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G Bernocchi

Publications and source records attributed to G Bernocchi.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cis-dichlorodiammineplatinum alters GABAergic structures in the immature rat cerebellum.

It has been reported that injection of the antitumoral drug cis-dichlorodiammineplatinum at 10 days of life affects cerebellar development in rats. After a single dose of 5 micrograms/g of body weight, the formation of granule cells is decreased and the maturation of postmitotic neurons is slowed down. A substantial time after treatment, reduced cell packing density of the internal granule layer and atrophy of the molecular layer can be observed. In addition, there is degeneration of some Purkinje cells and Golgi neurons. In spite of all these alterations, the regular architecture of the cerebellar folia is retained in many places. In the present study, we used immunocytochemistry with an immune serum raised against glutamic acid decarboxylase to further characterize the cis-dichlorodiammineplatinum-induced alterations of GABAergic neurons. The aim was to examine cerebellar development and to test for factors controlling the settling of GABAergic circuits. At all post-treatment intervals, most of the Purkinje and Golgi neurons and molecular layer interneurons showed stronger anti-glutamic acid decarboxylase immunoreactivity than in controls; this may have been due to altered fixation because of cis-dichlorodiammineplatinum-induced damages to the blood vessels; but could also reflect cellular retention of the enzyme, maybe due to cis-dichlorodiammineplatinum-induced damage of the microtubular apparatus. After seven days, large roundish immunoreactive varicosities were present in the molecular layer adjacent to the Purkinje cell dendritic poles. These varicosities, which were not observed in control animals, may be terminals of Purkinje cell axon recurrent collaterals contributing to the supraganglionic plexus, whose abnormal development would compensate for the reduced inhibitory inputs from inhibitory interneurons and/or Purkinje cells, which degenerated at early post-treatment intervals. At later post-treatment intervals (15 and 21 days), there were also alterations in the pericellular basket at the Purkinje cell axon hillock, which was poorly developed in or absent from the majority of cells. The finding was confirmed by morphological observation of basket cells in Golgi-Cox preparation and immunocytochemistry with an antibody raised against 200,000 mol. wt phosphorylated neurofilaments. It is concluded that early changes in anti-glutamic acid decarboxylase immunoreactivity of neurons may be due to a direct interference of the drug with the cellular metabolic pathways. The late anomalies in the anti-glutamic acid decarboxylase immunoreactivity appear to be secondary to changes in the tissue cytoarchitecture rather than being primary cis-dichlorodiammineplatinum-induced lesions of the cells.

Animals↗
PubMed1992

Experimental approaches to the study of degenerative and regenerative processes in the nervous tissue. I). Morphological changes in the frog cerebellum after unilateral transection of the VIII statoacustic nerve.

The cell density was evaluated in Purkinje neuron and internal granule cell layers of the frog (Rana esculenta L.) cerebellum at 3, 8, 14, or 30 days after unilateral transection of the VIII statoacustic nerve. After 3 days, the cell density of the Purkinje cell layer was markedly reduced, the cellular loss amounting to 30% at 30 days. In the internal granule cell layer (IGL), after an abrupt decrease in the cell density at 3 and 8 days, the number of cells increased at 14 days and reached the values of control animals at 30 days. In the dorsal part of the ependymal lining of the IV ventricle, there was morphological indication of resumption of the proliferative activity. This can be in relationship with the restored cytoarchitecture of the IGL after the initial cell degeneration. All the above changes were evident in both the ipsi and contralateral parts to the neurotomy though at different extent. This is in agreement with the anatomical data about the nervous circuit connection between the two cerebellar sides and may be also expression of vestibular compensation, induced by unilateral nerve transection in the contralateral side.

Animals↗
PubMed1991

Internalization of erythrocytes into liver parenchymal cells in naturally hibernating frogs (Rana esculenta L.).

Mature and intact red blood cells were found in hepatocytes of frogs during natural underground hibernation. No signs of erythrophagocytosis, e.g., separating membranes between erythrocyte and hepatocyte cytoplasm, and lysosomes, were observed. Red blood cells probably penetrated into hepatocytes by ameboid-like mechanisms, which can be deduced by cytoplasmic protrusions and invaginations. Most of the hepatocytes had large amounts of stored glycogen and few organelles, often segregated in condensed areas. The narrowed bile canalicular lumens without lysosomes and exocytotic vacuoles around them and the reduction of the Disse spaces indicate a low metabolic activity of liver during natural hibernation. The dramatic accumulation of red cells in the hepatocytes of hibernating frogs could share similarities with the phenomenon of internalization of leucocytes into epithelial cells of some vertebrate's tissues via emperipolesis, the mechanisms of which are not well understood.

Animals↗
PubMed1990

Premitotic DNA synthesis in the brain of the adult frog (Rana esculenta L.): an autoradiographic 3H-thymidine study.

Replicative synthesis of DNA in the brain of the adult frog was studied by light microscope autoradiography. Animals collected during the active period (May-June) and in hibernation (January) were used. In active frogs, 3H-thymidine labelling occurred mainly in the ependymal cells which line the ventricles. The mean labelling index (LI%) was higher in the ependyma of the lateral and fourth ventricles than in the ependyma of the lateral diencephalon and tectal parts of the mesencephalon. In the recessus infundibularis and preopticus the number of labelled cells (LCs) was several times greater than in the lateral parts of the third ventricle. LCs were seen subependymally only occasionally. The incidence of LCs in the parenchyma of the brain was much lower in most regions than in the ventricular ependyma; LCs were mainly small and, from their nuclear morphology, they were glial cells. The LI% reached the highest value in the septum hippocampi and in the nucleus entopeduncularis. In these locations, LCs were larger and closer in size to the nerve cells of these regions. From comparison with data obtained earlier in the brain of mammals, it is evident that the distribution of proliferating cells in the olfactory and limbic system is phylogenetically conservative. The occurrence of pyknotic cells in the same areas which contain LCs, suggests that cell division reflects in part the process of cell renewal observed in mammals. However, proliferating cells could also be linked to the continuous growth observed in non-mammalian vertebrates. In hibernating frogs, LCs and pyknoses were not seen or were found occasionally, which further indicates the functional significance of both processes.

Animals↗
PubMed1990

Developmental patterns in the rat cerebellum after cis-dichlorodiammineplatinum treatment.

A cytochemical study was made of some metabolic enzymes in the cerebellar neurons during postnatal ontogenesis after injection of cis-dichlorodiammineplatinum into 10-day-old rats. The profiles during development of neuron-specific enolase immunoreactivity (involved in the glycolytic pathway), dihydrofolate reductase activity (involved in the metabolism of nucleic acids and folate) and dipeptidylaminopeptidase II activity were determined in lobules V-VII of cerebellar vermis. At different developmental stages, treated rats had folia in which the morphology and cytochemical responses of Purkinje neurons were greatly affected. On postinjection day 1 (PD 11), only neuron-specific enolase immunoreactivity was changed, reactions being more intense at the basal pole, which was abnormally enlarged in several neurons. Seven days after treatment (PD 17), the dihydrofolate reductase reaction showed weakly positive cells with small grains of formazan in the perinuclear regions and dipeptidylaminopeptidase II activity, which had appeared at this time in some cells of the controls, was not observed. On PD 25 and PD 35, Purkinje cells, probably undergoing clear degeneration, were negative or very weakly positive in all the reactions. Some tracts of folia had no Purkinje cells. These results suggest that cis-dichlorodiammineplatinum affects the differentiation of Purkinje neurons and interferes first with the glycolytic enzyme and then with some enzymes of the synthetic and catabolic machinery, leading to cellular dysfunction and degeneration.

Aging↗
PubMed1989

Seasonal changes in the nucleoli of Purkinje cells of the hedgehog cerebellum.

A relationship between size and shape of nucleolus and cellular metabolic demands can be seen from measurements of Purkinje cell nucleoli in cerebellar hemispheres during the annual cycle of the hedgehog. During hibernation, nucleoli are smaller than during activity. The extent of the associated heterochromatin increases from activity to the beginning of hibernation. Moreover, during activity it is mostly distributed in small masses all around the nucleolus, while during hibernation it is clumped in a single mass. Data indicating a lesser protein synthesis by neurons during hibernation agree with electrophysiological indications that during hibernation the cerebral cortex, linked to the cerebellar hemispheres via afferent systems, is silent.

Animals↗
PubMed1989

Ectopic Purkinje-like cells are GABAergic: immunohistochemistry with an immune serum against glutamic acid decarboxylase.

Intensely stained cells are found in the cerebellar white matter of the vermis and paravermis in adult rats after immunoreaction with an immune serum raised against glutamic acid decarboxylase (GAD). The cells are similar in size to cortical Purkinje cells and three times the size of Golgi cells of the internal granule layer, and have a thick immunopositive cell process emerging from a well-defined cytoplasmic cone. In the cytoplasm, immunoprecipitates are more dense around the nucleus as in normally located Purkinje cells. The morphological appearance of the immunopositive cells suggests that they may be ectopically located Purkinje cells. The soma of the ectopic Purkinje cells is contacted by a few darkly stained terminal boutons. Data indicate that, in spite of the different cellular environment, ectopic Purkinje cells can develop not only the typical morphological pattern already described but also other intrinsic features, such as their typical inhibitory neurotransmitter.

Animals↗
PubMed1989

Chromatin changes in frog neurons after eighth nerve transection.

Fourteen days after unilateral eighth nerve transection in the frog, Purkinje neurons of the lobus vestibulolateralis and corpus of the cerebellum and medium-sized neurons of the vestibular nuclear complex showed changes in metabolic activity. In the ipsilateral parts, and to a lesser extent in the contralateral parts, of operated frogs, the Feulgen-DNA values were higher and the nuclear areas larger, associated with decondensation of chromatin. The cytoplasmic basophilia was also less. These changes could be due to anabolic responses of the neuronal populations during regeneration. The anabolic reaction of the corpus cerebelli and contralateral vestibular nuclear complex is only partially non-specific and ascribable to the surgical trauma (comparison between sham-operated and unoperated frogs). The results indicate clear patterns of connection between the ipsilateral and contralateral parts and between the cerebellar and vestibular nuclear complex neurons.

Animals↗
PubMed1988

Intranuclear differences in the response of Purkinje cell DNA of the rat cerebellum to bleomycin. A microphotometric and autoradiographic study.

A single dose of the DNA-binding cytostatic agent bleomycin (100 micrograms/g body weight, subcutaneously) was given to 10-day-old rats to study unscheduled repair DNA synthesis in nucleolar and in bulk nuclear chromatin of postmitotic Purkinje neurons. The Feulgen reaction and Hoechst 33342 staining were used for quantitative evaluation of nuclear DNA content and chromatin structure. The repair synthesis of DNA was detected by 3H-thymidine autoradiography. The data showed a lesser staining of Purkinje as well as granule cell DNA by Hoechst 33342 in bleomycin-treated animals than in controls, but there was no difference in staining with the Feulgen reaction. The mechanisms of DNA staining by both cytochemical methods suggest that bleomycin reacted preferentially with AT-rich and single stranded DNA in cerebellar cells in vivo. Weak 3H-thymidine labelling was found in Purkinje cells of both control and treated rats, but in the latter group the labelling was more pronounced near or over the nucleolus. The enhanced unscheduled DNA synthesis in the nucleolar region of Purkinje cells of treated animals may be due to greater damage of DNA in this region or may indicate a greater ability of the nucleolar chromatin to repair its DNA.

Animals↗
PubMed1988

Dihydrofolate reductase activity in the Purkinje neuron populations of some non-mammalian vertebrates.

The intensity and distribution of histochemically demonstrable dihydrofolate reductase (FH2-R EC 1.5.1.3.) in unfixed cryostat sections was studied in Purkinje neurons of adult vertebrates that have either simple neural circuits and cytoarchitectonics (Ictalurus nebulosus, Rana esculenta) or complex neural circuits and cytoarchitectonics (Coturnix coturnix japonica), compared with the rat as a control. The reaction was generally undetectable in Ictalurus nebulosus and in Rana esculenta; with positive reactions in only a few neurons. On the contrary, FH2-R in the Purkinje cell population of Coturnix coturnix japonica had several pattern (heterogeneity) as in the rat. These results suggest that the existence of FH2-R in Purkinje cell population may be correlated with the complexity of the neural circuits of the vertebrate's cerebellum and that the "heterogeneity" of the reaction may be related to the different functional states of the Purkinje cells within the cerebellum.

Animals↗
PubMed1987

Damage and repair of the immature rat cerebellum after cis-dichlorodiammineplatinum II (cis-DDP) treatment. An ultrastructural study.

The aim of this electron microscopy study was to further investigate the effects of cis-dichlorodiammineplatinum (cis-DDP) on the cerebellum of the immature rat. Ten-day-old animals were treated with cis-DDP subcutaneously and killed after 1, 7, 15 or 21 days. On postinjection day 1, cis-DDP effects were evident mainly in the external granular layer, with nuclear damage in many dividing cells, while their cytoplasm appeared to be less affected. Some binucleate cells were also present. On the contrary, in postmitotic or more differentiated cells, only cytoplasmic alterations were found. At later stages (postinjection day 7), the frequency of damaged cells in the external granular layer decreased, but there was a cellular deficit in the internal granular layer. Many postmitotic neurons underwent coagulative necrosis. Finally (postinjection days 15 and 21), the cellular deficit was partly compensated for by "reactive" structures, e.g., glial cell fibers, which underwent hypertrophy after initial edema. Moreover, packing densities of Bergmann astrocytes and oligodendrocytes were higher.

Animals↗
PubMed1987

Nuclear changes and morphology of the epidermis in the hibernating frog.

Cytochemical changes of chromatin and DNA in frog epidermal cells were correlated with some morphological features to investigate the skin physiology during hibernation in comparison with the active period. The epidermal cells of hibernating frogs showed less condensed chromatin in all the layers; a greater loss of DNA was found during the transition from the middle to the superficial layer. In the germinative layer, a lesser frequency of hyperdiploid cells and a remarkably low amount of mitoses were detected; this is accompanied by the increase of epidermal thickness and the presence of two layers of cornified cells. The slowing of tissue differentiation and cell renewal kinetics during hibernation can be related to lowered activity of the frog skin. Further, the smaller intercellular spaces as well as the scarcity of puffed ER and vacuoles may be indicative of a lower ion transport in epidermal cells during hibernation.

Animals↗
PubMed1986

Influence of cis-dichlorodiammineplatinum on the structure of the immature rat cerebellum.

Groups of 6- to 7-day-old and 10- to 11-day-old rats received cis-dichlorodiammineplatinum (cis-DDP) or inactive trans-DDP subcutaneously and were killed after 1, 6, 10, 15, or 21 days. In both age groups the acute effect (postinjection day 1) was most obvious in the germinal external granular layer (EGL), where many cells underwent shrinkage necrosis (pyknosis, apoptosis); the latter were more frequent within the fissures than on the surface of the cerebellar folia. Cell debris were often seen to be engulfed by macrophages, Bergmann cell fibers, and meningocytes. Bergmann cell bodies were swollen and the nuclei of Purkinje cells as well as of surviving cells of the EGL were enlarged. No comparable effects were observed in animals that had received an injection of trans-DDP in the same dose. Toward postinjection (p.i.) day 6, pyknotic cells disappeared from the EGL or, after the larger doses of cis-DDP, substantially decreased in number. Small nests of pyknotic cells appeared, however, at some places of the internal granular layer (IGL). The EGL was discontinuous or thinner in both age groups. In the IGL and molecular layer (ML) multiple focal fresh hemorrhages appeared together with some macrophages. The packing cell density in the IGL was less than in the controls, especially at the top of the cerebellar folia, i.e., contrary to the distribution of the primary damage in the EGL. Later, at p.i. day 10, ectopic nests of the IGL occurred occasionally in animals injected when 10 to 11 days old and severe atrophy of the ML and Purkinje cell population was observed at some places. At p.i. days 15 to 21, invasion of microglia-like cells appeared in the IGL and in some regions of the ML. Occasionally, subpial hemorrhages occurred at this interval. The acute damage caused by cis-DDP is thus similar to the effect of X rays or some, but not all, drugs with a cytostatic action. In addition, a more profound influence on dividing cells of the EGL within the fissures and distinct capillary lesions, indicated by hemorrhages, were found after cis-DDP. As in other experimental models, the acute cis-DDP damage of the immature cerebellum was partly repaired within a few p.i. days. Spatial difference of the repair process was inferred from the packing cell density in the IGL measured at the top and bottom of the cerebellar folia.

Animals↗
PubMed1986

Electron-cytochemical localization of succinic semialdehyde dehydrogenase activity in Purkinje neurons and hepatocytes of the rat.

A method is presented for the ultrastructural demonstration of succinate semialdehyde dehydrogenase (SSADH) activity in cerebellar Purkinje neurons and liver hepatocytes; SSADH is an enzyme involved in the degradation of gamma-aminobutyric acid (GABA). Incubation media originally used for light microscopy were considered. Reaction products were mainly detected when fresh tissue was used. In Purkinje cells, grains ascribable to SSADH activity were localized on the mitochondria (especially on the outer membrane); some extramitochondrial formazan deposits were also found. After brief fixation by immersion or perfusion, only a few formazan granules were detected in the cytoplasm. A similar distribution pattern was observed in hepatocytes, in which extramitochondrial grains and grains on the nuclear membrane were frequent. The actual existence and the possible meaning of extramitochondrial SSADH activity is critically discussed on the basis of the data in the literature.

Animals↗
PubMed1986

The annual cycle of Erinaceus europaeus L. as a model for a further study of cytochemical heterogeneity in Purkinje neuron nuclei.

The cytochemical heterogeneity of nuclei in Purkinje cells, which reflects differences in metabolic states within the population, has been studied by comparing cerebellar hemispheres of the hedgehog during periods of activity and hibernation. Cerebellar granule cells and hepatocytes served as controls for diploid cells. Three different cytochemical stains (Feulgen reaction, Propidium iodide and Hoechst 33342 fluorochromes) were used in order to evaluate by microdensitometry and microfluorometry how much the heterogeneity is dependent on the variations in DNA content and degree of chromatin compaction. In the active period, Feulgen-DNA values of Purkinje cells were more widely dispersed than in control cells. Some values (18-40% of the population) exceeded (hyperdiploid) the diploid value. With Propidium iodide and Hoechst 33342 (under conditions for quantitative evaluation of DNA), a few values also exceeded the maximum value for control cells. We conclude that there is nuclear heterogeneity (diploid-hyperdiploid) in the Purkinje neuron population during normal activity. The percentage of hyperdiploid nuclei changes according to the technique used; in particular, the comparison of the different stains indicates that a different chromatin compaction is mainly responsible for hyperdiploid Feulgen-DNA values, but in a few hyperdiploid cells there is an actual surplus of DNA. In view of the modalities of detection of DNA by the different cytochemical approaches utilized, this may be mainly single-stranded DNA. During hibernation nuclear heterogeneity is still present in Purkinje neurons, but with a shift of the distribution towards lower values; hyperdiploid nuclei were not detected with all the procedures used. Moreover, when Propidium iodide is used at the concentration suitable for qualitative studies, the dye intercalation is lower than during activity. Data suggest that both decreased DNA and increased chromatin compaction occur in Purkinje cells, thus pointing to a lower metabolic activity of these neurons in hibernating animals. The changes in diploid granule cells were always less than those in Purkinje neurons and could be ascribed to a further increase in chromatin compaction only, not requiring changes in DNA content.

Animals↗
PubMed1985

Synthesis of myelin proteins and ultrastructural investigations in regenerating rat sciatic nerve.

Myelin protein synthesis, as well as ultrastructural and morphometric changes in regenerating peripheral nerve, was studied. Sciatic nerves of rats were crushed unilaterally; sham-operated nerves of the contralateral side served as controls. For the in vivo experiments, rats were killed at selected periods after the nerves were crushed (30, 60, 90, and 120 days); seven days prior to killing, the animals were injected intravenously with L-[4,5-3H]leucine. For the in vitro experiments, proximal and distal segments of sciatic nerve and equivalent sham-operated nerves were labeled with 3H-amino acid mixture 90 days after axotomy. Purified myelin was isolated from nerve segments; specific radioactivity and gel electrophoretic patterns of proteins were analyzed. Cross-sectional electron microscope (EM) preparations of proximal, distal, and contralateral segments of nerves also were examined. Results showed that the incorporation of labeled amino acids into total myelin proteins was enhanced significantly in the distal segment of sciatic nerves at all of the periods of regeneration studied. The yield of myelin protein per mm distal nerve segment increased as regeneration proceeded. The remyelination of fibers early after nerve crush was weak, whereas it gradually attained the normal range 90-120 days after axotomy. Morphometric analysis of myelin sheath thickness of regenerating axons was consistent with the data obtained for myelin protein synthesis.

Animals↗
PubMed1985

Morphohistochemical changes in hepatocytes during the life cycle of the European eel.

The comparative analysis of morphological, histochemical and cytochemical patterns of eel (Anguilla anguilla L.) hepatocytes reveals clear differences between two stages of its life cycle, i.e. the trophic stage (yellow eel) and reproductive stage (silver eel). The storage of glycogen prevails in the yellow eel, whilst lipids appear to be remarkably increased in the silver eel, in which some hepatocytes also show glycogen-rich areas. Generally, in the silver eel dehydrogenase and acid phosphatase activities seem greater and different distribution of the reaction products is present; on the contrary, a lower G6PDH activity is observed. The electron microscopy characteristics and distribution of both cellular organelles and reserve materials reflect the modifications found at light microscopy. The ultrastructural patterns provide further evidence for the heterogeneity of liver parenchyma in silver eel. In particular, the coexistence of nuclei showing a different degree of chromatin compactness is also accounted for by the quantitative cytochemical data on the nuclear DNA after Feulgen reaction and intercalation with propidium iodide at low and high concentrations. With regard to the DNA content, the hepatocytes in the silver eel as well as in the yellow eel are mainly 2c. However, some 4c values are also found, which according to the literature can be ascribed to cells in G2 phase. The present data may express the onset of different functional requirements during the reproductive stage in comparison with the trophic one. Moreover, our results are consistent with modifications found by other authors as a consequence of interruption of nourishment and during gonad maturation, i.e. two phenomena characterizing the transition from yellow to silver eel.

Acid Phosphatase↗