2022, Vol. 26 ›› Issue (33): 5376-5383

Subarachnoid injection via the posterior atlanto-occipital interspace is an alternative way of administration in a rat model of spinal cord injury

Li Chuanhong, Yu Xing, Yang Yongdong, Yang Kaitan, Zhao He   

Abstract: BACKGROUND: Subarachnoid injection is a commonly used intervention method in animal experiments of spinal cord injury. However, at present, there is a lack of methods for one-time large dose of subarachnoid injection that can cooperate with sustained-release/controlled-release dosage forms to reduce the frequency of administration and avoid subarachnoid catheterization.  
OBJECTIVE: To investigate a method of subarachnoid injection for one-time large dose administration in a rat spinal cord injury model.
METHODS: Sprague-Dawley rats were randomly divided into six groups: a spinal cord injury group, a subarachnoid injection group, a spinal cord injury+subarachnoid injection group, a subarachnoid injection sham operation group, a spinal cord injury+subarachnoid injection sham operation group, and a control group. In the spinal cord injury group, New York University spinal cord impactor was used to establish the rat spinal cord injury model. In the subarachnoid injection group, 200 μL of simulated liquid (stroke-physiological saline solution) was injected into the subarachnoid space of rats via the posterior atlanto-occipital interspace. Rats in the spinal cord injury+subarachnoid injection group received subarachnoid injection after modeling. Rats in the control group were given no treatment. In the subarachnoid injection sham operation group, the posterior atlanto-occipital membrane was exposed and the incision was then sutured. In the spinal cord injury+subarachnoid injection sham operation group, the posterior atlanto-occipital membrane was exposed and the incision was then sutured after modeling. Toluidine blue staining was used to detect drug diffusion and distribution in the subarachnoid space at 1.5 hours after injection. Open field test, inclined plane test, hot-plate test, and body mass measurement were used to verify the occurrence of subarachnoid injection-related complications.  
RESULTS AND CONCLUSION: (1) Subarachnoid injection via the posterior atlanto-occipital interspace did not cause abnormal results of Basso-Beattie-Bresnahan score, hot-plate test, and inclined plane test in each group. (2) Rats in the subarachnoid injection sham operation and the subarachnoid injection groups regained their preoperative body mass at 1 week after operation (P > 0.05). Rats in the spinal cord injury group, the spinal cord injury+subarachnoid injection sham operation group, and the spinal cord injury+subarachnoid injection group regained their preoperative body mass at 2 weeks after operation (P > 0.05). (3) No special signs of central nervous system injury caused by subarachnoid injection were observed intraoperatively and postoperatively. No leakage of cerebrospinal fluid/simulated solution was found. After the operation, all rats could raise their head normally, and no listlessness or self-mutilating behavior occurred. Rats in the subarachnoid injection sham operation and the subarachnoid injection groups did not have dysuria and dysporia. (4) At 1.5 hours after subarachnoid injection, toluidine blue solution was widely diffused in the subarachnoid space and distributed throughout the whole spinal cord. (5) The above data indicate that subarachnoid injection via the posterior atlanto-occipital interspace is safe and reliable. A single dose of 200 μL administrated can reach the injured segment of the spinal cord quickly and has a less risk of serious complications in the rat model of spinal cord injury. Therefore, it is an alternative method of subarachnoid administration in the rat model of spinal cord injury.
Key words: subarachnoid injection, posterior atlanto-occipital interspace, posterior atlanto-occipital membrane, spinal cord injury, blood-spinal cord barrier, animal experiment, safety, reliability