RESUMO
STUDY DESIGN: Animal experimental study. OBJECTIVE: Evaluate the effect of physical activity and overtraining condition on glycosaminoglycan concentration on the intervertebral disc (IVD) using a rat running model. SUMMARY OF BACKGROUND DATA: Some guidelines recommend the implementation of a physical exercise program as treatment for low back pain; however, cyclic loading impact on the health of the IVD and whether there is a dose-response relationship is still incompletely understood. METHODS: Thirty-two rats ages 8 weeks were divided into four groups with eight animals each. The first 8 weeks were the adaptive phase, the overtraining phase was from the ninth to the eleventh week, which consisted of increasing the number of daily training sessions from 1 to 4 and the recovery phase was represented by the 12th and 13th weeks without training. Control group 1 (CG1) did not undergo any kind of training. Control group 2 (CG2) completed just the adaptive phase. Overtraining group 1 (OT1) completed the overtraining phase. Overtraining group 2 (OT2) completed the recovery phase. Running performance tests were used to assess the "overtraining" status of the animals. IVD glycosaminoglycans were extracted and quantified, and identified by electrophoresis. RESULTS: Glycosaminoglycans showed a distribution between chondroitin sulfate and dermatan sulfate. Glycosaminoglycans quantification showed decreasing concentration at the following order: OT1â>âCG2â>âOT2â>âCG1. Increased expression of dermatan sulfate was verified at the groups submitted to any training. CONCLUSION: Overtraining condition, as assessed by muscle and cardiovascular endurance did not lessen glycosaminoglycan concentration in the IVD. In fact, physical exercise increased glycosaminoglycan concentration in the IVD in proportion to the training load, even at overtraining condition, returning to normal levels after the recovery phase and glycosaminoglycan production is a reversible acute positive response for mechanical stimulation of the IVD. LEVEL OF EVIDENCE: N/A.
Assuntos
Disco Intervertebral/metabolismo , Dor Lombar/metabolismo , Condicionamento Físico Animal/fisiologia , Proteoglicanas/metabolismo , Animais , Glicosaminoglicanos/metabolismo , Masculino , Ratos , Ratos Wistar , Corrida/fisiologiaRESUMO
INTRODUCTION: Cytokines (IL-6, IL-10 and TNF-α) are increased after exhaustive exercise in the rat retroperitoneal (RPAT) and mesenteric adipose tissue (MEAT) pads. On the other hand, these cytokines show decreased expression in these depots in response to a chronic exercise protocol. However, the effect of exercise with overload combined with a short recovery period on pro- and anti-inflammatory cytokine expression is unknown. In the present study, we investigated the regulation of cytokine production in the adipose tissue of rats after an overtraining-inducing exercise protocol. METHODS: Male Wistar rats were divided into four groups: Control (C), Trained (Tr), Overtrained (OT) and recovered overtrained (R). Cytokines (IL-6, TNF-α and IL-10) levels and Toll Like Receptor 4 (TLR4), Nuclear Factor kBp65 (NF-kBp65), Hormone Sensitive Lipase (HSL) and, Perilipin protein expression were assessed in the adipose tissue. Furthermore, we analysed plasma lipid profile, insulin, testosterone, corticosterone and endotoxin levels, and liver triacylglycerol, cytokine content, as well as apolipoprotein B (apoB) and TLR4 expression in the liver. RESULTS: OT and R groups exhibited reduced performance accompanied by lower testosterone and increased corticosterone and endotoxin levels when compared with the control and trained groups. IL-6 and IL-10 protein levels were increased in the adipose tissue of the group allowed to recover, in comparison with all the other studied groups. TLR-4 and NF-kBp65 were increased in this same group when compared with both control and trained groups. The protein expression of HSL was increased and that of Perilipin, decreased in the adipose in R in relation to the control. In addition, we found increased liver and serum TAG, along with reduced apoB protein expression and IL-6 and IL-10 levels in the of R in relation to the control and trained groups. CONCLUSION: In conclusion, we have shown that increases in pro-inflammatory cytokines in the adipose tissue after an overtraining protocol may be mediated via TLR-4 and NF-kBp65 signalling, leading to an inflammatory state in this tissue.