Reproducible Motor Deficit Following Aortic Occlusion in a Rat Model Of Spinal Cord Ischemia

Summary

This study demonstrates the technique to make a minimally invasive and easily reproducible model of spinal cord ischemia in rats. Various degrees of hind limb motor deficit can be produced by controlling the aortic occlusion time.

Abstract

Spinal cord ischemia is a fatal complication following thoracoabdominal aortic aneurysm surgery. Researchers can investigate the strategies for preventing and treating this complication using experimental models of spinal cord ischemia. The model described here demonstrates varying degrees of paraplegia that relate to the length of occlusion following thoracic aortic occlusion in a rat spinal cord ischemia model.

A 2-Fr. balloon-tipped catheter was advanced through the femoral artery into the descending thoracic aorta until the catheter tip was placed at the left subclavian artery in anesthetized male Sprague-Dawley rats. Spinal cord ischemia was induced by inflating the catheter balloon. After a set period of occlusion (9, 10, or 11 min), the balloon was deflated. Neurologic assessment was performed using the motor deficit index at 24 h after surgery, and the spinal cord was harvested for histopathological examination.

Rats that underwent 9 min of aortic occlusion showed mild and reversible motor impairment in the hind limb. Rats subjected to 10 min of aortic occlusion presented with moderate but reversible motor impairment. Rats subjected to 11 min of aortic occlusion displayed complete and persistent paralysis. The motor neurons in the spinal cord sections were more preserved in rats subjected to shorter duration of aortic occlusion.

Researchers can achieve a reproducible hind limb motor deficit following thoracic aortic occlusion using this spinal cord ischemia model.

Introduction

Paraplegia is a fatal complication of thoracoabdominal aortic aneurysm surgery. It results from spinal cord ischemia-reperfusion injury that occurs during cross-clamping and unclamping of the aorta.¹ Several strategies including systemic hypothermia and cerebrospinal drainage have been introduced to protect the spinal cord,^2,3,4 but many patients remain affected by the injury.

Several animal spinal cord ischemia models have been introduced to investigate its pathogenesis and devise protective strategies against the injury. I....

Protocol

This protocol was approved by the Institutional Animal Care and Use Committee of Seoul National University Bundang Hospital. Animal care and experiments were conducted according to the United States National Institutes of Health Guide for the Care and Use of Laboratory Animals.

1. Surgical Preparation

1. Prior to surgery, flush the catheters with sterile saline to ensure patency.
2. Put a heating blanket on the operating table, and cover the table with a sterile drape.
3. Place Male Sprague−Dawley rats (270-330 g) in an acrylic box with 3.0%-4.0% of isoflurane in 100% oxygen.
4. Apply lubricant to the rat....

Results

During a period of spinal cord ischemia, aortic occlusion was performed for 9 min (n=3), 10 min (n=3), or 11 min (n=3). The motor deficit index in rats is presented in Table 2. Rats that underwent 9 min of aortic occlusion showed a mild and reversible motor impairment in the hind-limb. Rats subjected to 10 min of aortic occlusion presented with moderate motor deficit, but not complete paralysis. Rats that underwent 11 min of occlusion time displayed complete and persistent paralysis.

Represent.......

Discussion

In the current study, we demonstrated a rat model of spinal cord ischemia based on Taira and Marsala's method⁵ that induces variable degrees of motor deficit in the hind limb depending on the aortic occlusion time.

The length of aortic occlusion can affect the degree of motor deficit. If the aortic occlusion time is longer, the motor deficit becomes more severe. Thus, researchers can achieve a certain degree of motor deficit by controlling the aortic occlusion time .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Fogarty Arterial Embolectomy catheter	Edward Life Sciences	120602F	a balloon-tipped catheter inserted into the femoral artery
BD Insyte-N Autoguard Shielded IV catheter	BD	381411	24-gauge intravenous catheter
50 mL syringe	KOREA VACCINE	KOVAX-SYRINGE 50mL	Facial mask
1 mL syringe	KOREA VACCINE	KOVAX-SYRINGE 1ml
Recal probe	HARVARD APPARATUS	50-7221F	Rectal probe for temperature monitoring
Micro dissecting spring scissor	Jeung do bio & Plant co.LTD.	JD-S-10	Micro-scissor
SCISSOR (SHARP-SHARP)	Jeung do bio & Plant co.LTD.	S-51-12-S	Scissors
Retractor	Jeung do bio & Plant co.LTD.	JD-S-74A	Retractor
Micro forcep	Jeung do bio & Plant co.LTD.	JD-S-29	Micro-forceps
MOSQUITO FORCEP (Curved)	Jeung do bio & Plant co.LTD.	S-44-CPK	Curved forceps
DRESSING FORCEP	Jeung do bio & Plant co.LTD.	S-37-16S	Blunted forceps
4/0 black silk	Woori Medical	S431	4.0 black silk suture
3-WAY STOCK	Seonwon Medcal	D-98-01	3-way stopcock
Patient monitor	PHILIPS	MP20	The arterial pressure monitoring device.
Heating blanket	Self production		Heating blanket
Microtube and external reservoir	Self production		Microtube and external reservoir
Heparin	JW Pharmaceutical		Heparin
0.9% NS 1000ml	JW Pharmaceutical		Normal saline
Isoflurane	Hana Med		Isoflurane