Unexpected morphological changes within hippocampal structures in a photochemical ring model of cerebral ischaemia.

A photochemical ring model of ischaemia was introduced in the middle of the nineteen eighties. Irradiation by a laser or arc lamp followed by intravenous injection of rose bengal resulted in thrombosis of pial and superficial cortical vessels. This ring model imitated focal ischaemic damage in humans. In our experiment twenty-seven Wistar rats of both sexes weighing 250-300 grams were examined. A photochemical ring model based on irradiation of the area of parietal bone 4 mm posteriorly to the bregma and 4 mm laterally from the sagittal suture was applied. A ring-shaped light beam with a wavelength of 510-540 nm with 5 mm diameter was generated by a high pressure discharge lamp at a power of 400 W. Two groups of rats treated and untreated with MK-801 and two rings of the thickness of 0.35 mm and 0.5 mm were used in the experiment. Morphological examination was performed in animals sacrificed 1 and 4 days after the irradiation. On formalin-fixed and paraffin-embedded slices HE staining method and immunoreaction with antibodies to ubiquitin were applied. Our material confirmed well known information about the dynamics of infarct breakdown, ischaemic-induced angiogenesis, glial reaction and other typical changes described previously in handbooks and numerous papers. In the experiment, morphological changes were more intensive after the irradiation by 0.5 mm than 0.35 mm irradiating rings and 4 days than one day after the irradiation. A surprising finding observed in some of the examined animals was more intensive neuronal damage after treatment with MK-801. Another unpredicted discovery was intensive morphological alterations found in CA4 and CA3 hippocampal sectors. Moreover, these alterations were not limited to the damaged hemisphere, but were also observed contralaterally. In some of the rats, ischaemic and necrotic cells were additionally found within both parasagittal areas. We connect this atypical localization of the ischaemic changes with dispersion of light emitted by the used lamp. Dispersed light also leads to thrombotic occlusion of the meningeal arteries in the parasagittal area. Among these arteries, thrombosis in pericallosal and penetrating arteries was present. Our experiment demonstrated that if a non-laser lamp is used, brain areas distant from the necrotic ring must be carefully investigated.

Progression of morphological changes within CNS in a transgenic rat model of familial amyotrophic lateral sclerosis.

UNLABELLED: An analysis of the dynamics of histological and immunocytochemical changes in the CNS of a transgenic rat model of fALS in various periods of life was performed. Material was obtained from animals on the 60th day of age (4), 93rd day of age (3) and 120th presymptomatic day and from 3 animals in paretic stage of the disease. Formalin-fixed and paraffin-embedded slices were stained with HE and Klüver-Barrera method. Immunoreactions to GFAP, S-100, ferritin, neurofilament, ubiquitin, synaptophysin and tau protein were also performed. Within the brain tissues patchy neuronal loss and dark or ischaemic neurons were dispersed in cortical layers, CA1, CA3 and CA4 hippocampal areas and structures of the hemispheres and brain stem. In the spinal cord, numerous alpha motoneurons were dark or ischaemic. Vacuoles or small pale spots were visible in their cytoplasm. Microspongiosis surrounded some motoneurons, particularly cells subjected to neuronophagy. Neuronophagy, sporadically observed at the age of 60th day, was more extensive on the 93rd day of age, and at the age of 120 days already involved all interneurons of the anterior and posterior horns. In the immune reaction to neurofilament numerous fibres, often thick, fragmented or rosary-like, were observed. They were located within subcortical white matter, external and internal capsules, anterior horns of the spinal cord. Changes became more intensive with age. Astrocytic reactivity was weak in animals on the 60th and 93rd day of life. Non-numerous cells were immunoreactive to GFAP and S-100, although an increase of astrocytic nuclei was observed. On the 120th day of age and in symptomatic stage astrocytic hypertrophy and proliferation were intensive. But from the 60th day of age ubiquitin and tau protein immunopositive material was accumulated in the perinuclear area of astroglial cytoplasm. Immunoreaction of nerve cells to these proteins was negative. CONCLUSIONS: 1) In the subclinical stage of the disease the pathological process within the CNS takes place already on the 60th day of age and its intensity increases with age. 2) Morphological changes are not limited to motor neuronal cells. Various structures of the CNS are damaged. 3) Weak astroglial reaction probably depends on pathological accumulation of ubiquitin and tau protein in cytoplasm. 4) Astroglial cells are probably also a "target" for pathogenic factors in the rat model of fALS.

The pattern of irreversible brain changes after cardiac arrest in humans.

Irreversible brain damage resulting in sustained post-arrest coma is a most serious complication of CA in resuscitated patients. In this study we present the neuropathological examination performed on 17 brains of patients who had remained unconscious for variable post-resuscitation periods and died after survival time ranging from 1 day to 36 days following cardiac arrest. Two main types of irreversible brain lesions were observed. The first one consisted of primary ischaemic selective disseminated neuronal death appearing in the form of acidophilic neurones with consecutive neuronal loss and reactive astroglial activation in the brain regions vulnerable to ischaemia or in more widespread distribution. The second included microinfarcts or confluent areas of pancellular necrosis associated with perivascular and diffuse tissue sponginess and was considered as secondary to post-resuscitation systemic and regional circulatory disturbances. These lesions showed multifocal, perivascular and laminar distribution with apparent predilection to the cortical border zones of arterial supply territories and were associated with disintegration and loss of GFAP-reactive astrocytes. Continuity between the areas of selective neuronal loss and focal tissue pannecrosis with corresponding patchy disappearance of GFAP- and VIM-positive astrocytes indicates the contribution of astroglia in the progression of postischaemic brain lesions. Both types of changes, evaluated in the neocortex and hippocampus, were more intensive and heterogeneous in the patients dying after prolonged coma duration than in those with recovery of consciousness within the first days after resuscitation.