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The disturbances in cerebral circulation lead to focal brain ischaemia and brain infarcts. The pathogenesis of brain ischaemia has been a subject of numerous experimental studies employing different models and focusing on the anatomy of collateral circulation. The aim of this study was the evaluation of our own model of focatcerebral damage caused by a photodynamic reaction, and determination of its utility as a model of brain necrosis and blood-brain barrier damage in the rat. Wistar rats were used for the experiments. The animals were anaesthetised with 3% chloral hydrate (325 mg/kg) and injected intravenously with 40 mg/kg of 3% solution of rose bengal. After removal of the periostium the brain was irradiated through the skull for 30 min with a 250 W halogen, air-cooled light source. The material for morphologic studies was sampled 24 h, 4 days and 7 days after irradiation. The brains were fixed by perfusion, embedded in paraffin, and stained with haematoxilin-eosin (HE), acid vanadium fuchsin, cresyl violet, and GFAP. The results document the usefulness of this method for studying focal brain ischaemia in rats. The observed morphological changes and disturbances in blood-brain barrier provided information about the dynamics of the formation of gliosis, the formation of necrotic foci, and the quality and extent of brain damage in the surrounding tissue.

The aim of the present study was to investigate the changes in the localisation of glycoconjugates caused by 5-minute-long ischaemia as a consequence of bilateral ligation of common carotid arteries. Histochemical evaluation was performed using specific lectins that recognize the following sugar residues: 1) alpha-D-galactosyl and N-acetylgalactosaminyl (Bandeiraea simplicifolia agglutinin, BS-I), 2) N-acetyl-beta-D-galactosaminyl (Ricinus communis, agglutinin, RCA-60), 3) N-acetyl-alpha-D-galactosaminyl (Helix pomatia agglutinin, HPA), 4) alpha-D-mannosyl and alpha-D-glucosyl (Concanavalin A), 5) alpha-D-fucosyl (Tetragonolobus purpureas agglutinin, TG). It was found that the first two lectins (Bandeiraea simplicifolia and Ricinus communis) bound selectively to endothelium, while two others (Helix pomatia and Concanavalin A) showed affinity predominantly to cellular compartments of the brain, like neurons and glia, but also to neuropil and the white matter. Tetragonolobus purpureas agglutinin did not stain any brain structures. Significant changes in the arrangement of examined glycoconjugates as a result of ischaemia were observed. First, the intensity of binding of BS-I and RCA-60 to their complementary residues was increased in the capillary network as compared with control animals. Glycoconjugates recognised by these lectins were also found in reactive astrocytes in various brain structures. Second, the number of sugar receptors visualised by Con A and HPA was enhanced in the majority of cellular compartments of the brain and, though to a lesser extent, in terminal capillary network, especially in the neocortex, while in control animals these sugar receptors were detected in brain microvessels. Redistribution of particular sugar residues after ischaemia suggests that functional changes associated with this type of injury might take place in various CNS structures.

The gerbils brains after 3- and 4-minute-long ischemia caused by bilateral common carotid artery occlusion and 14 days survival were investigated using lectin techniques. Chosen lectins, represented by synthetic plant glycoproteids, which are specifically bound to particular sugar residues (receptors) located on the cell surfaces were examined. Lectins recognizing the following sugar residues have been used in our experiment: 1. N-acetyl-D-galactosyl (using Helix pomatia agg., HPA) 2. alpha-D-mannosyl and alpha-D-glucosyl (using Concanavalin A, Con A). 3. beta-D-galactosyl (using Ricinus communis agg., RCA-120). 4. beta-D-galactosyl and neuraminic acid (using Arachis hypogaea-Peanut agg., PNA). 5. N-acetyl-galactosaminyl and N-acetyl-neuraminic acid (using Wheat germ agg., WGA). Changes in the glycoconjugates localization were found in neurons, glial cells, vessels, white matter fibers or neuropil. They were expressed by the weaking of the reaction with HPA in the hippocampus and white matter comparing to control. Con A receptors were considerably less susceptible to ischemia, though appearance of positively stained glial cells not found in the control group has been observed. Reaction with RCA-120 localized selectively in the network of capillary vessels decreased considerably. Similarly, receptors marked using PNA revealed reduction of staining reaction in white matter as well as in hippocampal interneurons. Using WGA we have also observed that staining reaction was reduced in capillary as well as in neuropil. That lectin indicated additionally strong accumulation of its sugar residues in glial cells appearing as a result of ischemia in particular sectors of hippocampus. The same cells were also Con A positive. The presented results indicate functionally and histochemically perceptible changes taking place in particular CNS elements as a result of short ischemia, expressed by the disturbances in the localization and accumulation of specific sugar residues examined with the use of lectin technique.

Biotinyl derivatives of several lectins were used to study the localization of glycoconjugates in the cerebral microcapillaries and various brains of rats given at 24-h intervals two i.p. administrations of a hepatotoxin-thioacetamide (TAA) and examined 21 d posttreatment. At this time, the rats were asymptomatic with regard to hepatic encephalopathy but showed specific and selective changes in the blood-brain-barrier (BBB) transport of basic amino acid, but no BBB damage, and region-specific neuronal injury in the hippocampus and neocortex. The lectins tested recognized the following sugar residues: beta-D-galactosyl (Ricinus communis agglutinin [RCA-1]); N-acetyl-glucosaminyl and N-acetyl-neuraminic acid (wheat-germ agglutinin [WGA]); N-acetyl-D-galactosaminyl (Helix pomatia agglutinin [HPA]); beta-D-galactosyl and D-galactosyl neuraminic acid (peanut agglutinin [PNA]), and alpha-D-galactosyl and alpha-D-mannosyl (concanavalin A [Con A]). The treatment markedly decreased the binding to the cerebromicrovascular network of the hippocampus and neocortex of RCA-1 and WGA. The binding of these two lectins to their complementary monosaccharide residues appears to reflect subtle changes in BBB function, with a detection threshold below the conventional BBB permeability tests. The changes in the binding of the other two lectins: an increase of HPA binding and a decrease of Con A binding, confined to neocortical neurons and pyramidal cells of hippocampus injured by TAA treatment.

The morphological and histochemical changes in the rat brain, resulting from global cerebral ischemia due to cardiac arrest and cessation of respiratory function, connected with the disturbances of blood-brain barrier mechanisms inclined us to perform a series of studies on the localization of specific sugar residues in the membrane glycoprotein chains, using lectin techniques. Chosen lectins, represented by synthetic plant glycoproteins which are specifically bound to particular sugar residues located on the cell surfaces, made it possible to localize the following sugar residues: beta-D-galactose (using Ricinus communis agg.-RCA-1); beta-D-galactosyl (Ricinus communis agglutinin ), N-acetyl-glucosaminyl and N-acetyl-neuraminic acid (Wheat germ agglutinin WGA), N-acetyl-glucosaminyl (Helix pomatia agglutinin and Dolichos biflorus agglutinin), N-acetyl and N-glycol-neuraminic acid (Limax flavus agglutinin ), alpha-D-galactosyl and D-galactosyl neuraminic acid (Peanut agglutinin ), alpha-D-galactosyl and alpha-D-mannosyl (Concanavalin A ), alpha-D-galactosyl and alpha-D-galactopyranoside (Bandeirea simplicifolia agglutinin A ). In the presented paper changes in the localization of examined glycoconjugates found both in the vascular network as well as in other morphological elements of the brain (neurons, glial cells and neuropil), resulting from 10 min cardiac arrest, connected with global cerebral ischemia are characterized. In the group of control animals the strongest reaction of the vessels was obtained with RCA-1 and BSA, weaker with WGA and the weakest with DBA and LFA. Experimental rats, examined at different time following resuscitation showed significant changes in the histochemical reaction with use of different lectins. Sugar residues revealed by BSA disappeared from the brain vessels already 3 h following clinical death reappearing at 3 and 14 days after ischemia and regaining the picture described in control animals one year later. Additionally the experimental animals were characterized by a remarkably weaker reaction with WGA while location and intensity of RCA-1 receptors in the brain blood vessels remained unchanged or even increased. Additionally in the group of rats which survived 3 days after ischemia, the number of vascular receptors revealed by DBA also increased. The neuropil was characterized by a strong affinity to the sugar residues recognized by DBA, HPA, BSA, PNA, and LFA. As a rule it was stronger in the white structures of the brain than in the gray ones. Starting from the 24 h of postresuscitation till the end of the observation (1 year) staining reaction of neuropil with the above mentioned lectins was reduced. From the group of glycoconjugates used the strongest reaction in parenchymal brain cellular elements concerned those sugar residues which are identified Con A and HPA. In a group of experimental animals staining reaction with Con A was decreased whereas that with HPA was remarkably increased in all animals which survived ischemia. Additionally, BSA-recognized residues not detectable in normal conditions appeared in the neurons and glial cells of hippocampus and subiculum. The presented results indicate deep histochemical and probably functional changes taking place in endothelial cells as well as in other cellular elements of the brain and in neuropil of animals which survived clinical death. The abnormalities appearing in the early postischemic stage persisted for the long observation time indicating an active and progressing process leading to postischemic encephalopathy.

Some lectins were used to study the localization of sugar residues on the endothelial cell surface in the pia mater blood vessels of control (WKY) and hypertensive rats (SHR). The lectins tested recognized the following residues: beta-D-galactosyl (Ricinus communis agglutinin 120, RCA-1), alpha-L-fucosyl (Ulex europaeus agglutinin, UEA-1), N-acetylglucosaminyl and sialyl (Wheat germ agglutinin, WGA), N-glycolyl-neuraminic acid (Limax flavus agglutinin, LFA), and N-acetyl-D-galactosaminyl (Helix pomatia agglutinin, HPA). Several differences were revealed in the presence of sugar receptors on the surface of endothelial cells between the control and the hypertensive rats. Our studies showed also differences in the localization of the tested glycoconjugates between pial capillaries, small, medium-size and large pial arteries. The histochemical evaluation of alkaline phosphatase revealed an increased activity of the enzyme in the pial vessels of SHRs as compared with control rats with a similar localization of the enzyme activity. Some differences in the distribution of lectin binding sites and alkaline phosphatase activity could be associated with the different functions of particular segments of the pial vascular network.

In the brains of rats exposed to a dose of 800 rads of gammma radiation the location of phosphatases hydrolysing the following phosphate esters: adenosinetriphosphate (ATP), cytidinetriphosphate (CTP), guanosinetriphosphate (GTP) and inosinediphosphate (IDP) was determined in the ultramicroscopic structures. Changes were observed in their location in the gliovascular interphase. Early after the exposure (6 hours) the activity of specific phosphatases decreased in brain capillaries, then (48 hours) the reaction product disappeared from the basal membrane of the capillaries and appeared in the endothelium. Later (72 hours -- 7 days) the intensity of the reaction increased in the processes of the astrocytes adhering to the capillary. These changes took place concomitantly with an increase in the permeability of the blood-brain barrier and suggested that specific phosphatases participate in the barrier mechanisms.

Adenylate cyclase activity, stimulated by dopamine, norepinephrine and forskolin, was demonstrated histochemically in electron microscopy of the CA1 sector of Ammon's horn in Mongolian gerbil. Cobalt and strontium were used as precipitating agents. The reaction product located in the synapses was mostly associated with the postsynaptic membranes. It was also present in the plasma membrane of some nerve fibers. There were no differences in the enzyme activity in particular layers of Ammon's horn as well as between symmetric and asymmetric types of synapses. The intensity of the reaction product depended mostly on the stimulator used.