Uzawa Hironobu, Takeuch Shinta, Nishida Yusuke
Department of Physical Therapy, International University of Health and Welfare, Narita, Chiba, Japan.
Department of Rehabilitation, International University of Health and Welfare (IUHW) Narita Hospital, Narita, Chiba, Japan.
Pain Rep. 2024 Feb 1;9(2):e1123. doi: 10.1097/PR9.0000000000001123. eCollection 2024 Apr.
Sex differences in conditioned pain modulation (CPM) have not been sufficiently explored.
This pilot study aimed to examine sex differences in CPM effects and associations between autonomic activities and CPM effects in healthy, younger individuals.
University students were recruited from February to March 2021 and divided by sex. They remained seated for 10 minutes as a rest period, then immersed their right hands in cold water for 2 minutes as a cold period. The pressure pain threshold (PPT) was measured after each period, presenting the CPM index (%) using the formula: (PPT/PPT) × 100. Autonomic nervous system variables were calculated using the formula-(autonomic variable/autonomic variable) × 100-and suffixed by "index" such as low-frequency/high-frequency (LF/HF) index. Some psychological questionnaires were self-recorded. Sex differences in the CPM index were statistically compared, and a simple linear regression analysis between the CPM and autonomic indices was conducted.
Thirty-two participants were analyzed (14 women and 18 men; aged 21.1 ± 0.6 and 20.9 ± 0.3 years, respectively). Conditioned pain modulation effects were not different at 127.0 ± 19.1% in women and 124.0 ± 18.7% in men. The LF/HF index, LF normalized unit (nu) index (LFnu), and HFnu index had significant predictor variables for the CPM index across overall samples. The LF/HF index and LFnu index were significant predictor variables for the CPM index for women but not for men.
Conditioned pain modulation effects between groups seem to be similar. The LF/HF and LFnu indices in women were significant, indicating that descending pain modulations in women might be more associated with autonomic activities than those in men.
条件性疼痛调制（CPM）中的性别差异尚未得到充分研究。
本初步研究旨在探讨健康年轻个体中CPM效应的性别差异以及自主神经活动与CPM效应之间的关联。
于2021年2月至3月招募大学生并按性别分组。他们先静坐10分钟作为休息期，然后将右手浸入冷水中2分钟作为冷刺激期。在每个阶段后测量压力疼痛阈值（PPT），使用公式（PPT/PPT）×100计算CPM指数（%）。自主神经系统变量使用公式 -（自主神经变量/自主神经变量）×100计算，并后缀“指数”，如低频/高频（LF/HF）指数。一些心理问卷由受试者自行填写。对CPM指数的性别差异进行统计学比较，并对CPM指数与自主神经指数进行简单线性回归分析。
共分析了32名参与者（14名女性和18名男性；年龄分别为21.1±0.6岁和20.9±0.3岁）。女性的条件性疼痛调制效应为127.0±19.1%，男性为124.0±18.7%，两者无差异。在整个样本中，LF/HF指数、低频标准化单位（nu）指数（LFnu）和高频nu指数是CPM指数显著的预测变量。LF/HF指数和LFnu指数是女性CPM指数的显著预测变量，而对男性则不然。
各组间的条件性疼痛调制效应似乎相似。女性的LF/HF和LFnu指数具有显著性，表明女性下行性疼痛调制可能比男性更与自主神经活动相关。
