An important and urgent problem of neuroscience and medicine is the understanding of the mechanisms of reorganization of motor function under conditions accompanied by a restriction on the functional use of skeletal muscles. The aim of the study was to assess the condition of the neuromotor apparatus of the rat's calf muscles in conditions of simulated disuse.

All experiments were carried out in strict accordance with generally accepted bioethics norms. The animals were divided into experimental groups: unilateral compression of the sciatic nerve (n=5); unilateral tenotomy (n=5); antiorthostatic hanging (n=5). After 7 days, the electromyographic characteristics of the gastrocnemius, soleus, and tibialis anterior muscles were recorded. Data from intact animals served as a control (n=5). An increase in the reflex excitability of spinal cord motor neurons and a violation of the reliability of synaptic transmission were detected, regardless of the procedure for modeling disuse of the muscle. The transformations were more pronounced in the neuromotor apparatus of the extensor muscles. In addition, in nerve injury and tenotomy, changes were also recorded in the contralateral (undamaged) motor system.

Thus, the disuse of skeletal muscle initiates the transformation of the functional state of all links of symmetrical neuromotor systems. The main reason for the detected effects is assumed to be the restriction of peripheral afferentation, including support, and the activation of intraspinal bilateral connections.

This research was funded by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities, project no. FZSM-2023-0009.