Hemisphere Of Rats Research Articles

CURCUMIN RESTORES THE BALANCE OF NO-SYNTHASES IN THE BRAIN HEMISPHERES OF RATS EXPOSED TO ROUND-THE-CLOCK LIGHT UNDER CONDITIONS OF A DIET HIGH IN FRUCTOSE AND FAT

The aim of the study was to evaluate the effect of curcumin on the ratio of constitutive and inducible NOS isoforms in the cerebral cortex of rats under a round-the-clock lighting (RCL) with a high fructose and fat diet. The experiments were performed on 21 white Wistar rats weighing 235±20 g, divided into 3 groups. Animals in the first group (control) received a standard diet (energy value 2720 kcal/kg) and were exposed to an equal alternation of light and darkness. The rats of the second and third groups were kept in RCL conditions against the background of the administration of a high-calorie carbohydrate-lipid diet (HCCLD, 4477 kcal/kg). In addition, animals of the third group received curcumin daily through a gavage, intragastrically, at a dose of 200 mg/kg. The activity of total NOS and its constitutive isoforms (cNOS) in the cerebral homogenate was measured, inducible isoenzyme (iNOS) activity and cNOS coupling index were calculated. Curcumin administration significantly reduced the total and inducible activity of NOS in the cerebral homogenate– by 34 and 38%, respectively, compared with the values of the second group. At the same time, cNOS activity (2.3-fold) and its coupling index (3.8-fold) increased significantly compared with the data of the second group. It is concluded that the use of curcumin in metabolic disorders associated with pathogenic factors of the “Western lifestyle” – light disorders and the use of HCCLD restores the normal ratio of constitutive and inducible NOS isoforms, cNOS coupling in the rat cerebral hemispheres, which prevents the development of oxidative-nitrosative stress.

Dose-Related Difference and Involvement of Tyrosine Phosphorylation in Methylmercury-Induced Morphological Change in Cultured Astrocytes Obtained from Rat Cerebral Hemisphere

Dose-Related Difference and Involvement of Tyrosine Phosphorylation in Methylmercury-Induced Morphological Change in Cultured Astrocytes Obtained from Rat Cerebral Hemisphere

Involvement of Rho in Methylmercury-Induced Morphological Change in Cultured Astrocytes Obtained from Rat Cerebral Hemisphere

Involvement of Rho in Methylmercury-Induced Morphological Change in Cultured Astrocytes Obtained from Rat Cerebral Hemisphere

Segmentation of Rat Brains and Cerebral Hemispheres in Triphenyltetrazolium Chloride-Stained Images after Stroke.

Ischemic stroke is one of the leading causes of death among the aged population in the world. Experimental stroke models with rodents play a fundamental role in the investigation of the mechanism and impairment of cerebral ischemia. For its celerity and veracity, the 2,3,5-triphenyltetrazolium chloride (TTC) staining of rat brains has been extensively adopted to visualize the infarction, which is subsequently photographed for further processing. Two important tasks are to segment the brain regions and to compute the midline that separates the brain. This paper investigates automatic brain extraction and hemisphere segmentation algorithms in camera-based TTC-stained rat images. For rat brain extraction, a saliency region detection scheme on a superpixel image is exploited to extract the brain regions from the raw complicated image. Subsequently, the initial brain slices are refined using a parametric deformable model associated with color image transformation. For rat hemisphere segmentation, open curve evolution guided by the gradient vector flow in a medial subimage is developed to compute the midline. A wide variety of TTC-stained rat brain images captured by a smartphone were produced and utilized to evaluate the proposed segmentation frameworks. Experimental results on the segmentation of rat brains and cerebral hemispheres indicated that the developed schemes achieved high accuracy with average Dice scores of 92.33% and 97.15%, respectively. The established segmentation algorithms are believed to be potential and beneficial to facilitate experimental stroke study with TTC-stained rat brain images.

INHIBITION OF TRANSCRIPTION FACTORS NF KAPPA B AND AP-1 LIMITS THE PROGRESSION OF OXIDATIVE-NITROSATIVE STRESS IN THE TISSUE OF CEREBRAL HEMISPHERES IN RATS AFTER MODELLED TRAUMATIC BRAIN INJURY

The study was aimed as investigating the effects of inhibitors of transcription factors NF kappa B and AP-1 activation on the development of oxidative-nitrosative stress in rat cerebral hemispheres following experimental traumatic brain injury (TBI). The study included 60 white Wistar male rats weighing 180-220 g, divided into 4 groups of 7 animals in each: the 1st group included pseudo-injured animals subjected to the same manipulations (ether anaesthesia, fixation) as the animals in the experimental groups, except for TBI modelling, the 2nd group included the animals exposed to modelled TBI, the 3rd and 4th groups involved the rats who received ammonium pyrolidine dithiocarbamate, the nuclear translocation inhibitor NF kappa B in a dose of 76 mg/kg and the inhibitor AP-1 SR 11302 in a dose of 1 mg/kg, respectively for 7 days following the TBI modelling. On the 7th day after the simulation of a moderate TBI in rat cerebral hemisphere tissue, the following signs of oxidative-nitrosative stress have been detected: increased production of superoxide radical anion by NADPH and NADH-dependent electron transport chains, increased activity of nitric oxide synthase (total and inducible), a decrease and impairment of the coupling of its constitutive isoform, growth in the concentration of peroxynitrite, the development of decompensated lipid peroxidation. The application of transcription factor inhibitors NF kappa B (PDTC) and AP-1 (SR 11302) significantly reduces the signs of oxidative-nitrosative stress in the tissue of rat cerebral hemispheres on the 7th day of the experiment, reduces the production of superoxide anion radical and the activity of nitric oxide synthase (total and inducible), improves the coupling of its constitutive isoform, limits the peroxynitrite concentration, and enhances the antioxidant potential.

Effect Of 21‐Benzylidene Digoxin On Cancer Cells: A Cardenolide With No Inhibitory Effect On Na,K‐ATPase Activity

Recently, new data began to consider cardiac glycoside as a potential antitumor drug. We synthesized 21‐benzylidene digoxin (21‐BD) through an aldol condensation of digoxin lactone ring. Molecular docking was performed to assess the main interactions between cardiac glycosides and Na,K‐ATPase, demonstrating a more stable binding energy for 21‐BD, compared with digoxin. Therefore, we used HeLa and RKO cancer cell lines after their exposure to cardiac glycosides to asses the cell viability as to cytotoxicity and proliferative ability. On HeLa cells, digoxin presented an IC50 = 1,47 μM, whereas 21‐BD presented an IC50 = 56,16 μM. Nevertheless, on RKO cells, digoxin presented an IC50 = 0,46 μM and 21‐BD presented an IC50 = 54,36 μM. Cometa assay showed DNA damage upon 20 μM of both cardiac glycosides. The treatment of cells with 21‐BD for 48h caused an increase of Na,K‐ATPase activity, whereas digoxin caused a decrease on enzyme activity. However, 21‐BD did not cause inhibition of Na,K‐ATPase of a membrane preparation from rat cerebral hemisphere. In attempt to avoid the 21‐BD effect though estrogen receptor, the pre‐treatment with tamoxifen did not interrupted the DGB1 effect. Thus, these data demonstrate that this new glycoside has a different mechanism of action then digoxin, and it can be an important tool to study the enzyme.Supported by: FAPEMIG, CNPq and CAPES

Immunohistochemical and Morphological Changes in Neurons and Neuroglia in the Cerebral Nigrostriatal Structures under Conditions of Experimental Nigral Neurodegeneration

The count of dopamine-containing neurons decreased by 77%, the area of the remaining cells shrank by 75%, and the neuroglia doubled 4 weeks after injection of toxin (6-hydroxydopamine) into the compact part of the substantia nigra of the right cerebral hemisphere of rats, while no changes in the substantia nigra of the left hemisphere were observed. Neurons of the caudate nucleus were virtually unchanged in comparison with the intact control, while the neuroglia was activated: its total volume in the right hemisphere increased by 33% (50% increase in astrocyte count and a 25% increase of the rest neuroglia), while in the left hemisphere only astrocyte count increased by 20%. Astrocyte nuclei in the caudate nuclei of both hemispheres were enlarged by 22-23%. Hence, unilateral destruction of the nigral dopamine-containing neurons stimulated the neuroglia (particularly astroglia) in the caudate nuclei, especially on the side of damage.

Experience‐dependent brain plasticity after stroke: effect of ibuprofen and poststroke delay

Despite indications that brain plasticity may be enhanced after stroke, we have described impairment of experience-dependent plasticity in rat cerebral cortex neighboring the stroke-induced lesion. Photothrombotic stroke was centered behind the barrel cortex in one cerebral hemisphere of rats. Plasticity of cortical representation of one row of vibrissae was induced by sensory deprivation of all surrounding whiskers for 1 month, and visualized with [(14)C]-2-deoxyglucose autoradiography. In control rats deprivation resulted in an enlargement of functional cortical representation of the spared row of vibrissae. After a focal stroke neighbouring the barrel cortex, no plasticity of the spared row representation was found. Investigation of plastic changes with deprivation initiated 1 week and 1 month after stroke have shown that later poststroke onset of deprivation resulted in a partial recovery of cortical plasticity in the barrel field. Western blot analysis of proinflammatory enzyme cyclooxygenase-2 (COX-2) expression revealed its strong upregulation in the barrel cortex 24 h after stroke. When chronic treatment with the anti-inflammatory drug ibuprofen (10 mg/kg or 20 mg/kg) accompanied deprivation, plasticity was restored. Ibuprofen applied before the ischemia also prevented the poststroke upregulation of COX-2. The results strongly suggest that poststroke impairment of experience-dependent cortical plasticity is caused by stroke-induced inflammatory reactions that subside with poststroke delay and can be at least partially ameliorated by pharmacological treatment.

Ultrastructural Modifi cations in Neurons of the Rat Frontal Cortex Induced by Intoxication by tert-Butyl Methyl Ether

We examined ultrastructural modifications in cortical neurons of the frontal part of the cerebral hemispheres of rats under conditions of chronic intoxication of the animals by tert-butyl methyl ether (TBME). Everyday doses of intrastomachic introductions of TBME in the experimental groups were 0.5, 5, 50, and 500 mg/kg. Within 60 days of the experiment, the animals preserved their viability even in the case of the highest TBME doses, but significant negative structural changes were observed in neocortical neurons under these conditions. A significant part of the mitochondria demonstrated swelling, decreases in the number of the cristae, destruction of the external membrane, and, finally, transformation into vacuoles. The endoplasmic reticulum underwent comparable modifications (dilation and destruction of the cisterns and intense vacuolization). The osmiophilia of the neuronal nuclei increased, and the latter were also deformed; the integrity of the nuclear envelope was disturbed. Other cellular organelles also underwent spatial redistribution and destruction. All these processes led to death of a considerable part of cortical neurons because of intense apoptosis followed by phagocytation of the apoptotic bodies by microgliocytes. The above-described modifications progradiently increased throughout the experiment (up to the 60th day). Their pattern was most dramatic at the highest TBME dose used (500 mg/kg), but the corresponding manifestations were quite obvious (although mild) even at the lowest doses (0.5 and 5 mg/kg). High polymorphism and variability were characteristic features of TBME-induced ultrastructural modifications in the rat frontal cortex. Therefore, TBME, an agent extensively used in industry and transport, which is believed to demonstrate relatively low integral toxicity, exerts powerful negative neurotropic effects on neuronal systems in the cerebral cortex and dramatically intensifies apoptosis in these structures.

ChemInform Abstract: Novel Neurotrophic Isocuparane-Type Sesquiterpene Dimers, Mastigophorenes A, B, C and D, Isolated from the Liverwort Mastigophora diclados.

Four dimeric isocuparane-type sesquiterpenes, mastigophorenes A, B, C and D, isolated together with a new 3,4-dihydroxylated isocuparene from the liverwort Mastigophora diclados, have been assigned structures on the basis of detailed spectroscopic analyses. Among them, mastigophorenes A, B and D have been found to accelerate neuritic sprouting at 10–5–10–7 mol dm–3 in a neuritic cell culture of foetal rat cerebral hemisphere; their biosynthesis, initiated by phenolic oxidation of (–)-herbertenediol, is proposed.

Crucial role of the local micro‐environment in fate decision of neonatal rat NG2 progenitors

The fate choice of neural progenitor cells could be dictated by local cellular environment of the adult CNS. The aim of our study was to investigate the effect of hippocampal tissue on differentiation and maturation of oligodendrocyte NG2 precursor cells. Hippocampal slice culture was established from the brains of 7-day-old rats. NG2 precursor cells, obtained from a 12-day-old mixed primary culture of neonatal rat cerebral hemispheres, were labelled with chloromethyl-fluorescein-diacetete and seeded on the hippocampal slices. After 7-14 days in co-culture, cells were stained with neural markers. NG2 cells differentiated predominantly into oligodendrocytes, presenting various stages of maturation: progenitors (NG2), pre-oligodendrocytes (O4) and finally mature GalC-positive cells. However, except for a few cells with astrocyte-specific S100b staining, a considerable number of these cells differentiated into neurons: TUJ(+) and even MAP-2(+) cells were frequently observed. Moreover, a certain population of these cells preserved proliferative properties of primary precursor cells, as revealed by Ki67 expression. The neuronal micro-environment provided by the culture of hippocampal slices is potent for induction of neurogenesis from oligodendrocyte NG2(+)/PDGFRalpha(+)/CNP(+) progenitor cells and promotes their differentiation not only into macroglia but also into neurons. It also sustains their proliferative capacity. The results indicate the crucial role of the local cellular environment in fate decision of primary NG2(+) multipotent neural progenitor cells, which may affect their behaviour after transplantation into the central nervous system.

Diazepam affects the nuclear thyroid hormone receptor density and their expression levels in adult rat brain

Thyroid hormones (THs) are involved in the occurrence of anxiety and affective disorders; however, the effects following an anxiolytic benzodiazepine treatment, such as diazepam administration, on the mechanism of action of thyroid hormones has not yet been investigated. The effect of diazepam on the in vitro nuclear T 3 binding, on the relative expression of the TH receptors (TRs) and on the synaptosomal TH availability were examined in adult rat cerebral hemispheres 24 h after a single intraperitoneal dose (5 mg/kg BW) of this tranquillizer. Although, diazepam did not affect the availability of TH either in blood circulation or in the synaptosomal fraction, it decreased (33%) the nuclear T 3 maximal binding density ( B max). No differences were observed in the equilibrium dissociation constant ( K d). The TRα2 variant (non-T 3-binding) mRNA levels were increased by 33%, whereas no changes in the relative expression of the T 3-binding isoforms of TRs (TRα1, TRβ1) were observed. This study shows that a single intraperitoneal injection of diazepam affects within 24 h, the density of the nuclear TRs and their expression pattern. The latest effect occurs in an isoform-specific manner involving specifically the TRα2 mRNA levels in adult rat brain.

Influence of LIF and BMP‐2 on differentiation and development of glial cells in primary cultures of embryonic rat cerebral hemisphere

Cells prepared from the cerebral hemisphere of embryonic Day 18 rats were maintained for 2 days in serum-free modified Bottenstein-Sato (mBS) medium containing thyroid hormone (TH), with or without leukemia inhibitory factor (LIF) or bone morphogenetic protein (BMP)-2, and these influences on the differentiation and development of glial cells were investigated using the cells maintained in mBS medium containing TH as controls. The levels of glial fibrillary acidic protein (GFAP) expression and the number of GFAP-positive astrocytes increased markedly with the addition of LIF or BMP-2, and were enhanced further with the addition of both LIF and BMP-2. The number of O1-positive oligodendrocytes increased with the addition of LIF, whereas it decreased with the addition of BMP-2. The number did not change with the addition of both cytokines. Using antibody against platelet-derived growth factor (PDGF), we then excluded indirect effects of these cytokines through PDGF, which would increase by accelerated astrocyte development. When PDGF was neutralized, the number of oligodendrocytes increased under all conditions examined. As a result of the neutralization, the effect of BMP-2 on oligodendrocyte differentiation was eliminated, although LIF remained effective. These results suggest that the differentiation of oligodendrocytes was delayed partially by PDGF even in control cultures. It is also suggested that LIF and BMP-2, each of which accelerates the differentiation and development of astrocytes, would seem to have different effects on oligodendrocyte differentiation, i.e., LIF would directly affect oligodendrocyte differentiation, whereas BMP-2 would affect it mainly through PDGF.

Acute LiCl-treatment affects the cytoplasmic T 4 availability and the expression pattern of thyroid hormone receptors in adult rat cerebral hemispheres

We have previously reported that short-term LiCl-treatment affects the kinetic characteristics of thyroid hormone binding in adult rat brain (Bolaris, S., Margarity, M., Valcana, T., 1995. Effects of LiCl on triiodothyronine (T 3) binding to nuclei from rat cerebral hemispheres. Biol. Psychiatry 37, 106–111); however, the mechanism underlying the above effects of LiCl administration is yet to be determined. In this study, the effects of lithium within one day after its administration (5 mmol/kg BW) on the relative expression of thyroid hormone receptor isoforms and on the cytoplasmic and synaptosomal thyroid hormone availability in adult rat cerebral hemispheres were examined. Although short-term LiCl-treatment did not affect the levels of triiodothyronine either in the synaptosomal or in the cytoplasmic fraction 24 h after LiCl administration, the cytoplasmic availability of thyroxin was lower. In addition, 24 h after the administration of lithium the mRNA levels of the TRα1 isoform (T 3 binding) increased while the relative expression of the TRα2 variant (non-T 3 binding) was decreased. Notably, the decrease of the TRα2 mRNA levels was also observed 4 h after LiCl administration. The expression levels of the TRβ1 isoform were unaffected in any interval examined. The present study suggests that short-term lithium treatment regulates the relative expression of TRs in an isoform-specific manner and affects the cytoplasmic availability of thyroxin in adult rat brain.

Exposure of animals to artificial gravity conditions leads to the alteration of the glutamate release from rat cerebral hemispheres nerve terminals

The biochemical basis underlying the effects of altered gravity on the process of nervous signal transmission is not clear. We have investigated the effect of hypergravity stress (created by centrifugation of rats at l0 g for 1 h) on the basal and stimulated release of l-[ 14C]glutamate (a chemical transmitter of excitatory signals) from isolated rat brain nerve terminals (synaptosomes). It has been shown that the hypergravity stress exerted a different influence on the Ca 2+-dependent and the Ca 2+-independent component of neurotransmitter release. The Ca 2+-dependent l-[ 14C]glutamate release evoked by potassium chloride was equal to 14.4 ± 0.7% of total synaptosomal label for control animals and 6.2 ± 1.9% for animals, exposed to hypergravity ( P⩽0.05) and was more than twice decreased as a result of the hypergravity stress. We observed no statistically significant difference in the Ca 2+-independent component of l-[ 14C]glutamate release. For control group and animals exposed to the hypergravity stress it was equal to 7.7 ± 2.8% and 12.9 ± 2.0%, respectively. We have also investigated the effect of the hypergravity stress on the activity of high-affinity Na +-dependent glutamate transporters. K m and V max of l-[ 14C]glutamate uptake have been determined. The maximal velocity of glutamate uptake was decreased as a result of hypergravity loading, but no difference in the K m values between control rats and hypergravity exposed animals was observed. These findings indicate that hypergravity stress alters neurotransmitter reuptake and exocytotic neurotransmitter release processes.

Morphological development of microglia in the postnatal rat brain: A quantitative study

Morphological transformation of lectin-positive microglia/macrophages in the developing rat cerebral hemisphere was analysed using quantitative methods. During the first postnatal month, the cells showed increases in their size and fractal dimension accompanied by a simultaneous decrease in their solidity. Regional variations in dynamics of the process indicated the existence of spatio-temporal developmental gradients within the cerebral hemisphere wall which might correspond with regional patterns of neuronal differentiation. Results of the present study prove that the quantitative methods can be the source of reliable data replacing subjective cell typologies.

CNS region-specific regulation of glial glutamate transporter expression.

The neuronal cell death associated with certain neurodegenerative disorders as well as acute brain injuries is in part due to the reduced expression of glial glutamate transporters and the subsequent accumulation of toxic extracellular glutamate concentrations. Extracellular factors previously found to potently stimulate the expression of the glial glutamate transporters, GLT-1/EAAT2 and GLAST/EAAT1, in astroglial cultures of rat cerebral hemispheres are PACAP, TGF alpha, and EGF. In the present study, we sought to determine whether similar stimulatory influences apply for astroglia from other areas of the central nervous system (CNS). Immunoblot and real-time RT-PCR analysis of striatal astroglial cultures maintained for 72 h with PACAP, TGF alpha, or EGF revealed a prominent increase in GLT-1 and GLAST expression. In apparent contrast, all factors completely failed to affect GLT-1 and GLAST expression in astroglial cultures from the cerebellum, mesencephalon, and spinal cord between 36 h and 7 days. This failure was not due to the absence of functional recognition or transduction machineries for the extracellular factors as suggested by the additional observations that cerebellar, mesencephalic and spinal cord glia were capable of responding to stimulation with PACAP, TGF alpha, or EGF for 10 min with activation of CREB. Moreover, dibutyryl cyclic AMP (dbcAMP) potently promoted GLT-1 and/or GLAST expression in mesencephalic, cerebellar and spinal cord glia, further indicating that extracellular factors regulate glial glutamate transporter expression throughout the CNS. Together these findings identify PACAP, TGF alpha and EGF as potent regulators of glutamate transporter expression in striatal glia. In addition, these findings provide evidence for a CNS region-specific regulation of glial glutamate transport.

Stage-specific gene expression in early differentiating oligodendrocytes.

The screening of a differential library from precursor and differentiated oligodendrocytes, obtained through the representational difference analysis (RDA) technique, has generated a number of cDNA recombinants corresponding to mRNA coding for known and unknown proteins: (1) mRNA coding for proteins involved in protein synthesis, (2) mRNA coding for proteins involved in the organization of the cytoskeleton, and (3) mRNA coding for proteins of unknown function. The expression profile of the mRNA was studied by Northern blot hybridization to the poly-A(+) mRNA from primary rat progenitor and differentiated oligodendrocytes. In most cases, hybridization to the precursor was higher than hybridization to the differentiated mRNA, supporting the validity of the differential screening. Hybridization of the cDNA to rat cerebral hemisphere and brain stem poly-A(+) mRNA, isolated from 1- to 90-day-old rats, confirms the results obtained with the mRNA from differentiating oligodendrocytes. The intensity of the hybridization bands decreases as differentiation proceeds. The pattern of expression observed in oligodendrocytes is different from that found in the brain only in the case of the nexin-1 mRNA, the level of which remains essentially constant throughout differentiation both in the brain stem and in the cerebral hemispheres, in agreement with the published data. In contrast, the intensity of hybridization to the oligodendrocyte mRNA is dramatically lower in the differentiated cells compared with the progenitor oligodendrocyte cells. Some of the recombinant cDNA represent mRNA sequences present at high frequency distribution in the cells, while others belong to the rare sequences group. Six recombinants code for proteins of the ribosomal family, suggesting that of approximately 70 known ribosomal proteins, only a few are upregulated during oligodendrocyte differentiation. The third category of open reading frame (ORF) is represented by rare messengers coding for proteins of unknown functions and includes six clones: RDA 279, 11, 95, 96, 254, and 288.

Influence of cell density and thyroid hormone on glial cell development in primary cultures of embryonic rat cerebral hemisphere

The influence of cell density and thyroid hormone (TH) on the development of astrocytes and oligodendrocytes was investigated in primary cultures prepared from rat cerebral hemisphere on embryonic day (E)18. At the beginning of the culture, most of the cells were microtubule-associated protein 2 (MAP2)-positive neurons, whereas O1-positive oligodendrocytes and glial fibrillary acidic protein (GFAP)-positive astrocytes were rarely observed. After the cells were maintained in serum-free defined medium, astrocytes developed at high cell density but rarely at a low one. When leukemia inhibitory factor (LIF) was supplemented in low-density cultures, the levels of GFAP expression markedly increased to almost the same extent as in high-density culture without TH. This suggests that, in low-density cultures, astrocyte progenitors could not differentiate because of insufficient astrocyte-inducing factors. Interestingly, the addition of TH increased GFAP expression levels only at high density. The number of oligodendrocytes increased with TH addition at both cell densities, although the effects were more remarkable at high density. These results suggest that cell density and TH are pivotal factors in the development of both astrocytes and oligodendrocytes. It is also suggested that the effects of TH on glial cell development could be accelerated via cell-cell communications.

Зміна накопичення L- [14С] -глутамата нервовими закінченнями мозочка і великих півкуль головного мозку щурів в умовах модельованої гіпергравітації

Зміна накопичення L- [14С] -глутамата нервовими закінченнями мозочка і великих півкуль головного мозку щурів в умовах модельованої гіпергравітації