain. Treatment with cocaine causes a dramatic increase in DNA fragmentation in both primary cultures. The toxicity induced by cocaine was paralleled with a concomitant decrease in the microtubule associated protein 2 (MAP2) and/or neuronal nucleus protein (NeuN) staining. We also observed in both cultures that the cell death caused by cocaine was induced by an apoptotic mechanism, confirmed by TUNEL assay. Therefore, the present paper shows that cocaine causes apoptotic cell death and inhibition of the neurite prolongation in striatal and mesencephalic cell culture. These data suggest that if similar neuronal damage could be produced in the developing human brain, it could account for the qualitative or quantitative defects in neuronal pathways that cause a major handicap in brain function following prenatal exposure to cocaine.

Enhancement of endocannabinoid signaling protects against cocaine-induced neurotoxicity

Cocaine is an addictive substance with a potential to cause deleterious effects in the brain. The strategies for treating its neurotoxicity, however, are limited. Evidence suggests that the endocannabinoid system exerts neuroprotective functions against various stimuli. Thus, we hypothesized that inhibition of fatty acid amide hydrolase (FAAH), the main enzyme responsible for terminating the actions of the endocannabinoid anandamide, reduces seizures and cell death in the hippocampus in a model of cocaine intoxication. Male Swiss mice received injections of endocannabinoid-related compounds followed by the lowest dose of cocaine that induces seizures, electroencephalographic activity and cell death in the hippocampus. The molecular mechanisms were studied in primary cell culture of this structure. The FAAH inhibitor, URB597, reduced cocaine-induced seizures and epileptiform electroencephalographic activity. The cannabinoid CB1 receptor selective agonist, ACEA, mimicked these effects, whereas the antagonist, AM251, prevented them. URB597 also inhibited cocaine-induced activation and death of hippocampal neurons, both in animals and in primary cell culture. Finally, we investigated if the PI3K/Akt/ERK intracellular pathway, a cell surviving mechanism coupled to CB1 receptor, mediated these neuroprotective effects. Accordingly, URB597 injection increased ERK and Akt phosphorylation in the hippocampus. Moreover, the neuroprotective effect of this compound was reversed by the PI3K inhibitor, LY294002. In conclusion, the pharmacological facilitation of the anandamide/CB1/PI3K signaling protects the brain against cocaine intoxication in experimental models. This strategy may be further explored in the development of treatments for drug-induced neurotoxicity.

The involvement of secondary neuronal damage in the development of neuropsychiatric disorders following brain insults

Neuropsychiatric disorders are one of the leading causes of disability worldwide and affect the health of billions of people. Previous publications have demonstrated that neuropsychiatric disorders can cause histomorphological damage in particular regions of the brain. By using a clinical symptom-comparing approach, 55 neuropsychiatric signs or symptoms related usually to 14 types of acute and chronic brain insults were identified and categorized in the present study. Forty percent of the 55 neuropsychiatric signs and symptoms have been found to be commonly shared by the 14 brain insults. A meta-analysis supports existence of the same neuropsychiatric signs or symptoms in all brain insults. The results suggest that neuronal damage might be occurring in the same or similar regions or structures of the brain. Neuronal cell death, neural loss, and axonal degeneration in some parts of the brain (the limbic system, basal ganglia system, brainstem, cerebellum, and cerebral cortex) might be the histomorphological basis that is responsible for the neuropsychiatric symptom clusters. These morphological alterations may be the result of secondary neuronal damage (a cascade of progressive neural injury and neuronal cell death that is triggered by the initial insult). Secondary neuronal damage causes neuronal cell death and neural injury in not only the initial injured site but also remote brain regions. It may be a major contributor to subsequent neuropsychiatric disorders following brain insults.