Suppression of hypothalmic-pituitary-adrenal axis responses to stress in lactating women

J Clin Endocrinol Metab. 1995 Oct;80(10):2954-9. doi: 10.1210/jcem.80.10.7559880.

Abstract

In the rat, lactation suppresses a variety of physiological responses to stress. We investigated whether stress-responsive neurohormonal systems are also restrained during breast feeding in humans. We chose treadmill exercise as a stressor because this stimulus produces an exercise intensity-dependent activation of the hypothalamic-pituitary-adrenal axis and the sympathomedullary system that is independent of differences in physical conditioning among subjects. Ten lactating and ten nonlactating women who were between 7 and 18 weeks postpartum performed 20 min of graded treadmill exercise. The final 5 min of exercise was set to elicit 90% of the maximal oxygen uptake of each subject. Plasma ACTH, cortisol, and glucose responses to exercise were significantly attenuated in lactating women (P < 0.001, P < 0.05, and P < 0.001, respectively). Basal norepinephrine levels were also reduced in lactating women (P < 0.05). These results indicate that stress-responsive neurohormonal systems are restrained in lactating women.

Publication types

  • Comparative Study

MeSH terms

  • Adrenocorticotropic Hormone / blood
  • Adrenocorticotropic Hormone / metabolism
  • Adult
  • Animals
  • Blood Glucose / metabolism
  • Epinephrine / blood
  • Estradiol / blood
  • Estradiol / metabolism
  • Exercise Test*
  • Female
  • Hormones / blood
  • Hormones / metabolism*
  • Humans
  • Hydrocortisone / blood
  • Hydrocortisone / metabolism
  • Hypothalamo-Hypophyseal System / physiology*
  • Lactation / physiology*
  • Norepinephrine / blood
  • Oxytocin / blood
  • Oxytocin / metabolism
  • Pituitary-Adrenal System / physiology*
  • Postpartum Period / physiology*
  • Prolactin / blood
  • Prolactin / metabolism
  • Rats
  • Stress, Physiological*
  • Time Factors
  • Vasopressins / blood
  • Vasopressins / metabolism

Substances

  • Blood Glucose
  • Hormones
  • Vasopressins
  • Estradiol
  • Oxytocin
  • Adrenocorticotropic Hormone
  • Prolactin
  • Hydrocortisone
  • Norepinephrine
  • Epinephrine