The changing profiles of L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase activities in testicular cell types during sexual maturation of male rats.

To understand the involvement of polyamines in testicular maturation and spermatogenesis, the activity of two enzymes involved in the polyamine synthetic pathway, L-ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (AdoMetDC) were determined in whole testis and isolated testicular cell types during the sexual maturation of male rats. ODC activities per mg protein in whole testis and cultured Sertoli cells from 12- to 14-day-old rats were very high but declined as the age of the animals increased. ODC activities in both germ cells and interstitial cells increased as the age of the rats increased, reached a maximum at 22 days and then declined rapidly. On the other hand, AdoMetDC activity in whole testis, Sertoli cells, germ cells and interstitial cells was highest from 27 to 35 days, 18 to 22 days, 22 to 27 or 35 days, and 27 days of age, respectively, then decreased and remained at a constant lower level after 45 days. After 35 or 45 days of age, cellular AdoMetDC activities were relatively higher than ODC activities in the whole testis and germ cells, while the activity of both enzymes was comparable in the Sertoli cells. Correlation of these data with the development of germ cells during rat testicular maturation suggests that the high ODC activity in both Sertoli and germ cells is associated mainly with cell proliferation while the increase in AdoMetDC activity is most likely associated with the maturation of Sertoli cells and the meiosis of germ cells, particularly the formation of pachytene spermatocytes and the meiotic cell division of spermatocytes into spermatids.