The existence of a short-loop feedback inhibition of pituitary ACTH release by administration of β-endorphin was postulated. However, data on the effect of peripherally administered β-endorphin in humans are highly controversial. We infused human synthetic β-endorphin at a constant rate of 1 μg · kg−1 · min−1 or normal saline to 7 normal volunteers for 90 min. Thirty min after starting the β-endorphin or placebo infusion, releasing hormones were injected as a bolus iv (oCRH and GHRH 1 μg/kg, GnRH 100 μg, TRH 200 μg) and blood was drawn for measurements of β-endorphin immunoreactivity, all other pituitary hormones, and cortisol. Infusion of β-endorphin resulted in high β-endorphin plasma levels with a rapid decrease after the infusion was stopped. During the control infusion, β-endorphin plasma levels rose in response to CRH. Plasma ACTH and serum cortisol levels in response to the releasing hormone were not different in subjects infused with β-endorphin or placebo. The PRL response to TRH was significantly higher after β-endorphin than after placebo (area under the stimulation curve 1209±183 vs 834±104 μg · 1−1 · h). There was no difference in the response of all other hormones measured. Our data on ACTH and cortisol secretion do not support the concept of a shortloop negative feedback of β-endorphin acting at the site of the pituitary.
EJE is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
|Sept 2018 onwards||Past Year||Past 30 Days|
|Full Text Views||0||0||0|