Increased Pain Sensitivity In Low Blood Pressure Is Independent Of Circulating Beta Endorphin

Objectives: Sex, age, race/ethnic differences and blood pressure variability in pain have been reported in clinical and experimental research. However, it is not known whether cold and ischemic-induced pain models will explain variability in pain perception associated with low blood pressure. β-endorphin, has been shown to have an inhibitory role in pain pathway. The current study was designed to investigate the effect of low blood pressure on pain perception in healthy Nigeria human subjects and to possibly know if the variability in pain perception is dependent of circulating level of β-Endorphin. Methods: One hundred and sixty healthy volunteers are randomly selected from the four main ethnic groups in Nigeria (consisting of 40 volunteers from each tribe; Fulani, Hausa, Igbo and Yoruba). These individuals were recruited, informed what they should expect during the study and informed consent was obtained. Questionnaires were administered to gather volunteers’ biodata and socio-demographic background. Cold, ischemia and cold + ischemia- indued pain was administered, and the pain threshold and tolerance were estimated. Results: Our results show that low blood pressure group has significantly lower threshold/tolerance in cold-induced pain model and in ischemia-induced pain model with no significant difference in circulating level of beta endorphin. Conclusion: The present study demonstrates that low blood pressure leads to increase in pain perception and this is independent of circulating level of β-Endorphin.