Hormonal regulation of ornithine decarboxylase and spermidine spermine N-1-acetyltransferase activities by sex steroid hormones in rat seminal vesicles

The activities of ornithine decarboxylase (ODC) and spermidine/ spermine N- 1-acetyltransferase (SAT) in seminal vesicles were regulated by exogenous a dministration of the sex steroid hormones, testosterone and oestradiol, to young rats. ODC activity in the seminal vesicles was drastically decreased by castration. This enzyme activity was remarkably increased by subcutaneou s (s.c.) administration of testosterone to the castrated rats, but not by o estradiol administration. SAT activity in the organ was moderately decrease d by castration. This enzyme activity was further reduced by the administra tion of testosterone to the castrated rats, but slightly elevated by the tr eatment with oestradiol. Patterns of ODC activity alteration by these sex h ormones were very similar to the patterns of the organ weight alteration, d emonstrating that ODC activity was correlated to the growth of the organ. B y oestradiol administrations to sham-operated and castrated rats, the weigh ts of seminal vesicles were reduced to one-third, and increased about 2 tim es, respectively. ODC activities in the organs of sham-operated and castrat ed rats treated with oestradiol were reduced to one-third of its initial va lue, and increased about 5 times, respectively, while changes in SAT activi ty were slight, These findings demonstrate that ODC activity is correlated to the growth of seminal vesicles of the rats treated with these sex hormon es, but in contrary to ODC activity, SAT activity does change inversely.