Studies on ACTH Dynamics in Cultured Adenohypophyseal Cells: Effect of Adrenalectomy or Dexamethasone in Vivo

Abstract

Basal or hypothalamic extract-induced ACTH or TSH [thyrotropin] secretory capacity and intracellular ACTH content were assessed in cultured rat adenohypophyseal cells after various pretreatments of the donor animals. Medium and intracellular ACTH or TSH were measured by radioimmunoassay. Ten days to 2 mo. adrenalectomy enhanced, whereas dexamethasone pretreatment suppressed, synthesis and secretion of ACTH in the adenohypophyseal cells. Dexamethasone may also impair the replication of the adenohypophyseal cells in vivo, as indicated by the smaller number of cells obtained per animal in the dexamethasone-treated group. No significant increase in TSH secretion was observed when adenohypophyseal cells were derived from rats fed propyl-thiouracil (PTU) for 3 wk instead of from intact rats.