Effects of Central Command Induced by Repetitive Pain Experiences on Hemodynamic Responses during the Cold Pressor Test

Abstract

Background Central command (CC) is a neural activity that originates in the cerebral cortex and plays an important role in predictive circulatory regulation. It also controls circulation before the onset of habitual exercise. However, it is unclear whether CC induced by repetitive pain experiences has a predictive effect on hemodynamic responses before and/or during the same pain stimuli. We investigated whether repetitive pain stimuli evoked by the cold pressor test (CPT) alter cardiovascular responses to CPT and placebo tests. Methods Seven healthy young adults [age, 29 ± 8 (SD) years] were placed in the supine position. Beat-to-beat systolic and diastolic blood pressures (SBP and DBP, respectively), and heart rate (HR) were continuously measured during the 5-min rest, 30-s countdown (Q) before CPT, 2-min CPT, and 3-min recovery (CNT). Thereafter, the same protocols were repeated randomly with the second CPT (CPT+CC) or placebo test (PLCB+CC) with 20-min intervals. Results SBP tended to increase and be higher in CPT+CC and PLCB+CC than in CNT during Q. In addition, SBP increased significantly in a shorter time after the onset of CPT, and the peak value was higher in CPT+CC than in CNT (138 ± 17 vs. 152 ± 24 mmHg: P < 0.05). DBP significantly increased in both the CNT and CPT+CC during CPT; while however, it was higher in CPT+CC than in CNT (P < 0.05) only for 1 min immediately after the onset of CPT. In contrast, the increase in HR during CPT was smaller in CPT+CC than in CNT (P < 0.05). Conclusion The increase in SBP during Q observed in CPT+CC and PLCB+CC appeared to be due to the CC induced by the experience of previous CPT. Moreover, the shorter latency and enhancement of the pressor response in CPT+CC may also be involved in CC. The increase in HR was suppressed in CPT+CC probably because of the baroreflex with a higher increase in SBP. These results suggest that CC induced by experiences of uncomfortable stimuli may lead to a predictive increase in blood pressure, enhanced pressor response, and shortened response latency.