Search Results

You are looking at 1 - 2 of 2 items for

  • Author: T Usui x
  • Refine by Access: All content x
Clear All Modify Search
Restricted access

J. Fukata, T. Usui, Y. Naitoh, Y. Nakai, and H. Imura


The effects of recombinant human interleukin (rhIL)-1α, -1β, 2 and 6 on the release of ACTH from the ACTH-producing tumour cell line AtT-20 of the mouse were studied during relatively long periods of incubation. Levels of ACTH in the media, measured by radioimmunoassay, were increased by the addition of rhIL-1α or -1β after latent periods of more than 4 h. RhIL-1α and -1β were almost equally potent in this experiment and the minimum, half-maximum and maximum effective concentrations of both rhIL-1α and -1β were about 0·1 pmol/l, 1–3 pmol/l and 10–100 pmol/l respectively. During incubation with rhIL-1β, immunoreactive ACTH levels and mRNA levels of the ACTH precursor pro-opiomelanocortin in cells also increased without apparent changes in the growth rate of the cells. Although the AtT-20 cells used in this study were quite insensitive to human/rat corticotrophin-releasing hormone (CRH), the cells showed a significant response to CRH after incubation with rhIL-1β. RhIL-6 showed similar effects to those of rhIL-1β on ACTH synthesis and release; increasing ACTH in cells and media after a certain latent period. On the other hand, rhIL-2 did not change ACTH levels in the AtT-20 cells in this study. These observations indicate that rhIL-1α, -1β and rhIL-6 have direct effects on ACTH-producing cells to stimulate the release and synthesis of ACTH after a latent period.

Journal of Endocrinology (1989) 122, 33–39

Free access

T Usui, Y Ikeda, T Tagami, K Matsuda, K Moriyama, K Yamada, H Kuzuya, S Kohno, and A Shimatsu

Some plant compounds or herb mixtures are popular alternatives to conventional therapies and contain organic compounds that bind to some nuclear receptors, such as the estrogen receptor (ER), to exert various biological effects. We studied the effect of various herbal extracts on ERalpha and ERbeta isoforms. One herbal extract, Rhei rhizoma (rhubarb), acts as an agonist to both ERalpha and ERbeta. The phytochemical lindleyin, a major component of rhubarb, might contribute to this estrogenic activity through ERalpha and ERbeta. 4-Hydroxytamoxifen, an ER antagonist, completely reversed the estrogenic activity of lindleyin. Lindleyin binds to ERalpha in vitro, as demonstrated using a fluorescent polarization assay. The in vivo effect of rhubarb extract was studied using a vitellogenin assay system in the freshwater fish, Japanese medaka (Oryzias latipes). There were marked increases in serum vitellogenin levels in male medaka exposed to rhubarb extract. We conclude that lindleyin, a component of some herbal medicines, is a novel phytoestrogen and might trigger many of the biological responses evoked by the physiological estrogens.