Apocynin improves outcome in experimental stroke with a narrow dose range

Inflammation following ischemic stroke is known to contribute to injury. NADPH oxidase (NOX) is a major enzyme system originally studied in immune cells that leads to superoxide (O.*) generation. Apocynin is a NOX inhibitor that has been studied as a potential treatment in experimental stroke. Here we explored the effect of different doses of apocynin in a mouse model of 2 h transient middle cerebral artery occlusion (tMCAO) followed by 22 h reperfusion. Apocynin, given i.v. at a dose of 2.5 mg/kg 30 min before reperfusion, improved neurological function (P<0.01), reduced infarct volume (P<0.05), and reduced the incidence of cerebral hemorrhage (P<0.05), but not at higher doses of 3.75 and 5 mg/kg, where it actually increased brain hemorrhage. Apocynin also tended to reduce mortality at the lower dose, but not at higher doses. Using hydroethine fluorescence to delineate O.* in the brain, neurons and some microglia/macrophages, but not vascular endothelial cells were found to contain O.*. Apocynin at protective doses markedly prevented ischemia-induced increases in O.*. Our data suggested that apocynin can protect against experimental stroke, but with a narrow therapeutic window.     

Tyrosine kinase B and C receptors in the neostriatum and nucleus accumbens are co-localized in enkephalin-positive and enkephalin-negative neuronal profiles and their expression is influenced by cocaine

Single- and double-label immunohistochemistry were used to determine the extent to which the tyrosine kinase B and C receptors, are expressed in enkephalin-immunopositive or enkephalin-immunonegative neuronal profiles in the rat neostriatum and nucleus accumbens. Results indicate that tyrosine kinase B and C receptors are co-localized in both enkephalin-positive and enkephalin-negative neurons in both of these nuclei, which suggests that these receptors influence both the striatal-pallidal (enkephalin) and striatal-ventral mesencephalic (substance P/dynorphin) pathways. We also examined the influence of acute or repeated injections of cocaine on the number of tyrosine kinase B and C receptors immunoreactive neuronal profiles in the rat neostriatum and nucleus accumbens. Following an acute injection of cocaine (15 mg/kg, i.p.), there were significant decreases in the number of tyrosine kinase B and C receptors immunoreactive profiles in specific regions of the neostriatum and nucleus accumbens relative to saline-pretreated rats. One or 14 days following the last of seven daily injections of 15 mg/kg cocaine or saline there were no differences in the numbers of tyrosine kinase B or C receptors immunoreactive neuronal profiles between these treatment groups.Collectively, the present results indicate that tyrosine kinase B and C receptors in the neostriatum and nucleus accumbens are co-localized in enkephalin-positive and enkephalin-negative neuronal profiles, which suggests that the striatal medium spiny neurons expressing tyrosine kinase B and C receptors include those that project to the pallidum or the ventral mesencephalon. The current results also show that an acute injection of cocaine results in a decrease in the number of tyrosine kinase B and C receptors immunoreactive neuronal profiles in specific regions of the nucleus accumbens and neostriatum, indicating that cocaine-induced increases in extracellular dopamine in the striatal complex result in compensatory decreases in the expression of tyrosine kinase B and C receptors.     

Projections from the ventral tegmental area and mesencephalic raphe to the dorsal raphe nucleus in the rat

Summary The origins of the dopaminergic innervation of the rat dorsal raphe nucleus (NRD) have been investigated using a combination of fluorescent retrograde tracing and fluorescence histochemistry. Stereotaxic microinjections of True Blue were placed in the central, caudal and lateral portions of the NRD, and after 6–12 days survival the brains were processed for fluorescence histochemical detection of catecholamines. Retrogradely labeled neurons were searched for in the diencephalic A11 and A13 dopaminergic cell groups, substantia nigra, ventral tegmental area (VTA) and the linear, central superior and dorsal raphe nuclei. The various NRD injections consistently resulted in retrograde labeling of a small number of catecholamine-containing, presumed dopaminergic cell bodies, confined mainly to three regions: the VTA, the linear and central superior raphe nuclei and the NRD itself. The present findings indicate that not only dopaminergic neurons in the VTA but also the system of catecholamine-containing cells, extending dorsally and caudally from the VTA within the midline raphe area, project to the NRD. Although often similar in size, shape and distribution to the catecholaminergic neurons the majority of retrogradely labeled cells in these regions were, however, found to be non-catecholaminergic.Abbreviations 3 Principal oculomotor nucleus - 4 Trochlear nucleus - Aq Cerebral aqueduct - cp cerebral peduncle - cst cortico-spinal tract - dscp decussation of the superior cerebellar peduncle - DTg Dorsal tegmental nucleus - fr fasciculus retroflexus - IF Interfascicular nucleus - IP Interpeduncular nucleus - LL nucleus of the lateral lemniscus - ml medial lemniscus - mlf medial longitudinal fasciculus - mNV mesencephalic trigeminal nucleus - NLC Nucleus linearis caudalis - NLR Nucleus linearis rostralis - NRD Dorsal raphe nucleus - PAG Periaqueductal grey - PN Pontine nucleus - PRN Pontine raphe nucleus - R Red nucleus - RCS Nucleus raphe centralis superior - SN Substantia nigra - VTA Ventral tegmental area - VTg Ventral tegmental nucleus     

Atropine, a muscarinic cholinergic receptor antagonist increases serotonin, but not dopamine levels in discrete brain regions of mice

We investigated the effects of atropine, a muscarinic acetylcholine (ACh) receptor antagonist, on the level of serotonin in discrete brain regions, the nucleus raphe dorsalis (NRD), nucleus caudatus putamen (NCP), cerebral cortex and the cerebellum. Biogenic amines were assayed employing HPLC electrochemistry in these regions 30 min following different doses of atropine (5, 10, 25mg/kg; i.p.), and at various time points (15, 30, 60, 120 min) after 25mg/kg of the drug. The cholinergic receptor antagonist caused a dose-dependent alteration in the level of serotonin in NRD, but the increase was not dose-dependent for other regions studied. The metabolite of serotonin, 5-hydroxyindoleacetic acid was unaffected. Atropine did not affect the levels of dopamine or its metabolites dihydroxyphenyl acetic acid and homovanillic acid. The present study suggests significant effect of this antimuscarinic agent on the synthesis of serotonin in the central serotoninergic pathways, which may have clinical relevance.     

The effect of stimulation and blocking of histamine H2 receptors on the turnover of the serotonin in different parts of the alimentary tract and the brain of the rat

In the experiments performed on Wistar rats it was found that histamine (0.05 and 0.5 mg/kg i.p.) caused an acceleration of the turnover of serotonin (5-HT) in the stomach. After the lowest dose of ranitidine (3 mg/kg i.p.) a decrease in the rate of 5-HT turnover in the stomach was observed, whereas the higher doses (15.0 and 30 mg/kg i.p.) accelerated the turnover of this amine. In the duodenum, both doses of histamine accelerated the turnover of 5-HT, however, ranitidine in all doses induced a reduction in the rate of 5-HT turnover in this part of the alimentary tract. In the intestine, both doses of histamine enhanced the turnover of 5-HT but after all doses of ranitidine a decrease of the turnover was observed.The blockade of histamine H₂ receptors with ranitidine did not completely abolish the effects of histamine on the 5-HT system, in the parts of the rat digestive system studied which suggests also an indirect activity of other receptors in presented observations. In the rat brain, an acceleration of the turnover of 5-HT after both doses of histamine was found. However, ranitidine only reduced the rate of 5-HT turnover at the lowest dose. In animals treated with ranitidine (15 mg/kg i.p.) for three days, histamine did not produce any change in the turnover of 5-HT in rat brain.These experiments show, that in the alimentary tract a relationship exists between histaminergic and serotoninergic systems.     

The vigilance-promoting drug modafinil counteracts the reduction of tyrosine hydroxylase immunoreactivity and of dopamine stores in nigrostriatal dopamine neurons in the male rat after a partial transection of the dopamine pathway

We studied the ability of the vigilance-promoting drug modafinil to modulate the anterograde and retrograde changes in tyrosine hydroxylase (TH) immunoreactivity and in dopamine (DA) stores in the nigro-neostriatal DA neurons, following a partial hemitransection of this ascending DA system, using a combined morphometrical, biochemical and behavioural analysis. Modafinil was given daily i.p. in doses of 10–100 mg/kg, starting 15 min after the lesion, and the partially hemitransected rats were killed 2 weeks later. Changes in TH-immunoreactive nerve cell bodies and nerve terminals induced by the partial hemitransection were studied in the substantia nigra and neostriatum in combination with image analysis. The substantia nigra and neostriatum were also subjected to biochemical analysis of DA, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels. Modafinil treatment dose-dependently (10–100 mg/kg) counteracted the hemitransection-induced disappearance of nigral TH-immunoreactive nerve cell body profiles and neostriatal TH-immunoreactive nerve terminal profiles. A 2-week treatment with 100 mg/kg of modafinil also counteracted the hemitransection-induced depletion of DA stores in the neostriatum and the ventral midbrain. Moreover, the repeated daily treatment with modafinil (100 mg/kg) protected against the hemitransection-induced disappearance of striatal 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and noradrenaline levels. Striatal DA function was analysed by studying apomorphine-induced (1 mg/kg, s.c.) ipsilateral rotational behaviour 4 and 11 days after the operation. A marked dose-dependent reduction of ipsilateral rotational behaviour was demonstrated after the daily modafinil treatment in the partially hemitransected rats. In another model involving unilateral nigral microinjections of 6-hydroxydopamine, acute (one single dose) modafinil (100 mg/kg) did not affect the contralateral rotational behaviour induced by apomorphine (0.05 mg/kg s.c.), when given 30 min before the apomorphine. Taken together, morphological, neurochemical and behavioural evidence has been obtained that anterograde and retrograde changes induced in the DA stores and TH immunoreactivity of the nigro-neostriatal DA neurons by a partial hemitransection are counteracted by modafinil in a dose dependent way with 100 mg/kg producing a significant protective action against impairment of DA transmission. The results of this study open up the possibility that modafinil may protect against the anterograde and retrograde degeneration of nigrostriatal DA neurons seen after mechanically induced injury.     

Differential distribution of parvalbumin immunoreactive neurons in the striatum of cocaine sensitized rats

Intermittent administration of psychostimulants such as cocaine and amphetamine can result in behavioral sensitization, which is believed to model the onset of drug addiction, as well as possible neural adaptations that lead to addictive behaviors. The dorsal striatum and the nucleus accumbens (NAc) have been shown to play an integral role in this phenomenon. However, these structures comprise a complex neuroanatomical organization, and few studies have correlated anatomical differentiation within these brain regions with functional (i.e. behavioral) outcome, particularly after psychostimulant exposure. Parvalbumin (PV)-containing GABAergic interneurons are a key neuronal cell population that can significantly regulate input-output functions in these brain regions. The present study quantified parvalbumin-immunoreactive cells in subterritories of the striatum and NAc in animals behaviorally sensitized to cocaine. Rats received a sensitization-inducing regimen of cocaine (twice-daily injections of 15 mg/kg i.p. for 5 consecutive days). Two or 14 days following the last injection, rats were given a challenge injection of cocaine (15 mg/kg i.p.), and killed 2 h later. Sections through the striatum (including the NAc) were processed for parvalbumin immunoreactivity, and the number of immunoreactive neurons was quantified. Repeated cocaine administration resulted in robust sensitization that correlated with transient increases in the number of PV immunoreactive neurons in the ventrolateral, dorsolateral and dorsomedial striatum. After a 2-week withdrawal period, sensitized animals showed a significant decrease in the number of PV+ neurons in the ventrolateral shell of the NAc and dorsomedial striatum, and no significant difference in any other area examined. These data suggest a dichotomous role for PV interneurons in different subterritories of the striatum and NAc during the short-term (induction) vs. long-term (expression) phases of cocaine sensitization.     

Activity in the Hypothalamo-Hypophyseal-Adrenocortical System on Experimental Induction of Chronic Fatigue Syndrome

Changes in the activity of the hypothalamo-hypophyseal-adrenocortical system (HHACS) were studied in an experimental model of chronic fatigue syndrome induced by i.p. administration of synthetic doublestranded RNA (polyriboinosinic:polyribocytidylic acid, Poly I:C) at a dose of 3 mg/kg. Functional changes in the different components of the HHACS were detected using standard tests with i.p. ACTH or hydrocortisone on the background of cold stress and injections of Poly I:C. Single doses of Poly I:C were followed by the development of impairments to HHACS function, with decreases in the ACTH sensitivity of adrenal cells and suppression of the negative feedback mechanism, resulting in significant decreases in corticosterone concentrations in standard tests with administration of ACTH and hydrocortisone.     

Mesostriatal projections from ventral tegmentum and dorsal raphe: cells project ipsilaterally or contralaterally but not bilaterally

The cells of origin of the brainstem projection to the caudate-putamen (CP) were examined in the albino rat by the use of two fluorescent retrograde tracers. Nuclear yellow was injected into the CP of one hemisphere and granular blue was injected into the contralateral CP. Retrogradely labeled cells were studied in the substantia nigra (SN), ventral tegmental area (VTA) and dorsal raphe (DR). The results confirm previous findings indicating the existence of contralateral projections from SN and VTA to the CP. Cells on both sides of the midline of the DR also project to either CP. Contralaterally projecting SN/VTA cells were located in areas of these nuclei which corresponded to the center of the ipsilaterally projecting cell region; the exact locations depended on the placement of the injection in the CP. In DR, contralaterally projecting cells were most often observed near the midline, although labeled cells were occasionally observed in the lateral wings of the DR. Cells labeled by contralateral injections were interdigitated with, but not identical to, cells labelled by ipsilateral injections. That is, contralaterally projecting cells and ipsilaterally projecting cells constituted separate populations within the SN, VTA and DR.     

Manifestation and persistence of Pig-a mutant red blood cells in C57BL/6 mice following single and split doses of N-ethyl-N-nitrosourea

Treating rats with single doses of N-ethyl-N-nitrosourea (ENU) results in a time-dependent accumulation of Pig-a-mutant phenotype peripheral red blood cells (RBCs), reaching a plateau at about 6-weeks posttreatment, with the response persisting for at least 26 weeks. In the present study, groups of 5 C57BL/6 male mice were administered single i.p. doses of up to 140 mg/kg ENU, and blood samples were collected up to 26 weeks posttreatment. The samples were analyzed by flow cytometry for the frequency of CD24-deficient (presumed Pig-a mutant) reticulocytes (RETs) and total RBCs; micronucleated RET frequencies were evaluated at 1 day posttreatment. Mean Pig-a mutant frequencies and micronucleated RET frequencies increased in a dose-responsive manner, with maximum Pig-a frequencies in RETs and RBCs observed at Week 2 and Week 4 posttreatment, respectively. Mutant frequencies in RETs and RBCs generally decreased slowly with time after reaching their maxima. In a second experiment, groups of five male C57BL/6 mice were given single i.p. injections of 8, 32, or 160 mg/kg ENU, or four weekly doses of 8 or 40 mg/kg ENU (split doses totaling 32 and 160 mg/kg, respectively). In each case the maximum RET and RBC mutant frequencies produced by the split doses were similar to but not as great as the mutant frequencies produced by the equivalent single doses. The data indicate that ENU-induced Pig-a mutant RBC frequencies accumulate in mice as they do in rats; however, mice and rats differ in the manifestation kinetics and the persistence of the responses.     

Role of the Dopaminergic System of the Brain in the Effects of Glucocorticoid Hormones

The conditioned reinforcement properties of the synthetic glucocorticoid dexamethasone and the possible mechanisms of its action were studied using a conditioned place preference response. On test day 1, male Wistar rats were placed in a two-chamber apparatus and the time spent in each sector was measured for 10 min. Over the next six days, combinations of one of the chambers with administration of agents (reinforcement) were presented using injections of dexamethasone in one sector and injections of physiological saline in the other sector on alternate days. After combinations of dexamethasone (0.25–0.77 mg/kg, i.p.) with the non-preferred sector, rats showed dose-dependent place preference on test day 2; however, when dexamethasone was combined with the initially preferred sector, animals given dexamethasone at a dose of 0.75 mg/kg showed only a slight level of place avoidance. Subthreshold doses of phenamine (0.25 mg/kg) given alone had no effect; however, when given on a background of dexamethasone (0.25 mg/kg), phenamine evoked a place preference response in rats lacking an initial place preference for one sector. Administration of dexamethasone alone (0.25 mg/kg) in these conditions did not induce place preference. Administration of the dopamine D₂ receptor antagonist sulpiride (20 mg/kg) 30 min before combinations of dexamethasone (0.25 mg/kg) with the non-preferred sector completely prevented the acquisition of place preference. Administration of the D₁ dopamine receptor antagonist SCH23390 (0.05 mg/kg) had no effect on the acquisition of conditioned preference. These results provide evidence for the involvement of D₂ receptors in conditioned place preference induced by dexamethasone.     

The topical organization of the afferents to the caudatoputamen of the rat. A horseradish peroxidase study

The aim of the present study was to assess (1) whether the various brain areas known to send projections to the neostriatum of the rat (neocortex, thalamus, substantia nigra, ventral tegmental area and dorsal raphe nucleus) project to all parts of this structure, and (2) whether the subcortical projections show a topical organization. For these purposes, small deposits of horseradish peroxidase were delivered by iontophoretic application, so that the whole extent of the caudatoputamen could be covered in a total of 40 rats.Labeled cortical cells were present mainly in lamina V, and showed a roughly topographical organization. Small numbers of labelled cells were observed in the basal nucleus of the amygdala after injections into the dorsal and central parts of the caudatoputamen. The cells of origin of thalamic afferents to the neostriatum were found not only in the intralaminar nuclei, but also in various other anterior, ‘midline’, and posterior nuclei (e.g. the medial part of the medial geniculate body). In the thalamostriatal projection a topical organization was demonstrated, consisting of oblique thalamic zones, which cross the borders of several thalamic nuclei and project to different parts of the neostriatum. In the substantia nigra and ventral tegmental area many retrogradely labelled cells were present. This nigrostriatal projection appears to be organized along an oblique longitudinal neostriatal axis. The nucleus raphes dorsalis was labelled most abundantly after caudal and ventrolateral injections into the caudatoputamen.It is concluded that, despite the homogeneous cytoarchitectonic structure of the caudatoputamen in the rat, this brain area is rather heterogeneous as regards its afferent connections. In fact each part of the neostriatum receives a specific and unique combination of afferents. The main changes in the input of the neostriatum appear to occur along an oblique longitudinal axis, from the most rostromedial and dorsal part to the caudolateral and ventral part. Such a topographical organization suggests that the neostriatum is likely to be involved in very complex integrative functions involving several brain areas.     

Single or repeated administrations of SCH 23390 fail to affect serotonergic neurotransmission

In synaptic membrane preparations from the frontal cortex of rats treated with single or repeated administration of mianserin or methysergide (10 mg/kg i.p.) the number of 5-HT2 receptors was reduced. In contrast, single (0.1 mg/kg or 5 mg/kg i.p.) or repeated administration of SCH 23390 (0.05 mg/kg i.p. twice daily for 3 weeks) failed to change the kinetic characteristics of 5-HT2 receptors. Moreover, in several cerebral areas, 5-HT levels and turnover were not modified by any treatment. Although SCH 23390 has a high affinity for cerebral 5-HT2 receptors, and there are conflicting data on the antagonistic activity in the periphery, our data show that doses which selectively affect dopaminergic transmission are devoid of serotonergic effects.     

MDMA causes a redistribution of serotonin transporter from the cell surface to the intracellular compartment by a mechanism independent of phospho-p38-mitogen activated protein kinase activation

3,4-methylenedioxymethamphetamine (MDMA) causes long-term serotonin depletion and reduced serotonin transporter (SERT) function in humans and in animal models. Using quantitative Western blotting and real-time PCR, we have shown that total SERT protein in the striatum and nucleus accumbens and mRNA levels in the dorsal raphe nucleus were not significantly changed following MDMA exposure in rats (4×2 h i.p. injections, 10 mg/kg each). In mouse neuroblastoma (N₂A) cells transiently expressing green fluorescent protein-tagged human SERT (GFP-hSERT), we have shown redistribution of SERT from the cell surface to intracellular vesicles on exposure to MDMA using cell surface biotinylation, total internal reflection fluorescence microscopy (TIRFM) and live-cell confocal microscopy. To investigate the mechanism responsible for SERT redistribution, we used specific antibodies to phospho-p38-mitogen activated protein kinase (p38 MAPK), a known signalling pathway involved in SERT membrane expression. We found that p38 MAPK activation was not involved in the MDMA-induced redistribution of SERT from the cell-surface to the cell interior. A loss of SERT from the cell surface on acute exposure to MDMA may contribute to the decreased SERT function seen in rats exposed to MDMA.     

Effects of 5-hydroxydopamine and 6-hydroxydopamine on the ultrastructure of type I cells in paraganglia of the rat recurrent laryngeal nerve.

The ultrastructure of the Type I cells in paraganglia of rat recurrent laryngeal nerve (RLN) was studied after the administration of 5-hydroxydopamine (5-OHDA) and 6-hydroxydopamine (6-OHDA). Normal Type I cells of RLN-paraganglia contained abundant organelles and their cytoplasm was characterized by the presence of numerous membrane-bounded dense-cored vesicles (DCVs). The DCVs were round in profile (diameter 107.67 +/- 0.06 nm, all values expressed as mean +/- s.e.m. in the present study) and possessed dense cores of moderate to low electron density. After 5-OHDA treatment (single injection, 100 mg/kg b.w., i.v.), the majority of DCVs were filled with a material of high electron density. No significant difference was observed between the profile diameter of the DCVs in 5-OHDA-treated rats (104.96 +/- 0.06 nm) and that in normal rats. After 6-OHDA treatment (three injections, 100 mg/kg b.w. each at 12 h intervals i.p.), no significant alteration in the electron density of the core was noted. However, most of the DCVs were enlarged and round, elliptical or irregular in profile (190.57 +/- 2.77 nm x 130.34 +/- 2.09 nm). The dense core of DCVs was centrally or eccentrically located in DCVs. The results of the present study indicate that: 1) there is only one type of granulated glomus cell (i.e., Type I cells) in the rat RLN-paraganglia under normal physiological condition; and 2) since the ultrastructural morphology of DCVs in Type I cells of rat RLN-paraganglia is altered after 5-OHDA or 6-OHDA treatment, these cells may possess mechanisms for the uptake of false adrenergic neurotransmitter and/or neurotoxin.     

Post-ischemic delivery of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor rosuvastatin protects against focal cerebral ischemia in mice via inhibition of extracellular-regulated kinase-1/-2

After recent clinical trials, statins have gained increasing significance in secondary stroke prevention. From experimental studies, it is well established that statins have beneficial action when delivered prophylactically prior to a stroke. Conversely, much less is known about the effects of statins on injury development when delivered after ischemia. We here examined the effects of a post-ischemic delivery of rosuvastatin (0.5, 5 or 20 mg/kg, administered i.p. immediately after reperfusion onset), a potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on brain injury and cell signaling after focal cerebral ischemia, induced by 90 min of intraluminal middle cerebral artery occlusion in mice. In animals receiving normal saline, 0.5 or 5 mg/kg rosuvastatin, middle cerebral artery occlusions resulted in reproducible brain infarcts at 24 h after reperfusion onset, which did not differ in size. However, rosuvastatin, administered at higher doses (20 mg/kg), reduced infarct volume at 24 and 48 h after ischemia (by 34+/-16% and 18+/-3%, respectively, P<0.05). Western blots revealed that rosuvastatin decreased phosphorylated extracellular-regulated kinase-1/-2 and reduced activated caspase-3 levels in ischemic brain areas, while endothelial NO synthase expression, p38 and Jun kinase phosphorylation were not influenced by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. Rosuvastatin also significantly diminished expression levels of inducible NO synthase in the ischemic brain. Our results indicate that rosuvastatin may have utility not only as stroke prophylaxis but also as acute therapy inhibiting executive cell death pathways.     

Role of aminoguanidine in brain protection in surgical brain injury in rat

The study investigated the effect of aminoguanidine (AG) on surgical brain injury (SBI) in rat. AG (75, 150 and 300 mg/kg, i.p.) was administered immediately following surgical resection. Using a SBI model, we found that AG (150 mg/kg) significantly reduced cerebral edema, while AG at the doses of 75 and 300 mg/kg had no effect. And AG (150 mg/kg) significantly reduced Evans Blue extravasation into brain tissue and improved the neurological outcome compared to control group. Moreover, the expression of TNF-alpha and nuclear factor-kappaB (NF-kappaB) mRNA and protein in brain tissue at the edge of the resection site increased at 24h after SBI, which could be significantly attenuated by the treatment with AG via RT-PCR and Western blots methods. Our results demonstrated that SBI causes increased brain edema, BBB disruption and inflammation along the periphery of the site of surgical resection, which could be significantly improved by the treatment of AG.     

Centrilobular endothelial cell injury by diquat in the selenium-deficient rat liver

Low doses of diquat cause massive liver necrosis and death of selenium-deficient rats within a few hours. Protection against this injury by selenium correlates with the presence of selenoprotein P, an extracellular selenoprotein that associates with endothelial cells. Selenium-deficient rats were injected with diquat (10 mg/kg) and their livers were removed for light and electron microscopy at times up to 120 minutes after injection. Selenium-replete animals were studied before and 120 minutes after the same dose of diquat. With selenium deficiency, diquat caused injury to centrilobular endothelial cells. This injury was evident 20 minutes after diquat injection and progressed to cell loss at 60 minutes after diquat injection. At 120 minutes, endothelial cells were virtually absent from the centrilobular regions and hepatocytes in those areas were undergoing necrosis. Portal and midzonal areas remained normal in selenium-deficient livers, as did the entire liver lobule of selenium-replete rats. These findings indicate that the initial liver lesion in selenium-deficient rats given diquat is injury of the endothelial cells in the centrilobular region. After detachment of the endothelial cells, centrilobular hepatocytes undergo necrosis. We postulate that selenoprotein P protects the centrilobular endothelial cells against injury by oxidant molecules that result from diquat administration.     

Fluorescence and electron microscopic study of intracellular F-actin in concanavalin A-treated and cytochalasin B-treated Ehrlich ascites tumor cells

To investigate the involvement of actin filaments in concanavalin A (Con A)-induced cap formation and cytochalasin B (CB)-induced zeiotic knob migration, the distribution of F-actin was studied in Con A-treated and CB-treated Ehrlich ascites tumor cells (EATC) by fluorescence microscopy using heavy meromyosin conjugated with a fluorescent dye, N-(7-dimethylamino-4-methylcoumarinyl) maleimide, (DACM-HMM). In non-treated cells, the diffuse fluorescence of DACM-HMM was observed in the cytoplasm, particularly intensely under the plasma membrane and around the nucleus. In Con A- and CB-treated cells, the fluorescence was seen at Con A-induced-capped and CB-induced-knob-accumulated regions. This fluorescence was more intense in CB-treated cells. To study the actin filaments in these fluorescent regions more clearly, the soluble components of the cells were eliminated by treatment with Triton X-100 or saponin solution containing a low concentration of glutaraldehyde, and the detergent-treated and saponin-treated cells were observed under a transmission electron microscope. Concentrated actin filaments were observed directly beneath the Con A-induced capping area and CB-induced zeiotic knob-accumulation area. The area of concentrated actin filaments appeared to correspond to the electron dense area observed in the identical region in the cells fixed without detergent treatment. More actin filaments were observed in CB-treated cells than in Con A-treated ones.     

The influence of dfp, atropine and toxogonine on tryptophan pyrolase activity in mouse liver.

It was found that fluorostigmine (DFP) in doses 0-4 mg/kg i.p. reduced significantly tryptophan pyrolase activity in mouse liver homogenates.se liver homogenates 120 and 180 min after the administration of the drug. On the other hand, fluorostigmine administered in doses 0-8 mg/kg i.p. increases the activity of the enzyme studied at 30 and 60 min after the injection. DFP (0.4 mg/kg i.p.) given in combination with atropine (10 mg/kg i.p.) causes a significant increase in enzyme activity determined 30, 60, 120 and 180 min after the administration of the drug. Toxogonine (in doses 5 mg/kg s.c.) given together with DFP (0.4 mg/kg i.p.) intensifies the activity of tryplophan pyrolase at 180 min after their administration. Simultaneous treatment with toxogonine (5 mg/kg s.c.), atropine (10 mg/kg i.p.) and DFP (0.4 MG/KG I.P.) reduced significantly the activity of the enzyme studied at all time of determination. Moreover, the experiment in vitro showed that DFP in concentrations of 4x10(-9) M; 8X10(-9) M; 1.6X10(-8) M and 3.2x10(-8) M increased tryptophan pyrolase activity in mouse liver homogenates.