Hisao Nishimura

Immunohistochemical localization of metallothionein in the eye of rats

SummaryIn order to elucidate possible physiological roles of metallothionein (MT), we have studied immunohistological localization of MT in the eye of the rat, using an avidin-biotin peroxidase complex method. As a result, strong MT immunostaining was observed in the epithelium of the lens and cornea. In the retina, considerably strong MT immunostaining was observed in the pigment cell layer while the nerve fiber layer and inner plexiform layer showed weak MT staining. Glial cells in the optic nerve were found to have marked MT staining. The present result is consistent with the hypothesis that MT may be involved not only in activation of zinc enzymes and cell proliferation through supply of zinc ions, but also in a protective mechanism in the blood-retina barrier.

Metallothionein mRNA in the testis and prostate of the rat detected by digoxigenin-labeled riboprobe

Metallothionein (MT), a cysteine-rich heavy metal-binding protein, has been considered to play a role in the homeostatic control and detoxification of heavy metals, such as zinc, copper, and cadmium. In the present study, we have utilized a digoxigenin-labeled riboprobe to localize MT mRNA only by bright-field optics in the testis and prostate of the rat. In the rat testis, MT mRNA was found predominantly in primary spermatocytes and also in secondary spermatocytes and spermatids, but not in the spermatogonia, Sertoli cells, and Leydig cells. On the other hand, MT protein was present in these spermatogenic cells as well as in spermatozoa and Sertoli cells. In the prostate, MT mRNA was found predominantly in the epithelium of the dorsolateral lobes, but not in the ventral lobe, which is in agreement with the observed localization of MT protein. The utilization of both in situ hybridization and immunohistochemical staining on the same tissue specimens show MT gene expression in specific cell types in the male genital organs.

POSSIBLE ROLE OF METALLOTHIONEIN IN THE CELLULAR DEFENSE MECHANISM AGAINST UVB IRRADIATION IN NEONATAL HUMAN SKIN FIBROBLASTS

Abstract –The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS‐K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40‐HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.

Biliverdin initiates the liver regeneration in the rat — A hypothesis

Abstract Biliverdin has been observed to occur in the blood plasma of a 90% hepatectomized rat. It is also shown that the bile pigment induces a rise in mitotic index in the hepatic parenchymal cells of an intact rat at about 30 h and an elevated rate of hepatic DNA synthesis at 26 h after a single intraperitoneal injection. Hemoglobin, bilirubin, hemin, and protoporphyrin exhibited some of the inducing activity at lower degrees. It is hypothesized that biliverdin initiates the liver-cell-multiplication.

Immunohistochemical Localization of Metallothionein in Organs of Rats Treated with either Cadmium, Inorganic or Organic Mercurials

Metallothionein (MT) is a low, molecular, mass protein inducible by heavy metals such as cadmium (Cd), zinc and copper and having high affinity for these metals. In the present study, we have investigated immunohistological localization of metallothionein in the kidney and brain of rats treated with either Cd, inorganic mercury (Hg) or organic Hg.