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Catecholamine assays in a rat model for autonomic dysreflexia
F Y Chiou-Tan1, C S Robertson, G C Chiou
1Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX, USA.
Archives of Physical Medicine and Rehabilitation
|April 29, 1998
Summary
Norepinephrine (NE) levels significantly increased during autonomic dysreflexia (AD) hypertension in spinal cord injured rats. Chemical sympathectomy using 6-hydroxydopamine (6-OH DA) effectively blocked these elevated NE levels during AD.
Area of Science:
- Neuroscience
- Physiology
- Pharmacology
Background:
- Autonomic dysreflexia (AD) is a potentially life-threatening condition characterized by exaggerated sympathetic responses in individuals with spinal cord injury (SCI).
- Norepinephrine (NE), a key catecholamine, plays a crucial role in sympathetic nervous system function and cardiovascular regulation.
- Understanding NE's role in AD hypertension is vital for developing effective therapeutic strategies.
Purpose of the Study:
- To investigate the changes in norepinephrine (NE) levels during induced autonomic dysreflexia (AD) hypertension in a rat model of spinal cord injury (SCI).
- To evaluate the efficacy of chemical sympathectomy using 6-hydroxydopamine (6-OH DA) in mitigating NE release during AD.
Main Methods:
- A prospective, randomized study involving three groups of eight Sprague-Dawley male rats with C8 spinal cord transection.
- Autonomic dysreflexia (AD) was induced via bowel distension for 1 minute in two groups.
- Catecholamine samples were collected postoperatively; one group received preoperative chemical sympathectomy with 6-OH DA prior to AD induction.
Main Results:
- A statistically significant increase in mean NE levels was observed during AD hypertension in SCI rats (Group 2: 1,328+/-1,116 ng/mL) compared to controls (Group 1: 465+/-400 ng/mL).
- Preoperative chemical sympathectomy with 6-OH DA significantly attenuated NE levels during AD induction (Group 3: 31+/-61 ng/mL), indicating effective blockade.
- Statistical analysis (ANOVA, post hoc Tukey) confirmed significant differences between all groups (p=.0002).
Conclusions:
- Norepinephrine (NE) levels significantly increase during autonomic dysreflexia (AD) hypertension in spinal cord-injured rats.
- Chemical sympathectomy with 6-hydroxydopamine (6-OH DA) effectively blocks the NE surge associated with AD.
- These findings contribute to understanding AD pathophysiology and may inform future pharmacologic treatments for human patients.