Diurnal levels of polyamines and activities of ornithine and S-adenosyl-L-methionine decarboxylases in mouse brain.

The levels of putrescine and spermine in mouse brain were rather constant at different times of day, as were the activities of ornithine and S-adenosyl-L-methionine decarboxylases. Contrary to an earlier report, the level of spermidine was found to be relatively constant. A possibly significant feature in the present results was the steady decline during the light period and rise during darkness of cerebral spermidine and spermine levels, the differences between maximum and minimum being about 15% for both compounds.