Abnormal RNA metabolism in spinal motor neurons in the wobbler mouse.

RNA metabolism was studied in anterior horn neurons in wobbler mice. In the wobbler mice, RNA content was reduced in histologically normal neurons but not consistently reduced in vacuolated neurons, as compared with normal littermates. Nuclear and nucleolar incorporation of [5--3H]uridine was reduced both in vacuolated and in histologically normal neurons of wobbler mice, while cytoplasmic counts were higher in histologically normal neurons of wobbler mice than in vacuolated neurons or the neurons of normal littermates. These findings point to an abnormality of RNA synthesis which precedes the earliest morphological changes seen in nerve cells with the light microscope. Nuclear [5--3H]uridine uptake was reduced both in small and in large neurons, a finding suggesting that the metabolic abnormality is probably not confined to alpha-motoneurons.