Plasma β‐endorphin immunoreactivity in premenstrual tension

Summary. Plasma samples were collected twice during the follicular phase and three times during the luteal phase of the menstrual cycle in 12 women with premenstrual tension (PMT) and in 14 control subjects without symptoms. Concentrations of β-endorphin (β-E) immunoreactivity, cortisol, oestradiol, progesterone and LH were determined. Comparison of the mean concentrations of LH, cortisol, oestradiol and progesterone did not reveal any statistically significant differences between the PMT and the control groups. In the early luteal phase, the mean plasma β-E immunoreactivity was lower in the PMT group (10.7, SE 0.7 pg/ml) than in the control group (14.6, SE 1.6 pg/ml, P<0.05), suggesting that endorphin secretion is decreased in PMT. No significant change in the plasma β-E level was found in the PMT patients between the follicular and luteal phase when symptoms appeared. This does not exclude the possibility that in the central nervous system abnormal changes occur in the activity of endogenous opioids in PMT.