Effect of Roentgen Rays on the Peripheral Nerve of the Rat

This is the authors' abstract. We don't add key points for this paper.

The effect of roentgen rays on the peripheral nerves has practical implications because of the increasing use of large therapeutic doses to which they are incidentally exposed. This study aims at determining what, if any, histologic and physiological alterations result from exposure of nerves to x-ray and radium. Observations on human nerves have been contradictory and incomplete and therefore cannot easily be evaluated. Some workers have been unable to demonstrate any changes (1, 2), and the degeneration described by others (3) is of uncertain significance, since the conditions were not specified. The experimental data are somewhat more detailed. A mild degeneration of the neurones of the sympathetic ganglia of the rabbit has been produced by direct exposure to roentgen rays (4). Doses of 1,000 to 4,000 r hindered myelination and finally completely destroyed axones and neurones of the newborn rat (5). Rascanu (6), using the ultramicroscope, described a reversible change in the myelinoccurring at the Lantermann incisures of the frog nerve irradiated with roentgen rays. Several observations have been made on the effect of radiant energy on the excitability of the nerve of the frog. Lazarus- Barlow (7) described an increased excitability of the irradiated frog nerve during the thirty- to fifty-hour life of the preparation. Redfield (8) found with small doses of beta and gamma rays an initial increased excitability of the frog nerve, which was followed by a rapid rise in threshold. The initial decrement of threshold was absent when larger doses were used. Similar findings were described by Rascanu (6). Audiat (9) irradiated the isolated frog nerve in a moist chamber with 300,000 r of 1 Å. wavelength, and described loss of excitability developing in a few minutes to half an hour. This change spread 1 cm. above and below the irradiated segment and was reversible if the nerve was placed in physiological saline solution. Since we did not find any reports of similar work on the nerves of the mammal, it seemed that such experiments followed by histologic observations might add important information provided the time limitations which obtain with the use of an isolated nerve muscle preparation could be avoided. For this purpose we used the intact right sciatic nerve of the rat. The procedure was kept as constant as possible. Method Stock white rats weighing 170 to 210 grams each and maintained on a vitamin-rich diet were used. Under nembutal anesthesia both sciatic nerves were isolated in situ and kept moist with Tyrode's solution, care being taken to prevent the least trauma. A lead shield 10 × 10 × 0.2 cm. with an opening just large enough for exposure of the right nerve was placed over the animal, and the adjacent tissues were protected by a lead shield (0.1 cm, thick for 4,000 rand 0.2 cm. thick for 6,000-10,000 r) placed under the nerve.