Estradiol, but not testosterone, heightens cortisol-mediated negative feedback on pulsatile ACTH secretion and ACTH approximate entropy in unstressed older men and women

What Was Tested

This randomized controlled trial paper looks at ACTH (Corticotropin) and Leuprolide.

To test this hypothesis, 24 men and 24 women age 58 ± 2.4 yr were pretreated with leuprolide and either sex steroid (E2 in women, T in men) or placebo addback.

Placebo or ketoconazole (KTCZ) was administered overnight to inhibit adrenal steroidogenesis during overnight 14-h intravenous infusions of saline or cortisol in a continuous versus pulsatile manner to test for feedback differences.

Why It Was Studied

How sex steroids modulate glucocorticoid feedback on the hypothalamic-pituitary-corticotrope (HPC) unit is controversial in humans.

The researchers postulated that testosterone (T) in men and estradiol (E2) in women govern unstressed cortisol-mediated negative feedback on ACTH secretion.

Who Took Part

According to the abstract, 24 men were involved.

PubMed indexes the participants as middle-aged adults, both men and women.

How the Study Was Run

The design is described as randomized, double-blind, placebo-controlled and crossover.

Random assignment meant chance, not the researchers, decided who got ACTH (Corticotropin) and who got the comparison, which limits bias.

Neither the men nor the staff measuring them knew who was on ACTH (Corticotropin), so expectations could not easily colour the readings.

Some men received a placebo instead of ACTH (Corticotropin), giving a reference point.

In the crossover set-up each of the men took both ACTH (Corticotropin) and the comparison in turn, acting as their own control.

ACTH was measured every 10 min during the last 8 h of the infusions.

What Was Measured

The researchers postulated that testosterone (T) in men and estradiol (E2) in women govern unstressed cortisol-mediated negative feedback on ACTH secretion.

The main outcome measures were mean ACTH concentrations, pulsatile ACTH secretion, and ACTH approximate entropy (ApEn).

Topics PubMed links to this paper include Adrenocorticotropic Hormone, Age Factors, Aging, Enzyme Inhibitors, Estradiol, Feedback, Physiological and Hydrocortisone.

Author keywords: adrenocorticotropin, glucocorticoids, pulsatile, regulation and sex steroids.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of ACTH (Corticotropin) and Leuprolide in 24 men.

With fewer than 40 people, it is a small study, so it is better read as an early signal for further research than as a settled answer.

The publication is from 2014 (American journal of physiology. Regulatory, integrative and comparative physiology), a journal based in United States.

More context: the ACTH (Corticotropin) compound page and the Leuprolide compound page, all human trials.