Analysis of dynamics of degenerative and regenerative processes in the flexor and extensor collaterals of crushed sciatic nerve: Effects of parathyroid hormone
We performed morphological, histochemical, and electrophysiological analysis of changes in the state of the rat sciatic nerve after nerve crushing. The activity of Ca2+-dependent acidic phosphatase (AP) was measured in sections of the nerve fibers to trace the recovery of the nerve after its injury. The systemic application of parathyroid hormone (PTH) resulted in the acceleration of injured nerve recovery. Proliferation of both endoneurium and Schwann cells was observed on the 3rd day after the crushing of the ipsilateral extensor (N. peroneus communis) and flexor (N. gastrocnemius) nerve bundles. A complete recovery of the AP enzymatic activity was found on the 7–9th days after the crushing. From the 5th to 35th days after the crushing, we performed online registration and mathematical analysis of pulse activity. In the control experiments, from the 35th to 70th days, high-frequency stimulation of the nerves showed the regeneration of the extensor nerve only accompanied by alterations in fiber direction. In the presence of PTH, the regeneration was significantly accelerated and it was associated with early regeneration of the flexor nerve and more structured fiber morphology. We found a correlation between the electrophysiological and morphological data.
Keywordsnerve crushing sciatic nerve motoneurons spinal cord high frequency stimulation extensor and flexor collaterals parathyroid hormone
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