Metabolism of Polyamines in Normal and Scrapie‐affected Mouse Brain and Spleen

Following intracerebral inoculation of mouse adapted scrapie agent into mice, polyamine concentration in the brain decreases to about 75 per cent of the normal level during the first 2 months after intracerebral inoculation of the agent. Between 2 and 4 months after infection thelevel of spermidine and spermineincreased by 80 and 40 percent respectively to reach concentrations of 25 and 20 per cent higher than controls of the same age. During the same period the rate of incorporation of [14C]putrescine into spermidine is increased four‐fold as compared with controls. The changes in polyamine levels correlate well with the pattern of astrocyte hypertrophy and are similar to those reported for human brain tumours. The concentration of polyamines in spleen increases soon after inoculation. Whilst changes in brain polyamines might be referred to the hypertrophic growth of astrocytes those in spleen are perhaps due to an increased metabolic activity of spleen cells associated with the replication of the agent. These results are derived from experimental mouse scrapie and not naturally occurring disease in sheep.