Action of thyrotropin-releasing hormone (TRH) on the occurrence of fibrillation potentials and miniature end-plate potentials (MEPPs). An experimental study.

The effect of TRH on fibrillation potentials and MEPPs were studied to determine the sites of action of TRH on muscle weakness. Intravenous administration of 10(-4) U thyroid-stimulating hormone (TSH) did not change the fibrillation-frequency of the denervated muscles of rats, but subsequent intravenous administration of 1 mg TRH did. Drip application of 0.6 mg TRH directly onto the denuded denervated muscles of rats did not cause an increase in fibrillation. Application of 1 mg TRH to the rat diaphragm increased the frequency of MEPPs. Both the increase in frequency of fibrillation potentials and the increase in frequency of MEPPs by application of TRH suggest that TRH influences nerve terminals, and that TRH seems suitable for treatment of muscle weakness in patients with ALS.