Hormonal Regulation of Spermidine Formation during Spermatogenesis in the Rat*

Abstract

The activities of ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase have been correlated with spermidine content and morphological criteria of cell differentiation during hormone-dependent spermatogenesis in the rat. The specific activity of ornithine decarboxylase was maximal at 3 days of age at a time when only Sertoli cells were present in the seminiferous tubules, but the specific activity was markedly reduced with the formation of additional cell types. The specific activity of S-adenosyl-L-methionine decarboxylase increased steadily during spermatogenesis, reaching a plateau with spermatozoan maturation. Spermidine concentration generally paralleled the specific activity of ornithine decarboxylase, and evidenced an increase during spermatid maturation. Hypophysectomy prevented these characteristic developmental enzyme changes and reduced testis spermidine content. Stimulation with daily injections of FSH and LH or of testosterone maintained the normal developmental pattern and the sp...