Acute effect of triiodothyronine on the dynamics of thyrotropin release from superfused anterior pituitary cells

Kunio Shiota, Keiji Yoshida, Masahiro Kawase, Tsuneo Masaki, Katsuichi Sudo

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The effects of triiodothyronine (T3) on the dynamics of thyrotropin (TSH) release induced by TSH-releasing hormone (TRH) were examined in the presence or absence of a protein synthesis inhibitor, cycloheximide (CX), in a superfusion system using primarily cultured cells of the rat anterior pituitary gland on microcarrier beads. When the cells were continuously stimulated with TRH (10 nM, 180 min), TSH release occurred in a biphasic manner and the profile of TSH release was characterized by an initial sharp peak (phase I), followed by a lower plateau form phase (phase II). Both phase-I and phase-II releases were significantly suppressed in the presence of T3 (1 ng/ml), which was added to the superfusion medium l h before initiation of TRH stimulation. The biphasic nature of the release profile was maintained in the presence of T3, suggesting that the site of the T3 action may be common between phase-I and phase-II release. We have already suggested that phase-I release is protein synthesis-independent and phase-II release protein synthesis-dependent using CX in TRH-stimulated cells. In the presence of CX, phase-I release was not suppressed by T3, while phase-II release was still suppressed by T3. The inability of CX to reverse the T3-induced suppression of phase-II release may be masked by the direct CX effect on phase-II release of TSH. The present study indicates that each component (phase I and phase II) of the biphasic release of TSH induced by TRH stimulation was acutely suppressed by T3 and suggests that the T3 action is mediated through protein synthesis.

Original languageEnglish
Pages (from-to)79-84
Number of pages6
JournalMolecular and Cellular Endocrinology
Volume41
Issue number1
DOIs
Publication statusPublished - 1985
Externally publishedYes

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Keywords

  • anterior pituitary
  • negative feedback
  • protein synthesis
  • thyrotropin
  • thyrotropin-releasing hormone
  • triiodothyronine

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

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