Electrical stimulation of denervated rat skeletal muscle retards trabecular bone loss in early stages of disuse musculoskeletal atrophy

Objectives: We aimed to determine the intensity of muscle stimulation required to prevent structural failure as well as bone and skeletal muscle loss after denervation-induced disuse. Methods: Seven-week-old rats (weight, 198-225 g) were randomly assigned to age-matched groups comprising control (CON), sciatic nerve denervation (DN) or direct electrical stimulation (ES) one day later [after denervation] with 4, 8 and 16 mA at 10 Hz for 30 min/day, six days/week, for one or three weeks. Bone architecture and mean osteoid thickness in histologically stained tibial sections and tension in tibialis anterior muscles were assessed at one and three weeks after denervation. Results: Direct ES with 16 mA generated 23-30% maximal contraction force. Denervation significantly decreased trabecular bone volume fraction, thickness and number, connectivity density and increased trabecular separation in the DN group at weeks one and three. Osteoid thickness was significantly greater in the ES16 group at week one than in the DN and other ES groups. Trabecular bone volume significantly correlated with muscle weight. Conclusions: Relatively low-level muscle contraction induced by low-frequency, high-intensity electrical muscle stimulation delayed trabecular bone loss during the early stages (one week after DN) of musculoskeletal atrophy due to disuse.