Modulation by progesterone of pain sensitivity to mechanical and ischemic stimuli in young and healthy women - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: to investigate the relationship between pain perception (experimental pain threshold and tolerance, in response to ischemia and pressure) in young and healthy young women and female sexual hormone seric levels (estradiol and progesterone). METHODS: 18 volunteers have participated of this study, during three consecutive menstrual cycles. A pressure algometer and a manual dynamometer have been used to measure painful responses to pressure and ischemia algesic stimuli. Blood has been collected for assessment of both hormonal and painful variables, during three menstrual cycles, whose characterization was based on daily oral temperature record, a diary of the menstrual cycles with the onset and end of each cycle, and on estradiol and progesterone plasmatic levels. The average for the algesic variables measured has been compared by analysis of variance (ANOVA) and the Tukey-Kramer’s post-test, among the menstrual cycle phases (follicular, periovulatory, early luteal, late luteal and menstrual). The Pearson’s test has been used for correlation analysis between algesic and hormonal variables. Statistical significance has been defined as p<0.05. RESULTS: no significant change in pain parameters among the menstrual cycle phases has been observed. Nevertheless, there have been significant negative correlations between progesterone and ischemic threshold (r=-0.23; p<0.01), and pressure tolerance (r=-0.23; p<0.01) at the early luteal phase. CONCLUSIONS: these results indicate that the increase in progesterone levels correlates with a decrease of ischemic threshold and pressure tolerance, suggesting that progesterone plays a role in the pain modulation during the early luteal phase.