Increased Oxidative Stress Underlies Abnormal Pain Threshold in a Normoglycemic Japanese Population

• Main Authors: Sho Osonoi, Hiroki Mizukami, Chieko Itabashi, Kanichiro Wada, Kazuhiro Kudoh, Akiko Igawa, Saori Ogasawara, Yasuyuki Ishibashi, Makoto Daimon, Soroku Yagihashi, Shigeyuki Nakaji
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: International Journal of Molecular Sciences
• Subjects: elevated pain threshold; diabetic polyneuropathy; oxidative stress; 8-hydroxy-2′-deoxyguanosine; normal-high HbA1c; inflammation
• Online Access: https://www.mdpi.com/1422-0067/21/21/8306

Normal-high HbA1c levels are a risk factor for attenuated pain sensation in normoglycemic subjects. It is unclear, however, what mechanisms underlie the pathogenesis of attenuated pain sensation in such a population. We, therefore, explored the relationship between oxidative stress (OS) and pain sensation in a rural Japanese population. A population-based study of 894 individuals (average age 53.8 ± 0.5 years) and 55 subjects with impaired fasting glucose (IFG) were enrolled in this study. Individuals with diabetes were excluded. Relationships between pain threshold induced by intraepidermal electrical stimulation (PINT) and clinico-hematological parameters associated with OS were evaluated. Univariate linear regression analyses revealed age, BMI, HbA1c, the OS biomarker urine 8-hydroxy-2′-deoxyguanosine (8-OHdG), systolic blood pressure, and decreased Achilles tendon reflex on the PINT scores. Adjustments for age, gender, and multiple clinical measures confirmed a positive correlation between PINT scores and urine 8-OHdG (β = 0.09, <i>p</i> < 0.01). Urine 8-OHdG correlated positively with higher HbA1c levels and age in the normoglycemic population. Unlike in the normoglycemic population, both inflammation and OS were correlated with elevated PINT scores in IFG subjects. OS may be a major contributing factor to elevated PINT scores in a healthy Japanese population.