It could also be argued that the apocrine-secretory capabilities of the epididymal epithelium were impaired, resulting in a reduced content of UBE2 and other ubiquitin system enzymes in the epididymal fluid. We did not observe any major morphological changes in the epithelia, and the accumulation of presumed secretory ubiquitin on the apical secretory sites of the DNB epididymis appeared comparable to the control rats.
On the basis of compounded transcriptional profiling of all tissues by semiquantitative RT-PCR, the most pronounced THP- and DNB-induced change overall was a significant reduction in the expression of constitutive 20S proteasomal core subunit genes Psmbl, Psmb2, and Psmb5 across the male reproductive system. This is in agreement with the reduced expression of proteasomal subunits in the epididymis of aging rats. Also significant are the observations linking a reduced proteasomal subunit expression or an impaired proteasomal proteolytic activity in various human pathologies including, but not limited to, liver cirrhosis and neuronal Alzheimer disease.