RESUMO
PURPOSE: The aim of the present study was to investigate the modulation of pain perception, estimate by both threshold and tolerance to ischemic and pressure stimuli, by cortisol and humor states across the menstrual cycle. METHODS: Threshold and tolerance pain to ischemic and pressure stimuli were determined in eighteen healthy young women. The menstrual cycle phases were determined using oral temperature, documentation of the first and last day of menstruation and plasma levels of progesterone and estradiol. Statistical analysis using linear regression model (R2) indicate which hormonal variables (estradiol, progesterone and cortisol) and/or variables obtained from the questionnaire Profile of Mood States (POMS) (fatigue, tension, anger, vigor, confusion and depression) explain, isolated or together, each one of the pain parameters during the five phases of the menstrual cycle. RESULTS: In the follicular, periovulatory, early-to-middle luteal and menstrual phases hormones and subjective variables from POMS explained the responses for pain threshold and tolerance to ischemic and pressure stimulus. Estradiol (during follicular, peri-ovulatory and menstrual phases) and cortisol (during follicular, early-to-mid luteal and mestrual phases) explain only the pain perception to pressure. The differential participation of the hormones in the two types of pain suggests that estradiol, and probably cortisol, modulate the pathways related to pressure but not those related to ischemic pain. On the other hand only the mood states variables explained pain perception during late luteal phase. CONCLUSIONS: The analysis of hormonal and subjective variables (POMS) together, associated to detailed characterization of the menstrual cycle suggest that participation of estradiol and cortisol modulate pain perception to pressure stimulus but not to ischemic one. Indeed, suggest that in healthy women with regular menstrual cycles, only subjective variables explained pain perception during late luteal phase of menstrual cycle.