SERUM PROFILES OF OXYTOCIN DURING ORAL-CONTRACEPTIVE TREATMENT

Serum profiles of oxytocin were studied by means of a continuous blood sampling system in five young healthy women before and during treatme nt with a combined oral contraceptive. Oxytocin levels were determined by a specific radioimmunoassay in blood samples collected in 10-min f ractions from 22.00 to 06.00. The values were further analyzed by the pulse detection program PULSAR. Great individual differences in oxytoc in profiles were observed, and in some of the women these differences were also pronounced between the two sampling occasions. All 10 profil es demonstrated irregular peaks which occurred with varying frequency. Although the baseline level of oxytocin increased in all women and th e average concentration increased in four of the women during treatmen t, there was no clear-cut effect on the peak frequency. Based on resul ts from animal experiments, it is suggested that the increase in oxyto cin levels may be related to an excitatory effect exerted by estrogen on oxytocin secreting neurons.