Physical exercise-induced fatigue: the role of serotonergic and dopaminergic systems.

Brain serotonin and dopamine are neurotransmitters related to fatigue, a feeling that leads to reduced intensity or interruption of physical exercises, thereby regulating performance. The present review aims to present advances on the understanding of fatigue, which has recently been proposed as a defense mechanism instead of a "physiological failure" in the context of prolonged (aerobic) exercises. We also present recent advances on the association between serotonin, dopamine and fatigue. Experiments with rodents, which allow direct manipulation of brain serotonin and dopamine during exercise, clearly indicate that increased serotoninergic activity reduces performance, while increased dopaminergic activity is associated with increased performance. Nevertheless, experiments with humans, particularly those involving nutritional supplementation or pharmacological manipulations, have yielded conflicting results on the relationship between serotonin, dopamine and fatigue. The only clear and reproducible effect observed in humans is increased performance in hot environments after treatment with inhibitors of dopamine reuptake. Because the serotonergic and dopaminergic systems interact with each other, the serotonin-to-dopamine ratio seems to be more relevant for determining fatigue than analyzing or manipulating only one of the two transmitters. Finally, physical training protocols induce neuroplasticity, thus modulating the action of these neurotransmitters in order to improve physical performance.

Intrinsic exercise capacity is related to differential monoaminergic activity in the rat forebrain.

Monoamines levels in central nervous system have been associated with exercise performance and fatigue. The present study investigated whether intrinsic exercise capacity is associated with differential activity of monoamines in the caudate-putamen (CPu) and accumbens (ACC) nucleus. Male Wistar rats were subjected to a progressive testing protocol. Based on the maximal time of exercise in the progressive testing protocol (TEPmax), the animals were divided into low-performance (LP), high-performance (HP), and standard-performance (SP) groups. After classification, eight animals in each group were chosen randomly and evaluated in two experimental situations: rest (n=8) or moderate exercise (ME) at 60% of maximal velocity (n=8). The CPu and ACC were dissected for analyses of monoamine levels. At rest, HP rats exhibited higher 3,4-dihydroxyphenylacetic acid (DOPAC)/dopamine (DA) ratio and lower serotonin (5-HT) concentration compared other groups, and lower 5-hydroxyindoleacetic (5-HIAA) compared with the LP rats. The ME resulted in increased DOPAC/DA ratio in the CPu of all experimental groups. In both the CPu and ACC, ME increased 5-HIAA levels in SP and HP rats and 5-HIAA/5-HT ratio only in HP rats. Thus, our findings demonstrate that rats with natural intrinsic differences in performance to exercise exhibit alterations in dopaminergic and serotonergic systems at rest and after ME exercise until fatigue.

[Leiomyosarcoma of the left atrium]. / Leiomiossarcoma atrial esquerdo.

A 48-year-old man submitted to surgical excision of a left atrium leiomyosarcoma. The patient had a node close to the right suprarenal gland. The tumor was a casual echocardiographic finding as part of the cardiologic investigation, since the patient had shortness breath. Leiomyosarcomas of the heart are uncommon, and often the diagnosis is performed during postmortem examinations. Methods of diagnosis, specially the echocardiogram, were emphasised. Treatment and prognostic aspects on basis in a wide review of the literature were also emphasised.

Nonocclusive intestinal ischemia and necrosis after correction of interatrial communication with cardiopulmonary bypass. A rare and catastrophic complication.

The authors present a case of massive, nonocclusive intestinal ischemia and necrosis after surgery for correction of interatrial communication with cardiopulmonary bypass in a 22-year-old woman. This is an extremely serious complication that generally occurs in older patients. The literature mentions its occurrence in patients subjected to aortic valve replacement who have low cardiac output and in patients undergoing myocardial revascularization. Its occurrence in a young person with simple congenital cardiopathy is rare.

Nonfunctioning paraganglioma of the posterior mediastinum. Case report.

A case of nonfunctioning paraganglioma of the posterior mediastinum in a 20-year-old white man is presented. The diagnosis of aorticosympathetic paraganglioma (Glenner-Grimley classification) was established by histologic examination after surgical removal of the tumor.

Plasmocitoma extramedular de localizacao em trato gastrintestinal. / Extramedullary plasmacytoma located in gastrointestinal tract. Report of a case

O plasmocitoma extramedular e um tumor relativamente raro, localizando-se perfeitamente nas vias aereas superiores e cavidade oral, aparecendo em muito menor proporcao no tubo digestivo. O diagnostico de certeza e dificil mesmo histologicamente, discutindo-se inclusive a existencia desta patologia como entidade nosologica propria. Neste trabalho, os autores apresentam um caso de plasmocitoma extramedular recidivante, localizado na terceira porcao do duodeno, tratado por derivacao cirurgia do transito gastrintestinal e radioterapia com bom resultado