The Effect of Androgen Deprivation Therapy on Regulation of Muscle Protein Metabolism and Blood Glucose

Prostate cancer (PCa) patients receiving androgen deprivation therapy (ADT) (e.g., Zoladex), which leads to castrate levels of testosterone, experience troublesome side effects during and after treatment. Commonly reported side effects are loss of lean body mass (LBM) and increased fat mass, as well as impaired glucose- and fat metabolism. Strength training has shown positive effects on LBM in PCa patients on ADT, however, counteracting a substantial LBM loss observed in the control groups seem to account for the intervention effect seen in several of the individual studies. Thus, the real LBM gain following strength training in PCa patients on ADT may be hampered compared to healthy elderly men, but data on this is limited in the literature.

The planned acute recovery study is a continuation of the physical exercise and prostate cancer (PEPC) trial, which was a randomized controlled trial investigating the effects of strength training on body composition, muscle strength, and muscle cellular outcomes during ADT.

Beyond locomotion and activity of daily living, the skeletal muscle tissue plays an important role in glucose metabolism, and impaired glucose uptake to the muscle is associated with diseases such as diabetes mellitus and cardiovascular diseases. In fact, increased levels of fasted blood glucose and insulin have been reported during the first year of ADT. Interestingly, insulin resistance has been noted as early as three months into the treatment. Insulin resistance may, in addition to the increased risk for metabolic comorbidities, also impair the anabolic response in muscles to feeding and exercise. Consequently, the accelerated muscle mass loss, and the potential limited response to strength training might be interlinked to the reduction in insulin sensitivity in PCa patients receiving ADT.

Although the negative effects of ADT on muscle mass are well documented, the cellular effects of ADT on muscle tissue are still largely unknown, and studies investigating the mechanisms are highly warranted. Furthermore, understanding the cellular mechanisms through which ADT negatively influences muscle mass and glucose metabolism is important so that appropriate measures can be taken to counteract muscle wasting and comorbidities during ADT. The present study is designed to address these issues.

PCa patients on ADT (Zoladex), along with non-ADT treated PCa patients serving as controls, will be invited to participate in this study. The aim is to investigate the influence of ADT on the basal muscle protein turnover, as well as the responses to strength training. Furthermore, secondary aims are to investigate between-group differences in blood glucose and insulin responses following a meal).