Effect of gestational age, CRF and cortisol on ACTH secretion from slices of fetal sheep pituitaries in an in vitro perifusion system.

Abstract

We have investigated whether increasing gestational age has an effect on basal and K(+)- or CRF-stimulated ACTH secretion from slices of anterior pituitary from fetal sheep. We have also determined whether cortisol acts to inhibit basal or CRF-induced ACTH secretion from the fetal sheep pituitary between 106 and 144 days of gestation (term = 145 +/- 3 days of gestation). Four slices were collected from each fetal sheep pituitary at 106-116 (n = 4 pituitaries), 120-124 (n = 4), 130-137 (n = 8) and 140-144 days (n = 11) and perifused with Krebs buffer bubbled with 95% O2 and 5% CO2 at 37 degrees C. Slices were perifused for at least 120 min prior to one of the following treatments: K+ (100 mM); CRF (two separate boluses, 10 nM, administered 120 min apart); cortisol (100 nM, 30-min infusion), or cortisol (30-min infusion) with a CRF bolus administered 10 min after the start and 90 min after the end of the cortisol infusion. The basal output of ACTH (pg/mg/120 min) did not change significantly between 106 and 144 days of gestation. Bolus administration of K+ or CRF stimulated pituitary ACTH secretion above baseline values for 10 min at all ages.(ABSTRACT TRUNCATED AT 250 WORDS)