Effect of naltrexone treatment on the treadmill exercise-induced hormone release in amenorrheic women

Abstract

The effect of an acute physical stress on hormone secretions before and after a 10-day naltrexone treatment in untrained healthy and amenorrheic women was investigated. Plasma levels of pituitary (LH, FSH, prolactin, GH, ACTH, beta-endorphin) and adrenal (cortisol, androstenedione, testosterone) hormones were measured at rest and in response to 60 min of physical exercise. The test was done both before and after a 10-day naltrexone (50 mg/day) treatment. Graded levels of treadmill exercise (50, 70 and 90% of maximal oxygen uptake (VO2) every 20 min) was used as physical stressor. While mean +/- SE plasma LH levels in control women were higher than in amenorrheic patients and increased following the naltrexone treatment (p < 0.01), no significant differences of basal plasma hormonal levels were observed between amenorrheic and eumenorrheic women, both before and after naltrexone treatment. Physical exercise at 90% VO2 induced a significant increase in plasma GH, ACTH, beta-endorphin, cortisol, androstenedione and testosterone levels in controls before naltrexone treatment (p < 0.01). The mean increase in plasma androstenedione and testosterone levels in control women was significantly higher after naltrexone treatment (p < 0.01). In amenorrheic patients before naltrexone, physical exercise induced an increase in plasma prolactin and GH levels, but not in plasma ACTH, beta-endorphin, cortisol, testosterone and androstenedione. After naltrexone treatment, the exercise induced a significant plasma ACTH, beta-endorphin and cortisol levels, while the increase of plasma prolactin levels was significantly higher than before treatment (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Usos terapéuticos potenciales de los antagonistas opioides: Fisiopatología y evidencia preclínica

“…Sin embargo, estudios clínicos indican que el bloqueo de opioides por medio de naloxona no modifica los niveles de gonadotrofinas ni prolactina en este grupo de pacientes en comparación con atletas eumenorreicos [65] ni tampoco al compararlo con controles [66]. Así, el uso de antagonistas tales como naltrexona para el manejo de la amenorrea inducida por ejercicio o de otros disturbios ginecológicos, puede involucrar otros grupos de hormonas como la ACTH y cortisol [67], o involucrar mecanismos metabólicos [68] que restablecen el ciclo menstrual normal.…”