Long-term astroglial reaction and neuronal plasticity in the subcortical visual pathways after a complete ablation of telencephalon in pigeons (Columba livia).

This paper analyzes the astroglial and neuronal responses in subtelencephalic structures, following a bilateral ablation of the telencephalon in the Columba livia pigeons. Control birds received a sham operation. Four months later the birds were sacrificed and their brains processed for glial fibrillary acid protein (GFAP) and neurofilament immunohistochemistry, markers for astrocytes and neurons, respectively. Computer-assisted image analysis was employed for quantification of the immunoreactive labeling in the nucleus rotundus (N.Rt) and the optic tectum (OT) of the birds. An increased number of GFAP immunoreactive astrocytes were found in several subregions of the N.Rt (p< .001), as well as in layers 1, 2cd, 3, and 6 of the OT (p< .001) of the lesioned animals. Neurofilament immunoreactivity decreased massively in the entire N.Rt of the lesioned birds; however, remaining neurons with healthy aspect showing large cytoplasm and ramified branches were detected mainly in the periphery of the nucleus. In view of the recently described paracrine neurotrophic properties of the activated astrocytes, the data of the present study may suggest a long-lasting neuroglial interaction in regions of the lesioned bird brain far from injury. Such events may trigger neuronal plasticity in remaining brain structures that may lead spontaneous behavior recovery as the one promoted here even after a massive injury.

Responses of reactive astrocytes containing S100beta protein and fibroblast growth factor-2 in the border and in the adjacent preserved tissue after a contusion injury of the spinal cord in rats: implications for wound repair and neuroregeneration.

This paper demonstrates glial reaction and changes in the S100beta protein and basic fibroblast growth factor (bFGF, FGF-2) in the border and in the adjacent preserved tissue of the rat spinal cord after a contusion. In view of the expression of FGF-2 and S100beta in reactive glial cells and their ability to promote gliogenesis and neuronal trophism, the molecules have been considered to participate in the wound repair and regenerative events after nervous tissue injury. Adult rats were submitted to a moderate spinal cord (10th thoracic level) contusion induced by a New York University Impactor by dropping a 10 g rod from a distance of 25 mm onto the dorsal surface of the exposed dura spinal cord. Impactor curves and parameters were used to monitor the severity of the trauma. Control rats were submitted to sham operation. The motor behavioral spontaneous recovery was demonstrated by means of a BBB test and the combining behavior score up to 3 weeks after injury. Animals were killed 72 hours, 2, and 3 weeks after surgery and spinal cords were processed for immunohistochemistry to show glial fibrillary acidic protein positive astrocytes and OX-42-positive microglia/macrophages as well as changes in the S100beta and FGF-2 in the border and in the adjacent preserved tissue of the lesioned cords. The changes in the immunoreaction products were quantified by means of morphometric/microdensitometric image analysis, and the cell type expressing S100beta and FGF-2 was analyzed by means of two-color immunofluorescence procedures. Massive increases of S100beta and FGF-2 were found in reactive astrocytes, not in reactive microglia, in the border and in the white and gray matters of adjacent preserved tissue of the contused spinal cord in the periods studied. The results are discussed in view of possible paracrine trophic actions of the reactive astrocytes, mediated by S100beta and FGF-2, triggering wound repair events in the border of the trauma, and also leading to neurotrophism and neuronal plasticity in the adjacent regions. These cellular and molecular responses may interfere with the pattern of behavioral recovery after a contusion injury of the spinal cord.

Fibroblast growth factor-2 immunoreactivity is present in the central and peripheral auditory pathways of adult rats.

Recent findings have pointed out the role of neurotrophic factors in the survival and maintenance of neurons of the auditory system. Basic fibroblast growth factor (bFGF, FGF-2) is a potent neurotrophic molecule whose actions can be seen in the central and peripheral nervous systems. In the present study, FGF-2 immunoreactivity was analyzed in the auditory pathways of the adult rat, employing a well-characterized polyclonal antibody against FGF-2. In the cochlea, FGF-2 immunoreactivity was observed in the inner and outer hair cells of the organ of Corti, spiral ganglion neurons, spiral limbus, and stria vascularis. Stereological methods employing optical fractionator revealed the presence of 84.5, 15, and 0.5% of spiral ganglion neurons possessing FGF-2 immunoreactivity of strong, moderate, and weak intensity, respectively. In the central auditory pathways, FGF-2 immunoreactivity was found in the cytoplasm of the neurons of the cochlear nuclei, trapezoid body nuclei, medial geniculate nucleus, and inferior colliculus. The two-color immunoperoxidase method showed FGF-2 immunoreactivity in the nuclei of astrocytes throughout the central auditory pathway. Computer-assisted microdensitometric image analysis revealed higher levels of specific mean gray values of FGF-2 immunoreactivity in the trapezoid body and ventral cochlear nucleus and also in the spiral ganglion and inner hair cells. Sections incubated with FGF-2 antibody preabsorbed with human recombinant FGF-2 showed no immunoreaction in the majority of the studied regions, exhibiting only a slight immunoreactive product in the hair cells of the organ of Corti. Furthermore, no changes in immunoreactivity were observed in sections incubated with FGF-2 antiserum preincubated with human recombinant acidic FGF (FGF-1). The findings suggest that FGF-2 may exert paracrine and autocrine actions on neurons of the central and peripheral auditory systems and may be of importance in the mechanism of hearing diseases.

Basic fibroblast growth factor, neurofilament, and glial fibrillary acidic protein immunoreactivities in the myenteric plexus of the rat esophagus and colon.

The enteric nervous system consists of a number of interconnected networks of neuronal cell bodies and fibers as well as satellite cells, the enteric glia. Basic fibroblast growth factor (bFGF) is a mitogen for a variety of mesodermal and neuroectodermal-derived cells and its presence has been described in many tissues. The present work employs immunohistochemistry to analyze neurons and glial cells in the esophageal and colic enteric plexus of the Wistar rat for neurofilament (NF) and glial fibrillary acidic proteins (GFAP) immunoreactivity as well as bFGF immunoreactivity in these cells. Rats were processed for immunohistochemistry; the distal esophagus and colon were opened and their myenteric plexuses were processed as whole-mount preparations. The membranes were immunostained for visualization of NF, GFAP, and bFGF. NF immunoreactivity was seen in neuronal cell bodies of esophageal and colic enteric ganglia. GFAP-immunoreactive enteric glial cells and processes were present in the esophageal and colic enteric plexuses surrounding neuronal cell bodies and axons. A dense net of GFAP-immunoreactive processes was seen in the ganglia and connecting strands of the myenteric plexus. bFGF immunoreactivity was observed in the cytoplasm of the majority of the neurons in the enteric ganglia of esophagus and colon. The two-color immunoperoxidase and immunofluorescence methods revealed bFGF immunoreactivity also in the nucleus of GFAP-positive enteric glial cells. The results suggest that immunohistochemical localization of NF and GFAP may be an important tool in the study of the plasticity in the enteric nervous system. The presence of bFGF in neurons and glia of the myenteric plexus of the esophagus and the colon indicates that this neurotrophic factor may exert autocrine and paracrine actions in the enteric nervous system.

Striatal injection of 6-hydroxydopamine induces retrograde degeneration and glial activation in the nigrostriatal pathway

PURPOSE: The effect of a highly selective 6-hydroxydopamine (6-OHDA)-induced lesion of the nigrostriatal system on the astroglial and microglial activation was analysed in adult Wistar rats after an unilateral striatal injection of the neurotoxin. METHODS: Male rats received an unilateral stereotaxical injection of the 6-OHDA in the left side of the neostriatum and were sacrificed 22 days later. Control animals received the injection of the solvent. The rotational behaviour was registered by a rotometer just before the sacrifice. Immunohistochemistry was employed for visualization of the tyrosine hydroxylase (TH) positive dopamine cells, glial fibrillary acidic protein (GFAP) immunolabeled astrocytes and OX42 immunoreactive microglia. Stereological method employing the optical disector was used to estimate the degree of the changes. RESULTS: The striatal injection of the 6-OHDA induced a massive disappearance (32 percent of control) of the TH immunoreactive terminals in a defined area within the striatum surrounding the injection site. A disappearance (54 percent of control) of dopamine cell bodies was observed in a small region of the ipsilateral pars compacta of the substantia nigra (SNc). The GFAP and OX42immunohistochemistry revealed astroglial and microglial reactions (increases in the number and size of the cells) in the ipsilateral neostriatum and SNc of the 6-OHDA injected rats. CONCLUSIONS: The striatal injection of 6-OHDA leads to retrograde degeneration as well as astroglial and microglial activation in the nigrostriatal dopamine pathway. Modulation of activated glial cells may be related to wound repair and to the trophic paracrine response in the lesioned nigrostriatal dopamine system.

Os efeitos do alcoolismo gestacional sobre o trofismo e a plasticidade do sistema nigro-estriatal dopaminérgico no desenvolvimento, envelhecimento e na neurodegeneração / The effects of gestational alcoholism on the throphism and the plasticity of neurostrital dopamine system during development, aging and neurodegenaration

Este estudo analisou os efeitos do consumo crônico de álcool durante a gestação no desenvolvimento, maturação e envelhecimento do sistema nigro-estriatal dopaminérgico da prole de ratas e a possibilidade da facilitação do estabelecimento do parkinsonismo na prole senil que recebeu álcool na vida pré-natal. Ratas Wistar nulíparas foram divididas em dois grupos. Um deles recebeu uma dieta líquida hiperprotéica contendo 37,5 porcento dos valores calóricos derivados do etanol (grupo álcool) durante 21 dias. Outro grupo de ratas recebeu quantidade isocalórica de maltose-dextrina em substituição ao etanol (grupo controle). Após a fecundação, as ratas prenhes continuaram sendo alimentadas com as dietas descritas. Os embri6es foram estudados aos 19 dias de gestação (E19), e as proles com 5 dias pós-natais (P5), assim como com 3, 18 e 24 meses (M) após o nascimento. Os cérebros foram processados para a imunohistoquímica da tirosina hidroxilase (TH, marcador de células e terminais dopaminérgicos), da proteína fibrilar glial ácida (GFAP, marcador de astrócitos), da proteína OX-42 (marcador de microglia) e do fator de crescimento fibroblástico básico (bFGF) adaptada a estereologia. O dissector óptico foi utilizado para estimar o número total e a densidade dos neurônios e varicosidades dos terminais dopaminérgicos, bem como das células gliais na porção compacta da substância negra (SNc) e no neoestriado. A fração de volume dos prolongamentos neuronais e gliais e o volume das células imunomarcadas também foram quantificados. Observou-se redução da população de células dopaminérgicos imunorreativas à TH na SNc apenas em E 19. O volume destas células mostrou-se menor em E19, em P5 e em 24M. Os terminais dopaminérgicos no neoestriado apresentaram-se reduzidos apenas em E19 e P5. Os astrócitos estiveram em menor número na SNc e neoestriado apenas em P5, porém não em outras idades pós-natais, sendo que em 24M o volume destas células apresentou-se aumentado no neoestriado. Ainda, o número de perfis imunorreativos ao bFGF apresentou-se reduzido no neoestriado em P5, porém não em 24M. O parkinsonismo induzido pela injeção estriatal da 6-OHDA na prole de 24M foi mais potente no grupo dieta álcool, como evidenciado pelos movimentos estereotipados induzidos pela apomorfina (AU)

Os efeitos do alcoolismo gestacional sobre o trofismo e a plasticidade do sistema nigro-estriatal dopaminérgico no desenvolvimento, envelhecimento e na neurodegeneração / The effects of gestational alcoholism on the throphism and the plasticity of neurostrital dopamine system during development, aging and neurodegenaration

Este estudo analisou os efeitos do consumo crônico de álcool durante a gestação no desenvolvimento, maturação e envelhecimento do sistema nigro-estriatal dopaminérgico da prole de ratas e a possibilidade da facilitação do estabelecimento do parkinsonismo na prole senil que recebeu álcool na vida pré-natal. Ratas Wistar nulíparas foram divididas em dois grupos. Um deles recebeu uma dieta líquida hiperprotéica contendo 37,5 porcento dos valores calóricos derivados do etanol (grupo álcool) durante 21 dias. Outro grupo de ratas recebeu quantidade isocalórica de maltose-dextrina em substituição ao etanol (grupo controle). Após a fecundação, as ratas prenhes continuaram sendo alimentadas com as dietas descritas. Os embri6es foram estudados aos 19 dias de gestação (E19), e as proles com 5 dias pós-natais (P5), assim como com 3, 18 e 24 meses (M) após o nascimento. Os cérebros foram processados para a imunohistoquímica da tirosina hidroxilase (TH, marcador de células e terminais dopaminérgicos), da proteína fibrilar glial ácida (GFAP, marcador de astrócitos), da proteína OX-42 (marcador de microglia) e do fator de crescimento fibroblástico básico (bFGF) adaptada a estereologia. O dissector óptico foi utilizado para estimar o número total e a densidade dos neurônios e varicosidades dos terminais dopaminérgicos, bem como das células gliais na porção compacta da substância negra (SNc) e no neoestriado. A fração de volume dos prolongamentos neuronais e gliais e o volume das células imunomarcadas também foram quantificados. Observou-se redução da população de células dopaminérgicos imunorreativas à TH na SNc apenas em E 19. O volume destas células mostrou-se menor em E19, em P5 e em 24M. Os terminais dopaminérgicos no neoestriado apresentaram-se reduzidos apenas em E19 e P5. Os astrócitos estiveram em menor número na SNc e neoestriado apenas em P5, porém não em outras idades pós-natais, sendo que em 24M o volume destas células apresentou-se aumentado no neoestriado. Ainda, o número de perfis imunorreativos ao bFGF apresentou-se reduzido no neoestriado em P5, porém não em 24M. O parkinsonismo induzido pela injeção estriatal da 6-OHDA na prole de 24M foi mais potente no grupo dieta álcool, como evidenciado pelos movimentos estereotipados induzidos pela apomorfina

Estudo imunohistoquímico das respostas tróficas e plásticas no cérebro do rato submetido à calosotomia estereotóxica

Estuda a calosotomia, intervenção neurocirúrgica adotada no tratamento de indivíduos portadores de crises epilépticas, que não respondem ao tratamento clínico. Isto porque não se conhece as modificações neuronais e gliais, bem como o estado trófico da substância branca e do cortex cerebral subseqüentes à calostomia, no indivíduo adulto. Faz análise temporal das respostas à lesão experimental do corpo caloso no cérebro do rato adulto de 7, 14 e 28 dias após a cirurgia. A lesão estereotóxica do corpo caloso é efetuada com o auxílio de microfaca acoplada a um micromanipulador. Utiliza métodos imunohistoquímicos para análise histológica da proteína fibrilar glialácida (GFAP), do OX42, do neurofilamento, do fator básico de crescimento de fibroblasto (bFGF) e da proteína S100. A imunohistoquímica revela aumentos persistentes e generalizados das imunorreatividades da GFAP, do OX42, da S100 e do bFGF glial na substância branca dos animais calosotomizados. Observa diminuição progressiva da imunorreatividade do neurofilamento em diversas áreas, na substância branca dos ratos lesados nos tempos pós-cirúrgicos estudados. No córtex cerebral a imunorreatividade da GFAP aumenta persistentemente nos animais lesados. Nesta região, as imunorreatividades do bFGF e da proteína S100 e glial apresentam um pico de aumento de 7 dias e 14 dias, respectivamente, após a calosotomia e declínio subseqüente. Entretanto, as imunorreatividades do OX42 e do bFGF neuronal corticais apresentam aumento significativo de 28 e 14 dias, respectivamente. A análise da imunorreatividade do neurofilamento no córtex frontal do rato calosotomizado demonstra que o número de neurônios imunorreativos não altera, entretanto, nestes animais, o volume de neurônios e apresentam neuropil corticais aumentados. A análise da marcação imunohistoquímica dupla no cérebro dos animais transientemente controles e tratados revela a presença da imunorreatividade do bFGF no interior de astrócitos marcados pela GFAP e S100 (AU)