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Evidence for in vivo high-frequency periodicity of plasma beta-endorphin in humans
B Imthurn1, M Rosselli, J Beran
1Department of Gynecology and Obstetrics, University Hospital, Zurich, Switzerland.
Objective:
To investigate whether high-frequency periodic fluctuation in the release of plasma immunoreactive (ir)-beta-endorphin occurs in humans.
Design, Patients And Measurements:
Blood was collected at 90-sec intervals for 1 hour from the forearm vein of four healthy women and subsequently analysed for ir-beta-endorphin by radioimmunoassay.
Results:
In all women circulating beta-endorphin release followed a high-frequency periodic rhythm pattern. The estimated spectral densities within the four subjects varied between 3.6 min to 4.9 min.
Conclusions:
Our results provide the first in vivo evidence that fluctuations in the release of beta-endorphin in humans cannot only be characterized by low-frequency pulses, but also by a high frequency periodic rhythm.