Correlation Of Pain Threshold And The Intensity Of Traumatic Stress Reaction In Rats

OBJECTIVE To investigate the association between pain threshold and the intensity of traumatic stress reaction in rats, and to provide new evidences for clinical research.METHODS One hundred healthy adult Sprague-Dawley rats were randomly assigned to experimental group (n=50) or control group (n=50). Rats in experimental group were measured arterial pressure, heart rate, and tail-flick latency (TFL), and then they were adopted amputation wound model after 30 minutes. Thirty minutes later, mean arterial pressure, heart rate as well as TFL were measured again; serum norepinephrine (NE), malondialdehyde (MDA) level, and superoxide dismutase (SOD) activity were also detected. While rats in control group did not adopt wound model and were tested the same parameters and time-points as those in experimental group. The asociation between pain threshold and mean arterial pressure changes, heart rate changes, serum NE, serum MDA level or serum SOD activity were analyzed by method of Pearson correlation test.RESULTS The difference of pain threshold was not statistically significant between two groups (,P>0.05). The difference of average arterial pressure and heart rate were not statistically significant between before and after amputation in control group (P>0.05). The average blood pressure and heart rate after amputation in the experimental group were higher than before amputation as well as that in the control group (P<0.05). Serum NE, MDA level, as well as SOD activity in experimental group were higher than that in the control group (P<0.05). In experimental group, pain threshold was negatively correlated to the difference of average arterial pressure and heart rate changes before and after amputation, and was also inversely correlated to serum NE, MDA level, and SOD activity.CONCLUSIONS The pain threshold was inversely correlated to the intensity of traumatic stress reaction in rats.