Effect of hypophysectomy on plasma catecholamines and enkephalins in fetal sheep

The aim of this study was to determine the effect of fetal hypophysectomy on the plasma concentrations of catecholamines and enkephalins in the fetal sheep between 120 and 140 days gestation under basal and hypoxic conditions. During basal conditions, there was no difference in the plasma concentrations of norepinephrine and epinephrine between intact and hypophysectomized groups. Fetal plasma norepinephrine concentrations were significantly increased during hypoxia in intact fetal sheep (7.2 +/- 2.2 pmol/ml, -15 min; 20.2 +/- 7.7 pmol/ml, 30 min) between 130 and 140 days, but after fetal hypophysectomy there was no significant norepinephrine response to hypoxia at this gestational age (4.7 +/- 1.3 pmol/ml, -15 min; 8.8 +/- 2.8 pmol/ml, 30 min). In contrast, fetal plasma epinephrine concentrations were significantly increased during hypoxia in both the intact (1.5 +/- 0.5 pmol/ml, -15 min; 3.3 +/- 1.7 pmol/ml, 30 min) and hypophysectomized groups (1.8 +/- 0.6 pmol/ml, -15 min; 6.8 +/- 4.1 pmol/ml, 30 min) between 130 and 140 days. During basal conditions, plasma concentrations of free Met-Enk were significantly less in hypophysectomized fetal sheep (170.8 +/- 34.3 pg/ml; 120-140 days) than in intact fetal sheep (305.6 +/- 47.3 pg/ml). There were no differences, however, in the fetal plasma concentrations of total Met-Enk between the intact (18.0 +/- 1.9 ng/ml) and hypophysectomized (16.9 +/- 2.6 ng/ml) groups. During hypoxia, there were no changes in the fetal plasma concentrations of either free or total Met-Enk in the intact or hypophysectomized groups.(ABSTRACT TRUNCATED AT 250 WORDS)