The trophic factors S-100β and basic fibroblast growth factor are increased in the forebrain reactive astrocytes of adult callosotomized rat

S-100 is a calcium-binding protein that is predominantly found in astrocytes of the central nervous system. In the present study, we investigated the temporal and spatial changes of S-100β immunoreactivity after a stereotaxic mechanical lesion of the adult rat corpus callosum performed with an adjustable wire knife. Rats were killed 7, 14 and 28 days after surgery. S-100β immunoreactivity was found within the cytoplasm and processes of quiescent putative astrocytes that were observed throughout the gray and white matters of the forebrain of sham-operated rats. Following callosotomy, the S-100β immunoreactive profiles showed increased size and thick processes, as well as increased amount of S-100β immunoreactivity. Unbiased stereologic analysis revealed a sustained and widespread increase of the Areal Fraction of S-100β immunoreactive profiles in the medial and lateral regions of the white matter of callosotomized rats at the studied time-intervals. In the cerebral cortex of callosotomized rats, the estimated total number of S-100β immunoreactive profiles was also increased 7 and 14 days after the lesion. Since the cellular and temporal changes in S-100β immunoreactivity were closely similar to those described for basic fibroblast growth factor (bFGF) following brain lesions, we co-localized the S-100β and bFGF immunoreactivities after callosotomy. bFGF immunoreactivity was found in the nuclei of S-100β immunoreactive glial profiles throughout the forebrain regions of the sham-operated rats. bFGF immunoreactivity was increased in the nuclei of reactive S-100β immunoreactive putative astrocytes in the forebrain white matter and in the cerebral cortex of callosotomized rats. These results indicate that after transection of the corpus callosum of adult rats, the reactive astrocytes may exert paracrine trophic actions through S-100β and bFGF. Interactions between S-100β and bFGF may be relevant to the events related to neuronal maintenance and repair following brain injury.     

Glial bFGF and S100 immunoreactivities increase in ascending dopamine pathways following striatal 6-OHDA-induced partial lesion of the nigrostriatal system: a sterological analysis

S100, a calcium-binding protein, and basic fibroblast growth factor (bFGF, FGF-2) are found predominantly in astrocytes in the central nervous system. Those molecules show trophic properties to neurons and are upregulated after brain lesions. The present study investigated the changes in the S100beta and bFGF immunoreactivities after a partial lesion of the rat midbrain ascending dopamine pathways induced by intrastriatal injection of 6-hydroxydopamine (6-OHDA). Stereological method revealed increases in the estimated total number and density of bFGF immunoreactive astroglial profiles in the ipsilateral pars compacta of the substantia nigra (SNc) and ventral tegmental area (VTA). Increases in the counts of astroglial S100beta immunoreactive profiles were found in the striatum, SNc, and VTA mainly ipsilateral but also in the contralateral nuclei. These results open up the possibility that interactions between astroglial S100beta and bFGF may be relevant to paracrine events related to repair and maintenance of remaining dopamine neurons following striatal 6-OHDA induced partial lesion of ascending midbrain dopamine pathway.     

Neuronal and inducible nitric oxide synthase immunoreactivity following serotonin depletion

Serotonin (5HT) modulates the development and plasticity of its innervation areas in the central nervous system (CNS). Astrocytic 5HT(1A) receptors are involved in the plastic phenomena by releasing the astroglial-derived neurotrophic factor S-100beta. Several facts have demonstrated that nitric oxide (NO) and the nitric oxide synthase enzyme (NOS) may also be involved in this neuroglial interaction: (i) NO, S-100beta and 5HT are involved in CNS plasticity; (ii) micromolar S-100beta concentration stimulates inducible-NOS (iNOS) expression; (iii) neuronal NOS (nNOS) immunoreactive neurons are functionally and morphologically related to the serotoninergic neurons; (iv) monoamines level, including 5HT, can be modulated by NO release. We have already shown that 5HT depletion increases astroglial S-100beta immunoreactivity, induces neuronal cytoskeletal alterations and produces an astroglial reaction, while once 5HT level is recovered, a sprouting phenomenon occurs [Brain Res. 883 (2000) 1-14]. To further characterize the relationship among nNOS, iNOS and 5HT we have analyzed nNOS and iNOS expression in the CNS after 5HT depletion induced by parachlorophenylalanine (PCPA) treatment. Studies were performed immediately after ending the PCPA treatment and during a recovery period of 35 days. Areas densely innervated by 5HT fibers were studied by means of nNOS and iNOS immunoreactivity as well as NADPH diaphorase (NADPHd) staining. All parameters were quantified by computer-assisted image analysis. Increased nNOS immunoreactivity in striatum and hippocampus as well as increased NADPHd reactivity in the striatum, hippocampus and parietal cortex were found after PCPA treatment. The iNOS immunoreactivity in the corpus callosum increased 14 and 35 days after the end of PCPA treatment. These findings showed that nNOS immunoreactivity and NADPHd activity increased immediately after 5HT depletion evidencing a close functional interaction between nitrergic and serotoninergic systems. However, iNOS immunoreactivity increased when 5HT levels were normalized, which could indicate one of the biological responses to S-100beta release.     

Glial and nerve cell changes in rats with porto-caval anastomosis

Summary Nuclear size and density were determined in brain regions with different glial—neurone composition in rats up to 35 weeks after porto-caval anastomosis.In the white matter, i.e. corpus callosum, both the total cell count and the percentage of astrocytes and oligodendrocytes were unchanged.In the corpus striatum, where the glial/neurone ratio is about 1, the number of nuclei registered as astrocytes increased, and after 35 weeks astrocytes comprised 29% of glial cells (compared with 15% in controls). However, the number of oligodendrogial nuclei decreased simultaneously, leaving the total glial number unchanged. In the animals with longest experimental period there was a 15% loss of neurones.In a region with higher glial/neurone ratio, i.e. the Purkinje cell layer, the neurones showed a similar reduction, whereas the number of Bergmann astrocyte nuclei increased less than striatal astrocytes.A small group of animals with pronounced signs of encephalopathy had a higher loss of neurones and, furthermore, the glial number in corpus striatum and callosum was reduced, due to loss of oligodendrocytes.Despite the use of perfusion fixation, the size of astrocyte nuclei increased, this was reversible, as only slight changes were seen after 35 weeks.A possible explanation of the increase in astrocyte nuclear count and decrease in oligodendroglial count could be that nuclei normally considered to the oligodendroglial are transformed into nuclei with morphological characteristics of astrocytes.     

A procedure for culturing astrocytes from white matter and the application of the siRNA technique for silencing the expression of their specific marker, S100A4

White matter astrocytes have physiological functions which are distinct from those of astrocytes in gray matter. White matter becomes highly non-permissive to neurite growth after injury, but the role of white matter astrocytes in this process is incompletely understood. Current protocols for making primary astroglial cultures are inadequate for exploring the specific properties of white matter astrocytes in vitro. We describe a procedure for obtaining cultures of white matter astrocytes from the rodent corpus callosum. In this procedure, we take advantage of our previous finding that white, but not gray matter astrocytes express the calcium-binding protein S100A4. S100A4 expressing astrocytes are abundant in the corpus callosum, and we show that cultures, highly enriched in S100A4 expressing white matter astrocytes, can be reproducibly generated from this area. Key factors for successful cultures are (i) meticulous dissection of the corpus callosum from 4-day-old rats, and (ii) Percoll density gradient centrifugation to purify astrocytes. As a means of exploring the possible role of S100A4 in white matter astrocytes, we describe the use of the siRNA technique to eliminate the expression of S100A4 in our in vitro system.     

Perinatal exposure to music protects spatial memory against callosal lesions

Several studies have indicated that the exposure of rodents to music modulates brain development and neuroplasticity, by mechanisms that involve facilitated hippocampal neurogenesis, neurotrophin synthesis and glutamatergic signaling. This study focused on the potential protection that the perinatal exposure to music, between postnatal days 2 and 32, could offer against functional deficits induced by neonatal callosotomy in rats. The spontaneous alternation and marble-burying behaviors were longitudinally measured in callosotomized and control rats that had been exposed to music or not. The results indicated that the neonatal callosotomy-induced spontaneous alternation deficits that became apparent only after postnatal day 45, about the time when the rat corpus callosum reaches its maximal levels of myelination. The perinatal exposure to music efficiently protected the spontaneous alternation performance against the deficits induced by callosotomy. The present findings may offer important insights into music-induced neuroplasticity, relevant to brain development and neurorehabilitation.     

Increase in basic fibroblast growth factor-like immunoreactivity in rat brain after forebrain ischemia

Using immunohistochemical techniques, a study was conducted to determine whether basic fibroblast growth factor (bFGF) is generated as one of the 'self-repair' responses in rat brain following transient forebrain ischemia. In normal brain, slight bFGF-like immunoreactivity was observed. However, in rats exposed to 20 min of forebrain ischemia, intense bFGF-like immunoreactivity was observed in the CA1 subfield of the hippocampus and the caudate putamen, and marked activity was evident in the temporal cortex, corpus callosum and the CA4 subfield of the hippocampus. Marked neuronal degeneration was also observed in these brain regions following forebrain ischemia. These results suggest that induction of bFGF-like immunoreactivity may be related to the healing which follows brain ischemia.     

Glial expression of fibroblast growth factor-9 in rat central nervous system.

We examined the expression of fibroblast growth factor (FGF)-9 in the rat central nervous system (CNS) by immunohistochemistry and in situ hybridization studies. FGF-9 immunoreactivity was conspicuous in motor neurons of the spinal cord, Purkinje cells, and neurons in the hippocampus and cerebral cortex. In addition to the neuronal localization of FGF-9 immunoreactivity that we reported previously, the present double-label immunohistochemistry clearly demonstrated that the immunoreactivity was present in glial fibrillary acidic protein (GFAP)-positive astrocytes preferentially present in the white matter of spinal cord and brainstem of adult rats and in CNPase-positive oligodendrocytes that were arranged between the fasciculi of nerve fibers in cerebellar white matter and corpus callosum of both adult and young rats. There was a tendency for FGF-9 immunoreactivity in oligodendrocytes to be more pronounced in young rats than in adult rats. The variation of oligodendrocyte FGF-9 immunoreactivity in adult rats was also more pronounced than that in young rats. With in situ hybridization, FGF-9 mRNA was observed in astrocytes in the white matter of rat spinal cord and oligodendrocytes in the white matter of cerebellum and corpus callosum of adult and young rats. The expression of FGF-9 mRNA in glial cells was lower than in neurons, and not all glial cells expressed FGF-9. In the present study, we demonstrated that FGF-9 was expressed not only in neurons but also in glial cells in the CNS. FGF-9 was considered to have important functions in adult and developing CNS.     

Tract-based spatial statistics of diffusion tensor imaging after corpus callosotomy in relation to seizure recurrence

Purpose

To delineate microstructural changes in transected white matter tracts after corpus callosotomy in relation to seizure recurrence using tract-based spatial statistics of diffusion tensor imaging (DTI-TBSS).

Methods

We retrospectively included 12 total corpus callosotomy patients who had undergone serial pre- and postoperative DTI studies. The first postoperative DTI was performed within 6 months after callosotomy. The second postoperative DTI was performed in five patients with seizure recurrence (symptomatic group) and in seven patients without seizure recurrence (asymptomatic group) after 1 year following surgery. Group comparisons of fractional anisotropy (FA) with age- and sex-matched controls were performed in a whole brain voxel-wise manner using DTI-TBSS.

Results

The first postoperative DTI-TBSS showed a significant FA decrease in the entire corpus callosum in all patients. The second postoperative DTI-TBSS showed that a significant FA decrease remained in the entire corpus callosum in the asymptomatic group. However, in the symptomatic group, no significant decrease of FA was observed in some parts of the posterior body and splenium of the corpus callosum, although there was still a significant FA decrease in the genu of the corpus callosum.

Conclusions

Using DTI-TBSS analysis, we characterized and visualized microstructural white matter changes over time in relation to seizure recurrence in callosotomy patients, suggesting that reorganization of some transected white matter tracts may be related to seizure recurrence. DTI-TBSS analysis can provide reliable and useful information about the state of white matter bundles affected by corpus callosotomy in a noninvasive manner.     

Immunohistological study of globoid cell leukodystrophy

We examined three autopsy cases of globoid cell leukodystrophy (GLD) with different survival, using immunohistochemistry and in situ nick end labeling (ISEL). The white matter lesion was pronounced in the corona radiata, corpus callosum and cerebellar peduncles in three cases, where a spongy state developed, in addition to the neuronal loss in the thalamus, cerebellum and inferior olivary nucleus. Ramified microglia, being immunoreactive for ferritin and HLA-DR alpha, were scattered in the white matter, and some of them also had immunoreactivity for TNF-alpha. Both the small-sized and large-sized globoid cells showed immunoreactivity for ferritin KP-1 and NCAM, while some of the small-sized globoid cells were also immunoreactive for HLA-DR alpha and TNF-alpha. As the survival became longer, the occurrence of the globoid cells decreased, however, they were commonly observed in the corpus callosum and cerebellar peduncle in three cases. T lymphocytes immunoreactive for LCA, UCHL-1 and CD3 were increased around the vessels in the white matter. ISEL stained nuclei of mononuclear cells in the white matter in two cases with short survival, although the cell origin was not verified. ISEL also visualized a few nuclei of the small-sized globoid cells in one case. On the other hand, immunostainings against cell death proteins such as bcl-2 family members and p53 failed to identify any significant changes. These data suggest that the immunological step and to a lesser extent the apoptotic process may partly be involved in the myelin breakdown and glial pathology in GLD, as reported in the twitcher mouse, a murine model of GLD.     

MRI signal changes in the white matter after corpus callosotomy

Magnetic resonance imaging (MRI) changes reported after corpus callosotomy include hyperintensity in the corpus callosum, perifalcine hyperintensity caused by surgical retraction, and acute changes associated with surgical complications. The authors have observed MRI signal changes in the cerebral white matter of corpus callosotomy patients that are separate from the sectioned callosum and not clearly related to surgical manipulation or injury. Brain MRI scans were retrospectively reviewed in 25 of 38 patients who underwent anterior, posterior, or total callosotomy for refractory seizures between 1988 and 1995. Nine patients had signal changes in the cerebral white matter on postoperative MRI. Six of these patients had preoperative MRI studies available for comparison, and none of the white matter signal abnormalities were evident preoperatively. T2 prolongation or hyperintensity on proton-density images was observed in areas including the centrum semiovale, forceps major, and forceps minor. Three patients had signal changes that had distinct borders extending only to the posterior limit of the callosotomy. MRI signal changes in the cerebral white matter after corpus callosotomy have not been previously reported and may represent distant effects of callosal section. Wallerian degeneration occurring in the neuronal processes cut during surgery could account for the signal changes.     

Improved acquisition of left-right response differentiation in the rat following section of the corpus callosum.

Split-brained rats learned a left-right response differentiation in a water maze significantly faster than rats with sham surgery. It is unlikely that this superiority resulted from improvement in performance variables since callosotomized rats did not differ significantly from sham operates in speed of acquisition of a brightness discrimination in the same apparatus. Additionally, callosotomy likewise had no effect on the acquisition of a water-maze task requiring consistent unilateral responses. The superiority of the callosotomized animals in forming the left-right response differentiation supports a hypothesis implicating the forebrain commissures in left-right confusion.     

Appearance of neuronal S-100β during development of the rat brain

In addition to being an astroglial protein, S-100β is localised in distinct populations of neurons in the adult rat hindbrain. We report, here, the expression of S-100β in both neurons and glia of the rat brain during development. Prenatally, S-100β immunoreactivity was confined to glial cells close to the germinal zone. After birth, S-100β positive glial cells were seen mainly in the brainstem and cerebellum, while only a few were detected in cerebral cortex and hippocampus. The number of S-100β containing glial cells increased steadily during the first 2 postnatal weeks after which the adult pattern was attained. No S-100β containing neurons were present prenatally. The first S-100β containing neurons were seen in the mesencephalic trigeminal nucleus at postnatal day 1 (P1), and in the motor trigeminal nucleus at P3. Neuronal S-100β immunoreactivity in other nuclei was mostly attained from the 10th to the 21st postnatal day. The neuronal S-100β immunoreactivity was first detected in the cell nuclei during development, then increased in the cytoplasm with ages. A nuclear staining in many immunoreactive neurons persisted until the adult. It usually took 1 to 2 weeks for neuronal S-100β to attain the adult staining pattern, i.e., heavy staining of the cytoplasm and processes, after its appearance. The forebrain never contained S-100β positive neurons. The S-100β is first expressed in glial cells, suggesting it is primarily of the glial origin. Coupled with neurotrophic effects of the protein, the time course of neuronal S-100β expression during the critical period of neuronal development implies that it may be involved in neuronal differentiation and maturation.     

Tyrosine kinase A but not phosphacan/protein tyrosine phosphatase-zeta/beta immunoreactivity and protein level changes in neurons and astrocytes in the gerbil hippocampus proper after transient forebrain ischemia

In the present study, ischemia-related changes in tyrosine kinase A (trkA) and phosphacan/protein tyrosine phosphatase-zeta/beta (PTP-zeta/beta) immunoreactivities and protein contents were examined in the hippocampus proper after transient forebrain ischemia for 5 min in a gerbil model. Our investigations showed that ischemia-induced changes occurred in trkA immunoreactivity in the hippocampal CA1 region, but not in the CA2/3 region of the hippocampus proper. In the sham-operated group, trkA immunoreactivity was barely detectable. trkA immunoreactivity increased from 30 min after ischemia and peaked at 12 h. Four days after ischemic insult, trkA immunoreactivity was observed in GFAP-immunoreactive astrocytes in the strata oriens and radiatum. In addition, we found that ischemia-related changes in trkA protein content were similar to immunohistochemical changes. On the other hand, PTP-zeta/beta immunoreactivities in the hippocampus proper were unaltered by forebrain ischemia. These results suggest that chronological changes of trkA after transient forebrain ischemia may be associated with an ischemic damage compensatory mechanism in CA1 pyramidal cells.     

Effects of diabetes mellitus on astrocyte GFAP and glutamate transporters in the CNS

Diabetes mellitus increases the risk of central nervous system (CNS) disorders such as stroke, seizures, dementia, and cognitive impairment. The cellular mechanisms responsible for the increased risk of these disorders are incompletely understood. Astrocytes are proving critical for normal CNS function, and alterations in their activity could contribute to diabetes-related disturbances in the brain. We examined the effects of streptozotocin (STZ)-induced diabetes in rats on the level of the astrocyte intermediate filament protein, glial fibrillary acidic protein (GFAP), number of astrocytes, and levels of the astrocyte glutamate transporters, glutamate transporter-1 (GLT-1) and glutamate/aspartate transporter (GLAST), in the cerebral cortex, hippocampus, and cerebellum by Western blotting (WB) and immunohistochemistry (IH). Studies were carried out at 4 and 8 weeks of diabetes duration. Diabetes resulted in a significant decrease in GFAP protein levels (WB) in the hippocampus and cerebellum at 4 weeks and in the cerebral cortex, hippocampus and cerebellum by 8 weeks. Attenuated GFAP immunoreactivity (IH) was evident in the hippocampus, cerebellum and white matter regions such as the corpus callosum and external capsule at both 4 and 8 weeks of diabetes. Astrocyte cell counts of adjacent sections immunoreactive for S-100B were not different between control and diabetic animals. No significant differences were noted in astrocyte glutamate transporter levels in the cerebral cortex, hippocampus, or cerebellum at either time period (WB, IH). With the expanding list of astrocyte functions in the CNS, the role of astrocytes in diabetes-induced CNS disorders clearly warrants further investigation.     

Origin of contralateral reactive gliosis in surgically injured rat cerebral cortex

While reactive gliosis is readily observed close to the site of cerebral injury, astrocyte reactivity can also occur in distant areas either ipsilateral or contralateral to the lesion site. The present experiments were designed to address the origin of contralateral gliosis in adult rats following a cortical stab wound injury. One-month-old rats were subjected to either left cortical stab wound alone, callosotomy alone, callosotomy plus left cortical stab wound, or no surgery; 7 days later, animals were sacrificed. Formalin-fixed, paraffin-embedded sections were obtained and immunostained for GFAP. While untreated controls showed no cortical gliosis, callosotomy alone induced mild bilateral cortical gliosis. Whether or not rats were subjected to a callosotomy, the left cortical stab wound produced identical results: severe ipsilateral cortical gliosis and moderate contralateral gliosis. In all lesion models, both the intensity of GFAP staining and the number of reactive astrocytes were most marked in cortical areas abutting the subarachnoid spaces and decreased gradually into the deeper cortical layers. Our results suggest that the origin of contralateral gliosis in cortical stab injury is more likely due to the release of soluble substance(s) which diffuse to distant areas, rather than the migration of astrocytes through the corpus callosum from the lesion site, or being subsequent to degeneration of neurons which fibers traverse the corpus callosum.     

Metastasis-associated mts1 (S100A4) protein in the developing and adult central nervous system

We have found recently that white matter astrocytes in the spinal cord constitutively express immunoreactivity for Mts1 (S100A4) protein and that this expression is up-regulated ipsilaterally after sciatic nerve or dorsal root injury. Here, we have studied the expression pattern of Mts1 throughout the rat central nervous system (CNS). We found Mts1 immunoreactivity in myelinated tracts such as the olfactory tract, optic nerve, corpus callosum, internal capsule, fimbria, and spinal cord funiculi but not in cerebellar white matter. Mts1-immunoreactive (IR) cells were consistently astrocytic (glial fibrillary acidic protein positive). In addition to myelinated tracts, Mts1 immunoreactivity was also present in a few nonmyelinated or poorly myelinated areas, such as pituitary gland, olfactory bulb, and around the lateral ventricle. Based on location, three Mts1-IR astrocyte groups were distinguished: 1) astrocytes at the surfaces of the CNS, i.e., adjacent to the cerebrospinal fluid, organized perpendicularly to the bundles of axonal tracts; 2) astrocytes located in parallel to, and inserted between, axonal bundles; and 3) clusters of astrocytes around the lateral ventricle and in the olfactory bulb. We further analyzed the relationship between Mts1 immunoreactivity and the development of CNS fiber tracts by combining staining for Mts1 and myelin basic protein (MBP). Mts1 immunoreactivity appeared postnatally in recently myelinated areas. During the development of corpus callosum and the optic tract, Mts1 immunoreactivity was concentrated at the frontier of myelination. The developmental expression pattern suggests a role of Mts1-IR astrocytes in the maturation of myelinated fiber tracts. The preferential localization of Mts1 to the subpial region in the mature CNS suggests that Mts1 participates in astrocyte-mediated CNS-cerebrospinal fluid exchange.     

Interhemispheric EEG coherence after corpus callosotomy

Interhemispheric coherence analysis of scalp electroencephalograms (EEGs) in three intractable epileptic patients before and after surgical section of the anterior part of the corpus callosum was performed. Equidistant EEG periods recorded under resting conditions free of interictal epileptic activity and periods with generalized spike-and-wave discharges were investigated. Mean coherence values for five frequency EEG bands (delta, theta, alpha, beta 1 and beta 2) before and after corpus callosotomy were compared with each other and statistically evaluated. Anterior callosotomy led, in all cases, to a decrease of interhemispheric EEG coherence in most localizations, with the most profound decreases in the region corresponding to the section. These results support the hypothesis that the corpus callosum plays an important role in resting interhemispheric integration and EEG synchronization, similar to its central role in propagation of specific epileptic activity.     

间歇性θ爆发式磁刺激对高血压大鼠胼胝体髓鞘及局部炎症反应的影响

目的探究间歇性θ爆发式磁刺激对慢性高血压大鼠胼胝体区域髓鞘脱失、星形胶质细胞增生和小胶质细胞活化的改善作用。方法对雄性Sprague-Dawley大鼠随机进行双肾双夹术,制作易卒中型肾血管性高血压大鼠模型。术后22周,模型制备成功的高血压大鼠随机接受连续14 d间歇性θ爆发式磁刺激治疗(intermittent theta burst stimulation,iTBS)(高血压iTBS组,n=6)或假性刺激(高血压假刺激组,n=6),假手术大鼠接受假性刺激(假手术假刺激组,n=6)。HE染色观察胼胝体小动脉形态。免疫荧光染色观察胼胝体MBP标记的髓鞘脱失情况。免疫荧光染色观察GFAP标记的星形胶质细胞数量和IBa-1标记的小胶质细胞数量和形态,以评价星形胶质细胞增生和小胶质细胞活化。结果高血压iTBS组和高血压假刺激组出现明显小动脉管壁增厚。与假手术假刺激组相比,高血压假刺激组胼胝体MBP阳性面积比例减少(P<0.01),GFAP阳性细胞和IBa-1阳性细胞数量明显增加(P<0.01),IBa-1阳性细胞胞体增大,突起变粗,分枝变少。iTBS治疗明显增加了高血压大鼠胼胝体MBP阳性面积比例,降低GFAP阳性细胞和IBa-1阳性细胞数量(P<0.01),IBa-1阳性细胞胞体变小,突起变细,分枝变多。结论iTBS治疗可减轻高血压大鼠胼胝体区域髓鞘脱失,抑制星形胶质细胞增生和小胶质细胞活化。     

Increased expression and nuclear accumulation of basic fibroblast growth factor in primary cultured astrocytes following ischemic-like insults.

Basic fibroblast growth factor (bFGF) is a biological active polypeptide with potent trophic effects on neurons, glia and endothelial cells. In the present study, we examined the temporal expression profile of bFGF protein in cultured cortical astrocytes under ischemic-like conditions such as serum-free, glucose-free or glutamate application. A peak increase of bFGF level was observed at 24 h after the initiation of insults. A striking increase in the bFGF immunoreactivity and a moderate increase in the fibroblast growth factor receptor-1 (FGFR-1) immunoreactivity were also found in the astrocytes treated with serum- or glucose-deprivation or glutamate. The increased bFGF immunoreactivity and FGFR-1 immunoreactivity were mainly accumulated in the nuclei of astrocytes. The results suggest that the expression of bFGF and FGFR-1 in the astrocytes, especially in the nuclear interior, can be up-regulated under ischemic-like conditions and that the up-regulation of bFGF and FGFR-1 may play an important role in the maintenance and repair of the central nervous system (CNS) after ischemia.