Effects of ligation, orchidectomy, and hypophysectomy on expression of the Yf subunit of GST-P in principal and basal cells of the adult rat epididymis and on basal cell shape and overall arrangement.

Abstract

Glutathione S-transferases (GSTs) are a family of isozymes that catalyze the conjugation of glutathione to various electrophilic compounds. Recently, the Yf subunit of GST-P, found in high concentrations in the epididymis, has been immunolocalized within epithelial principal and basal cells of this tissue. In order to determine which factor(s) were involved in the regulation of expression of this protein, adult rats were orchidectomized and treated with or without testosterone implants, ligated or hypophysectomized. The epididymides were fixed by perfusion with Bouin's fixative and examined with an anti-Yf antibody using light microscope immunocytochemistry. In normal untreated animals, principal cells were reactive in the distal initial segment, intermediate zone and caput epididymidis, but unreactive in all other epididymal regions. Ligation of the efferent ducts up to day 14 had no effect on expression of the Yf protein in principal cells of any region. The staining pattern was comparable to that observed in normal untreated animals suggesting that luminally derived testicular factors were not involved in regulation of Yf expression. Following orchidectomy, principal cells became unreactive by day 14 in all epididymal regions. However, administration of testosterone to orchidectomized animals prevented the loss of reactivity seen in principal cells of the distal initial segment, intermediate zone, and caput epididymidis, suggesting that expression of the Yf protein in principal cells of these regions is regulated by circulating testosterone. In contrast, basal cells after each experimental treatment including hypophysectomy maintained the exact staining pattern observed in normal untreated animals, i.e., they were intensely reactive in the proximal initial segment, distal caput, corpus, and proximal cauda regions, suggesting that expression of the Yf protein in these cells does not require factors derived from the testis or pituitary gland. However, a change in the shape and arrangement of basal cells was noted following each treatment. These cells transformed from flattened hemispherical cells showing thin elongated lateral processes to large bulbous, dome-shape cells closely packed together and showing only a few short lateral processes. In basal cells, expression of the Yf protein is not regulated by testicular or pituitary factors, whereas expression in principal cells is regulated by circulating testosterone. Due to the decrease in size of the epididymal tubules after each treatment, it is postulated that the shape and arrangement of basal cells in normal untreated animals are governed in part by the volume and pressure exerted upon the tubules by luminal fluids and spermatozoa derived from the testis.