Progesterone relates to enhanced incisional acute pain and pinprick hyperalgesia in the luteal phase of female volunteers.

ABSTRACT

The role of sex hormones on postsurgical pain perception is basically unclear. Here, we studied the role of endogenous gonadal hormones for pain and hyperalgesia in human volunteers after experimental incision. A 4-mm incision was made in the volar forearm of 15 female volunteers both in the follicular and the luteal phase (random block design). Somatosensory profiles were assessed at baseline and 1 to 72 hours after incision by quantitative sensory testing, compared between both cycle phases, and related to individual plasma levels of gonadal hormones. Sensory testing at baseline revealed significantly lower pain thresholds (25 vs 46 mN, P < 0.005) and increased pain ratings to pinprick (0.96 vs 0.47, P < 0.0001) in the luteal phase; similarly, 1 hour after incision, pain intensity to incision (38 vs 21/100, P < 0.005), pinprick hyperalgesia by rating (P < 0.05), and area of secondary hyperalgesia (P < 0.001) were enhanced in the luteal phase. Multiple regression analysis revealed that pinprick pain sensitivity at baseline was significantly predicted by progesterone (partial r = 0.67, P < 0.001), follicle-stimulating hormone (FSH) (partial r = 0.61, P < 0.005), and negatively by testosterone (partial r = -0.44, P < 0.05). Likewise, incision-induced pain and pinprick hyperalgesia (rating and area) were significantly predicted by progesterone (partial r = 0.70, r = 0.46, and r = 0.47, respectively; P < 0.05-0.0001) and in part by FSH; the contribution of estrogen, however, was fully occluded by progesterone for all measures. In conclusion, pinprick pain and incision-induced pain and mechanical hyperalgesia were greater in the luteal phase and predicted by progesterone, suggesting a major role for progesterone. Other hormones involved are testosterone (protective) and in part FSH.