Background and objective
Evidence has accumulated that men and women show different responses to noxious stimuli, with women exhibiting greater sensitivity to pain than men . Data concerning sex differences in cortisol response patterns have revealed inconsistent results so far. While some studies showed no differences in cortisol reaction to psychosocial stress others found marked sex differences showing higher cortisol levels in men [2,3]. The purpose of the present study was to examine sex differences in cortisol reaction to a noxious stressor.
Seventy-six subjects (39 male and 37 female) participated in a modification of cold-pressor stimulation that consisted of periodic exposure of the hand into ice water (plunge-test, PT) . The whole PT consisted of two consecutive trials and at each trial tolerance time and pain ratings (VAS) were assessed. Eight saliva samples (c1-c8) were collected to determine cortisol levels at baseline (c1-c3), directly before (c4) and 20 min after noxious stress (c5), and during the recovery period (c6-c8).
We found no significant sex differences in tolerance time for PT1 (F (1/74) = 3.04, P < 0.10) but highly significant differences in tolerance time for PT2 (F (1/74) = 7.59, P < 0.01), indicating higher tolerance times in men (Fig. 1). No significant sex differences were found for pain intensity and unpleasantness in the two trials. However, a significantly larger cortisol increase was observed in men compared to women (F (1/72) = 5.30, P < 0.05) (Fig. 2). MANCOVA revealed that this result could not be attributed to sex differences in tolerance time.
The present study demonstrates that men show a larger cortisol response to a noxious stressor than women that is not attributable to sex differences in subjective pain. Our findings corroborate results of earlier studies [1,2] showing stronger cortisol reactions in men to psychosocial stress. A causal relation between larger cortisol responses and higher pain tolerance thresholds in men is yet speculative but a putative analgesic action of cortisol could also be derived from endocrine studies in chronic pain patients.
This study was supported in part by a grant from the Deutsche Schmerzstiftung. We thank Conny Würz of the University of Marburg for conducting the salivary cortisol assays.
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