Immunohistochemical quantitative study of the peritubular lamina propria after induction of testicular atrophy induced by epinephrine.

Changes in the testicular peritubular lamina propria in rats treated for 1-11 weeks with intra-scrotal injections of epinephrine were studied by quantitative immunohistochemical methods. In control testes, BrdU-labelled nuclei (proliferating cells) were observed only in spermatogonia and some primary spermatocytes, whereas testes from epinephrine-treated rats showed BrdU labelling in some of the spermatogonia and in peritubular cells. Immunostaining for transforming growth factor beta 1 (TGF-beta 1) was present in germ cells, Sertoli cells and Leydig cells; vimentin immunostaining was found mainly in Sertoli cells; desmin immunostaining was found in the peritubular cells, and immunostaining for type IV collagen, laminin and fibronectin was found in the extracellular matrix of the lamina propria. The volume densities of seminiferous tubules (including seminiferous epithelium, lamina propria and tubular lumen) that immunostained for TGF-beta 1, vimentin, laminin, desmin or fibronectin were calculated. All of these parameters increased significantly in testes from epinephrine-treated animals during the course of the experiment, except for desmin immunostaining which showed no significant change in volume density. Since total seminiferous tubule volume decreased markedly in the testes of treated rats during the experiment, the transformation of relative values for immunostaining into absolute volumes per testis revealed a significant increase in TGF-beta 1 immunostaining, no significant change in vimentin immunostaining, and a significant decrease in desmin immunostaining during the time of the study. The absolute volume occupied by laminin and fibronectin immunostaining decreased from the 3rd to the 8th weeks of treatment, and increased from the 8th to the 11th weeks. These changes, associated with germ cell depletion and tubular fibrosis, suggest that tubular ischaemic atrophy caused by epinephrine alters the peritubular myoid cells, which change immunophenotype and increase their secretion of the extracellular matrix components producing tubular fibrosis. The mechanism of this alteration may involve direct effects on the peritubular cells or the changes may be secondary to germ cell and/or Sertoli cell lesions.