Endogenous peroxidatic activity in astrocytes after spinal cord injury

Abstract

After spinal cord injury, endogenous peroxidatic-like activity develops along the axis of the cord. At 2 weeks postinjury, this activity appears in cells whose processes are intimately associated with microvessels. The objectives of this study were to further characterize this response and to identify the cellular localization of endogenous peroxidatic-like activity. After traumatic injury to the rat spinal cord, adjacent sections of spinal cord were processed in medium to visualize antiglial fibrillary acidic protein, endogenous peroxidatic activity, or cytochrome oxidase activity. In addition, certain sections, stained for endogenous peroxidatic-like activity, were prepared for electron microscopy. To identify the nature of the activity, some sections were exposed to an incubation medium that included inhibitors of either catalase or heme protein activity. The distribution of prominent glial fibrillary acidic protein immunoreactivity in the dorsal columns corresponded to that of marked staining for endogenous peroxidatic-like activity and cytochrome oxidase. At the ultrastructural level, endogenous peroxidatic-like activity was identified in the cytoplasmic compartment of the astrocyte. This activity was abolished when potassium cyanide (an inhibitor of heme protein) was added to the incubation medium. Spinal cord injury elicited a pronounced cellular response along the axis of the cord that was characterized by enhanced staining for antiglial fibrillary acidic protein, cytochrome oxidase activity, and endogenous peroxidatic-like activity. It is not clear whether pronounced cytochrome oxidase activity corresponded to astrocytes that also expressed prominent endogenous peroxidatic-like activity. However, according to both light and ultrastructural findings, endogenous peroxidatic-like activity was prominently associated with the astrocytic cytoplasm. The biochemical nature of the peroxidatic activity is unknown, but these results suggest that it is related to a heme-containing protein.

Reconstruction of the transected cat spinal cord following NeuroGel™ implantation: axonal tracing, immunohistochemical and ultrastructural studies

“…Their morphology, with long fine processes extending longitudinally in the white matter in association with regenerating axons, and their topology strongly suggest that these cells form the glial framework of the white matter described by Li and Raisman (1997). These cells exhibited an endogenous perioxidative-like activity after injury (Noble et al, 1990) and thus were labelled after incubation with DAB. As expected, labelled cells were not observed in the non-injured intact spinal cord.…”

Vascular Pathology as a Potential Therapeutic Target in SCI

“…Blood is well known to be toxic to the CNS tissue [90,131]. The heme cofactor in hemoglobin and its iron produce oxidative stress and are toxic to CNS tissue including the spinal cord [109,131]. At least two defense mechanisms are in place.…”

Cellular inflammatory response after spinal cord injury in sprague-dawley and lewis rats

“…Tissues were rinsed with TBS (32) and endogenous peroxidase activity was quenched using a methanol:hydrogen peroxide (30%) solution in a 4:1 ratio for 5 minutes. Tissues treated in this manner then incubated with DAB/H 2 O 2 substrate showed no signs of endogenous peroxidase which is known to be elevated in the injured spinal cord (Noble et al, 1990). The ABC complex (Vector Laboratories) then was applied to each section for 1 hour at room temperature followed by TBS rinses (33).…”