Studies have demonstrated menstrual cycle influences on basal pain perception, but direct evidence of menstrual cycle influences on analgesic responses has not been reported in humans. Our aim was to determine whether the magnitude of morphine and pentazocine analgesia varied across the menstrual cycle. Sixty-five healthy women, 35 taking oral contraceptives (OC) and 30 normally cycling (NOC), underwent experimental pain assessment both before and after intravenous administration morphine (0.08 mg/kg) or pentazocine (0.5 mg/kg) compared to saline placebo. Both active drug and placebo were administered once during the follicular phase and once during the luteal phase. Measures of heat, ischemic and pressure pain sensitivity were obtained before and after drug administration. Change scores in pain responses were computed to determine morphine and pentazocine analgesic responses, and medication side effects were recorded. The data were analyzed using mixed-model ANOVAs. NOC women showed slightly greater heat pain sensitivity in the follicular vs. luteal phase, while the reverse pattern emerged for OC women (p=0.046). Also, OC women showed lower pressure pain thresholds compared to NOC women (p < .05). Regarding analgesic responses, NOC women showed greater morphine analgesia for ischemic pain during the follicular vs. the luteal phase (p=0.004). Likewise, side effects for morphine were significantly higher in NOC women in the follicular phase than in the luteal phase (p=0.02). These findings suggest that sex hormones may influence opioid responses; however, the effects vary across medications and pain modalities and are likely to be modest in magnitude. KeywordsMenstrual Cycle; Morphine; Pentazocine; Analgesic Response; Pain Sensitivity; Opioid Side Effect Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.There are no conflicts of interest. NIH Public Access Author ManuscriptPain. Author manuscript; available in PMC 2012 March 1. 1-IntroductionThe body is widely responsive to gonadal steroid hormones. Aside from their reproductive functions, gonadal hormones act on nervous system regions involved in higher cognitive functions such as mood, motor behavior, and pain mechanisms [33]. For example, pregnancy-related changes in reproductive hormone levels increase pain thresholds and decrease anesthesia requirements in humans and some non-human animals; a phenomenon that can be re-created by hormonal simulation in non-pregnant animals [22,41]. The influence of gonadal hormones, particularly estrogens, has been implicated as a potential mechanism for explaining sex difference...

Introduction: Conditioned pain modulation (CPM) is a laboratory test resulting in pain inhibition through activation of descending inhibitory mechanisms. Older adults consistently demonstrate reduced CPM compared with younger samples; however, studies of sex differences in younger cohorts have shown mixed results. Objectives: This study tested for sex differences in CPM within samples of younger and older adults. Methods: Participants were 67 younger adults (mean age = 25.4 years) and 50 older adults (66.4 years). Study conditioning paradigms were the cold-pressor test and contact heat pain administered in separate sessions. Pressure pain threshold and ramping suprathreshold heat were the test stimuli across three time points after presentation of the conditioning stimuli (CS). Results: Significant inhibition was observed during both testing sessions. The hypothesis for sex differences across both age cohorts was supported only for ∆PPTh. However, sex differences did not reach significance for either paradigm using ascending suprathreshold heat as the test stimuli. The overall trend was that younger males experienced the strongest CPM and older females the weakest. From a methodological perspective, duration differences were seen in CPM, with inhibition decaying more quickly for PPTh than for suprathreshold heat pain. Furthermore, there were no differences in inhibition induced by cold-pressor test and contact heat pain as CS. Conclusion: Sex differences were similar across both age cohorts with males experiencing greater inhibition than females. Cross-sectional associations were also demonstrated between CPM inhibition and measures of recent pain, further supporting CPM as an experimental model with clinical utility.

AIM: The aim of this study was to test the influence of acculturation and socioeconomic status on orofacial pain selfcare across race/ethnicity stratified by sex among South Florida residents, using a sample of residents of Miami-Dade and Broward counties in Florida. METHODOLOGY:This study reports data on respondents who self-endorsed their race and ethnicity as Hispanic, non-Hispanic White, or non-Hispanic Black and reported tooth pain (n=1,767) or jaw joint/face pain (n=1,199). Acculturation was associated with self-care use for pain among Whites and Hispanics. Socioeconomic status (SES) was associated with several self-care behaviors and was most predictive among White women. Acculturation towards other ethnic groups led to differential self-care use dependent on the type of self-care, pain condition, and ethnicity. RESULTS: Black and Hispanic women were greater users of self-care for orofacial pain than other sex/ethnicities. CONCLUSION:The associations between SES and self-care were stronger in White women than in Black and Hispanic women.