Adenohypophysial Corticotrophin, Plasma Free Corticosteroids and Adrenal Weight Following Surgical Trauma in the Rat

Abstract

1. — Adenohypophysial corticotrophin, plasma free corticosteroids and adrenal weight were studied as ordinates of time following splenectomy in the rat. 2. — Pituitary corticotrophin fell to 50–60% of the control level within 4 hours, remained depressed for periods of 8–20 hours, rose from then on to a peak concentration of 200% reached after 1–4 days, and regressed thereafter to normal values. 3. — Plasma free corticosteroids rose to 600% of the baseline during the first hour and returned to the original level within 24 hours. 4. — Adrenal weight increased to 120% of the control level within 12 hours, stabilized at this level until the 4th postoperative day, and slowly tapered off, from then on, to the normal values recorded after 64 days. 5. — It is inferred from these data that the rates of corticotrophin release and synthesis are accelerated, in successive and overlapping stages, by a mechanism triggered by stress, and depressed, in a similar fashion, by the elevation of the steroid level.