Marker Microtubule-associated Protein Research Articles

Characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei of the Brazilian opossum

The characterization and ontogeny of synapse-associated proteins in the developing facial and hypoglossal motor nuclei were examined in the Brazilian opossum (Monodelphis domestica). Immunohistochemical markers utilized in this study were the synaptic vesicle-associated proteins synaptophysin and synaptotagmin; a synaptic membrane protein, plasma membrane-associated protein of 25 kDa (SNAP-25); a growth cone protein, growth-associated phosphoprotein-43 (GAP-43); and the microtubule-associated proteins axonal marker tau and dendritic marker microtubule-associated protein-2 (MAP-2). In this study, we have found that, during the first 10 postnatal days (1-10 PN), the facial motor nucleus lacked immunoreactivity for synaptophysin, synaptotagmin, GAP-43, tau, and SNAP-25. After 10 PN, immunoreactivity increased in the facial motor nucleus for synaptophysin, synaptotagmin, GAP-43, and tau, whereas immunoreactivity for SNAP-25 was not evident until between 15 and 25 PN. Conversely, immunoreactivity for MAP-2, was present in the facial motor nucleus from the day of birth. In contrast, the hypoglossal motor nucleus displayed immunoreactivity from 1 PN for synaptophysin, synaptotagmin, SNAP-25, GAP-43, tau, and MAP-2. These results suggest that the facial motor nucleus of the opossum may not receive afferent innervation as defined by classical synaptic markers until 15 PN and, further, that characteristic mature synapses are not present until between 15 and 25 PN. These results indicate that there may be a delay in synaptogenesis in the facial motor nucleus compared to synaptogenetic events in the hypoglossal motor nucleus. Because the facial motor nucleus is active prior to completion of synaptogenesis, we suggest that the facial motoneurons are regulated in a novel or distinct manner during this time period.

Selective vulnerability of hippocampal CA3 neurons to hypoxia after mild concussion in the rat

Immunohistochemical staining for microtubule-associated protein 2 (MAP2) and synaptophysin was used to investigate the effect of hypoxia on hippocampal neurons after mild concussion in the rat. Male Sprague-Dawley rats were divided into four groups: Group 1 (n = 3) was subjected to a mild impact-acceleration closed head injury, group 2 (n = 3) was subjected to 30 min of moderate hypoxia, group 3 (n = 5) was subjected to head trauma followed by 30 min of moderate hypoxia, and group 4 (n = 3) comprised sham-operated controls. All rats were fixed by transcardial perfusion 24 h after insult. No damage was observed in CA1 or CA2 neurons in any of the rats. However, rats in group 3 showed selective damage of hippocampal CA3 neurons manifested by a pycnosis and a marked decrease in MAP2 immunoreactivity. Presynaptic terminals visualized by synaptophysin immunostaining showed no differences among groups. The loss of immunoreactivity for the post-synaptic somal and dendritic protein marker MAP2 from the CA3 subfield 24 h after combined insults indicates an increased vulnerability of pyramidal cells in this brain area.

Phenytoin inhibits expression of microtubule-associated protein 2 and influences cell-viability and neurite growth of cultured cerebellar granule cells

The objective of this study was to show whether an in vitro model for Phenytoin-related cytoskeletal impairment could be helpful to investigate cerebellar side effects of Phenytoin (DPH). DPH dose-and time-dependently resulted in decreasing numbers of vital cells. Cells formed only a rarefield intercellular neuritic network. This effect was already evident 24 h after plating. Western-blot analysis revealed that the expression of the dendritic marker microtubule-associated protein 2 (MAP2) was dramatically decreased in DPH-treated cultures.

Neurotoxic effects of aluminium on embryonic chick brain cultures.

Toxic damage of brain cells by aluminium (Al) is discussed as a possible factor in the development of neurodegenerative disorders in humans. To investigate neurotoxic effects of Al, serum-free cultures of mechanically dissociated embryonic chick (stage 28-29) forebrain, brain stem and optic tectum, and for comparison meningeal cells, were treated with Al (0-1000 microM) for 7 days. Effects of Al on cell viability (lysosomal and mitochondrial activity) and differentiation (synthesis of cell-specific proteins) were found to the brain area specific with the highest sensitivity observed in optic tectum. No inhibiting effects on cell viability could be observed in cultures of forebrain and meninges in the concentration range tested. In all three brain tissue cultures, threshold levels for the reduction of cell differentiation parameters were found at lower concentrations [concentration resulting in a 50% decrease (IC50) > 180 microM] than for the inhibition of cell viability (IC50 > 280 microM), indicating a specific toxic potential of Al for cytoskeletal alterations. The culture levels of nerve cell-specific markers microtubule-associated protein type 2 (the most sensitive parameter) and the 68-kDa neurofilament were inhibited at lower concentrations (IC50 180-630 microM) than the astrocyte-specific glial fibrillary acidic protein (IC50 700-approximately 1000 microM), demonstrating a particularly high sensitivity of neurons in comparison to astrocytes. Based on these differences in Al sensitivity observed for different cell markers in the various brain tissue cultures, the in vitro system used in the present study proved to be a suitable model to assess brain area and cell type-specific neurotoxic effects of Al.

Immunohistochemical demonstration of neuron-specific enolase and microtubule-associated protein 2 in reactive astrocytes after injury in the adult forebrain

Transformation of normal resting astrocytes to reactive astrocytes in the adult brain after injury has been well documented. Using double immunofluorescent labeling methods, we report that astrocytes in both the ischemically damaged and the retrogradely/ anterogradely degenerating forebrain nuclei express not only the glial cell markers glial fibrillary acidic protein and vimentin, but also the neuronal markers neuron-specific enolase and microtubule-associated protein 2. Since these neuronal markers are expressed in glial precursor cells, these results suggest that one of the characteristic responses of astrocytes in the adult brain after injury may be re-expression of fetal trait(s) of early differentiating glial cells/neurons.

Sulphamerazine for Pneumonia in Adults

Estradiol is protective in experimental cerebral ischemia, but the precise mechanisms remain unknown. Signal transducer and activator of transcription-3 (STAT3) is a transcription factor that is activated by estrogen, translocates to the nucleus, and induces the transcription of neuroprotective genes, such as <i>bcl-2</i>. We determined whether estradiol increases STAT3 activation in female rat brain after focal cerebral ischemia and whether STAT3 activation contributes to estradiol-mediated neuroprotection against ischemic brain injury. Ovariectomized (OVX) female rats with and without estradiol replacement were subjected to 2 h of middle cerebral artery occlusion (MCAO), and phosphorylated STAT3 (P-STAT3) and total STAT3 (T-STAT3) were quantified by Western blot analysis at 3 and 22 h of reperfusion. STAT3 activation was colocalized with neuronal and survival markers microtubule-associated protein 2 (MAP2) and Bcl-2 using immunohistochemistry. Infarct size was measured at 22 h after MCAO in estradiol-treated OVX animals in the presence and absence of STAT3 inhibitor cucurbitacin I (JSI-124) using 2,3,5-triphenyltetrazolium chloride staining. Estradiol increased P-STAT3 in the ischemic cortex cytosolic fraction at 3 h after MCAO without affecting T-STAT3. This was associated with increased P-STAT3 in the nuclear fraction, which remained elevated at 22 h after MCAO. The nuclear P-STAT3 colocalized with MAP2 and Bcl-2 within the peri-infarct zone. The P-STAT3 inhibitor JSI-124 abolished the protective effect of estradiol without affecting infarct size in untreated OVX rats. We conclude that estradiol increases STAT3 phosphorylation in neurons after MCAO and that STAT3 activation plays an important role in estradiol-mediated neuroprotection.