Níveis de beta-endorfina em resposta ao exercício e no sobretreinamento: [revisão] / Levels of beta-endorphin in response to exercise and overtraining: [review]

O sobretreinamento (ST) é um fenômeno esportivo complexo e multifatorial; e atualmente não existe nenhum marcador independente que possa diagnosticá-lo. Interessantemente, alguns sintomas do ST apresentam relação com os efeitos da b-endorfina (b-end1-31). Alguns de seus efeitos são importantes para o treinamento, como analgesia, maior tolerância ao lactato e euforia do exercício. Esses efeitos podem ser revertidos por destreinamento ou por ST, ocasionando diminuição no desempenho, redução da tolerância à carga e depressão. O exercício físico é o principal estímulo da b-end1-31, pois sua secreção é volume/intensidade dependente, tanto para exercícios aeróbios quanto anaeróbios. No entanto, o treinamento excessivo pode diminuir suas concentrações, alterando assim seus efeitos benéficos para o treinamento. Portanto, a b-end1-31 poderia ser utilizada como um marcador adicional de ST, principalmente porque seus efeitos apresentam extensa relação com os sintomas do ST.

Overtraining (OT) is a complex and multifactorial sport phenomenon, and there is no independent marker that can diagnose OT. Interestingly, some symptoms of OT are related to b-endorphin (b-end1-31) effects. Some of its effects, such as analgesia, increasing lactate tolerance, and exercise-induced euphoria, are important for training. These effects can be reverted by detraining or OT, which may cause decrease in performance, reduced load tolerance, and depression. The main stimulus for b-end1-31 secretion is to exercise because its secretion is volume/intensity dependent for both aerobic and anaerobic exercise. Excess training, however, may reduce b-end1-31 concentrations, thus altering its beneficial effects. Therefore, b-end1-31 could be used as an additional OT marker, mainly because its effects are strongly related to OT symptoms.

Papel da atividade física regular realizada durante vários anos na função imune do idoso / Role of regular practice of physical activity over several plus om immune function in the elderly

Para avaliar o efeito da atividade física regular na imunosenescência, comparou-se parâmetros imunológicos de 20 idosos corredores aos de 20 idosos sedentários e 10 jovens sedentários. Os idosos corredores apresentaram resposta proliferativa de linfócitos T a OKT-3 e produção de interleucina-2 maiores do que os idosos sedentários, porém similares aos jovens. Eles apresentaram produção de interleucina-3 menor, mas também semelhante aos jovens. A interleucina-6 sérica deles foi menor do que a dos idosos sedentários. Conclui-se que a prática regular de atividade física por longos anos tem o potencial de desacelerar a imunosenescência / To access the effect of regular physical activity on immunosenescence, the immunological parameters of 20 elderly runners were compared to those of 20 elderly sedentary persons and 10 sedentary young persons. The running elderly subjects presented a higher T lymphocyte proliferative response to OKT-3 and a higher interleukin-2 production than elderly sedentary subjects, but similar to that of young subjects, plus a lower production of interleukin-3, but also similar to that of young subjects. Their serum interleukin-6 was lower than that of sedentary elderly subjects. We conclude that practicing regular physical activity for many years has the potential to decelerate immunosenescence...

Exercício físico e memória / Physical exercise and memory

A memória é susceptível às influências endógena, hormonal e neuro-humoral especialmente logo após a aquisiçäo da informaçäo. A amígdala, o septo medial, o hipocampo e o córtex entorrinal estäo envolvidos nos processos de consolidaçäo, armazenamento e evocaçäo. A resposta ao problema dos mecanismos de armazenamento podem encontrar-se tanto pelo caminho da potenciaçäo delonga duraçäo como pelo das redes neurais, através de uma interaçäo complementar. A modulaçäo da memória enfoca a atençäo na análise das condiçöes sob as quais a consolidaçäo da memória pode ser alterada. Uma informaçäo adquirida em um determinado contexto neuro-humoral será melhor evocada se durante o processo de evocaçäo o contexto neuro-humoral for similar ao do momento da aquisiçäo, caracterizando a existência de uma periférica pós-treino de hormônios normalmente liberados por experiências emocionais e estresses, tais como: catecolaminas, ACTH, vasopressina, além do peptídio opióide B-endorfina. Os hormônios e opióides envolvidos na regulaçäo da memória também estäo envolvidos na regulaçäo, homeostática do exercício. Estudos têm demonstrado que a liberaçäo das catecolaminas, vasopressina, ACTH e B-endorfina é estimulada pelo exercício, fazendo-se uma relaçäo do efeito do exercício na regulaçäo da memória, especialmente exercícios intensos e os moderados de longa duraçäo

Breve introducción a la neuroinmunología / Brief introduction to the neuroimmunology

A partir de la década de los setentas se ha demostrado una importante dependencia direccional entre los sistemas inmune (SI) y el sistema nervioso central (SNC), con la intervención de mensajeros comunes. Las citocinas del SI son capaces de modular respuestas y procesos a nivel del SNC, mientras que los neurotransmisores y neuropéptidos pueden a su vez ejercer su efecto sobre grupos celulares especificos del SNC. Un grupo importante de estos péptidos es el de los opioides endógenos, como las endorfinas y las encefalinas. Las endorfinas alfa y beta tienen la capacidad de activar la quimiotaxis e influenciar la diferenciación y proliferación de linfocitos T y B. La ß-endorfina incrementa la actividad de las células natural killer (NK). La met-encefalina y la leu-encefalina desarrollan funciones de tipo inmunomodulador con respecto a la producción de anticuerpos (Acs) por las células plasmáticas. Incrementan la producción de Acs., pueden aumentar el número de leucocitos circulantes y la producción de interleucina-2 (IL-2). Una vía en el sistema neuroinmunológico es controlada por el eje-HPA (hipotálamo-pituitaria-adrenales, principal coordinador y regulador de las interacciones entre el sistema inmune, el SNC y el endocrino

Effects of post-training ß-endorphin and Met-enkephalin administration on two-way active avoidance task in well-nourished and protein malnourished rats

Protein malnutrition during suckling period or throughout the life affects the hypothalamic ß-endorphinergic system of adult rats. In the present study, rats were under nourished during suckling by feeding their dams an 8% casein diet whereas well-nourished dams recived a 25% casein diet from birth until weaning (21 day of postnatal life). After weaning, the offsprings were maintained with the same diet as their dams. When rats were 3 month-old, they were subjected to two-way active avoidance task. Protein malnutrition did not affect the performance in the two-way active avoidance task. Post-training ß-endorphin or Met-enkephalin administration impaired the retention of shuttle avoidance tast in both well-nourished and undernourished rats. However, the amnesic effect of the peptides was only achieved in undernourished rats with higher doses of apioids when compared to the well-nourished rats. These data suggest that undernourished rats present alterations in opioid sensitivity which may be related to changes in the levels of ß-endorphin previously observed both in brain and hypothalamus of early undernourished adults rats

Age-related changes in the neuromodulatory effect of opioid peptides on sympathetic nerve terminals

A alteraçäo, dependente da idade, do efeito neuromodulador da ß-endorfina nos terminais nervosos simpáticos foi estudada na porçäo prostática de vasa diferentia de ratos de 4 e 20 meses. O efeito da ß-endorfina e naloxona sobre a contraçäo induzida pelo estímulo transmural dos terminais nervosos (0.2 Hz, 0.5 ms, metade da voltagem supramáxima) foi analisado. Na ausência da droga näo ocorreram alteraçöes dependentes da idade na contraçäo induzida pelo estímulo nervoso. ß-Endorfina causava inibiçäo dose-dependente da contraçäo muscular. A sensibilidade da inibiçäo pela ß-endorfina duplicava entre 4 e 20 meses. Naloxona potenciava de maneira dose-dependente as contraçöes campo-estimuladas induzidas. A potência da naloxona era seis vezes maior em animais de 20 do que de 4 meses. Os dados deste trabalho säo comparados com as alteraçöes relacionadas à idade na reatividade pós-juncional, e é proposto o desenvolvimento de mecanismos compensatórios da idade no nível pré-juncional

Effects of ACTH, epinephrine and met-enkephalin on brain B-endorphin-like immunoreactivity, and of ACTH, epinephrine, met-enkephalin and naloxone on retention, in normal and in protein- malnourished rats

Rats raised and maintained on a normal-protein diet (25% protein) responded to the ip adminsitration of ACTH-(1-24), epinephrine or Met-enkephalin with a decrease in hypothalamic Beta-endorphin-like immunoreactivity, which is attributable to a release of this substance. This effect was not seen in rats raised an maintained on a low-protein diet (8% protein). In the normal animals, the pre-test administration of ACTH, epinephrine or Met-enkephalin and the post-training adminsitration of naloxone enhanced retention-test performance of a step-down inhibitory avoidance task. These behavioral effects were absent in the protein-malnourished rats. Previous studies have shown that the behavioral effect of post-training naloxone is secondary to the release of brain Beta-endorphin during training, and that the pre-test it is not likely that the differences were caused by hyperreactivity to the aversive stimuli employed, the suggested interpretation is that protein-malnourished rats present a dysfunction in the brain Beta-endorphin system which renders it unresponsive not only to novel training experiences, but also to the pre-test retrieval enchancing effects of ACTH, epinephrine and Met-enkephalin

Undernutrition during suckling does not change the specific or total activity of hypothalamic proline endopeptidase in adult rats

Undernutrition during suckling causes a decrease in hypothalamic beta-endorphin-like immunoreactivity in rats. Since proline endopeptidase (E.C. 3.4.21.26) has been proposed to play a role in the processing of Beta-endorphin, we examined the effects of undernutrition during suckling on the enzyme activity. Rats were undernourished by feeding their dams an 8% casein diet from the day of birth until weaning (21 days). Dams of well-nourished rats were fed a 25% casein diet during the same period. After weaning, all rats received a 20% protein diet until 90 to 120 days of age when they were killed for the enzyme assay. The specific and total activity of hypothalamic proline endopeptidase was not altered by undernutrition followed by nutritional rehabilitation(2.37 + or - 0.24 nmol sulphamethoxazole min-1 mg-1 for well-nourished rats vs 2.68 + or - 0.24 nmol sulphamethoxazole min-1 mg-1 for undernourished rats). This lack of correlation suggests that proline endopeptidase is probably not responsible for the low levels of hypothalamic Beta-endorphin found in adult rats submitted to undernutrition during suckling

ß-endorphin and electroconvulsive shock alter the retrieval of two avoidance tasks when given after the first, but not the second, training session

1. Rats were submitted to three consecutive sessions, one sessions per day, of two-way active avoidance or of step-down inhibitory avoidance, and received 1 µg/Kgß-endorphin intraperitoneally or an electroconvulsive shock immediately aftere the first or after the second training session. 2. Administration of either treatment after the first session caused a reduction of performance in the second session in both tasks. There was no impairment of performance in the third session. 3. Administration of either treatment after the second session did not affect performance during the third session. 4. Therefore the effect of ß- endorphin and of electroconvulsive shock on active and inhibitory avoidance performance was expressed only when treatments were administered after the first, i.e., novel, training experience. We suggest this effect is on mechanisms acting on retrieval, since the retention performance of all groups for the third session were identical

Evidence for a role of beta-endorphin in activity of nigrostriatal neurons in the rat

The effects of icv administration of ß-endorphin on secretory activity of dopaminergic neurons is described. Homovanillic and dihydroxyphenyl acetic acid levels in cerebrospinal fluid and extracts of brain tissue were determined after administration of ß-endorphin to animals pretreated or not with saloxone. The results suggest that ß-endorphin interferes with formation of dopaminergic metabolites by acting on opioid receptors

Effects of undernutrition during suckling and of post-training ß-endorphin administration on avoidance performances of adult rats

1. The effects of undernutrition during suckling and of post-training ß-endorphin administration on avoidance task were invstigated in adult rats. 2. young rats were undernourished from delivery until weaning (21 days) by feeding their mothers a diet conatining 8% protein (w/w). Mothers of well-nourished rats were fed a 20% protein diet. After weaning, both groups of rats were fed a 20% protein diet until 90-120 days if age, when they were subjected to behavioral sessions. 3. Acquistion was measured in training sessions and retention in test sessions 24 h after training. Beta-endorphin or salina (control) was injected ip immdiately after training. Rats were subjected to shuttle and step-down inhibitory avoidance sessions using footshock of 0.2 or 0.8 mA intensity. 4. Undernutrition during suckling caused hyperreactivity to 0.2 mA footshocks. Beta-endorphin caused amnesia to shuttle avoidance task only in normal rats trained with 0.8 mA. Foor-shocks. In the step-down inhibitory avoidance task, ß-endorphin was amnesic only for normal rats and only for 0.2-mA footshocks. Beta-endorphin was not amnesic in undernourished rats