Testosterone-induced changes in nuclear pore complex number of prostatic nuclei from castrated rats

The time-course effect of testosterone on nuclear pore formation was studied in ventral prostate isolated nuclei from castrated rats. The pore density was determined by the freeze-etching technique and electron microscopy; the nuclear envelope surface area was estimated by phase-contrast microscopy. The first detectable changes occurred 1 day after hormone stimulation and consisted of an increase in nuclear surface with a consequent increase in the total number of pores per nucleus although the pore density remained statistically unchanged. Again, between the second and third days of stimulation the pore density remained unchanged, while total pore number increased due to an increase of nuclear surface. These results show that the pore density variations are partly independent of additional nuclear membrane synthesis. Nuclear pore-density increase was found to present a biphasic pattern that correlates with the rate of DNA replication and mitosis known to be stimulated in these cells by testosterone. The progressive increase in both pore number and density beyond the periods of maximal cell division, however, is best related to the stimulation of the cell metabolism.