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Open Access journal
ISSN (Online) 0327-9545
Published by SciELO

Age related interaction of dopamine and serotonin synthesis in striatal
synaptosomes
- Abstract: Tyrosine hydroxylase and tryptophan hydroxylase are key rate limiting enzymes in the biosyn-thesis of dopamine and serotonin, respectively. Since both enzymes are active in striatum, and affected by age, this study was undertaken to investigate interaction between dopamine and serotonin synthesis in brain striatal synaptosomes of aging rat. Male Wistar rats (3 and 30 month old) were killed by decapitation and brain striatal synaptosomes were prepared by discontinuous Ficoll/sucrose gradient technique. Synaptosomes were incubated in the presence of added pargiline (monoamineoxidase inhibitor), dopamine or serotonin synthesized during 25 min was measured by HPLC, employing electrochemical detection. Dopamine synthesis in synaptosomes prepared from young animals was markedly inhibited by addition of 5 μM serotonin concentrations (30%) and increasing serotonin concentrations up to 50 μM caused only a smaller additional inhibition. Dopamine synthesis in synaptosomes obtained from old rats was significantly lower than that of youg animals and addition of serotonin concentrations up to 50 μM had little effect on these preparations. In case of serotonin synthesis, exogenously added 5 μM dopamine inhibited serotonin synthesis in the synaptosomes of both ages by about 40%, whereas with higher concentration of dopamine (10-50 μM) the rate of inhibition was highly pronounced in old rats as compared to that of young animals. It is concluded that dopamine and serotonin interaction may be significant, and that these should be considered in long-term treatments of Parkinson’s disease with L-DOPA.
Autophagy, apoptosis and organelle features during cell exposure to
cadmiumc
- Abstract: Cadmium (Cd) induces several effects in different tissues, but our knowledge of the toxic effects on organelles is insufficient. To observe the progression of Cd effects on organelle structure and function, HuH-7 cells (human hepatic carcinoma cell line) were exposed to CdCl2 in increasing concentrations (1 μM - 20 μM) and exposure times (2 h - 24 h). During Cd treatment, the cells exhibited a progressive decrease in viability that was both time- and dose-dependent. Cd treated cells displayed progressive morphological changes that included cytoplasm retraction and nuclear condensation preceding a total loss of cell adhesion. Treatment with 10 μM for 12 h led to irreversible damages. Before these drastic and irreparable damages, treated cells (5 μM for 12 h) presented a progressive loss of mitochondrial function and cytoplasm acidification as well as dysfunction and disorganization of microfilaments and endoplasmic reticulum. These damages led to the induction of apoptotic events and an increase in autophagic bodies in the cytoplasm. These results revealed that Cd affects multiple intra-cellular targets that induce alterations in the mitochondria, cytoskeleton, endoplasmic reticulum and acidic compartments, ultimately culminating in cell death via apoptotic and autophagic pathways.
Creatine supplementation in trained rats causes changes in myenteric
neurons and intestinal wall morphometry
- Abstract: Creatine is widely used by athletes as an ergogenic resource. The aim of this study was to evaluate the influence of creatine supplementation on the duodenum of rats submitted to physical training. The number and myenteric neuronal cell bodies as well mucosal and muscular tunic morphometry were evaluated. Control animals received a standard chow for 8 weeks, and the treated ones received the standard chow for 4 weeks and were later fed with the same chow but added with 2% creatine. Animals were divided in groups: sedentary, sedentary supplemented with creatine, trained and trained supplemented with creatine. The training consisted in treadmill running for 8 weeks. Duodenal samples were either processed for whole mount preparations or for paraffin embedding and hematoxylin-eosin staining for histological and morphometric studies of the mucosa, the muscular tunic and myenteric neurons. It was observed that neither creatine nor physical training alone promoted alterations in muscular tunic thickness, villus height or crypts depth, however, a reduction in these parameters was observed when both were associated. The number of myenteric neurons was unchanged, but the neuronal cell body area was reduced in trained animals but not when training and creatine was associated, suggesting a neuroprotector role of this substance.
Confocal laser scanning microscopy and immunohistochemistry of cerebellar
Lugaro cells
- Abstract: The present paper shows by means of confocal laser scanning microscopy the immunoreactivity of rat cerebellar Lugaro cells for calbindin, synapsin-I, PSD-95, GluR1, CaMKII alpha, and N-cadherin. Lugaro cells were easily characterized by their location beneath Purkinje cells. Calbindin revealed immunoreactivity in the cell body, and the axonal and dendritic processes. Synapsin-I labelled the presynaptic endings on Lugaro cells. Synapsin-I and PSD-95 immunoreactivity demonstrated the localization of presynaptic and postsynaptic endings surrounding cell soma, corresponding to afferent extrinsic and intrinsic cerebellar fibers. GluR1 immunoreactivity of the soma and cell processes indicates that Lugaro cells have functional ionotropic glutamate receptors that regulate calcium levels. CaMKII alpha immunoreactivity of Lugaro cell soma and processes suggest its participation as a molecular switch for long-term information storage, and serving as a molecular basis of long-term synaptic memory. N-cadherin immunoreactivity was correlated with somato-somatic and somato-dendritic junctions between Lugaro cells and their synaptic connections.
Post-treatment with plant extracts used in Brazilian folk medicine caused
a partial reversal of the antiproliferative effect of glyphosate in the
Allium cepa test
- Abstract: Species of the genus Psychotria are used for multiple purposes in Brazilian folk medicine, either as water infusions, baths or poultices. This study was aimed to evaluate the genotoxic and antiproliferative effects of infusions of Psychotria brachypoda and P. birotula on the Allium cepa test. Exposure to distilled water was used as a negative control, while exposure to glyphosate was used as a positive control. The interaction of extracts (as a post-treatment) with the effects of glyphosate was also studied. Results showed that glyphosate and the extracts of both P. brachypoda and P. birotula reduced the mitotic index as compared with the negative control (distilled water). Surprisingly, however, both extracts from P. brachypoda and P. birotula caused a partial reversal of the antiproliferative effect of glyphosate when used as a post-treatment. Glyphosate also induced the highest number of cells with chromosomal alterations, which was followed by that of P. birotula extracts. However, the extracts from P. brachypoda did not show any significant genotoxic effect. Post-treatment of glyphosate-treated samples with distilled water allowed a partial recovery of the genotoxic effect of glyphosate, and some of the Psychotria extracts also did so. Notably, post-treatment of glyphosate-treated samples with P. brachypoda extracts induced a statistically significant apoptotic effect. It is concluded that P. brachypoda extracts show antiproliferative effects and are not genotoxic, while extracts of P. birotula show a less potent antiproliferative effect and may induce chromosomal abnormalities. The finding of a partial reversion of the effects of glyphosate by a post-treatment with extracts from both plants should be followed up.

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Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
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Fax: +00 44 (0)131 4513327

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