In vitro effects of thyroid hormones on ectonucleotidase activities in synaptosomes from hippocampus of rats
| Autor: | José Alfredo de Aguiar, Matos, Alessandra Nejar, Bruno, Jean Pierre, Oses, Carla Denise, Bonan, Ana Maria Oliveira, Battastini, Maria Luiza M, Barreto-Chaves, João José Freitas, Sarkis |
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| Jazyk: | portugalština |
| Rok vydání: | 2002 |
| Předmět: |
Male
Thyroid Hormones Adenosine Hydrolysis Presynaptic Terminals Thyroid Gland 5´-nucleotidase Hippocampus Adenosine Monophosphate Rats Adenosine Diphosphate Thyroxine Adenosine Triphosphate Animals Triiodothyronine ATP diphosphohydrolase Pyrophosphatases Rats Wistar Extracellular Space Synaptosomes |
| Zdroj: | Repositório Institucional PUCRS Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) instacron:PUC_RS |
| Popis: | 1. Studies have shown that adenosine transport and adenosine A1 receptors in rat brain are subjected to regulation by thyroid hormone levels. Since the ectonucleotidase pathway is an important source of adenosine extracellular, in the present study the in vitro action of T3 and T4 hormones on ectonucleotidase activities in hippocampal synaptosomes was evaluated. 2. T3 (Triiodo-l-thyronine) significantly inhibited, in an uncompetitive manner, the ATP and ADP hydrolysis promoted by ATP diphosphohydrolase activity in hippocampal synaptosomes of adult rats. 3. In contrast, T4 (Thyroxine) only inhibited ATP hydrolysis in an uncompetitive mechanism, at the concentrations tested (100-500 microM), but at the same time did not affect ADP hydrolysis. 4. In the present study, we also investigate the in vitro effect of T3 and T4 on 5'-nucleotidase activity. However, there are no changes in the activity of this enzyme in the presence of T3 and T4 in the hippocampal synaptosomes of rats. 5. These results suggest that thyroid hormones could be involved in the regulation of ectonucleotidase activities, such as ecto-ATP diphosphohydrolase and ecto-ATPase, possibly exerting a modulatory role in extracellular adenosine levels. |
| Databáze: | OpenAIRE |
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