Lumbar epidural injection of methylene blue affects the spinal cord and spinal ganglia structures / 中国组织工程研究

ABSTRACT

BACKGROUND:Methylene blue can hinder abnormal pain conduction via the sensory nerve, and its mechanism is to block bradykinin-induced hyperalgesia and eliminate pain caused by local tissue inflammation. OBJECTIVE:To observe the influence of methylene blue solution on the lumbar spinal cord and spinal ganglia function of rats, and to investigate whether methylene blue is safe for treating discogenic low back pain. METHODTotal y 120 Wistar rats were randomly divided into five groupthree experimental groups, a saline control group and a blank control group, n=24 in each group. Lumbar segmental dura was exposed in rats. In the three experimental groups, 0.2, 1, and 2 mL methylene blue were injected epidural y, respectively. The saline control group was subjected to the epidural injection of 1 mL saline. In the blank control group, there was no treatment. Six rats from each group were selected randomly and perfused at 30 minutes, 2 hours, 24 hours, 72 hours after injection, respectively. Then, the corresponding segments of the spinal cord and ganglions were removed. Hematoxylin eosin staining was used for comparing histological and structural changes under light microscope. RESULTS AND CONCLUSION:Hematoxylin-eosin staining showed that at 30 minutes, 2 hours, 24 hours and 72 hours after injection of methylene blue, the spinal dorsal side exhibited the structural integrity, clear boundaries between the white matter and gray matter, dense nerve fibers in the white matter, and round or oval nuclei of glial cells among fibers;dense nerve fibers in the posterior horn of gray matter;light-colored neuronal nuclei with prominent nucleoli;a bundle of nerve fibers among cellpopulations. There was no significant change in tissue structure of lumbar spinal cord and spinal ganglia between the experimental groups and the saline control group or between the experimental groups and the blank control group. Thus, the epidural injection of 1%methylene blue has no significant effect on the spinal cord and spinal nerve structures.