Effect of oral contraceptives on plasma beta-endorphin and corticotropin at rest and during exercise.
Concentrations of immunoreactive beta-endorphin and corticotropin in plasma were studied in 27 healthy physically active women at rest and after the exercise test on a treadmill requiring 60% and 90% of the maximal oxygen consumption. Eleven of the subjects were on a combination-type of oral contraceptive pills, and the remaining 16 did not use any pills. Plasma immunoreactive beta-endorphin levels at rest were higher in pill non-users than in pill users. Corticotropin levels at rest did not differ between the pill users and non-users. After the 60% exercise test a slight increase was found in the concentrations of corticotropin and beta-endorphin in the pill non-users but not in the pill users. In the 90% exercise test, plasma beta-endorphin and corticotropin levels increased significantly in both groups. We conclude that the use of oral contraceptives may elevate the threshold of the intensity of exercise required to increase beta-endorphin and corticotropin secretion. Decreased resting concentration of beta-endorphin in pill users can be explained by suppression of normal cyclic ovarian function.
Rahkila
P
P
Rehabilitation and Physical Exercise Center, Peurunka, Laukaa.
Laatikainen
T
T
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000328:Adult; D003277:Contraceptives, Oral, Combined / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D010101:Oxygen Consumption; D001615:beta-Endorphin / Q000097:blood*
D003277:Contraceptives, Oral, Combined; D007773:Lactates; D019344:Lactic Acid; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone