Changes in Glial Support of the Hippocampus during the Development of an Alzheimer's Disease-like Pathology and Their Correction by Mitochondria-Targeted Antioxidant SkQ1.

Astrocytes and microglia are the first cells to react to neurodegeneration, e.g., in Alzheimer's disease (AD); however, the data on changes in glial support during the most common (sporadic) type of the disease are sparse. Using senescence-accelerated OXYS rats, which simulate key characteristics of sporadic AD, and Wistar rats (parental normal strain, control), we investigated hippocampal neurogenesis and glial changes during AD-like pathology. Using immunohistochemistry, we showed that the early stage of the pathology is accompanied by a lower intensity of neurogenesis and decreased astrocyte density in the dentate gyrus. The progressive stage is concurrent with reactive astrogliosis and microglia activation, as confirmed by increased cell densities and by the acquisition of cell-specific gene expression profiles, according to transcriptome sequencing data. Besides, here, we continued to analyze the anti-AD effects of prolonged supplementation with mitochondria-targeted antioxidant SkQ1. The antioxidant did not affect neurogenesis, partly normalized the gene expression profile of astrocytes and microglia, and shifted the resting/activated microglia ratio toward a decrease in the activated-cell density. In summary, both astrocytes and microglia are more vulnerable to AD-associated neurodegeneration in the CA3 area than in other hippocampal areas; SkQ1 had an anti-inflammatory effect and is a promising modality for AD prevention and treatment.

Simple Fabrication of Flexible Biosensor Arrays Using Direct Writing for Multianalyte Measurement from Human Astrocytes.

Simultaneous measurements of glucose, lactate, and neurotransmitters (e.g., glutamate) in cell culture over hours and days can provide a more dynamic and longitudinal perspective on ways neural cells respond to various drugs and environmental cues. Compared with conventional microfabrication techniques, direct writing of conductive ink is cheaper, faster, and customizable, which allows rapid iteration for different applications. Using a simple direct writing technique, we printed biosensor arrays onto cell culture dishes, flexible laminate, and glass to enable multianalyte monitoring. The ink was a composite of PEDOT:PSS conductive polymer, silicone, activated carbon, and Pt microparticles. We applied 0.5% Nafion to the biosensors for selectivity and functionalized them with oxidase enzymes. We characterized biosensors in phosphate-buffered saline and in cell culture medium supplemented with fetal bovine serum. The biosensor arrays measured glucose, lactate, and glutamate simultaneously and continued to function after incubation in cell culture at 37 °C for up to 2 days. We cultured primary human astrocytes on top of the biosensor arrays and placed arrays into astrocyte cultures. The biosensors simultaneously measured glucose, glutamate, and lactate from astrocyte cultures. Direct writing can be integrated with microfluidic organ-on-a-chip platforms or as part of a smart culture dish system. Because we print extrudable and flexible components, sensing elements can be printed on any 3D or flexible substrate.

Pubertal development of estradiol-induced hypothalamic progesterone synthesis.

In females, a hallmark of puberty is the luteinizing hormone (LH) surge that triggers ovulation. Puberty initiates estrogen positive feedback onto hypothalamic circuits, which underlie the stimulation of gonadotropin releasing hormone (GnRH) neurons. In reproductively mature female rodents, both estradiol (E2) and progesterone (P4) signaling are necessary to stimulate the surge release of GnRH and LH. Estradiol membrane-initiated signaling facilitates progesterone (neuroP) synthesis in hypothalamic astrocytes, which act on E2-induced progesterone receptors (PGR) to stimulate kisspeptin release, thereby activating GnRH release. How the brain changes during puberty to allow estrogen positive feedback remains unknown. In the current study, we hypothesized that a critical step in estrogen positive feedback was the ability for estradiol-induced neuroP synthesis. To test this idea, hypothalamic neuroP levels were measured in groups of prepubertal, pubertal and young adult female Long Evans rats. Steroids were measured with liquid chromatography tandem mass spectrometry (LC-MS/MS). Hypothalamic neuroP increases from pre-puberty to young adulthood in both gonad-intact females and ovariectomized rats treated with E2. The pubertal development of hypothalamic E2-facilitated progesterone synthesis appears to be one of the neural switches facilitating reproductive maturation.

Protective effects of taurine against inflammation, apoptosis, and oxidative stress in brain injury.

The protective effect of taurine against inflammation, apoptosis and oxidative stress in traumatic brain injury was investigated in the present study. Taurine is a non­proteogenic and essential amino acid in animals. It plays a critical nutritional role in brain cell growth, differentiation, and development. Taurine is involved in regeneration and neuroprotection in the injured nervous system, and is an effective antioxidant against lead­, cadmium­, and exercise­induced oxidative stress. Astrocytes and neuron cells were co­cultured and cells were treated with different concentrations of taurine (100, 200 and 300 mg/l) for 72 h, and the levels of reactive oxygen species, malondialdehyde, reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase, acetylcholinesterase, tumor necrosis factor­α, interleukin­6, caspase­3, p53, B­cell lymphoma 2 and Bcl­2­associated X protein were determined. These inflammatory, apoptotic, and oxidative stress markers were substantially increased in injured cells, and returned to normal levels following taurine supplementation. Thus, taurine supplementation may be effective against oxidative stress, apoptosis, and inflammation in injured brain cells.

Astrocytes in mouse models of tauopathies acquire early deficits and lose neurosupportive functions.

Microtubule-associated protein tau aggregates constitute the characteristic neuropathological features of several neurodegenerative diseases grouped under the name of tauopathies. It is now clear that the process of tau aggregation is associated with neurodegeneration. Several transgenic tau mouse models have been developed where tau progressively aggregates, causing neuronal death. Previously we have shown that transplantation of astrocytes in P301S tau transgenic mice rescues cortical neuron death, implying that the endogenous astrocytes are deficient in survival support. We now show that the gliosis markers Glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100ß) are elevated in brains from P301S tau mice compared to control C57Bl/6 mice whereas the expression of proteins involved in glutamine/glutamate metabolism are reduced, pointing to a functional deficit. To test whether astrocytes from P301S mice are intrinsically deficient, we co-cultured astrocytes and neurons from control and P301S mice. Significantly more C57-derived and P301S-derived neurons survived when cells were cultured with C57-derived astrocytes or astrocyte conditioned medium (C57ACM) than with P301S-derived astrocytes or astrocyte conditioned medium (P301SACM), or ACM from P301L tau mice, where the transgene is also specifically expressed in neurons. The astrocytic alterations developed in mice during the first postnatal week of life. In addition, P301SACM significantly decreased presynaptic (synaptophysin, SNP) and postsynaptic (postsynaptic density protein 95, PSD95) protein expression in cortical neuron cultures whereas C57ACM enhanced these markers. Since thrombospondin 1 (TSP-1) is a major survival and synaptogenic factor, we examined whether TSP-1 is deficient in P301S mouse brains and ACM. Significantly less TSP-1 was expressed in the brains of P301S tau mice or produced by P301S-derived astrocytes, whereas supplementation of P301SACM with TSP-1 increased its neurosupportive capacity. Our results demonstrate that P301S-derived astrocytes acquire an early functional deficiency that may explain in part the loss of cortical neurons in the P301S tau mice.

Phytochemical analysis of hydroethanolic extract of Turnera diffusa Willd and evaluation of its effects on astrocyte cell death.

OBJECTIVE: To evaluate the phytochemical composition of hydroethanolic extracts from powdered aerial parts of Turnera diffusa Willd (Turneraceae; T. diffusa), as well as its toxicity in astrocytes. METHODS: Chemical analyses of hydroethanolic extract from powdered aerial parts ofT. diffusa were carried out using HPLC-DAD-ESI-MS/MS.In vitro assays using astrocytes culture were performed to evaluate cell death. RESULTS: Flavone-C, O-diglycosides, such as, luteolin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside, apigenin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside and apigenin-7-O-6"-p-coumaroylglucoside were the main compounds found in this hydroethanolic extract. Concentration time-effect demonstrated the toxicity of this extract at a concentration of 1,000µg/mL in astrocyte culture, after 6 and 24 hours of incubation. CONCLUSION: In phytochemical analyses, important antioxidants (mainly flavonoids) were observed. T. diffusa extracts presented cytotoxic effect in high concentrations, leading to increased cell death in astrocyte culture.

Phytochemical analysis of hydroethanolic extract of Turnera diffusa Willd and evaluation of its effects on astrocyte cell death / Análise fitoquímica do extrato hidroetanólico de Turnera diffusa Willd e avaliação de seus efeitos na morte de astrócitos

ABSTRACT Objective To evaluate the phytochemical composition of hydroethanolic extracts from powdered aerial parts of Turnera diffusa Willd (Turneraceae; T. diffusa), as well as its toxicity in astrocytes. Methods Chemical analyses of hydroethanolic extract from powdered aerial parts ofT. diffusa were carried out using HPLC-DAD-ESI-MS/MS.In vitro assays using astrocytes culture were performed to evaluate cell death. Results Flavone-C, O-diglycosides, such as, luteolin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside, apigenin-8-C-[6-deoxy-2-O-rhamnosyl]-xylo-hexos-3-uloside and apigenin-7-O-6”-p-coumaroylglucoside were the main compounds found in this hydroethanolic extract. Concentration time-effect demonstrated the toxicity of this extract at a concentration of 1,000µg/mL in astrocyte culture, after 6 and 24 hours of incubation. Conclusion In phytochemical analyses, important antioxidants (mainly flavonoids) were observed. T. diffusa extracts presented cytotoxic effect in high concentrations, leading to increased cell death in astrocyte culture.

RESUMO Objetivo Avaliar a composição fitoquímica do extrato hidroetanólico das partes aéreas de Turnera diffusa Willd (Turneraceae; T. diffusa) e sua toxicidade em astrócitos. Métodos Análises químicas do extrato hidroetanólico de partes aéreas de T. diffusa foram feitas por HPLC-DAD-ESI-MS/MS. Os ensaiosin vitro utilizaram culturas de astrócitos para avaliar morte celular. Resultados Flavonas-C, O-diglicosídeos, como, luteolina-8-C-[6-deoxi-2-O-raminosil]-xilo-hexos-3-ulosideo, apigenina-8-C-[6-deoxi-2-O-raminosil]-xilo-hexos-3-ulosideo e apigenina-7-O-6”-p-cumaroilglucosídeo foram os principais constituintes encontrados neste extrato hidroetanólico. Uma curva tempo-concentração demonstrou toxicidade desse extrato na concentração de 1.000µg/mL, na cultura de astrócitos após 6 e 24 horas de incubação. Conclusão Nas análises fitoquímicas, importantes antioxidantes, sobretudo flavonoides, foram observados. Extratos de T. diffusa apresentaram efeitos citotóxicos em altas concentrações, ocasionando aumento de morte celular em cultura de astrócitos.

Chronic sleep deprivation-induced proteome changes in astrocytes of the rat hypothalamus.

Sleep deprivation (SD) can influence cognition, memory, and sleep/wake homeostasis and can cause impairments in many physiological processes. Because the homeostatic control of the sleep/wake cycle is closely associated with the hypothalamus, the current study was undertaken to examine proteomic changes occurring in hypothalamic astrocytes following chronic partial SD. After chronic partial SD for 7 days, astrocytes were prepared from rat hypothalamus using a Percoll gradient method, and their proteome profiles were determined by LC-MS/MS. Comparisons of the proteome profiles of hypothalamic astrocytes revealed that chronic partial SD increased (≥1.5-fold) 89 proteins and decreased (≤0.7-fold) 50 proteins; these changes in protein expression were validated by western blot or immunohistochemistry. DAVID and IPA analyses of these proteins suggested that SD may influence gliotransmission and astrocyte activation. PPP2R1A, RTN4, VAMP-2, LGI-1, and SLC17A7 were identified and validated as the main targets of SD in astrocytes. Our results suggest that SD may modulate gliotransmission in the hypothalamus, thereby disturbing sleep/wake homeostasis and increasing susceptibility to neurological disease; however, further studies are required to confirm whether the proteome changes are specific to SD.

Effects of palmitoylethanolamide on release of mast cell peptidases and neurotrophic factors after spinal cord injury.

Spinal cord injury (SCI) has a significant impact on quality of life, expectancy, and economic burden, with considerable costs associated with primary care and loss of income. The complex pathophysiology of SCI may explain the difficulty in finding a suitable therapy for limiting neuronal injury and promoting regeneration. Although innovative medical care, advances in pharmacotherapy have been limited. The aim of the present study was to carefully investigate molecular pathways and subtypes of glial cells involved in the protective effect of PEA on inflammatory reaction associated with an experimental model of SCI. The compression model induced by applying an aneurysm clip to the spinal cord in mice is closer to the human situation, since it replicates the persistence of cord compression. Spinal cord trauma was induced in mice by the application of vascular clips to the dura via a four-level T5-T8 laminectomy. Repeated PEA administration (10 mg/kg i.p., 6 and 12 h after SCI) significantly reduced the degree of the severity of spinal cord trauma through the reduction of mast cell infiltration and activation. Moreover, PEA treatment significantly reduced the activation of microglia and astrocytes expressing cannabinoid CB(2) receptor after SCI. Importantly, the protective effect of PEA involved changes in the expression of neurotrophic factors, and in spinal cord dopaminergic function. Our results enhance our understanding about mechanisms related to the anti-inflammatory property of the PEA suggesting that this N-acylethanolamine may represent a crucial therapeutic intervention both diminishing the immune/inflammatory response and promoting the initiation of neurotrophic substance after SCI.

Genoprotective effects of the green tea-derived polyphenol/epicatechin gallate in C6 astroglial cells.

In vitro and in vivo studies have recently reported significant chemopreventive effects of green tea-derived polyphenols in different diseases. However, it remains unclear how such effects could be triggered. In order to elucidate the effects of epicatechin gallate (ECG) in C6 cells, both by itself and against H2O2-induced genotoxicity, measurements of DNA strand breaks and chromosome loss were performed. DNA damage was measured by comet and micronucleus assays. The present study shows for the first time how ECG, the major green tea-derived polyphenol, is able to exert dose-dependent genoprotective effects in an H2O2-induced toxicity model of C6 astroglial cells. We demonstrate that doses of ECG in a range from 0.1 to 1 µM were able to completely prevent H2O2-induced genotoxicity in vitro. In contrast, considerably higher concentrations of ECG (10 µM) were able to reverse previous positive effects in a dose- and time-dependent manner. The same results were confirmed by both comet (F(3,9) = 336,148; P < .001) and micronucleus (F(3,9) = 23,228; P < .001) methods. Together, our data show ECG as a dose-dependent genoprotective compound in C6 astroglial cells. This indicates that small doses of polyphenols included in our diet could have beneficial effects on neural cells, contributing to prevention of oxidative stress-associated brain pathologies. In addition, our data highlight the importance of strictly modulating doses and/or consumption of antioxidant-fortified foods or additional supplements containing such beneficial molecules.

Consumption of green tea alters glial fibriliary acidic protein immunoreactivity in the spinal cord astrocytes of STZ-diabetic rats.

We examined the effect of green tea consumption on glial fibriliary acidic protein (GFAP) expression in spinal cord of streptozotocin (STZ) treated rats. Three groups (n = 10) were used in this study: (i) controls; (ii) STZ-induced diabetic rats given tap water; and (iii) an STZ-induced diabetic group given green tea. Immunohistochemistry showed a significant (P < 0.001) decrease in the number of GFAP immunoreactive astrocytes in spinal cord sections of diabetic rats compared to non-diabetic controls. Diabetic rats treated with green tea showed a significant (P < 0.01) increase in the number GFAP-immunoreactive astrocytes in all the spinal cord gray areas as compared to water-drinking diabetic rats. Immunoblotting confirmed that the diabetic spinal cord tissue expressed 71.0 +/- 7.0% less GFAP compared to non-diabetic controls and that the GFAP content in diabetic rats increased up to 86.34 +/- 18.74% compared to non-diabetic controls after 12 weeks of green tea consumption. In conclusion, consumption of green tea may represent an achievable adjunct therapy for improving changes seen in diabetic spinal cord.

Expanded-polyglutamine huntingtin protein suppresses the secretion and production of a chemokine (CCL5/RANTES) by astrocytes.

Huntington's disease (HD) is a hereditary neurological disease caused by expended CAG repeats in the HD gene, which codes for a protein called Huntingtin (Htt). The resultant mutant Huntingtin (mHtt) forms aggregates in neurons and causes neuronal dysfunction. In astrocytes, the largest population of brain cells, mHtt also exists. We report herein that astrocyte-conditioned medium (ACM) collected from astrocytes of R6/2 mice (a mouse model of HD) caused primary cortical neurons to grow less-mature neurites, migrate more slowly, and exhibit lower calcium influx after depolarization than those maintained in wild-type (WT) ACM. Using a cytokine antibody array and ELISA assays, we demonstrated that the amount of a chemokine [chemokine (C-C motif) ligand 5 (CCL5)/regulated on activation normal T cell expressed and secreted (RANTES)] released by R6/2 astrocytes was much less than that by WT astrocytes. When cortical neurons were treated with the indicated ACM, supplementation with recombinant CCL5/RANTES ameliorated the neuronal deficiency caused by HD-ACM, whereas removing CCL5/RANTES from WT-ACM using an anti-CCL5/RANTES antibody mimicked the effects evoked by HD-ACM. Quantitative PCR and promoter analyses demonstrated that mHtt hindered the activation of the CCL5/RANTES promoter by reducing the availability of nuclear factor kappaB-p65 and, hence, reduced the transcript level of CCL5/RANTES. Moreover, ELISA assays and immunocytochemical staining revealed that mHtt retained the residual CCL5/RANTES inside R6/2 astrocytes. In line with the above findings, elevated cytosolic CCL5/RANTES levels were also observed in the brains of two mouse models of HD [R6/2 and Hdh((CAG)150)] and human HD patients. These findings suggest that mHtt hinders one major trophic function of astrocytes which might contribute to the neuronal dysfunction of HD.

Morphological evidence for direct interaction between gonadotrophin-releasing hormone neurones and astroglial cells in the human hypothalamus.

In rodents, there is compelling evidence indicating that dynamic cell-to-cell communications involving cross talk between astroglial cells (such as astrocytes and specialised ependymoglial cells known as tanycytes) and neurones are important in regulating the secretion of gonadotrophin-releasing hormone (GnRH), the neurohormone that controls both sexual maturation and adult reproductive function. However, whether such astroglial cell-GnRH neurone interactions occur in the human brain is not known. In the present study, we used immunofluorescence to examine the anatomical relationship between GnRH neurones and glial cells within the hypothalamus of five women. Double-staining experiments demonstrated the ensheathment of GnRH neurone perikarya by glial fibrillary acidic protein (GFAP)-immunoreactive astrocyte processes in the periventricular zone of the tuberal region of the hypothalamus. GFAP immunoreactivity did not overlap that of GnRH at the GnRH neurone's projection site (i.e. the median eminence of the hypothalamus). Rather, human GnRH neuroendocrine fibres were found to be closely associated with vimentin or nestin-immunopositive radial glial processes likely belonging to tanycytes. In line with these light microscopy data, ultrastructural examination of GnRH-immunoreactive neurones showed numerous glial cells in direct apposition to pre-embedding-labelled GnRH cell bodies and/or dendrites in the infundibular nucleus, whereas postembedding immunogold-labelled GnRH nerve terminals were often seen to be enwrapped by glial cell processes in the median eminence. GnRH nerve button were sometimes visualised in close proximity to fenestrated pituitary portal blood capillaries and/or evaginations of the basal lamina that delineate the pericapillary space. In summary, these data demonstrate that GnRH neurones morphologically interact with astrocytes and tanycytes in the human brain and provide evidence that glial cells may contribute physiologically to the process by which the neuroendocrine brain controls the function of GnRH neurones in humans.

Astrocyte-conditioned medium protecting hippocampal neurons in primary cultures against corticosterone-induced damages via PI3-K/Akt signal pathway.

Prolonged or excessive exposure to corticosterone leads to neuronal damages in the brain regions, including hippocampus. We reported that astrocyte-conditioned medium (ACM) protected the neurons of the primary hippocampal cultures against the corticosterone-induced damages. Corticosterone added to the cultures resulted in a significant number of TUNEL-positive cells. However, corticosterone-induced TUNEL labeling was suppressed as for ACM-cultured neurons. To delineate the molecular basis underlying the neuroprotection of ACM, we assessed the activation of ERK1/2 and (PI3-K)/Akt signal pathways in response to corticosterone-induced neuronal damages. Western blot test revealed that corticosterone increased the phosphorylation of ERK1/2 and PI3-K/Akt in hippocampal neurons grown in Neurobasal medium supplemented with B27 and 500 microm L-glutamine (NBM+). Interestingly, the increase of phospho-ERK1/2 and Akt levels was much pronounced and the time course of phosphorylation was altered in ACM, suggesting that both signaling pathways might participate in ACM protection. Furthermore, the selective inhibitor of Akt, rather than ERK1/2, blocked the neuroprotective activity against corticosterone in ACM-cultured neurons. In summary, our data showed that ACM had a potent neuroprotective effect in cultured neurons. PI3-K/Akt signal pathway, but not ERK1/2, was involved in the protective activity against the corticosterone-induced damages.

Insulin-like growth factor binding protein-6 transgenic mice: postnatal growth, brain development, and reproduction abnormalities.

In biological fluids, IGFs bind to six distinct binding proteins (IGFBP-1 to -6). IGFBP-6 is of particular interest because it has been shown to inhibit proliferation in many cell types and to be synthesized in the central nervous system (CNS). It also has the strongest affinity for IGF-II among the IGFBPs. To study IGFBP-6 function in vivo, we established IGFBP-6 transgenic mice in which human IGFBP-6 (hIGFBP-6) cDNA is expressed under the control of the glial fibrillary acidic protein (GFAP) promoter. Northern and Western blot analysis revealed strong transgene expression in the CNS. With histological examination of the CNS, cerebellum size and weight proved to be reduced by about 25% and 35%, respectively, and there were smaller numbers of differentiated, GFAP-expressing astrocytes than in wild-type mice. Between birth and 1 month of age, transgenic mice had high levels of circulating hIGFBP-6 and reduced plasma IGF-I, and, as a result, body weight was significantly reduced. Reproductive physiology was also affected. Litter size was reduced by 27% when wild-type males were mated with 3-month-old transgenic females and by 66% when mated with 6-month-old transgenic females. Histological examination of ovaries of transgenic mice revealed a marked decrease in weight and in the number of corpora lutea, suggesting altered ovulation, and circulating LH levels were reduced by 50%. Our results indicate that this new model of transgenic mouse may prove to be a useful tool in elucidating the in vivo role of IGFBP-6 in the brain, especially in regard to hypothalamic control, and in reproductive physiology.

Neuronal and astrocyte expression of nicotinic receptor subunit beta4 in the adult mouse brain.

Neuronal nicotinic acetylcholine receptor (nAChR) expression and function are customized in different brain regions through assembling receptors from closely related but genetically distinct subunits. Immunohistochemical analysis of one of these subunits, nAChRbeta4, in the mouse brain suggests an extensive and potentially diverse role for this subunit in both excitatory and inhibitory neurotransmission. Prominent immunostaining included: 1) the medial habenula, efferents composing the fasciculus retroflexus, and the interpeduncular nucleus; 2) nuclei and ascending tracts of the auditory system inclusive of the medial geniculate; 3) the sensory cortex barrel field and cell bodies of the ventral thalamic nucleus; 4) olfactory-associated structures and the piriform cortex; and 5) sensory and motor trigeminal nuclei. In the hippocampus, nAChRbeta4 staining was limited to dendrites and soma of a subset of glutamic acid dehydrogenase-positive neurons. In C57BL/6 mice, but to a lesser extent in C3H/J, CBA/J, or CF1 mice, a subpopulation of astrocytes in the hippocampal CA1 region prominently expressed nAChRbeta4 (and nAChRalpha4). Collectively, these results suggest that the unique functional and pharmacological properties exerted by nAChRbeta4 on nAChR function could modify and specialize the development of strain-specific sensory and hippocampal-related characteristics of nicotine sensitivity including the development of tolerance.

Functional improvement by electro-acupuncture after transient middle cerebral artery occlusion in rats.

Functional recovery by the application of electro-acupuncture (EA) on different acupoints was investigated using a transient middle cerebral artery occlusion (MCAO) model in rat. Acupoints were Baihui (D20) plus Renzhong (D26) (MCAO + D group), and Hanyan (G4), Xuanlu (G5), Xuanli (G6), plus Qubin (G7) (MCAP + G group). Animals with EA treatment showed significant functional improvements from 12 days after the reperfusion against those without EA treatment. Among EA treated groups, MCAO + G showed a more significant recovery than MCAO + D. Infarct volume revealed the significant reduction in the EA treated groups especially in MCAO + G at 30 days. Immunohistochemical study showed a remarkable induction of vascular endothelial growth factor (VEGF) in astrocytes of the peri-infarct area at 30 days, more in EA treated groups than in groups treated with MCAO alone. These results suggest that the acupoints applied in this study are effective for the functional recovery, and an enhanced expression of VEGF may play a certain role in recovery process after stroke.

Distribution of aromatase mRNA and protein in the brain and pituitary of female rainbow trout: Comparison with estrogen receptor alpha.

Recent data indicate that estrogens locally produced in the brain by aromatization of androgens could be important for neurogenesis and brain repair. In this respect, fish are interesting because of the extremely high aromatase activity of their brain. In this study, the rainbow trout brain aromatase was cloned and riboprobes were used to map the distribution of cells expressing the corresponding mRNAs. A very strong hybridization signal was detected in the pituitary and in cells bordering the ventricles in the telencephalon and ventral diencephalon, with the highest expression in the preoptic area and hypothalamus. A weaker signal was detected in the ependymal layer bordering the torus semicircularis and optic tectum. This localization was fully confirmed by immunohistochemistry using antibodies against a teleost aromatase. In addition, this antibody showed that aromatase expression in fact corresponds to radial glial cells because immunoreactive cells had long cytoplasmic processes extending toward the pial surface. Because brain aromatase was shown to be upregulated by estradiol in fish, the distribution of aromatase mRNAs was compared with that of rainbow trout estrogen receptor alpha (rtERalpha) on adjacent sections. Although the highest aromatase expression was found in regions expressing rtERalpha, no obvious coexpression was found, as rtERalpha was never observed in radial cells. However, reverse transcriptase-polymerase chain reaction experiments performed on brain cell cultures enriched in glial cells suggest that a weak expression of rtERalpha in glial cells cannot be excluded. The possible role of the high brain aromatase content in fish could be related to the continuous growth of their central nervous system during adulthood.

Stimulatory effect of vitamin C on autophagy in glial cells.

Intracellular accumulation of damaged or abnormal proteins is a common event associated with numerous neurodegenerative diseases and other age-related pathologies. Increasing the activity of the intracellular proteolytic systems normally responsible for the removal of these abnormal proteins might be beneficial in lessening the severity or development of those pathologies. In this study we have used human astrocyte glial cells to investigate the effect of vitamin C (ascorbate) on the intracellular turnover of proteins. Supplementation of the culture medium with physiological concentrations of vitamin C did not affect protein synthesis, but did increase the rate of protein degradation by lysosomes. Vitamin C accelerated the degradation of intra- and extracellular proteins targeted to the lysosomal lumen by autophagic and heterophagic pathways. At the doses analyzed, vitamin C lowered and stabilized the acidic intralysosomal pH at values that result in maximum activation of the lysosomal hydrolases.

Anatomical relationship between specialized astrocytes and leptin-sensitive neurones.

We have previously reported that a specialized subpopulation of astrocytes in the arcuate nucleus of the hypothalamus show an unusually intense immunoreactivity for brain fatty acid binding protein (bFABP). Since bFABP has been shown to regulate the activity of an enzyme, fatty acid synthase, that has a potent influence upon the regulation of feeding by the hypothalamus, it was of interest to determine if bFABP + astrocytes are positioned to potentially influence the activity of feeding-regulating neurones. In this study, we examined the anatomical relationship between specialized arcuate astrocytes immunoreactive for bFABP and feeding-regulating neurones that are responsive to leptin and which are immunoreactive for the transcription factor STAT3. The results show that both cell types are abundant in the arcuate nucleus of the hypothalamus and are frequently closely adjacent to each other. This study provides an anatomical basis for the possibility that specialized arcuate astrocytes regulate the function of leptin-sensitive, feeding-regulating neurones of the arcuate nucleus.