Relationship between polyamine contents and protease activity in the rat submaxillary gland

The effect of polyamines on the protease activity in the submaxillary gland of castrated rats has been investigated in vivo. The protease activity, which is increased by testosterone, is also increased to a lesser degree by the subcutaneous administration of spermidine. The administration of putrescine was less effective than that of spermidine. The increase of polyamine contents in the submaxillary gland of the castrated rats administered either testosterone or spermidine was nearly parallel to the increase of the enzymatic activity. The administration of methylglyoxal bis(guanylhydrazone), a potent inhibitor of spermidine synthesis, with testosterone inhibited slightly the increase of the protease activity by testosterone, while the administration of the inhibitor with spermidine had essentially no effect on the increase of the enzymatic activity by spermidine. The administration of testosterone also caused a slight increase of $\text{S-}\text{adenosyl-}\text{L}\text{-menthionine}$ decarboxylase activity. These results suggest that spermidine synthesis may be necessary for the stimulation by testosterone of protease synthesis in the rat submaxillary gland.