Nuclear Concentration of Gold Labeled-testosterone bovine Serum Albumin Conjugate Injected Intravenously in the Hormone-target Cells of Rat.

Abstract

JapanKey words: testosterone-bovine serum albumin conjugate/target cell nuclei/colloidal gold/silver enhancement/in vivo/electron microscope ABSTRACT. Weexaminedwhether testosterone-bovine serum albumin conjugate (testosterone-BSA) showed similar distribution to radiolabeled testosterone in vivo, by injecting 2-nm colloidal gold labeled-testosterone-BSA (testosterone-BSA-gold) from rat tail vein. The testosterone-BSA-gold with the silver enhancement becamevisible as silver deposits under electron microscope in nuclei of Leydig cells, Sertoli cells, spermatogonia, spermatocytes and spermatids in the testis, those of the epithelial cells in the seminal vesicle and of the cardiac muscle cells in the heart of rat killed 2 h after the injection. Few deposits were present on the non-target cell nuclei in thymus and spleen. In the liver cells, the deposits were observed in the cytoplasm, but few in the nucleus. At high-power magnification without silver enhancement, the gold particles were found in the target cell nuclei in the testis. In control rat injected with BSAlabeled with 2-nm colloidal gold, the percentages of nuclei showing the deposits were fewer than those in the rat injected testosterone-BSA-gold in the target cells. The deposits were also few in the nuclei of non-target cells in control rat. These results suggest that testosterone-BSAgold is useful for morphological study of testosterone target cells, and imply that BSAconjugated with testosterone can enter the target cell nuclei of the rat.

Immunocytochemical Localization of Bovine Serum Albumin (BSA) in the Liver and Testis of Rats injected with Testosterone-BSA, Hydrocortisone-BSA or Corticosterone-BSA.

“…In previous studies in which testosterone-BSA-gold was injected into rats, silver deposits implying the presence of testosterone-BSA-gold were abundantly observed in the nuclei of spermatocytes and round spermatids in the target cells with silver enhancement (Nishimura and Ichihara, 1997;Nishimura and Nakano, 1997). The present study confirms the results of these previous studies, and suggests that testosterone-BSA enters the nuclei of spematocytes and spermatids with the antigenicity of BSA kept intact.…”

“…The nuclear concentration of testosterone-BSA-gold was observed mainly in spermatogenic cells, with few in hepatocytes (Nishimura and Ichihara, 1997), as reported in studies using radiolabeled testosterone (Sar et al, 1970(Sar et al, , 1975. In contrast nuclear localization of hydrocortisone-BSA-gold was done in hepatocytes and hepatic stellate cells (Nishimura and Nakano, 1999).…”

“…Through observations of colloidal gold with silver enhancement, we have demonstrated that 2-nm colloidal gold labeled-testosterone-bovine serum albumin (BSA) conjugate or hydrocortisone-BSA conjugate injected intravenously enters the hormone-target cell nuclei of rats (Nishimura and Ichihara, 1997; Nakano, 1997, 1999). To confirm immunocytochemically whether the nature of BSA in the steroid hormone-BSA conjugates (steroid-BSAs) remains intact in the hormone-target cell nuclei, testosterone-BSA, hydrocortisone-BSA or corticosterone-BSA was injected into the vascular system of rats, then the liver and testes of rats killed 2 h postinjection were reacted with FITC-conjugated anti-BSA antibody, and examined under fluorescence microscopy and confocal laser scanning microscopy.…”

“…Gold labeled-steroid-BSA binds to nuclear receptors in the sectioned cells (Beppu, 1989;Okuda et al, 1989). We have reported that 2-nm colloidal gold labeled-testosterone-BSA (testosterone-BSAgold) and gold labeled-hydrocortisone-BSA (hydrocortisone-BSA-gold) injected into rats enters the hormone-target cell nuclei (Nishimura and Ichihara, 1997;Nakano, 1997, 1999), and have also demonstrated the possibility that testosterone-BSA-gold taken up in the vesicle by receptor-mediated endocytosis can enter the nucleoplasm through the fusion of the vesicle membrane with the partial diaphragm in the nuclear envelope, without coming in direct contact with the cytosol (Nishimura and Nakano, 1997). A wide variety of macromolecules taken up by endocytosis are incorporated by lysosomes, or the Golgi apparatus, or both (Alberts et al, 1994;Claus et al, 1998;Olkkonen and Stenmark, 1997;Rothman and Wieland, 1996).…”

“…In contrast nuclear localization of hydrocortisone-BSA-gold was done in hepatocytes and hepatic stellate cells (Nishimura and Nakano, 1999). In control, there was little nuclear localization of colloidal gold labeled-BSA in these cells (Nishimura and Ichihara, 1997). Since hydrocortisone is not synthesized in rats, corticosterone acts as a glucocorticoid (Pescovitz et al, 1990).…”