The evaluation of oxidative DNA damage in children with brain damage using 8-hydroxydeoxyguanosine levels

Urinary and cerebrospinal fluid (CSF) levels of 8-hydroxydeoxyguanosine (8-OHdG) were examined to estimate the relevance of oxidative stress in children with brain damage. Urinary 8-OHdG levels were measured in 51 children with various forms of central nervous system (CNS) disorders (status epilepticus [SE], hypoxic-ischemic encephalopathy [HIE], CNS infections and chronic epilepsy) and these levels were compared with those in 51 healthy children. CSF 8-OHdG levels were measured in 25 children with brain damage and in 19 control subjects. In addition, urinary and CSF levels of 8-OHdG were compared between the children with brain damage and healthy children. Finally, the relationship between urinary and CSF levels of 8-OHdG was determined in 12 children that provided both urinary and CSF samples. Our results showed that urinary 8-OHdG levels in children with HIE and CNS infections were higher than those of controls (Steel test; p < 0.05 and p < 0.05, respectively) and that CSF 8-OHdG levels were higher in children with SE, HIE, and CNS infections than in control subjects (Steel test; p < 0.01, 0.05 and 0.05, respectively). In addition, a positive correlation between the levels of urinary and CSF 8-OHdG was noted in the 12 children that provided both CSF and urinary samples (Spearman's rank correlation; rho = 0.82, p < 0.01). Further, we observed changes in the urinary 8-OHdG in a patient with HHV-6 encephalopathy, and found that the changes correlated well with the patient's clinical condition. These results suggest that oxidative stress is strongly related to acute brain damage in children, and that 8-OHdG is a useful marker of brain damage. Therefore, repeated measurements of urinary 8-OHdG may be helpful in estimating the extent of brain damage.     

Expression of P-glycoprotein (ABCB1) and Mrp1 (ABCC1) in adult rat brain: focus on astrocytes

P-glycoprotein (P-gp, ABCB1) and the multidrug resistance-associated protein 1 (Mrp1, ABCC1) are two ATP-driven pumps that mediate the export of organic anions from cells and may confer cellular resistance to many cytotoxic hydrophobic drugs. Immunohistochemistry has shown that P-gp is expressed in rat brain capillary vessels forming the blood-brain barrier (BBB). Mrp1 mRNAs have been detected by RT-PCR in rat brain isolated capillaries. Although many studies have been published in this field, very little information is available on the expression, distribution and physiological functions of the two pumps in rat brain. To characterize the cerebral expression of both P-gp and Mrp1 transporters, we studied immunoreactions of rat brain sections with the two most commonly used antibodies: the monoclonal C219 (anti-P-gp) and the polyclonal 6KQ (anti-Mrp1). Immunological analyses revealed heterogeneity of the P-gp and Mrp1 expressions in rat brain. Indeed, choroidal and ependymal cells expressed Mrp1 rather than P-gp. However, tanycytes lining the third ventricle were strongly immunoreactive with both antibodies, suggesting a particular role for these cells in drug efflux mechanisms. Because of the detection of a 70-kDa component with 6KQ antibodies, immunoreactions obtained in rats were compared with these obtained in wild type and mrp1(-/-) mice. It showed that a positive reaction at the apical surface of the ependymal layer remained obvious, showing that 6KQ antibodies recognize an ependymal molecule, differing from the Mrp1. In addition, a continuous expression of C219-labeled epitopes, similar to endothelial labeling, was detected at the blood-brain barrier, whereas a discontinuous labeling, co-localized with glial fibrillary acidic protein (GFAP) immunostaining, was obtained with 6KQ antibodies. We showed that P-gp was preferentially expressed in the endothelial component and Mrp1 in the astroglial component of the blood-brain barrier. Moreover, Mrp1 was rather expressed than P-gp in parenchyma astrocytes and in glia limitans lining the meninges. These findings provide new insights into the cerebral distribution of two ABC transporters linked to multidrug resistance (MDR).     

The evolution of violence in men: The function of central cholesterol and serotonin

Numerous studies point to central serotonin as an important modulator of maladaptive behaviors. In men, for instance, low concentrations of this neurotransmitter are related to hostile aggression. A key player in serotonin metabolism seems to be central cholesterol. It plays a fundamental role in maintaining the soundness of neuron membranes, especially in the exocytosis transport of serotonin vesicles into the synaptic cleft. In this review, we attempt an evolutionary approach to the neurobiological basis of human male violence. Hominid evolution was shaped by periods of starvation but also by energy demands of an increasingly complex brain. A lack of food resources reduces uptake of glucose and results in a decreased energy-supply for autonomous brain cholesterol synthesis. Consequently, concentrations of neuromembrane cholesterol decrease, which lead to a failure of the presynaptic re-uptake mechanism of serotonin and ultimately to low central serotonin. We propose that starvation might have affected the larger male brains earlier than those of females. Furthermore, this neurophysiological process diminished the threshold for hostile aggression, which in effect represented a prerequisite for being a successful hunter or scavenger. In a Darwinian sense, the odds to acquire reliable energetic resources made those males to attractive spouses in terms of paternal care and mate support. To underpin these mechanisms, a hypothetical four-stage model of synaptic membrane destabilization effected by a prolonged shortage of high-energy, cholesterol-containing food is illustrated.     

The role of glutamate receptors in traumatic brain injury: implications for postsynaptic density in pathophysiology

Traumatic brain injury (TBI) is the major cause of death and disability, and the incidence of TBI continues to increase rapidly. In recent years, increasing attention has been paid to an important structure at the postsynaptic membrane: the postsynaptic density (PSD). Glutamate receptors, as major components of the PSD, are highly responsive to alterations in the glutamate concentration at excitatory synapses and activate intracellular signal transduction via calcium and other second messengers following TBI. PSD scaffold proteins (PSD-95, Homer, and Shank), which anchor glutamate receptors and form a network structure, also have potential effects on these downstream signaling pathways. The changes in the function and structure of these major PSD proteins are also induced by TBI, indicating that there is a more complicated mechanism associated with PSD proteins in the pathophysiological process of TBI.     

The role of the CB1 receptor in the regulation of sleep

During the 1990s, transmembranal proteins in the central nervous system (CNS) that recognize the principal compound of marijuana, the delta-9-tetrahydrocannabinol (Delta9-THC) were described. The receptors were classified as central or peripheral, CB1 and CB2, respectively. To this date, it has been documented the presence in the CNS of specific lipids that bind naturally to the CB1/CB2 receptors. The family of endogenous cannabinoids or endocannabinoids comprises oleamide, arachidonoylethanolamine, 2-arachidonylglycerol, virodhamine, noladin ether and N-arachidonyldopamine. Pharmacological experiments have shown that those compounds induce cannabimimetic effects. Endocannabinoids are fatty acid derivates that have a variety of biological actions, most notably via activation of the cannabinoid receptors. The endocannabinoids have an active role modulating diverse neurobiological functions, such as learning and memory, feeding, pain perception and sleep generation. Experimental evidence shows that the administration of Delta9-THC promotes sleep. The activation of the CB1 receptor leads to an induction of sleep, this effect is blocked via the selective antagonist. Since the system of the endogenous cannabinoids is present in several species, including humans, this leads to the speculation of the neurobiological role of the endocannabinoid system on diverse functions such as sleep modulation. This review discusses the evidence of the system of the endocannabinoids as well as their physiological role in diverse behaviours, including the modulation of sleep.     

A brain slice culture model of viral encephalitis reveals an innate CNS cytokine response profile and the therapeutic potential of caspase inhibition

Viral encephalitis is a significant cause of human morbidity and mortality in large part due to suboptimal diagnosis and treatment. Murine reovirus infection serves as a classic experimental model of viral encephalitis. Infection of neonatal mice with T3 reoviruses results in lethal encephalitis associated with neuronal infection, apoptosis, and CNS tissue injury. We have developed an ex vivo brain slice culture (BSC) system that recapitulates the basic pathological features and kinetics of viral replication seen in vivo. We utilize the BSC model to identify an innate, brain-tissue specific inflammatory cytokine response to reoviral infection, which is characterized by the release of IL6, CXCL10, RANTES, and murine IL8 analog (KC). Additionally, we demonstrate the potential utility of this system as a pharmaceutical screening platform by inhibiting reovirus-induced apoptosis and CNS tissue injury with the pan-caspase inhibitor, Q-VD-OPh. Cultured brain slices not only serve to model events occurring during viral encephalitis, but can also be utilized to investigate aspects of pathogenesis and therapy that are not experimentally accessible in vivo.     

The role of glutamate on the action of antidepressants

Major depressive disorder (MDD) is a common, chronic, recurrent mental illness that affects millions of individuals worldwide. Currently available antidepressants are known to affect the monoaminergic (e.g., serotonin, norepinephrine, and dopamine) systems in the brain. Accumulating evidence suggests that the glutamatergic neurotransmission via the excitatory amino acid glutamate also plays an important role in the neurobiology and treatment of this disease. Clinical studies have demonstrated that the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has rapid antidepressant effects in treatment-resistant patients with MDD, suggesting the role of glutamate in the pathophysiology of treatment-resistant MDD. Furthermore, a number of preclinical studies demonstrated that the agents which act at glutamate receptors such as NMDA receptors, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors and metabotropic glutamate receptors (mGluRs) might have antidepressant-like activities in animal models of depression. In this article, the author reviews the role of glutamate in the neuron-glia communication induced by potential antidepressants.     

The formation of cerebrospinal fluid: Nearly a hundred years of interpretations and misinterpretations

The first scientific and experimental approaches to the study of cerebrospinal fluid (CSF) formation began almost a hundred years ago. Despite researchers being interested for so long, some aspects of CSF formation are still insufficiently understood. Today it is generally believed that CSF formation is an active energy consuming metabolic process which occurs mainly in brain ventricles, in choroid plexuses. CSF formation, together with CSF absorption and circulation, represents the so-called classic hypothesis of CSF hydrodynamics. In spite of the general acceptance of this hypothesis, there is a considerable series of experimental results that do not support the idea of the active nature of CSF formation and the idea that choroid plexuses inside the brain ventricles are the main places of formation. The main goal of this review is to summarize the present understanding of CSF formation and compare this understanding to contradictory experimental results that have been obtained so far. And finally, to try to offer a physiological explanation by which these contradictions could be avoided. We therefore analyzed the main methods that study CSF formation, which enabled such an understanding, and presented their shortcomings, which could also be a reason for the erroneous interpretation of the obtained results. A recent method of direct aqueductal determination of CSF formation is shown in more detail. On the one hand, it provides the possibility of direct insight into CSF formation, and on the other, it clearly indicates that there is no net CSF formation inside the brain ventricles. These results are contradictory to the classic hypothesis and, together with other mentioned contradictory results, strongly support a recently proposed new working hypothesis on the hydrodynamics of CSF. According to this new working hypothesis, CSF is permanently produced and absorbed in the whole CSF system as a consequence of filtration and reabsorption of water volume through the capillary walls into the surrounding brain tissue. The CSF exchange between the entire CSF system and the surrounding tissue depends on (patho)physiological conditions that predominate within those compartments.     

The role of IL-6, IL-8 and MCP-1 and their promoter polymorphisms IL-6 -174GC, IL-8 -251AT and MCP-1 -2518AG in the risk of venous thromboembolism: a case-control study

Introduction

Cytokines increased the risk of venous thromboembolism (VTE) in some case-control studies, but not in a prospective study. Data concerning the role of cytokines in the risk of VTE are limited. We examined in a case-control study the association of VTE and levels of interleukin (IL)-6, IL-8 and monocyte chemotactic protein-1 (MCP-1) and assessed whether promoter polymorphisms (IL-6 -174GC, IL-8 -251AT, MCP-1 -2518AG) would affect the thrombotic risk and cytokine levels.

Materials and methods

The study included 119 patients (94 women) with a first event of VTE aged between 18-60 years, and 126 healthy controls (100 women) matched for age (± 5 years). Blood was collected > 7 months after the thrombotic event. Odds ratios (ORs) were calculated per increase of cytokines levels by 1 pg/mL.

Results

ORs adjusted for age and sex were 1.520 [95% Confidence Interval (CI) 1.177 - 1.962] for IL-6, 1.095 (95% CI 1.002 - 1.196) for IL-8 and 1.000 (0.988 - 1.012) for MCP-1. With additional adjustment for ethnic composition, body mass index (BMI) and high sensitive C-reactive protein (hs-CRP), risk estimates remained significant for IL-6 and became of borderline statistical significance for IL-8. Polymorphisms did not influence the thrombotic risk and the cytokine levels in study participants.

Conclusion

VTE was associated with IL-6 and IL-8 levels, and for IL-6 this association was independent of BMI and hs-CRP. Thus far, a causal relationship between inflammation and VTE remains to be clarified and more prospective data are warranted.     

Acute stress differentially affects corticotropin-releasing hormone mRNA expression in the central amygdala of the "depressed" flinders sensitive line and the control flinders resistant line rats

Preclinical and clinical evidence suggests that neuropeptides play a role in the pathophysiology of mood disorders. In the present study, we investigated the involvement of the peptides corticotropin-releasing hormone (CRH), neuropeptide Y (NPY) and nociceptin/orphanin FQ (N/OFQ) and of their receptors in the regulation of emotional behaviours. In situ hybridization experiments were performed in order to evaluate the mRNA expression levels of these neuropeptidergic systems in limbic and limbic-related brain regions of the Flinders Sensitive Line (FSL) rats, a putative genetic animal model of depression. The FSL and their controls, the Flinders Resistant Line (FRL) rats, were subjected to one hour acute restraint and the effects of the stress exposure, including possible strain specific changes on these neuropeptidergic systems, were studied. In basal conditions, no significant differences between FSL and FRL rats in the CRH mRNA expression were found, however an upregulation of the CRH mRNA hybridization signal was detected in the central amygdala of the stressed FRL, compared to the non stressed FRL rats, but not in the FSL, suggesting a hypoactive mechanism of response to stressful stimuli in the "depressed" FSL rats. Baseline levels of NPY and N/OFQ mRNA were lower in the FSL rats compared to the FRL in the dentate gyrus of hippocampus and in the medial amygdala, respectively. However, the exposure to stress induced a significant upregulation of the N/OFQ mRNA levels in the paraventricular thalamic nucleus, while in the same nucleus the N/OFQ receptor mRNA expression was higher in the FSL rats. In conclusion, selective alterations of the NPY and N/OFQ mRNA in limbic and limbic-related regions of the FSL rats, a putative animal model of depression, provide further support for the involvement of these neuropeptides in depressive disorders. Moreover, the lack of CRH activation following stress in the "depressed" FSL rats suggests a form of allostatic load, that could alter their interpretation of environmental stimuli and influence their behavioural response to stressful situations.