Base Composition of RNA Obtained from Motor Neurons in Amyotrophic Lateral Sclerosis

Abstract

The base composition of RNA obtained from the large motor neurons of the cervical and lumbar swelling was examined in amyotrophic lateral sclerosis (ALS) patients and a similar number of age-matched controls. Spinal cords were obtained at autopsy and immediately fixed in buffered formalin. The single cell technique of Edström was employed to extract, hydrolyze, and electrophorese the RNA. The base composition obtained for the controls was 17.47% adenine, 28.88% guanine, 28.50% cytidylic acid, and 25.14% uridylic acid. The cervical intumescence revealed higher levels of uridylic acid than the lumbar, 27.23% in the cervical and 23.31% in the lumbar intumescence. The motor neuron cell bodies isolated from patients having had ALS revealed a lower percentage of adenine in both the cervical (13%) and lumbar (10%) intumescences. When the data for these areas were combined, the percentage of adenine was 15.52, compared to 17.47% in the controls (p < 0.01). The A/U ratio was also significantly reduced in the ALS group. The composition of the remaining bases in ALS appeared to be similar to the controls. The significant change in adenine, coupled with the quantitative reduction in total neuronal RNA, suggests that a disorder of nucleic acid metabolism may relate to the pathogenesis of ALS.