The Effect of Long-Term Reduction of Aortic Blood Flow on Spinal Cord Gray Matter in the Rabbit. Histochemical Study of NADPH-Diaphorase

Abstract

1. The aim of this work was to study the influence of reduced aortic blood flow on NADPH-diaphorase (NADPH-d) staining in the gray matter of L4-S3 spinal cord segments. 2. Surgery was performed on the abdominal aorta of the rabbit. Spinal cord ischemia was introduced by infrarenal aortic constriction to 30% from the normal blood flow. Animals were allowed to survive 1 week, 1 month and 3 months after surgery. Neurological outcome was studied in relation to the duration of aortic occlusion. The NADPH-d histochemistry was used for the visualisation of spinal cord sections. 3. The most affected area of the spinal cord was pericentral region, and slight changes were seen in the NADPH-d activities of both dorsal and ventral horns. One week after surgery, NADPH-d positive pericentral neurons were almost unchanged in their shape and intensity of staining, the only difference was seen in slightly increased staining of the background around the central canal. One month following surgery neurons exhibited shrinkage or were swollen, NADPH-d staining was less intensive in the pericentral zone and positively stained vessels were present. 4. Three months of ischemia influenced the NADPH-d activity: (a) In the pericentral region were seen intensively NADPH-d stained neurons almost normal in shape of their bodies but with shortened processes or without them; (b) NADPH-d staining of neuropil was greatly enhanced mostly around the central canal and in the dorsal commissure; (c) Numerous vessels were present in the pericentral zone and in the location of the ventral horn. 5. It can be concluded that the reduction of blood flow in the abdominal aorta makes most changes in the pericentral region of the rabbit spinal cord. Increased NADPH-d staining of neuropil and the presence of positively stained vessels reflect increased NADPH-d/NOS production in the spinal cord gray matter after long-term incomplete aortic occlusion.

Degeneration of white matter and gray matter revealed by diffusion tensor imaging and pathological mechanism after spinal cord injury in canine

“…SCI easily causes vascular damage, flooding the blood in the gray matter. Neurons that are more sensitive to injury and ischemia rapidly lose their vitality in this microenvironment and promote the proliferation of glial cells . Our results showed that the FA values of gray matter were decreased correspondingly with time, but showed no statistical significance.…”

“…Neurons that are more sensitive to injury and ischemia rapidly lose their vitality in this microenvironment and promote the proliferation of glial cells. 34 Our results showed that the FA values of gray matter were decreased correspondingly with time, but showed no statistical significance. This indicated that the compositional structure of gray matter was not sensitive to the FA value, and there might be less axons in gray matter.…”

Region-specific sensitivity of the spinal cord to ischemia/reperfusion: the dynamic of changes in catalytic NOS activity

“…The pronounced elevation of cNOS activity in the dorsal horns after 17-min ischemia and its further progression during reperfusion implies that neurons, mainly those associated with dorsal root afferents, are also vulnerable to ischemic insult. In the dorsal horns, especially in its superficial layers (laminae I-III), there is an abundance of NADPH diaphorase-positive and/or nNOS immunoreactive neurons [37]. This fact is now generally attributed to NO-neuroprotective effects, most probably to vasodilatatory action of NO on microcirculation, and is confirmed by the evident resistance of dorsal horn neurons and lack of evident necrotic foci in the corresponding areas under ischemic conditions [11].…”