Activation Of Astroglial Cells Research Articles

Pharmacological impact on the expression of microglial and astroglial proteins involved in the regulation of epileptogenesis as a possible new strategy for epilepsy therapy

Pharmacological impact on the expression of microglial and astroglial proteins involved in the regulation of epileptogenesis as a possible new strategy for epilepsy therapy

Serum and CSF brain damage markers NFL and GFAP correlate with tick-borne encephalitis disease severity - a multicenter study on Lithuanian and Swedish patients.

Our aim was to examine the correlation between biomarkers of neuronal and glial cell damage and severity of disease in patients with tick-borne encephalitis. One hundred and fifteen patients with tick-borne encephalitis diagnosed in Lithuania and Sweden were prospectively included, and CSF and serum samples obtained shortly after hospitalization. Using pre-defined criteria, cases were classified as mild, moderate, or severe TBE. Additionally, the presence of spinal nerve paralysis (myelitis) and/or cranial nerve affection were noted. Concentrations of brain cell biomarkers glial fibrillary acidic protein (GFAP), YKL40, S-100B, neurogranin, neurofilament light (NFL), and tau were analyzed in CSF, and in addition, NFL, GFAP and S-100B levels were measured in serum. The Jonckheere Terpstra test was used for group comparisons of continuous variables and Spearman's partial correlation test to adjust for age. CSF and serum concentrations of GFAP and NFL correlated with disease severity, independent of age, and with presence of nerve paralysis. The markers neurogranin, YKL40, tau and S-100B in CSF and S-100B in serum were detected, but their concentrations did not correlate with disease severity. Neuronal cell damage and astroglial cell activation with increased NFL and GFAP in CSF and serum were associated with a more severe disease, independent of age. Increased GFAP and NFL concentrations in CSF and NFL in serum were also indicative of spinal and/or cranial nerve damage. NFL and GFAP are promising prognostic biomarkers in TBE, and future studies should focus on determining the association between these biomarkers and long-term sequelae.

Acute Sleep Deprivation-Induced Anxiety and Disruption of Hypothalamic Cell Survival and Plasticity: A Mechanistic Study of Protection by Butanol Extract of Tinospora cordifolia.

Since sleep is a key homeostatic phenomenon of the body, therefore understanding the complex etiology of the neurological outcome of sleep deprivation (SD) such as anxiety, depression, cognitive dysfunctions, and their management is of utmost importance. The findings of the current study encompass the neurobehavioral as well as hormonal, and neuroinflammatory changes in serum and hypothalamus region of the brain as an outcome of acute SD and their amelioration by pre-treatment with butanol extract of Tinospora cordifolia. SD group animals showed anxiety-like behavior as evident from Elevated Plus Maze data and higher serum cortisol levels, whereas, pre-treatment with B-TCE showed anxiolytic activity and also reduced cortisol levels which was corroborated by an increase in leptin and insulin levels. Further, SD induced elevation of serum pro-inflammatory cytokines IL-6, TNF-α, IL-1β, and MCP-1 and subsequent activation of astroglial cells in the hypothalamus was suppressed in B-TCE pre-treated animals. The current findings suggest that besides the cortical structures, hypothalamus region's synaptic plasticity and cell survival are adversely impacted by acute SD. Further active ingredients present in B-TCE may be useful for the management of SD-induced anxiety, systemic inflammation, and neuroinflammation by targeting hypothalamic BDNF-TrkB/PI3K-Akt pathways.

Elucidation of the mechanism of substantia nigra astroglial cell activation by metabolic reactive oxygen species

Elucidation of the mechanism of substantia nigra astroglial cell activation by metabolic reactive oxygen species

Short-term consumption of alcohol (vodka) mixed with energy drink (AMED) attenuated alcohol-induced cerebral capillary disturbances and neuroinflammation in adult wild-type mice

ABSTRACT Background: The ingestion of combinatory Alcohol Mixed with Energy Drink (AMED) beverages continues to increase markedly, particularly among young adults. Some studies suggest detrimental health effects related to the combination of alcohol with energy drink formulations; however, the consumption of AMED has not been investigated in context of the cerebral microvasculature or neuroinflammation. We hypothesized that cerebral capillary integrity and glial cells are particularly vulnerable to the combination of AMED. Methods:12-week old wild-type C57BL/6J mice were orally gavaged with either vehicle (water), alcohol (vodka), an energy drink (MotherTM), or a combination AMED, daily for five days. Thereafter, mice were sacrificed, blood alcohol concentrations were analysed and cryosections of brain specimens were subjected to confocal immunofluorescent analysis for measures of cerebral capillary integrity via immunoglobulin G (IgG), and markers of neuroinflammation, ionized-calcium-binding-adaptor-molecule 1 (Iba1) and Glial-Fibrillary-Acidic-Protein (GFAP). Proinflammatory cytokines, IL-2, IL-17A, IFN-ϒ, and anti-inflammatory cytokines, IL-4, IL-6 and IL-10, were also measured in serum. Results: Consistent with previous studies, cerebral capillary dysfunction and astroglial cell activation were markedly greater in the alcohol-only group (AO); however, the AO-induced effects were profoundly attenuated with the AMED combination. Mice maintained on AO and AMED interventions exhibited a moderate increase in microglial recruitment. There were no significant changes in pro-inflammatory nor anti-inflammatory cytokines in ED or AMED treated mice. Conclusion: This study suggests that paradoxically the acute detrimental effects of alcohol on cerebral capillary integrity and astrogliosis are counteracted with the co-provision of an ED, rich in caffeine and taurine and containing B-group vitamins.

Cerebrospinal fluid levels of glial marker YKL-40 strongly associated with axonal injury in HIV infection

BackgroundHIV-1 infects the central nervous system (CNS) shortly after transmission. This leads to a chronic intrathecal immune activation. YKL-40, a biomarker that mainly reflects activation of astroglial cells, has not been thoroughly investigated in relation to HIV. The objective of our study was to characterize cerebrospinal fluid (CSF) YKL-40 in chronic HIV infection, with and without antiretroviral treatment (ART).MethodsYKL-40, neopterin, and the axonal marker neurofilament light protein (NFL) were analyzed with ELISA in archived CSF samples from 120 HIV-infected individuals (85 untreated neuroasymptomatic patients, 7 with HIV-associated dementia, and 28 on effective ART) and 39 HIV-negative controls.ResultsCSF YKL-40 was significantly higher in patients with HIV-associated dementia compared to all other groups. It was also higher in untreated neuroasymptomatic individuals with CD4 cell count < 350 compared to controls. Significant correlations were found between CSF YKL-40 and age (r = 0.38, p < 0.001), CD4 (r = − 0.36, p < 0.001), plasma HIV RNA (r = 0.35, p < 0.001), CSF HIV RNA (r = 0.35, p < 0.001), CSF neopterin (r = 0.40, p < 0.001), albumin ratio (r = 0.44, p < 0.001), and CSF NFL (r = 0.71, p < 0.001). Age, CD4 cell count, albumin ratio, and CSF HIV RNA were found as independent predictors of CSF YKL-40 concentrations in multivariable analysis. In addition, CSF YKL-40 was revealed as a strong independent predictor of CSF NFL together with age, CSF neopterin, and CD4 cell count.ConclusionsCSF YKL-40 is a promising biomarker candidate for understanding the pathogenesis of HIV in the CNS. The strong correlation between CSF YKL-40 and NFL suggests a pathogenic association between astroglial activation and axonal injury, and implies its utility in assessing the prognostic value of YKL-40.

An In-silico Approach to Explore the Possible Multifunctional Neuroprotective Efficacy of Violacein against Ischemic Stroke

Introduction: Cerebral ischemia arise due to insufficient/ interrupted blood supply to brain and is accompanied by pathologies like degradation of extracellular matrix resulting in blood brain barrier disruption, intra cranial haemorrhage, activation of astroglial cells and hence death of neurons. In addition, oxidative stress and inflammation is common to all neurodegenerative diseases enhancing the harmful consequences of diseases. Matrix Metalloproteinases (MMP) are normally involved in extracellular matrix remodelling and are regulated while injury and inflammation in tissue. Over expression of MMP2 and MMP9 results in progression of ischemic conditions by extracellular matrix degradation thus compromising the structural integrity of Blood Brain Barrier (BBB) proving them a potent targets for the disease. Violacein (source: Chromobacterium violaceum), purple pigment from microbial origin is a bisindole have high anti-inflammatory, anti-oxidant, anti-bacterial, anti-cancer and anti-parasitic properties. Present study is to study the effective potential of violacein against cerebral ischemia. Methods and findings: Violacein’s ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity), properties were calculated and structural inhibition of MMPs through molecular docking was evaluated. Violacein resulted six H-bonds with MMP2 with high binding energy of -11.83 kcal/mol and two H-bonds with MMP9 with binding energy of -9.889 kcal/mol. The Ki values of violacein with MMP2 and MMP9 were 2.12 nM and 56.14 nM respectively which proved high affinity of violacein towards the target. Conclusion: Violacein with its high antioxidant and anti-inflammatory property can be a potent all round treatment for cerebral ischemia and demands extensive research.

Immunohistochemical evidence of tissue hypoxia and astrogliosis in the rostral ventrolateral medulla of spontaneously hypertensive rats

Increased activity of the sympathetic nervous system has been highlighted as a key factor that contributes to the development and maintenance of arterial hypertension. However, the factors that precipitate sustained increases in sympathetic activity remain poorly understood. Resting tissue oxygen partial pressure (PtO2) in the brainstem of anesthetized spontaneously hypertensive rats (SHRs) has been shown to be lower than in normotensive rats despite normal levels of arterial PO2. A hypoxic environment in the brainstem has been postulated to activate astroglial signalling mechanisms in the rostral ventrolateral medulla (RVLM) which in turn increase the excitability of presympathetic neuronal networks. In this study, we assessed the expression of indirect markers of tissue hypoxia and astroglial cell activation in the RVLM of SHRs and age-matched normotensive Wistar rats. Immunohistochemical labelling for hypoxia-induced factor-1α (HIF-1α) and bound pimonidazole adducts revealed the presence of tissue hypoxia in the RVLM of SHRs. Double immunostaining showed co-localization of bound pimonidazole labelling in putative presympathetic C1 neurons and in astroglial cells. Quantification of glial fibrillary acidic protein (GFAP) immunofluorescence showed relatively higher number of astrocytes and increased GFAP mean grey value density, whilst semi-quantitative analysis of skeletonized GFAP-immunoreactive processes revealed greater % area covered by astrocytic processes in the RVLM of adult SHRs. In conclusion, the morphological findings of tissue hypoxia and astrogliosis within brainstem presympathetic neuronal networks in the SHR support previous observations, showing that low brainstem PtO2 and increased astroglial signalling in the RVLM play an important role in pathological sympathoexcitation associated with the development of arterial hypertension.

Neuronal-derived Ccl7 drives neuropathic pain by promoting astrocyte proliferation.

Recent studies suggest that peripheral nerve injury converts resting spinal cord astroglial cells into an activated state, which is required for the development and maintenance of neuropathic pain. However, the underlying mechanisms of how resting astrocytes are activated after nerve injury remain largely unknown. Astroglial cell proliferation and activation could be affected by endogenous factors including chemokines, growth factors, and neurotropic factor. Chemokine (C-C motif) ligand 7 (Ccl7) is essential in facilitating the development of neuropathic pain; however, the mechanism is unknown. In the present study, we found that Ccl7 promoted astrocyte proliferation and thus contributed toward neuropathic pain. Spinal nerve ligation increased the expression in the spinal cord of neuronal Ccl7. Behavioral analyses showed that knockdown of Ccl7 alleviated spinal nerve ligation-induced neuropathic pain. Further in-vitro study showed that neuronal-derived Ccl7 was sufficient for the proliferation and activation of astroglial cells. We found a novel mechanism of Ccl7 stimulating the proliferation and activation of spinal cord astrocytes that contributes toward neuropathic pain.

Neuroprotection by JM-20 against oxygen-glucose deprivation in rat hippocampal slices: Involvement of the Akt/GSK-3β pathway

Cerebral ischemia is the third most common cause of death and a major cause of disability worldwide. Beyond a shortage of essential metabolites, ischemia triggers many interconnected pathophysiological events, including excitotoxicity, oxidative stress, inflammation and apoptosis. Here, we investigated the neuroprotective mechanisms of JM-20, a novel synthetic molecule, focusing on the phosphoinositide-3-kinase (PI3K)/Akt survival pathway and glial cell response as potential targets of JM-20. For this purpose, we used organotypic hippocampal slice cultures exposed to oxygen-glucose deprivation (OGD) to achieve ischemic/reperfusion damage in vitro. Treatment with JM-20 at 0.1 and 10 μM reduced PI incorporation (indicative of cell death) after OGD. OGD decreased the phosphorylation of Akt (pro-survival) and GSK 3β (pro-apoptotic), resulting in respective inhibition and activation of these proteins. Treatment with JM20 prevented the reduced phosphorylation of these proteins after OGD, representing a shift from pro-apoptotic to pro-survival signaling. The OGD-induced activation of caspase-3 was also attenuated by JM-20 treatment at 10 μM. Moreover, in cultures treated with JM-20 and exposed to OGD conditioning, we observed a decrease in activated microglia, as well as a decrease in interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α release into the culture medium, while the level of the anti-inflammatory IL-10 increased. GFAP immunostaining and IB4 labeling showed that JM-20 treatment significantly augmented GFAP immunoreactivity after OGD, when compared with cultures exposed to OGD only, suggesting the activation of astroglial cells. Our results confirm that JM-20 has a strong neuroprotective effect against ischemic injury and suggest that the mechanisms involved in this effect may include the modulation of reactive astrogliosis, as well as neuroinflammation and the anti-apoptotic cell signaling pathway.

Pathogenic Role of Phosphodiesterase 4B (PDE4B) in Alcohol‐induced Neuro‐inflammation

Chronic ethanol consumption significantly increases brain TLR4 expression and downstream inflammatory gene expression, contributing to microglial activation and neuro-inflammation. Our group has shown that TLR4 inducible PDE4 expression plays a major role in regulating inflammatory cytokine expression in alcohol exposed peripheral macrophages. Hence, we examined its role in alcohol-inducible activation of astroglial cells and neuro-inflammation. We utilized, C57Bl/6 wild-type (WT) and Pde4b-/-mice that were pair-fed or alcohol-fed for 4 weeks, Inhibition of PDE4 was achieved by treatment with a specific inhibitor rolipram (5mg/kg). Further, primary microglial cells were treated in vitro with ethanol (50mM) and LPS (100ng/ml). Results demonstrated that alcohol exposure increases PDE4B expression in brain tissue as well as primary microglial cells. Along with PDE4B, alcohol was also observed to induce activation of astroglial cells as indicated by an increase in glial fibrillary acidic protein - GFAP+ astrocytes and ionized calcium-binding adapter molecule 1 - IBA-1+ microglial cells. Importantly, alcohol-induced activation of astroglial cells was markedly attenuated in (i) Pde4b-/- mice and by (ii) pharmacologic inhibition of PDE4. These data show that PDE4B plays a critical role in regulating alcohol-induced neuro-inflammation and could serve as a significant therapeutic target.

Inflammation and brain aging

The review covers current concepts on cell and molecular mechanisms of neuroinflammation and aging with the special focus on the regulation of cytokine-producing activity of astroglial cells and intercellular communication. The review reflects that a key component of the aging phenomenon as a result of ineffective implementation of anti-inflammatory response are processes of the dysregulated cytokine production, in particular, an increase in the secretion of proinflammatory cytokines and an imbalance in the expression of the receptors and receptor associated proteins. Interpretation of the molecular mechanisms of cell conjugating neuroinflammation and aging cells can give rise to new therapeutic strategies that are relevant to the treatment of a wide range of central nervous system diseases and the development of new experimental models of diseases of the central nervous system.

Changes in Neuroglial Interactions in Nigrostriatal Brain Structures on Modeling of Dopamine System Dysfunction

Hypofunction of the dopamine system was induced by prolonged administration of reserpine or haloperidol in Wistar rats. Reserpine increased the number of astrocytes containing glial fibrillary acidic protein in the striatum by 49%, but decreased the number of astrocytes containing glutamine synthase by 23% and reduced monoamine oxidase B activity by one third. Haloperidol had no significant effect on morphochemical measures of astrocytes but increased the number of oligodendrocytes. It is suggested that activation of astroglial cells by reserpine in a model of dopamine hypofunction is induced by metabolic impairment in the corticostriate glutamatergic system resulting from suppression of dopaminergic transmission in the basal nuclei. Changes in neuroglial interactions in the striatum, leading to imbalance of neurotransmitter systems, may underlie dysfunction of the basal nuclei in a number of human diseases, including Parkinson’s disease.

Involvement of astroglial glutamate–glutamine shuttle in modulation of the jaw‐opening reflex following infraorbital nerve injury

To evaluate the mechanisms underlying orofacial motor dysfunction associated with trigeminal nerve injury, we studied the astroglial cell activation following chronic constriction injury (CCI) of the infraorbital nerve (ION) immunohistochemically, nocifensive behavior in ION-CCI rats, and the effect of the glutamine synthase (GS) blocker methionine sulfoximine (MSO) on the jaw-opening reflex (JOR), and also studied whether glutamate-glutamine shuttle mechanism is involved in orofacial motor dysfunction. GFAP-immunoreactive (IR) cells were observed in the trigeminal motor nucleus (motV) 3 and 14days after ION-CCI, and the nocifensive behavior and JOR amplitude were also strongly enhanced at these times. The number of GS- and GFAP-IR cells was also significantly higher in ION-CCI rats on day 7. The amplitude and duration of the JOR were strongly suppressed after MSO microinjection (m.i.) into the motV compared with that before MSO administration in ION-CCI rats. After MSO administration, the JOR amplitude was strongly suppressed, and the duration of the JOR was shortened. Forty minutes after m.i. of glutamine, the JOR amplitude was gradually returned to the control level and the strongest attenuation of the suppressive effect of MSO was observed at 180min after glutamine m.i. In addition, glutamine also attenuated the MSO effect on the JOR duration, and the JOR duration was extended and returned to the control level thereafter. The present findings suggest that astroglial glutamate-glutamine shuttle in the motV is involved in the modulation of excitability of the trigeminal motoneurons affecting the enhancement of various jaw reflexes associated with trigeminal nerve injury.

Involvement of neuronal IL-1β in acquired brain lesions in a rat model of neonatal encephalopathy

BackgroundInfection-inflammation combined with hypoxia-ischemia (HI) is the most prevalent pathological scenario involved in perinatal brain damage leading to life-long neurological disabilities. Following lipopolysaccharide (LPS) and/or HI aggression, different patterns of inflammatory responses have been uncovered according to the brain differentiation stage. In fact, LPS pre-exposure has been reported to aggravate HI brain lesions in post-natal day 1 (P1) and P7 rat models that are respectively equivalent - in terms of brain development - to early and late human preterm newborns. However, little is known about the innate immune response in LPS plus HI-induced lesions of the full-term newborn forebrain and the associated neuropathological and neurobehavioral outcomes.MethodsAn original preclinical rat model has been previously documented for the innate neuroimmune response at different post-natal ages. It was used in the present study to investigate the neuroinflammatory mechanisms that underline neurological impairments after pathogen-induced inflammation and HI in term newborns.ResultsLPS and HI exerted a synergistic detrimental effect on rat brain. Their effect led to a peculiar pattern of parasagittal cortical-subcortical infarcts mimicking those in the human full-term newborn with subsequent severe neurodevelopmental impairments. An increased IL-1β response in neocortical and basal gray neurons was demonstrated at 4 h after LPS + HI-exposure and preceded other neuroinflammatory responses such as microglial and astroglial cell activation. Neurological deficits were observed during the acute phase of injury followed by a recovery, then by a delayed onset of profound motor behavior impairment, reminiscent of the delayed clinical onset of motor system impairments observed in humans. Interleukin-1 receptor antagonist (IL-1ra) reduced the extent of brain lesions confirming the involvement of IL-1β response in their pathophysiology.ConclusionIn rat pups at a neurodevelopmental age corresponding to full-term human newborns, a systemic pre-exposure to a pathogen component amplified HI-induced mortality and morbidities that are relevant to human pathology. Neuronal cells were the first cells to produce IL-1β in LPS + HI-exposed full-term brains. Such IL-1β production might be responsible for neuronal self-injuries via well-described neurotoxic mechanisms such as IL-1β-induced nitric oxide production, or IL-1β-dependent exacerbation of excitotoxic damage.

Anti-inflammatory and neuroprotective effects of an orally active apocynin derivative in pre-clinical models of Parkinson’s disease

BackgroundParkinson’s disease (PD) is a devastating neurodegenerative disorder characterized by progressive motor debilitation, which affects several million people worldwide. Recent evidence suggests that glial cell activation and its inflammatory response may contribute to the progressive degeneration of dopaminergic neurons in PD. Currently, there are no neuroprotective agents available that can effectively slow the disease progression. Herein, we evaluated the anti-inflammatory and antioxidant efficacy of diapocynin, an oxidative metabolite of the naturally occurring agent apocynin, in a pre-clinical 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD.MethodsBoth pre-treatment and post-treatment of diapocynin were tested in the MPTP mouse model of PD. Diapocynin was administered via oral gavage to MPTP-treated mice. Following the treatment, behavioral, neurochemical and immunohistological studies were performed. Neuroinflammatory markers, such as ionized calcium binding adaptor molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), gp91phox and inducible nitric oxide synthase (iNOS), were measured in the nigrostriatal system. Nigral tyrosine hydroxylase (TH)-positive neurons as well as oxidative markers 3-nitrotyrosine (3-NT), 4-hydroxynonenal (4-HNE) and striatal dopamine levels were quantified for assessment of the neuroprotective efficacy of diapocynin.ResultsOral administration of diapocynin significantly attenuated MPTP-induced microglial and astroglial cell activation in the substantia nigra (SN). MPTP-induced expression of gp91phox and iNOS activation in the glial cells of SN was also completely blocked by diapocynin. Notably, diapocynin markedly inhibited MPTP-induced oxidative markers including 3-NT and 4-HNE levels in the SN. Treatment with diapocynin also significantly improved locomotor activity, restored dopamine and its metabolites, and protected dopaminergic neurons and their nerve terminals in this pre-clinical model of PD. Importantly, diapocynin administered 3 days after initiation of the disease restored the neurochemical deficits. Diapocynin also halted the disease progression in a chronic mouse model of PD.ConclusionsCollectively, these results demonstrate that diapocynin exhibits profound neuroprotective effects in a pre-clinical animal model of PD by attenuating oxidative damage and neuroinflammatory responses. These findings may have important translational implications for treating PD patients.

Modeling the contribution of neuron-astrocyte cross talk to slow blood oxygenation level-dependent signal oscillations

A consistent and prominent feature of brain functional magnetic resonance imaging (fMRI) data is the presence of low-frequency (<0.1 Hz) fluctuations of the blood oxygenation level-dependent (BOLD) signal that are thought to reflect spontaneous neuronal activity. In this report we provide modeling evidence that cyclic physiological activation of astroglial cells produces similar BOLD oscillations through a mechanism mediated by intracellular Ca(2+) signaling. Specifically, neurotransmission induces pulses of Ca(2+) concentration in astrocytes, resulting in increased cerebral perfusion and neuroactive transmitter release by these cells (i.e., gliotransmission), which in turn stimulates neuronal activity. Noticeably, the level of neuron-astrocyte cross talk regulates the periodic behavior of the Ca(2+) wave-induced BOLD fluctuations. Our results suggest that the spontaneous ongoing activity of neuroglial networks is a potential source of the observed slow fMRI signal oscillations.

Mechanisms Involved in Extraterritorial Facial Pain following Cervical Spinal Nerve Injury in Rats

BackgroundThe aim of this study is to clarify the neural mechanisms underlying orofacial pain abnormalities after cervical spinal nerve injury. Nocifensive behavior, phosphorylated extracellular signal-regulated kinase (pERK) expression and astroglial cell activation in the trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal dorsal horn (C1-C2) neurons were analyzed in rats with upper cervical spinal nerve transection (CNX).ResultsThe head withdrawal threshold to mechanical stimulation of the lateral facial skin and head withdrawal latency to heating of the lateral facial skin were significantly lower and shorter respectively in CNX rats compared to Sham rats. These nocifensive effects were apparent within 1 day after CNX and lasted for more than 21 days. The numbers of pERK-like immunoreactive (LI) cells in superficial laminae of Vc and C1-C2 were significantly larger in CNX rats compared to Sham rats following noxious and non-noxious mechanical or thermal stimulation of the lateral facial skin at day 7 after CNX. Two peaks of pERK-LI cells were observed in Vc and C1-C2 following mechanical and heat stimulation of the lateral face. The number of pERK-LI cells in C1-C2 was intensity-dependent and increased when the mechanical and heat stimulations of the face were increased. The decrements of head withdrawal latency to heat and head withdrawal threshold to mechanical stimulation were reversed during intrathecal (i.t.) administration of MAPK/ERK kinase 1/2 inhibitor PD98059. The area of activated astroglial cells was significantly higher in CNX rats (at day 7 after CNX). The heat and mechanical nocifensive behaviors were significantly depressed and the number of pERK-LI cells in Vc and C1-C2 following noxious and non-noxious mechanical stimulation of the face was also significantly decreased following i.t. administration of the astroglial inhibitor fluoroacetate.ConclusionsThe present findings have demonstrated that mechanical allodynia and thermal hyperalgesia occur in the lateral facial skin after CNX and also suggest that ERK phosphorylation of Vc and C1-C2 neurons and astroglial cell activation are involved in orofacial extraterritorial pain following cervical nerve injury.

Relevance of the ability of fructose 1,6-bis(phosphate) to sequester ferrous but not ferric ions

The cytoprotective activity of F16BP has been documented in severe conditions such as convulsions, reperfusion injury, septic shock, diabetic complications, hypothermia-induced injury, UV-provoked skin damage and in other processes including apoptosis and excitotoxicity. F16BP shows very efficient cytoprotective activity in astroglial cells exposed to H 2O 2-provoked oxidative stress and during neuronal injury caused by hypoxic conditions. As most of the aforementioned processes involve iron activity-related conditions, we investigated the ferric and ferrous iron binding properties of F16BP under physiological conditions using 31P NMR and EPR spectroscopy. Our results indicate that cytoprotective F16BP activity is predominantly based on ferrous iron sequestration. 31P NMR spectroscopy of F16BP employing paramagnetic properties of iron clearly showed that F16BP forms stabile complexes with Fe 2+ which was verified by EPR of another divalent cation—Mn 2+. On the other hand, F16BP does not sequester ferric iron nor does it increase its redox activity as shown by 31P NMR and EPR spin-trapping. Therefore, F16BP may be beneficial in neurodegenerative and other conditions that are characterised by ferric iron stores and deposits.

In vivo monitoring of extracellular 13N-glutamine derived from blood-borne 13N-ammonia in rat striatum using microdialysis with radio-LC method

Glutamine synthetase (GS) is selectively localized in astrocytes and has important roles in the central nervous system (CNS). Cerebral extracellular excess ammonia and glutamate are taken up by astrocytes and converted to glutamine via GS to protect the CNS against neurotoxicity. In this study, we monitored cerebral extracellular 13N-glutamine derived from 13N-ammonia as a potential marker for astroglial metabolism using in vivo microdialysis combined with ultra performance liquid chromatography-radiometric detection. This method allowed rapid and highly sensitive radiometric analysis of 13N-ammonia and its metabolite, 13N-glutamine, in striatal extracellular fluid with good time resolution. Inhibition of GS with methionine sulfoximine resulted in a decrease of extracellular 13N-glutamine accompanied by an increase of 13N-ammonia as compared with control. Fluorocitrate, a selective inhibitor of glial metabolism, also decreased 13N-glutamine production and increased unmetabolized 13N-ammonia. In contrast, 13N-glutamine was increased with 5 mmol/kg of ammonium acetate without significant changes in 13N-ammonia as compared with control. These results suggest that the concentration of extracellular 13N-glutamine strongly reflects the biological changes in the metabolic activity of astroglial cells.