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Background: After peripheral nerve injury, there is an increase in calcium concentration in the injured nerves. Our previous publications have shown that increase in calcium concentration correlated well with degree of nerve injury and that local infusion of calcitonin has a beneficial effect on nerve recovery. Schwann cells play a pivotal role in regeneration and recovery. We aim to examine cultured Schwann cell survivals in various concentrations of calcium-containing growth media and the effect of calcitonin in such media. Methods: To establish baseline in postinjury state, crush injury was induced in male Sprague-Dawley rats' sciatic nerves. Extra- and intraneural calcium concentrations were measured. To study Schwann cell survival, uninjured sciatic nerve segment was harvested and cultured in media containing various amounts of calcium. To study the effect of calcitonin, nerve harvest and culture were done in four additional media: (1) normal control, (2) normal control with calcitonin, (3) high calciummedium, and (4) high calcium medium with calcitonin. Schwann cells were studied and analyzed under fluorescent conditions. Results: With increasing calciumconcentration, there was a significant decrease in the number of Schwann cells. For the experimental groups, in which calcitonin had been added to the growth medium, there were similar amounts of Schwann cells present in both high and low calcium-containing medium. Conclusion: Schwann cells are sensitive to increasing calcium concentration. Calcitonin counteracts the detrimental effects of high calcium on Schwann cell survival. This can have significant future clinical implications for patients with peripheral nerve injuries. [ABSTRACT FROM AUTHOR]

Background Histological analysis remains a cornerstone approach for the investigation of peripheral nerve regeneration. This study investigates a newly recognized histological difference between peripheral and central zones within the regenerating nerve trunks. Purpose The purpose of the study was to determine if the nerve axonal area (NXA) in regenerating peripheral nerves differs within central and peripheral areas, when viewed in cross-section. Methods A total of 14 rats were divided into two groups, and subjected to different injuries to the right sciatic nerve. Group 1: Transection injury with immediate repair. Group 2: Crush injury without any treatment. The left sciatic nerve was left uninjured and served as a control in each rat. Following 4 weeks of recovery, nerve trunk cross-sections were prepared. Computerized techniques were then employed to divide nerve sections into central and peripheral zones and calculate corresponding NXA values for subsequent statistical analysis. Results NXA of injured nerves was greater within peripheral as compared with the central zones, independent of injury type (p < 0.05). No statistically significant difference existed within the control groups or between the injury methods with regards to NXA regeneration extent. Conclusion NXA in regenerating peripheral nerves was greater in the peripheral zones than within the central zones. [ABSTRACT FROM AUTHOR]