Figure 4.

Characterization of Wm-inhibition of basal prolactin secretion in cultured anterior pituitary cells. (A, B) Concentration-dependence of Wm effect on prolactin (PRL) release in pituitary cells in static cultures during 3 h incubation (A) and in perfused pituitary cells (B). Vertical dotted line in (A) indicates the IC₅₀ value. In subsequent experiments, Wm was used at 10 µM concentration. (C) Comparison of the time-course of effects of Wm (black circles) and cycloheximide (CHX), a protein synthesis inhibitor (orange circles), on basal PRL release. Note the different time scale of this experiment vs. panel (B). Vertical dotted lines indicate time points when 50% decrease of hormone secretion was reached, horizontal arrow indicates the difference in half-times, and vertical arrow indicates the beginning of continuous treatments with Wm and CHX. Data points shown in panel A are mean ± SEM of sextuplicate incubation and data shown in panels (B, C) are representative from two experiments. In this and following figures, PRL was measured by radioimmunoassay, unless stated otherwise.