Preliminary Investigation of Cerebellar Alterations induced by Cachexia and Endurance Training in C26 Tumor-Bearing Mouse Model

Cachexia is a syndrome characterized by significant weight loss and is a major complication in cancer development. Despite its importance, there are no effective treatments available. Recently, resistance training has been suggested as a non-pharmacological therapy to prevent muscle atrophy and functional decline in preclinical models. The C26 tumor-bearing mouse model is commonly used, showing progressive muscle and fat loss along with systemic inflammation. However, the impact of these changes on the cerebellum, which is crucial for motor function and balance, remains unclear. In this study, we combined the C26 tumor model with an endurance protocol to investigate cerebellar alterations in sedentary (SED T+) and trained (TR T+) tumor groups compared to sedentary (SED T-) and trained (TR T-) non-tumor groups. The tumor groups were sacrificed at the onset of cachexia to assess the impact of proactive endurance training. After confirming cachexia onset through body weight and strength loss, histological analysis revealed that the cerebellar area was similar across groups. However, a significant reduction in the Purkinje cell layer (PCL) thickness was observed in SED T+ mice. Since PCs are the sole efferent neurons in the cerebellum, we examined their condition using histological analysis, immunohistochemistry, and immunofluorescence by ZIC4 labelling. The PC body size decreased in the tumor groups, while their number was reduced only in TR T+ mice. Interestingly, the SED T+ group exhibited the highest number of PC with abnormal morphology. Additionally, to assess the effects on cerebellar vascularity, we found that tumor groups had an increased number of vessels in the white matter. Altogether, these results suggest that in the C26 tumor mouse model, the cerebellum is affected by PCL hypotrophy with smaller and abnormal PC. Endurance training only partially counteracts these alterations. Further studies are needed to clarify Purkinje cell aberrations due to their crucial role in motor function.