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Gynecol Endocrinol. 1994 Jun;8(2):121-6.

Serum profiles of oxytocin during oral contraceptive treatment.

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Department of Woman and Child Health, Karolinska Hospital, Stockholm, Sweden.


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


In Sweden, to establish secretory profiles of oxytocin, a portable, battery-charged eccentric pump effected continuous blood sampling from an antecubital vein over an 8-hour period in 5 healthy 21-29 year old women before they began treatment with an oral contraceptive (OC) containing 30 mcg ethinyl estradiol and 150 mcg desogestrel. Secretory profiles of oxytocin were also obtained 2-3 months after OC treatment. The PULSAR program analyzed the profiles. There were considerable individual differences in the oxytocin profiles with regard to shape and oxytocin concentration. In some women, the before and after profiles were very different from each other. The baseline oxytocin level increased in all women during OC treatment (31-56 fmol/ml; p = 0.043). In 4 women, the mean oxytocin level also increased. Peaks lasted anywhere from 10 to 60 minutes and did not occur regularly. Neither OC treatment nor the absence of OC treatment effected peak occurrence. Findings from animal research suggest that estrogen may exert an excitatory effect on oxytocin secreting neurons, resulting in a rise in oxytocin levels.

[Indexed for MEDLINE]

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