Progressive muscular weakness and wasting was induced in rats by prolonged administration of cortisone. Electromyographic data at various intervals revealed no evidence of established or impending neuropathy. There were no fibrillation potentials in the skeletal muscle even after eight weeks of intensive cortisone treatment. The spontaneous or evoked EMG patterns were essentially similar to those in nontreated control rats, the only difference being a somewhat decreased total electrical output (voltage and frequency of firing) of muscle from the cortisone-treated rat. Impulse transmission across the neuromuscular junction of the cortisone-treated rat was essentially the same as that of the control rat, as indicated by the magnitude of isometric twitch after direct or indirect (neural) stimulation. The effects of cortisone are exerted on muscle, not nerve or neuromuscular junction.
Prabhu VG, Oester YT. Electromyographic Studies of Skeletal Muscle of Rat Given Cortisone. Arch Neurol. 1971;24(3):253–258. doi:10.1001/archneur.1971.00480330081007
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