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- Boletín médico del Hospital Infantil de México 08/2015; DOI:10.1016/j.bmhimx.2015.06.007
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ABSTRACT: To investigate if the changes in the activity of the tryptophan-5-hydroxylase and in brain serotonin synthesis provoked by diabetes mellitus persist or return to normal in the diabetic rats submitted to treatment with insulin. Diabetes induced by the administration of streptozotocin in rats and their treatment with insulin was the paradigm used. At days 7, 14 and 21 of evolution, the brain serotonergic biosynthetic activity was evaluated. The diabetic rats showed a significant decrease of body weight. Also, they showed a low concentration of I-tryptophan, as well as a diminution in the activity of the key enzyme tryptophan-5-hydroxylase and its product serotonin in the cerebral cortex and brainstem. Interestingly, the activity of the enzyme was higher in the brainstem from day 14, accompanied with an elevation of the neurotransmitter. The diabetic rats submitted to treatment with insulin showed a complete physical recovery and a return to normal of plasma and brain I-tryptophan. The activity of the enzyme not only normalized but was elevated and with an increase of serotonin in the brainstem and cerebral cortex. The present findings confirm that diabetes mellitus produced a chronic anabolic deficit and a decrease in some brain regions of serotonin synthesis. Also, demonstrate that the diabetic rats under specific treatment with insulin had a complete physical recovery and a return to normal of the serotonin precursor in the blood and brain. However, the activity of the limiting enzyme TrpOH case was elevated with an increase of the neurotransmitter in all regions studied. Since the diabetic animal, insulin treated, does recover metabolically, the mechanism of activation of the serotonin biosynthetic path in the brain may not be dependent on the decreased availability of its precursor the free plasma I-tryptophan. Instead, it might be due to a change in the kinetics of tryptophan-5-hydroxylase, since its activity remains significantly increased in spite of plasma and brain normalization of its substrate. Altogether these changes in the biosynthesis of an important brain neurotransmitter may be of relevance in the pathophysiology of the psychoneurological complications in diabetic patients.Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion 06/2015; 52(5):509-16.
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ABSTRACT: We undertook this study to present biochemical and morphological characterization of serotonergic cells during fetal heart development. Wistar rats (10, 12, 16 and 20 days of gestation) were used. After obtaining the fetuses by Cesarean section, the hearts were removed and fixed for immunohistochemical assay of tryptophan-5-hydroxylase (Tph), in addition to Western blot for enzyme. Serotonin concentration and Tph were also evaluated with high-performance liquid chromatography. Results were analyzed using Mann-Whitney U test with a significance level of p <0.05. Metachromatic cells immunoreactive for Tph were observed from day 10 of gestation. Nerve fibers were also labeled, apparently making contact with serotonergic cells. Tph activity was measurable and serotonin levels increased with gestational age. The presence of Tph protein was confirmed by Western blot on day 16. The present results support the existence of cells located in the fetal myocardium, capable of producing serotonin whose phenotype belongs to cardiac mast cells. Their presence in this tissue strongly suggests that serotonin may play a key role in normal and abnormal development of cardiac tissue.Cirugia y cirujanos 06/2015; 77(6):395-400.
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