Absence of effect of estrogen on dopamine, norepinephrine and beta-endorphin-like immunoreactivity in human plasma

The plasma concentrations of immunoreactive norepinephrine (NE), dopamine (DA), beta-endorphin (beta-E), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were determined by RIA and HPLC every 6 h until 72 h after iv administration of conjugated estrogens during the midfollicular phase. The LH level showed a biphasic pattern after the injection of conjugated estrogens, i.e. significant suppression (-50%) for 6-42 h after the injection, followed by a rebound increase with a peak (+85%) at 72 h. The plasma levels of immunoreactive beta-E, NE and DA did not change significantly for 72 h after the injection.