Immunochemical distribution of 20beta-hydroxysteroid dehydrogenase (HSD) in neonatal
pig tissues was investigated by Western blot analysis of the proteins reacting with
anti-20beta-HSD antibody. 20beta-HSD was present in all organs investigated: brain,
lung, thymus, submandibular gland, heart, liver, kidney, spleen, adrenal gland, testis,
epididymis, prostate, vas deferens and seminal vesicle. In particular, high concentrations
of 20beta-HSD were detected in the testis, followed by the kidney and liver, by the
[125I]-protein A binding method. Immunohistochemical localization of the enzyme was
achieved in paraffin sections of the testis, kidney, liver, epididymis, and vas deferens
by the streptoavidin-biotin complex method. In the testis, very strong immunostaining
was found only in interstitial Leydig cells, whereas the cells in seminiferous tubules,
such as Sertoli cells and spermatogenic cells, were entirely negative. In the kidney,
strong immunostaining was detected in epithelial cells of Henle's loop. The immunoreactive
proteins were also localized in the hepatic lobules of the liver, tall columnar cells
of the ductus epididymidis of the epididymis, and mucosal epithelium cells and muscularis
of the vas deferens. These observations indicate that tissue distribution of 20beta-HSD
is similar to that of carbonyl reductase in the human and rat. However, the specific
and abundant expression of 20beta-HSD in testicular Leydig cells of the neonatal pig,
which are concerned with the synthesis of androgens, suggests that 20beta-HSD has
a very important physiological role in testicular function during the neonatal stage.