AJP - Endocrinology and Metabolism, Vol 249, Issue 4 350-E354, Copyright © 1985 by American Physiological Society
By 94 days of gestation plasma cortisol increases block ACTH response to hypotension in lamb fetuses
B. Y. Hargrave and J. C. Rose
By use of a crossover design, we studied the effects of increasing plasma
cortisol concentration on ACTH responses to a standardized stress in 14
lamb fetuses between 94 and 108 days gestation. On a random basis we
assigned the animals into two groups of seven. Animals in groups I and II
received infusions of cortisol (5 and 1 microgram/min, respectively) or
saline for 4 h. After the cortisol or saline pretreatment, we reduced
arterial pressure approximately 40-50% in both groups of animals with
nitroprusside. After saline pretreatment, hypotension in the group I
animals produced an increase in the fetal plasma ACTH from 15 +/- 3 to 200
+/- 20 pg/ml (P less than 0.001), and in the group II animals pretreated
with saline plasma ACTH increased from 21 +/- 4 to 141 +/- 19 pg/ml (P less
than 0.001) with hypotension. Cortisol pretreatment elevated fetal plasma
cortisol levels from 7 +/- 3 to 36 +/- 5 ng/ml in group I and from 8 +/- 4
to 20 +/- 2 ng/ml in group II. The ACTH response to hypotension in both
groups was abolished by the cortisol pretreatment. We conclude that by 94
days gestation increases in plasma cortisol within a physiological range
block ACTH responses to hypotension in lamb fetuses.
