Aberrant gastrocnemius muscle innervation by tibial nerve afferents after implantation of chitosan tubes impregnated with progesterone favored locomotion recovery in rats with transected sciatic nerve

Abstract

obJect Transection of peripheral nerves produces loss of sensory and/or motor function. After complete nerve cutting, the distal and proximal segment ends retract, but if both ends are bridged with unaltered chitosan, progesteroneimpregnated chitosan, or silicone tubes, an axonal repair process begins. Progesterone promotes nerve repair and has neuroprotective effects thwarting regulation of neuron survival, inflammation, and edema. It also modulates aberrant axonal sprouting and demyelination. The authors compared the efficacy of nerve recovery after implantation of progesterone-loaded chitosan, unaltered chitosan, or silicone tubes after sciatic nerve transection in rats. methods After surgical removal of a 5-mm segment of the proximal sciatic nerve, rats were implanted with progesterone-loaded chitosan, unaltered chitosan, or silicone tubes in the transected nerve for evaluating progesterone and chitosan effects on sciatic nerve repair and ipsilateral hindlimb kinematic function, as well as on gastrocnemius electromyographic responses. In some experiments, tube implantation was performed 90 minutes after nerve transection. results At 90 days after sciatic nerve transection and tube implantation, rats with progesterone-loaded chitosan tubes showed knee angular displacement recovery and better outcomes for step length, velocity of locomotion, and normal hindlimb raising above the ground. In contrast, rats with chitosan-only tubes showed reduced normal raising and pendulum-like hindlimb movements. Aberrant fibers coming from the tibial nerve innervated the gastrocnemius muscle, producing electromyographic responses. Electrical responses in the gastrocnemius muscle produced by sciatic nerve stimulation occurred only when the distal nerve segment was stimulated; they were absent when the proximal or intratubular segment was stimulated. A clear sciatic nerve morphology with some myelinated fiber fascicles appeared in the tube section in rats with progesterone-impregnated chitosan tubes. Some gastrocnemius efferent fibers were partially repaired 90 days after nerve resection. The better outcome in knee angle displacement may be partially attributable to the aberrant neuromuscular synaptic effects, since nerve conduction in the gastrocnemius muscle could be blocked in the progesterone-impregnated chitosan tubes. In addition, in the region of the gap produced by the nerve resection, the number of axons and amount of myelination were reduced in the sciatic nerve implanted with chitosan, progesteroneloaded chitosan, and silicone tubes. At 180 days after sciatic nerve sectioning, the knee kinematic function recovered to a level observed in control rats of a similar age. In rats with progesterone-loaded chitosan tubes, stimulation of the proximal and intratubular sciatic nerve segments produced an electromyographic response. The axon morphology of the proximal and intratubular segments of the sciatic nerve resembled that of the contralateral nontransected nerve. coNclusioNs Progesterone-impregnated chitosan tubes produced...

Effects of Strength Training and Anabolic Steroid in the Peripheral Nerve and Skeletal Muscle Morphology of Aged Rats

“…The administration of steroid hormones in the treatment of peripheral trauma is becoming increasingly important (Mitro et al, 2014; Giatti et al, 2015; Sarabia-Estrada et al, 2015). However, it is not known whether this practice is consistent in disrupting or reversing the neuronal loss observed over the course of aging.…”

Kinematic Locomotion Changes in C57BL/6 Mice Infected with Toxoplasma Strain ME49

“…All mice from the three groups were marked with nontoxic indelible ink in the (A) iliac crest, (B) the hip, (C) the knee, (D) the ankle, and (E) the phalangeal metatarsus, in both the left and right hindlimbs (Figure 1A). Mice were video recorded at 90 fps at a resolution of 640 x 480 pixels while walking freely in a transparent Plexiglass tunnel [14,15].…”

Metastatic human breast cancer to the spine produces mechanical hyperalgesia and gait deficits in rodents

“…To evaluate the functional effects of spine tumor growth, analysis of rat locomotion was performed as previously described [31, 32]. Briefly, each rat was trained to walk on a narrow Plexiglas tunnel (100 cm long x 10 cm wide x 14 cm high) to ensure locomotion in a straight line.…”

“…The duration (in seconds) and length (in centimeters) of each stride were determined, and from these parameters, the stride speed was calculated (in cm/sec). These parameters were calculated and each rat’s mean hind limb stride is reported using previous definitions of stride and elevation coordinates for hind limbs [28, 32, 33]. Briefly, the marked points in the rat’s hind limb were tracked frame by frame, obtaining a two-dimensional coordinates (x, y) using the ImageJ software (NIH; Bethesda, MD, USA), then data is imported into Microsoft Office Excel (Microsoft) and further analyzed with pre-assembled Excel sheets to modeled body segments as rigid straight lines between the marked points.…”