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The Relationship Between Blood Pressure, Locomotor Performance, and Hemorrhage After Noxious Input
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Pain input after a spinal cord injury (SCI) has been shown to be detrimental to recovery. Animal models show that noxious input soon after injury leads to an increase in hemorrhage three hours after stimulation and long-term detriments in locomotion and lesion extent. In this dissertation, I explored the relationship between noxious input and hemorrhage, and evaluated whether hypertension contributes to these effects. The current dissertation employed a rat contusion model of SCI. The first set of experiments found that electrical stimulation increased hemorrhage when given at time points soon after injury. I also established the minimum shock duration and intensity that induces hemorrhage. The next set of experiments showed that electrical stimulation also induced an acute increase in blood pressure. Stimulation with capsaicin did not change blood pressure, but it did increase hemorrhage. Both forms of stimulation had an acute effect on locomotor performance. In the next experiment, blood pressure and hemorrhage were examined after controllable and uncontrollable stimulation. Previous research has shown that only uncontrollable stimulation causes a change in locomotor recovery after SCI. The present study found that behavioral control affected blood pressure, but did not have a significant effect on acute hemorrhage or locomotor performance. The next set of experiments found sex and age differences in hemorrhage and blood pressure after noxious input. Females showed the same increase in blood pressure and decrease in locomotor performance after stimulation, but did not show the increase in hemorrhage. Females and males showed identical results after capsaicin. The last set of experiments pharmacologically manipulated blood pressure after SCI. Decreasing systolic blood pressure with prazosin before shock prevented the induction of hemorrhage at three hours, but did not improve long-term recovery at 21 days. Increasing the blood pressure with norepinephrine after SCI decreased locomotor performance but did not increase hemorrhage. These studies highlight the importance of blocking pain and blood pressure spikes after SCI. While blood pressure was not affected by capsaicin treatment, it did seem to correlate with hemorrhage and locomotion after stimulation. Further, blocking or inducing changes in blood pressure had effects on hemorrhage and locomotor performance, respectively.
Malamakal, Misty Marie (2017). The Relationship Between Blood Pressure, Locomotor Performance, and Hemorrhage After Noxious Input. Doctoral dissertation, Texas A & M University. Available electronically from