Efeitos da atividade física sobre a memória e estresse oxidativo plasmático e hipocampal de ratas na senescência / Effects of physical activity on memory, plasma and hippocampal oxidative stress of rats on senescence

Há evidências que a prática regular de atividade física potencializa a memória, diminui o estresse oxidativo plasmático e hipocampal e a ansiedade na senescência. Neste trabalho foram utilizadas 40 ratas (Rattus norvegicus albinus, Wistar), com 13 meses de idade ao início do experimento, divididas em quatro grupos: um grupo controle (GC) e três grupos tratamento (GT1, GT2 e GT3), sendo 10 animais em cada grupo. O grupo controle foi mantido apenas sob observação. Aos grupos tratamento foram aplicados exercícios físicos e de memória, sendo que ao GT1, apenas exercícios de memória; ao GT2 escalada em escada, e ao GT3 ambos os exercícios. Os animais que foram submetidos à escalada em escada três vezes por semana durante três meses consecutivos e aos testes de memória, apresentaram melhor desempenho nas memórias de curto e longo prazo e de habituação, bem como menor ansiedade em teste de campo aberto. A baixa concentração de malonaldeído (MDA), o equilíbrio da superóxido dismutase (SOD) e o aumento da capacidade antioxidante total (Ferric Reducing Antioxidant Power- FRAP, foram observados nas amostras plasmáticas e hipocampais de ratas submetidas aos tratamentos. Concluiu-se que a prática de exercício físico regular associado a exercícios de memória melhorou as capacidades mnemônicas, diminuiu o estresse oxidativo e a ansiedade de ratas na senescência(AU)

There is evidence that regular physical activity enhances memory, decreases plasma and hippocampal oxidative stress, and anxiety in senescence. In this work, 40 rats (Rattus norvegicus albinus, Wistar), 13 months old at the start of the experiment, were divided into four groups: one control group (CG) and three treatment groups (GT1, GT2 and GT3), 10 animals in each group. The control group was kept under observation only. In the treatment groups, physical and memory exercises were applied, and to GT1, only memory exercises; to GT2 climbing stairs, and to GT3 both exercises. Animals that underwent ladder climbing three times a week for three consecutive months and memory tests showed better performance in short and long term memory and habituation as well as lower anxiety in the open field test. The low concentration of malonaldehyde (MDA), the balance of superoxide dismutase (SOD) and the increase in total antioxidant capacity (Ferric Reducing Antioxidant Power - FRAP) were observed in the plasma and hippocampal samples of rats submitted to treatments. Regular exercise practice associated with memory exercises improved mnemonic abilities, decreased oxidative stress and anxiety of rats in senescence(AU)

Promoter methylation of TGFbeta receptor I and mutation of TGFbeta receptor II are frequent events in MSI sporadic gastric carcinomas.

Transforming growth factor beta (TGFbeta) is a potent inhibitor of cell growth, whose action is transduced through interaction between type I (RI) and type II (RII) receptors. Abnormal expression of these receptors has been identified in several human cancers and was found to be associated with resistance to TGFbeta. TGFbeta RII mutations occur in many types of malignancy. TGFbeta RI hypermethylation has been suggested as a cause of abnormal or absent expression of this receptor in cancer. This study has analysed the methylation status of the promoter region of the TGFbeta RI gene using a methylation-sensitive enzyme followed by polymerase chain reaction (PCR), and TGFbeta RII mutations (BAT-RII and a GT(3)) in order to determine the frequency of alteration of the TGFbeta receptors in a series of 40 sporadic gastric carcinomas (SGCs), 25 of which showed microsatellite instability (MSI) and 15 of which were microsatellite stable (MSS). Methylation in the promoter region of the TGFbeta RI gene was detected in 20 of the 40 (50%) SGCs (64% of the MSI cases and 26.7% of the MSS); 17 of the 40 (42.5%) cases had mutations in the BAT-RII region of the TGFbeta RII gene (68% in the MSI cases; 0% in the MSS). In total, 25 of the 40 (62.5%) SGCs had alterations in at least one of the TGFbeta receptors (84% of the cases in the MSI group, in contrast with 16% of the MSS cases) (p = 0.0003). The clinicopathological features of the cases were also studied and significant associations were found between the presence of alterations in TGFbeta receptors and the age of the patients (p = 0.046), size (p = 0.011), and proliferative rate of the tumours (p = 0.048). In conclusion, alterations in the receptors of TGFbeta (TGFbeta RI promoter hypermethylation and TGFbeta RII mutations) are frequent events in MSI SGC and are associated with large size and high proliferative activity of the tumours, in keeping with loss of the growth inhibitory effects of TGFbeta in this setting.