Cardiovascular Responses to Tonic Pain in REM Sleep-Deprived Rats Role of Melatonin and Beta Endorphin
Journal Title: Sultan Qaboos University Medical Journal - Year 2006, Vol 6, Issue 1
Abstract
Objective: Chronic pain is associated with increased incidence of hypertension. Sleep deprivation, common in patients with chronic pain, is associated with increased blood pressure and heart rate. Tis study was designed to determine whether sleep deprivation induces increased cardiovascular responses to pain. In addition; we examined the role of melatonin and endorphins in mediating these responses. Method: Te study was conducted in Sprague-Dawely rats divided into a control group (n=8) and Rapid Eye Moment sleep deprived (REMSD) group (n=8). REM sleep deprivation was done for three days using the inverted flowerpot technique. Systolic BP and HR were recorded at baseline as well as 5, 10 and 30 minutes after intra-plantar formalin injection. In addition, serum melatonin and endorphin levels were determined. Results: Under basal conditions, BP and HR and following acute pain (1st phase of formalin injection) were comparable with non-sleep deprived (non-SD) state. In contrast, the REMSD rats showed significantly greater increases in HR and BP during the 2nd phase of formalin pain as compared to non-SD state. Tese changes were associated with significant reductions in serum melatonin and endorphin levels in REMSD rats. Conclusion: Tese data indicate that exaggerated blood pressure and HR responsiveness to pain in sleep deprivation could be mediated through reductions in melatonin and endorphin.
Authors and Affiliations
Salah Kassab| Department of Physiology, College of Medicine and Medical Sc-iences, Arabian Gulf University, P.O. Box 22979, Manama, Bahrain, Usha Sachdeva| Department of Physiology, College of Medicine and Medical Sc-iences, Arabian Gulf University, P.O. Box 22979, Manama, Bahrain, Nagalla Das| Department of Clinical Biochemistry, Salmaniya Medical Complex, Bahrain, Tarik Al-Shaibani| Department of Physiology, College of Medicine and Medical Sc-iences, Arabian Gulf University, P.O. Box 22979, Manama, Bahrain, Usha Nayar| Department of Physiology, College of Medicine and Medical Sc-iences, Arabian Gulf University, P.O. Box 22979, Manama, Bahrain
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