Degenerating and regenerating changes in remote areas from the caudo-putaminal mass lesion in rats

The degree of interancerebral damage after hemorrhage usually depends on the localization and size of hematora. However, unexpected worsening of symptoms can occur in some patients with intracerebral hematoma, partly due to reduction of cerebral blood flow (CBF) or metabolism in areas remote from the primary lesion. In order to examine the features of neuronal degeneration and synaptic reorganization in such remote areas, we investigated neuropathological changes using a modified hemorrhagic rat brain model. Intracerebral mass lesions were created by inflating a microballoon in the caudo-putamen for 10 or 120 min. Physiolosical parameters, including mean arterial blood pressure and blood gas and pH, were measured at three time points (before, 60min after micro balloon inflation, and after microballoon deflation). Neuropathological changes were assessed in animals sacrificed 1, 2 and 7 days after microballoon deflation, using the suppressive Nauta silver method and immunostaining for growth-associated protein (GAP)-43. These were no significant differences in any of the physiological variables. The forcal CBF in the contralateral primary somatosensony cortex decreased 5 min after microballoon inflation, then returned to the baseline 30 min after inflation. After inflation. After microballoon deflation, the focal cortical CBF increased, being greater than the baseline level 30 min later. In this model, neuronal demage was not observed neurons were observed widely in duction in cortical CBF. Argyrophilic degenerated neurons were observed widely in laminae 3 and 5 of the bilateral cerebral contex (more so ipsilaterally) and in the substantia nigra one day after microballoon deflation. The difference in the number of degenerrated neurons between rats subjected to microballoon inflation for 10 and 120 min did not reach statistical signficance. GAP-43 immunoreactivity became apparent 2 days after deflation and lasted for 7 days. Inhibition of neuronal degeneration and promotion of synaptic reorganization in remote areas could improve the outcome of patients with intracerebral hemorrhage. (303 words)

transneural degeneration

synaptic reorganization

suppressive Nautamethod

GAP-43