Lateralized effect of cerebral infarction on spinal fluid monoamine metabolite concentrations in rats

Osteopontin expression during early cerebral ischemia-reperfusion in rats: enhanced expression in the right cortex is suppressed by acetaminophen

Osteopontin (OPN) is a pleiotropic protein implicated in various inflammatory responses including ischemia-reperfusion (I-R) injury. Two distinct forms of the protein have been identified: an extensively studied secreted form (sOPN) and a less-well-known intracellular form (iOPN). Studies have shown that increased OPN expression parallels the time course of macrophage infiltration into injured tissue, a late event in the development of cerebral infarcts. sOPN has been suggested to promote remodeling of the extracellular matrix in the brain; the function of iOPN may be to facilitate certain signal transduction processes. Here, we studied OPN expression in adult male Sprague-Dawley rats subjected to global forebrain I-R injury. We found iOPN in the cytoplasm of both cortices and the hippocampus, but unexpectedly only the right cortex exhibited a marked increase in the iOPN level after 45 min of reperfusion. Acetaminophen, a drug recently shown to decrease apoptotic incidence, caspase-9 activation, and mitochondrial dysfunction during global I-R, significantly inhibited the increase in iOPN protein in the right cortex, suggesting a role for iOPN in the response to I-R injury in the right cortex.

Asymmetrical effects of cortical ablation on brain monoamines in mice

Neurochemical changes induced by right or left cortical ablation which have previously been described to have immunological effects were investigated in mice. Catecholamine and indolamine levels were determined in the contralateral cortex and in subcortical structures involved in immunoregulation 14 and 60 days after unilateral cortical ablation. Unilateral cortical ablation induced profound and widespread changes in the contralateral cortex but also in subcortical regions of both sides at 14 days after surgery. Lesions of the left neocortex appeared mainly to affect the activity of serotoninergic inputs to the right neocortex, whereas ablations of the right cortex influenced the activity of the catecholaminergic inputs to the left. Sixty days after surgery, modifications in monoamine levels were observed only in the ipsilateral, but not contralateral, subcortical regions, the only exception being that DA turnover in the tuberoinfundibular system remained lowered in both hemispheres after either right or left cortical ablations. Furthermore, some asymmetrical effects of cortical lesions depended on functional brain lateralization as assessed by paw preference. It may be hypothesized that some neurochemical modifications induced by unilateral cortical lesions are, at least partially, responsible for the immunological perturbations observed after cortical ablation.