Histochemistry of enzyme response to trauma in the neocortex and corpus callosum of developing rat brain

Abstract

SUMMARYThe enzyme response to injury of the brain was well localized and limited. Some enzymes, even in 12 day old brain, increased rapidly, mainly in neocortical glial cells. In the corpus callosum enzymes were not significantly hyperactive before the light myelination stage. Some hyperactivity declined after 21 days. Oxidative processes and phosphate metabolism were most disturbed.The effect of intracerebral penetration of a syringe needle on the metabolism of nerve and glial cells in the adult rat brain is reflected in wide variations in the response of enzyme activities to trauma, the variations persisting in the neocortex and subadjacent white matter over a period of 31 days post-injection (Robinson, 1969a).Driving a needle through the neocortex and into the subadjacent white matter results in tissue necrosis in the line of needle penetration with diminishing effects receding from the site of necrosis. Morphological, colloidal, and chemical changes transmitted through the tissue by the needle produce disturbances of the metabolism of nerve cells, glial cells, and myelinating fibres and it is thought that the magnitude of the disturbances and the rates of recovery would be different at different stages of development. This paper describes the changes in activities of enzymes of important metabolic pathways of brain at the site of intracerebral penetration into the neocortex and corpus callosum at different stages of myelination. METHODSMale Sprague-Dawley rats, aged 12, 20, and 30 days old, were used. The animals were lightly anaesthetized, hair shaved off the scalp, and a sagittal incision