Efeitos do treinamento resistido e da atividade física em camundongos C57BL/6 com caquexia associada ao modelo tumoral singênico de melanoma cutâneo

Abstract

The objective of this study was to investigate the effects of resistance training and physical activity in C57BL/6 mice with cachexia associated with the syngeneic tumoral model of cutaneous melanoma. For the construction of this thesis, three products were made. First, a prototype (utility model) was developed for resistance exercise with C57BL/6 mice, and the first article that analyzed the effects of resistance exercise using electric shock stimulus (prototype) on the variables of muscle strength, body composition, limb volume, muscle fiber area, number of muscle fiber nuclei, and plasma lactate levels. For this, we analyzed healthy C57BL/6 mice practicing physical activity, resistance exercise, resistive exercise with shock stimulus and sedentary animals. According to the data, the vertical electrostimulation ladder model presented acute effects on lactate levels similar to other experimental models of resistance exercise and spontaneous physical activity. In addition, in the short-term chronic response, the comparison between the proposed model and the other interventions showed that the best results of the prototype were obtained in the performance of limb traction muscle strength, brown adipose and quadriceps muscle weight gain femoral, and greater number of nuclei in the skeletal striated muscle fibers (p <0.05 in all comparisons). Later, after the findings of the second product, a new study (third product) was carried out to verify the effects of resistance exercise and physical activity on skeletal muscle structure, white adipose tissue, and survival in C57Bl/6 mice with cutaneous cachexia related to melanoma. Interventions of resistive exercise and physical activity contributed to an increase in muscle strength, improvement in body composition (muscle tissue and brown adipose tissue) and histomorphometry of the gastrocnemius muscle of animals with cachexia associated with melanoma when the interventions were performed before the establishment of the condition cachectic. The resistance exercise performed after the diagnosis of cachexia did not change significantly in the genetic expression (MYOG, FXOB32, IGF1, TRIM63 and PPARγ),, we believe that the load control (intensity and volume) should be modified to better yield these variables. Regarding survival, our findings showed that the proposed interventions did not provide greater overall survival. Thus, experimental studies with other methodological models of physical exercise with mice with cutaneous melanoma should be encouraged to elucidate the shortcomings of the current study, since resistance exercise and physical activity presented benefits due to the gain of muscle strength and an increase of the gastrocnemius muscle in animals with cachexia associated with melanoma.