The Matrix Receptor CD44 Is Present in Astrocytes throughout the Human Central Nervous System and Accumulates in Hypoxia and Seizures

In the mammalian isocortex, CD44, a cell surface receptor for extracellular matrix molecules, is present in pial-based and fibrous astrocytes of white matter but not in protoplasmic astrocytes. In the hominid isocortex, CD44+ astrocytes comprise the subpial "interlaminar" astrocytes, sending long processes into the cortex. The hippocampus also contains similar astrocytes. We have examined all levels of the human central nervous system and found CD44+ astrocytes in every region. Astrocytes in white matter and astrocytes that interact with large blood vessels but not with capillaries in gray matter are CD44+, the latter extending long processes into the parenchyma. Motor neurons in the brainstem and spinal cord, such as oculomotor, facial, hypoglossal, and in the anterior horn of the spinal cord, are surrounded by CD44+ processes, contrasting with neurons in the cortex, basal ganglia, and thalamus. We found CD44+ processes that intercalate between ependymal cells to reach the ventricle. We also found CD44+ astrocytes in the molecular layer of the cerebellar cortex. Protoplasmic astrocytes, which do not normally contain CD44, acquire it in pathologies like hypoxia and seizures. The pervasive and inducible expression of CD44 in astrocytes is a novel finding that lays the foundations for functional studies into the significance of CD44 in health and disease.

Single unit analysis and wide-field imaging reveal alterations in excitatory and inhibitory neurons in glioma

While several studies have attributed the development of tumour-associated seizures to an excitatory-inhibitory imbalance, we have yet to resolve the spatiotemporal interplay between different types of neuron in glioma-infiltrated cortex. Herein, we combined methods for single unit analysis of microelectrode array recordings with wide-field optical mapping of Thy1-GCaMP pyramidal cells in an ex vivo acute slice model of diffusely infiltrating glioma. This enabled simultaneous tracking of individual neurons from both excitatory and inhibitory populations throughout seizure-like events. Moreover, our approach allowed for observation of how the crosstalk between these neurons varied spatially, as we recorded across an extended region of glioma-infiltrated cortex. In tumour-bearing slices, we observed marked alterations in single units classified as putative fast-spiking interneurons, including reduced firing, activity concentrated within excitatory bursts and deficits in local inhibition. These results were correlated with increases in overall excitability. Mechanistic perturbation of this system with the mTOR inhibitor AZD8055 revealed increased firing of putative fast-spiking interneurons and restoration of local inhibition, with concomitant decreases in overall excitability. Altogether, our findings suggest that diffusely infiltrating glioma affect the interplay between excitatory and inhibitory neuronal populations in a reversible manner, highlighting a prominent role for functional mechanisms linked to mTOR activation.

Synaptic hyperexcitability of cytomegalic pyramidal neurons contributes to epileptogenesis in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a developmental disorder associated with epilepsy, autism, and cognitive impairment. Despite inactivating mutations in the TSC1 or TSC2 genes and hyperactive mechanistic target of rapamycin (mTOR) signaling, the mechanisms underlying TSC-associated neurological symptoms remain incompletely understood. Here we generate a Tsc1 conditional knockout (CKO) mouse model in which Tsc1 inactivation in late embryonic radial glia causes social and cognitive impairment and spontaneous seizures. Tsc1 depletion occurs in a subset of layer 2/3 cortical pyramidal neurons, leading to development of cytomegalic pyramidal neurons (CPNs) that mimic dysplastic neurons in human TSC, featuring abnormal dendritic and axonal overgrowth, enhanced glutamatergic synaptic transmission, and increased susceptibility to seizure-like activities. We provide evidence that enhanced synaptic excitation in CPNs contributes to cortical hyperexcitability and epileptogenesis. In contrast, astrocytic regulation of synapse formation and synaptic transmission remains unchanged after late embryonic radial glial Tsc1 inactivation, and astrogliosis evolves secondary to seizures.

Wu et al. demonstrate that Tsc1 inactivation in late embryonic radial glial cells (RGCs) produces cytomegalic pyramidal neurons that mimic TSC-like dysplastic neurons. They find that enhanced excitatory synaptic transmission in Tsc1-null cytomegalic pyramidal neurons contributes to cortical hyperexcitability and epileptogenesis.

High Dietary Advanced Glycation End Products Impair Mitochondrial and Cognitive Function

BACKGROUND

Advanced glycation end products (AGEs) are an important risk factor for the development of cognitive decline in aging and late-onset neurodegenerative diseases including Alzheimer's disease. However, whether and how dietary AGEs exacerbate cognitive impairment and brain mitochondrial dysfunction in the aging process remains largely unknown.

OBJECTIVE

We investigated the direct effects of dietary AGEs on AGE adducts accumulation, mitochondrial function, and cognitive performance in mice.

METHODS

Mice were fed the AGE+ diet or AGE- diet. We examined levels of AGE adducts in serum and cerebral cortexes by immunodetection and immunohistochemistry, determined levels of reactive oxygen species by biochemical analysis, detected enzyme activity associated with mitochondrial respiratory chain complexes I & IV and ATP levels, and assessed learning and memory ability by Morris Water Maze and nesting behavior.

RESULTS

Levels of AGE adducts (MG-H1 and CEL) were robustly increased in the serum and brain of AGE+ diet fed mice compared to the AGE- group. Furthermore, greatly elevated levels of reactive oxygen species, decreased activities of mitochondrial respiratory chain complexes I & IV, reduced ATP levels, and impaired learning and memory were evident in AGE+ diet fed mice compared to the AGE- group.

CONCLUSION

These results indicate that dietary AGEs are important sources of AGE accumulation in vivo, resulting in mitochondrial dysfunction, impairment of energy metabolism, and subsequent cognitive impairment. Thus, reducing AGEs intake to lower accumulation of AGEs could hold therapeutic potential for the prevention and treatment of AGEs-induced mitochondrial dysfunction linked to cognitive decline.

Single-nucleus RNA-seq identifies Huntington disease astrocyte states

Huntington Disease (HD) is an inherited movement disorder caused by expanded CAG repeats in the Huntingtin gene. We have used single nucleus RNASeq (snRNASeq) to uncover cellular phenotypes that change in the disease, investigating single cell gene expression in cingulate cortex of patients with HD and comparing the gene expression to that of patients with no neurological disease. In this study, we focused on astrocytes, although we found significant gene expression differences in neurons, oligodendrocytes, and microglia as well. In particular, the gene expression profiles of astrocytes in HD showed multiple signatures, varying in phenotype from cells that had markedly upregulated metallothionein and heat shock genes, but had not completely lost the expression of genes associated with normal protoplasmic astrocytes, to astrocytes that had substantially upregulated glial fibrillary acidic protein (GFAP) and had lost expression of many normal protoplasmic astrocyte genes as well as metallothionein genes. When compared to astrocytes in control samples, astrocyte signatures in HD also showed downregulated expression of a number of genes, including several associated with protoplasmic astrocyte function and lipid synthesis. Thus, HD astrocytes appeared in variable transcriptional phenotypes, and could be divided into several different “states”, defined by patterns of gene expression. Ultimately, this study begins to fill the knowledge gap of single cell gene expression in HD and provide a more detailed understanding of the variation in changes in gene expression during astrocyte “reactions” to the disease.

Ex vivo multi-electrode analysis reveals spatiotemporal dynamics of ictal behavior at the infiltrated margin of glioma

The purpose of this study is to develop a platform in which the cellular and molecular underpinnings of chronic focal neocortical lesional epilepsy can be explored and use it to characterize seizure-like events (SLEs) in an ex vivo model of infiltrating high-grade glioma. Microelectrode arrays were used to study electrophysiologic changes in ex vivo acute brain slices from a PTEN/p53 deleted, PDGF-B driven mouse model of high-grade glioma. Electrode locations were co-registered to the underlying histology to ascertain the influence of the varying histologic landscape on the observed electrophysiologic changes. Peritumoral, infiltrated, and tumor sites were sampled in tumor-bearing slices. Following the addition of zero Mg²⁺ solution, all three histologic regions in tumor-bearing slices showed significantly greater increases in firing rates when compared to the control sites. Tumor-bearing slices demonstrated increased proclivity for SLEs, with 40 events in tumor-bearing slices and 5 events in control slices (p-value = .0105). Observed SLEs were characterized by either low voltage fast (LVF) onset patterns or short bursts of repetitive widespread, high amplitude low frequency discharges. Seizure foci comprised areas from all three histologic regions. The onset electrode was found to be at the infiltrated margin in 50% of cases and in the peritumoral region in 36.9% of cases. These findings reveal a landscape of histopathologic and electrophysiologic alterations associated with ictogenesis and spread of tumor-associated seizures.

Identification and Characterization of Amyloid-β Accumulation in Synaptic Mitochondria

Mitochondrial and synaptic dysfunction is an early pathological feature of Alzheimer's disease (AD). Accumulation of amyloid beta-peptide (Aβ) in mitochondria, particularly in synaptic mitochondria, potentiates and amplifies synaptic injury and disruption of synaptic transmission, leading to synaptic dysfunction and ultimately to synaptic failure. Thus, determination of the presence and levels of Aβ in synaptic mitochondria associated with amyloid pathology is important for studying mitochondrial amyloid pathology. Here, we present a detailed methodology for the isolation of synaptic mitochondria from brain tissues and the determination of Aβ levels in the isolated mitochondria as well as ultrastructural localization of synaptic mitochondrial Aβ. These methods have been used successfully for the identification and characterization of Aβ accumulation in synaptic mitochondria from mouse brains derived from transgenic AD mouse model. Additionally, we comprehensively discuss the sample preparation, experimental details, our unique procedures, optimization of parameters, and troubleshooting.

Deletion of Ripk3 Prevents Motor Neuron Death In Vitro but not In Vivo

Increasing evidence suggests that necroptosis, a form of programmed cell death (PCD), contributes to neurodegeneration in several disorders, including ALS. Supporting this view, investigations in both in vitro and in vivo models of ALS have implicated key molecular determinants of necroptosis in the death of spinal motor neurons (MNs). Consistent with a pathogenic role of necroptosis in ALS, we showed increased mRNA levels for the three main necroptosis effectors Ripk1, Ripk3, and Mlkl in the spinal cord of mutant superoxide dismutase-1 (SOD1G93A) transgenic mice (Tg), an established model of ALS. In addition, protein levels of receptor-interacting protein kinase 1 (RIPK1; but not of RIPK3, MLKL or activated MLKL) were elevated in spinal cord extracts from these Tg SOD1G93A mice. In postmortem motor cortex samples from sporadic and familial ALS patients, no change in protein levels of RIPK1 were detected. Silencing of Ripk3 in cultured MNs protected them from toxicity associated with SOD1G93A astrocytes. However, constitutive deletion of Ripk3 in Tg SOD1G93A mice failed to provide behavioral or neuropathological improvement, demonstrating no similar benefit of Ripk3 silencing in vivo. Lastly, we detected no genotype-specific myelin decompaction, proposed to be a proxy of necroptosis in ALS, in either Tg SOD1G93A or Optineurin knock-out mice, another ALS mouse model. These findings argue against a role for RIPK3 in Tg SOD1G93A-induced neurodegeneration and call for further preclinical investigations to determine if necroptosis plays a critical role in the pathogenesis of ALS.

The origin of Rosenthal fibers and their contributions to astrocyte pathology in Alexander disease

Rosenthal fibers (RFs) are cytoplasmic, proteinaceous aggregates. They are the pathognomonic feature of the astrocyte pathology in Alexander Disease (AxD), a neurodegenerative disorder caused by heterozygous mutations in the GFAP gene, encoding glial fibrillary acidic protein (GFAP). Although RFs have been known for many years their origin and significance remain elusive issues. We have used mouse models of AxD based on the overexpression of human GFAP (transgenic, TG) and a point mutation in mouse GFAP (knock-in, KI) to examine the formation of RFs and to find astrocyte changes that correlate with the appearance of RFs. We found RFs of various sizes and shapes. The smallest ones appear as granular depositions on intermediate filaments. These contain GFAP and the small heat shock protein, alphaB-crystallin. Their aggregation appears to give rise to large RFs. The appearance of new RFs and the growth of previously formed RFs occur over time. We determined that DAPI is a reliable marker of RFs and in parallel with Fluoro-Jade B (FJB) staining defined a high variability in the appearance of RFs, even in neighboring astrocytes. Although many astrocytes in AxD with increased levels of GFAP and with or without RFs change their phenotype, only some cells with large numbers of RFs show a profound reconstruction of cellular processes, with a loss of fine distal processes and the appearance of large, lobulated nuclei, likely due to arrested mitosis. We conclude that 1) RFs appear to originate as small, osmiophilic masses containing both GFAP and alphaB-crystallin deposited on bundles of intermediate filaments. 2) RFs continue to form within AxD astrocytes over time. 3) DAPI is a reliable marker for RFs and can be used with immunolabeling. 4) RFs appear to interfere with the successful completion of astrocyte mitosis and cell division.

Composition of Rosenthal Fibers, the Protein Aggregate Hallmark of Alexander Disease

Alexander disease (AxD) is a neurodegenerative disorder characterized by astrocytic protein aggregates called Rosenthal fibers (RFs). We used mouse models of AxD to determine the protein composition of RFs to obtain information about disease mechanisms including the hypothesis that sequestration of proteins in RFs contributes to disease. A method was developed for RF enrichment, and analysis of the resulting fraction using isobaric tags for relative and absolute quantitation mass spectrometry identified 77 proteins not previously associated with RFs. Three of five proteins selected for follow-up were confirmed enriched in the RF fraction by immunobloting of both the AxD mouse models and human patients: receptor for activated protein C kinase 1 (RACK1), G1/S-specific cyclin D2, and ATP-dependent RNA helicase DDX3X. Immunohistochemistry validated cyclin D2 as a new RF component, but results for RACK1 and DDX3X were equivocal. None of these was decreased in the non-RF fractions compared to controls. A similar result was obtained for the previously known RF component, alphaB-crystallin, which had been a candidate for sequestration. Thus, no support was obtained for the sequestration hypothesis for AxD. Providing possible insight into disease progression, the association of several of the RF proteins with stress granules suggests a role for stress granules in the origin of RFs.

Increased neuronal PreP activity reduces Aβ accumulation, attenuates neuroinflammation and improves mitochondrial and synaptic function in Alzheimer disease's mouse model

Accumulation of amyloid-β (Aβ) in synaptic mitochondria is associated with mitochondrial and synaptic injury. The underlying mechanisms and strategies to eliminate Aβ and rescue mitochondrial and synaptic defects remain elusive. Presequence protease (PreP), a mitochondrial peptidasome, is a novel mitochondrial Aβ degrading enzyme. Here, we demonstrate for the first time that increased expression of active human PreP in cortical neurons attenuates Alzheimer disease's (AD)-like mitochondrial amyloid pathology and synaptic mitochondrial dysfunction, and suppresses mitochondrial oxidative stress. Notably, PreP-overexpressed AD mice show significant reduction in the production of proinflammatory mediators. Accordingly, increased neuronal PreP expression improves learning and memory and synaptic function in vivo AD mice, and alleviates Aβ-mediated reduction of long-term potentiation (LTP). Our results provide in vivo evidence that PreP may play an important role in maintaining mitochondrial integrity and function by clearance and degradation of mitochondrial Aβ along with the improvement in synaptic and behavioral function in AD mouse model. Thus, enhancing PreP activity/expression may be a new therapeutic avenue for treatment of AD.

Drp1-mediated mitochondrial abnormalities link to synaptic injury in diabetes model

Diabetes has adverse effects on the brain, especially the hippocampus, which is particularly susceptible to synaptic injury and cognitive dysfunction. The underlying mechanisms and strategies to rescue such injury and dysfunction are not well understood. Using a mouse model of type 2 diabetes (db/db mice) and a human neuronal cell line treated with high concentration of glucose, we demonstrate aberrant mitochondrial morphology, reduced ATP production, and impaired activity of complex I. These mitochondrial abnormalities are induced by imbalanced mitochondrial fusion and fission via a glycogen synthase kinase 3β (GSK3β)/dynamin-related protein-1 (Drp1)-dependent mechanism. Modulation of the Drp1 pathway or inhibition of GSK3β activity restores hippocampal long-term potentiation that is impaired in db/db mice. Our results point to a novel role for mitochondria in diabetes-induced synaptic impairment. Exploration of the mechanisms behind diabetes-induced synaptic deficit may provide a novel treatment for mitochondrial and synaptic injury in patients with diabetes.

Epileptogenic but MRI-normal perituberal tissue in Tuberous Sclerosis Complex contains tuber-specific abnormalities

INTRODUCTION

Recent evidence has implicated perituberal, MRI-normal brain tissue as a possible source of seizures in tuberous sclerosis complex (TSC). Data on aberrant structural features in this area that may predispose to the initiation or progression of seizures are very limited. We used immunohistochemistry and confocal microscopy to compare epileptogenic, perituberal, MRI-normal tissue with cortical tubers.

RESULTS

In every sample of epileptogenic, perituberal tissue, we found many abnormal cell types, including giant cells and cytomegalic neurons. The majority of giant cells were surrounded by morphologically abnormal astrocytes with long processes typical of interlaminar astrocytes. Perituberal giant cells and astrocytes together formed characteristic "microtubers". A parallel analysis of tubers showed that many contained astrocytes with features of both protoplasmic and gliotic cells.

CONCLUSIONS

Microtubers represent a novel pathognomonic finding in TSC and may represent an elementary unit of cortical tubers. Microtubers and cytomegalic neurons in perituberal parenchyma may serve as the source of seizures in TSC and provide potential targets for therapeutic and surgical interventions in TSC.

Cyclophilin D deficiency rescues Aβ-impaired PKA/CREB signaling and alleviates synaptic degeneration

The coexistence of neuronal mitochondrial pathology and synaptic dysfunction is an early pathological feature of Alzheimer's disease (AD). Cyclophilin D (CypD), an integral part of mitochondrial permeability transition pore (mPTP), is involved in amyloid beta (Aβ)-instigated mitochondrial dysfunction. Blockade of CypD prevents Aβ-induced mitochondrial malfunction and the consequent cognitive impairments. Here, we showed the elimination of reactive oxygen species (ROS) by antioxidants probucol or superoxide dismutase (SOD)/catalase blocks Aβ-mediated inactivation of protein kinase A (PKA)/cAMP regulatory-element-binding (CREB) signal transduction pathway and loss of synapse, suggesting the detrimental effects of oxidative stress on neuronal PKA/CREB activity. Notably, neurons lacking CypD significantly attenuate Aβ-induced ROS. Consequently, CypD-deficient neurons are resistant to Aβ-disrupted PKA/CREB signaling by increased PKA activity, phosphorylation of PKA catalytic subunit (PKA C), and CREB. In parallel, lack of CypD protects neurons from Aβ-induced loss of synapses and synaptic dysfunction. Furthermore, compared to the mAPP mice, CypD-deficient mAPP mice reveal less inactivation of PKA-CREB activity and increased synaptic density, attenuate abnormalities in dendritic spine maturation, and improve spontaneous synaptic activity. These findings provide new insights into a mechanism in the crosstalk between the CypD-dependent mitochondrial oxidative stress and signaling cascade, leading to synaptic injury, functioning through the PKA/CREB signal transduction pathway.

The mTOR pathway is activated in glial cells in mesial temporal sclerosis

Mammalian target of rapamycin (mTOR) is a key protein kinase that regulates basic cellular processes, including development and growth. Mutations in mTOR cause tuberous sclerosis complex (TSC), a condition that is characterized by developmental brain malformations (cortical tubers) and epilepsy. Although considerable insight has been gained recently into the pathologic dysfunction of mTOR in tubers in TSC-related epilepsy, data on the mTOR cascade in mesial temporal lobe epilepsy (MTLE) are lacking. Immunohistochemical investigation with confocal microscopy was performed to evaluate mTOR cascade and to correlate its activity with cellular alterations observed in surgically resected samples of human neocortex and hippocampus in MTLE. We compared results in human tissue to findings in the rat pilocarpine model of sclerotic MTLE. In nonsclerotic and control hippocampus, many neurons in the CA1 subfield expressed high levels of phospho-S6 (p-S6), a reliable marker of mTOR activation. In nonsclerotic and control hippocampus, as well as in magnetic resonance imaging (MRI) normal human neocortex, protoplasmic astrocytes did not express p-S6. In contrast, in sclerotic hippocampus, prominent p-S6 immunostaining was observed mainly in astrocytes and microglia located in the areas of neuronal loss and astrogliosis, whereas neurons in preserved areas of CA1 expressed significantly lower levels of p-S6 immunopositivity than neurons in nonsclerotic or control CA1 subfields. In surgically resected neocortex with chronic astroglial scar tissue, only microglia revealed moderate p-S6 immunoreactivity. Different from human sclerotic epileptic hippocampus, astrogliosis in the chronic rat pilocarpine model of epilepsy was not characterized by glial cells with mTOR activation. The mTOR cascade is activated in astroglial cells in sclerotic MTLE, but not in astrocytes in chronic neocortical scarring or in the pilocarpine model of MTLE. These findings suggest that the astroglial "scar" in sclerotic MTLE has active, ongoing cellular changes. Targeting mTOR in MTLE may provide new pathways for the medical therapy of epilepsy.

[Participation of NO-synthase system in the stress-mediated reactions of the brain]

Neurosis-like status developing as a result of the exposure of animals to chronic stress, which is associated with a transitory cerebral hypoxia, could cause significant structural and functional alterations in many brain structures. Realization of humoral stress effects on the brain is mediated by both extra- and intracelullar signal molecules, among which nitric oxide (NO) is considered to be one of the most potent ones. Expression of neuronal constitutive (nNOS) and inducible (iNOS) isoforms of NO-synthase was studied by immunohistochemistry in the neurons of albino rat brain after exposure of animals to chronic stress resulting in the development of neurosis-like status. Chronic stress was shown to result in the increased expression of both nNOS and iNOS in many brain areas with the predominance in neocortex and hippocampus. The administration of nonspecific inhibitor of NOS, Nomega-nitro-1-arginine methyl ester hydrochloride (L-NAME) (10 mg/kg) resulted in the aggravated depression of the animals, associated with a decrease of locomotor and exploring activities that were evaluated using the traditional tests. The application of NOS activity inhibitor caused an insignificant rise only in iNOS expression. Thus the results obtained suggest that NO is involved in the realization of stress effects with the development of a neurosis-like status.

NPY mediates basal and seizure-induced proliferation in the subcallosal zone

Stem cell niches exist around the lateral ventricle and in the subgranular layer of the dentate gyrus, supporting adult neurogenesis. Recently, a third germinal layer, the subcallosal zone has been identified supporting the generation of oligodendrocytes in the adult brain. We have previously described a proliferative role for neuropeptide Y on precursors in the dentate gyrus, caudal subventricular zone and subcallosal zone under basal conditions and in the dentate gyrus after seizures. Here we sought to determine a role for neuropeptide Y in seizure-induced proliferation in the subcallosal niche. Using the chemoconvulsant kainate and neuropeptide Y(-/-) mice with controls, we show an effect of neuropeptide Y on basal proliferation and demonstrate a significant reduction in seizure-induced proliferation in the subcallosal zone.

An in vivo correlate of exercise-induced neurogenesis in the adult dentate gyrus

With continued debate over the functional significance of adult neurogenesis, identifying an in vivo correlate of neurogenesis has become an important goal. Here we rely on the coupling between neurogenesis and angiogenesis and test whether MRI measurements of cerebral blood volume (CBV) provide an imaging correlate of neurogenesis. First, we used an MRI approach to generate CBV maps over time in the hippocampal formation of exercising mice. Among all hippocampal subregions, exercise was found to have a primary effect on dentate gyrus CBV, the only subregion that supports adult neurogenesis. Moreover, exercise-induced increases in dentate gyrus CBV were found to correlate with postmortem measurements of neurogenesis. Second, using similar MRI technologies, we generated CBV maps over time in the hippocampal formation of exercising humans. As in mice, exercise was found to have a primary effect on dentate gyrus CBV, and the CBV changes were found to selectively correlate with cardiopulmonary and cognitive function. Taken together, these findings show that dentate gyrus CBV provides an imaging correlate of exercise-induced neurogenesis and that exercise differentially targets the dentate gyrus, a hippocampal subregion important for memory and implicated in cognitive aging.

The contribution of intermittent hypoxemia to late neurological handicap in mice with hyperoxia-induced lung injury

Bronchopulmonary dysplasia (BPD) is considered by many to be an independent risk factor for poor neurodevelopment in premature infants. However, infants with BPD experience intermittent hypoxic episodes. This study was undertaken to determine whether intermittent hypoxic stress associated with BPD contributes to the development of neurological deficit. The model of BPD was produced in neonatal mice by exposure to hyperoxia (65% O(2)) for 4 weeks. Arterial blood gases, pulmonary mechanics, and histopathology were used to define the degree of lung injury. The mice were subjected to brief (10 min/day) and intermittent (10 days) hypoxic stress (8% O(2)) at different stages of the development of hyperoxia-induced lung injury. At 8 weeks of life, the neurofunction was assessed by water maze and rota-rod tests followed by cerebral morphological analysis using Nissl, bromodeoxyuridine, and caspase-3 immunostaining. Data were compared to naïve normoxic littermates and those mice that were exposed only to hyperoxia or intermittent hypoxia alone. Mice with BPD subjected to brief/intermittent hypoxia demonstrated a significantly poorer navigational memory performance as compared with normoxic mice and mice with BPD that were not subjected to intermittent hypoxia. The neurofunctional handicap in these mice was associated with significantly decreased brain weight and increased cerebral expression of caspase-3. Our results suggest that intermittent hypoxia associated with hyperoxia-induced lung injury, but not lung injury itself, results in significant neurological handicap in neonatal mice with BPD.

Neuropeptide Y is important for basal and seizure-induced precursor cell proliferation in the hippocampus

We have shown that neuropeptide Y (NPY) regulates neurogenesis in the normal dentate gyrus (DG) via Y(1) receptors (Howell, O.W., Scharfman, H.E., Herzog, H., Sundstrom, L.E., Beck-Sickinger, A. and Gray, W.P. (2003) Neuropeptide Y is neuroproliferative for post-natal hippocampal precursor cells. J Neurochem, 86, 646-659; Howell, O.W., Doyle, K., Goodman, J.H., Scharfman, H.E., Herzog, H., Pringle, A., Beck-Sickinger, A.G. and Gray, W.P. (2005) Neuropeptide Y stimulates neuronal precursor proliferation in the post-natal and adult dentate gyrus. J Neurochem, 93, 560-570). This regulation may be relevant to epilepsy, because seizures increase both NPY expression and precursor cell proliferation in the DG. Therefore, the effects of NPY on DG precursors were evaluated in normal conditions and after status epilepticus. In addition, potentially distinct NPY-responsive precursors were identified, and an analysis performed not only of the DG, but also the caudal subventricular zone (cSVZ) and subcallosal zone (SCZ) where seizures modulate glial precursors. We show a proliferative effect of NPY on multipotent nestin cells expressing the stem cell marker Lewis-X from both the DG and the cSVZ/SCZ in vitro. We confirm an effect on proliferation in the cSVZ/SCZ of Y(1) receptor(-/-) mice and demonstrate a significant reduction in basal and seizure-induced proliferation in the DG of NPY(-/-) mice.

Upregulation of RAGE and its ligands in proliferative retinal disease

We sought to study the presence of the receptor for advanced glycation endproducts (RAGE) and its ligands, advanced glycation endproducts (AGEs), S100/calgranulins and amphoterin (high mobility group box 1 protein; HMGB1), in the vitreous cavity and epiretinal membranes (ERMs) of eyes of patients with proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). Undiluted vitreous specimens were collected from 30 eyes of 30 patients undergoing pars plana vitrectomy for repair of retinal detachment (RD) secondary to PDR (n = 15) or PVR (n = 15). The vitreous samples obtained from 10 eyes undergoing macular hole repair were used as controls. Epiretinal membranes were obtained from eight eyes with PDR and from 10 eyes with PVR. The levels of AGEs in the vitreous were measured using ELISA. The vitreous levels of soluble RAGE (sRAGE), S100/calgranulins and amphoterin were measured using Western blot analyses. The localization of RAGE and its ligands in ERMs was determined with immunohistochemistry. The vitreous levels of sRAGE were significantly increased in both PDR and PVR (p < or = 0.05) compared to control vitreous. In both PDR and PVR, the vitreous levels of AGEs (p < or = 0.01), S100/calgranulins (p < or = 0.05), and amphoterin (p < or = 0.01) were also elevated compared to control eyes. Expression of RAGE was detected in six of eight ERMs from eyes with PDR and eight of 10 ERMs from eyes with PVR. Many cells expressing RAGE also expressed vimentin, suggesting a glial cell origin. Ligands for RAGE were also detected in ERMs, with AGEs detected in five eyes with PDR and eight eyes with PVR. Similarly, S100 and amphoterin ERM expression was observed in six eyes with PDR; these ligands were also expressed in ERMs from eyes with PVR (8 and 7 cases, respectively). We conclude that RAGE and its ligands are increased in the vitreous cavity of eyes with PDR and PVR and are present in ERMs of eyes with these proliferative retinal disorders. These findings suggest a role for the proinflammatory RAGE axis in the pathogenesis of proliferative retinal diseases.

Spinal cord endoplasmic reticulum stress associated with a microsomal accumulation of mutant superoxide dismutase-1 in an ALS model

Mutation in superoxide dismutase-1 (SOD1), which is a cause of ALS, alters the folding patterns of this protein. Accumulation of misfolded mutant SOD1 might activate endoplasmic reticulum (ER) stress pathways. Here we show that transgenic mice expressing ALS-linked SOD1 mutants exhibit molecular alterations indicative of a recruitment of ER's signaling machinery. We demonstrate by biochemical and morphological methods that mutant SOD1 accumulates inside the ER, where it forms insoluble high molecular weight species and interacts with the ER chaperone immunoglobulin-binding protein. These alterations are age- and region-specific, because they develop over the course of the disease and occur in the affected spinal cord but not in the nonaffected cerebellum in transgenic mutant SOD1 mice. Our results suggest a toxic mechanism for mutant SOD1 by which this ubiquitously expressed pathogenic protein could affect motor neuron survival and contribute to the selective motor neuronal degeneration in ALS.

Studies of damage to hippocampal neurons in inbred mouse lines in models of epilepsy using kainic acid and pilocarpine

Identification of the mechanisms of damage to neurons is an important task in contemporary neuroscience and is of enormous importance in medicine. This report compares two models of neuron damage due to hyperexcitation induced by kainic acid and pilocarpine, using two lines of mice, C57BL/6J and FVB/NJ. Neuron damage was more marked in FVB mice, though lethality was greater in C57BL mice. The levels of convulsive activity were not significantly different. Kainic acid had greater tropism for the hippocampus than pilocarpine. Hsp-70 and Egr-1 expression was not significantly different in C57BL and FVB mice. Analysis of the isolated mitochondrial fraction showed that free radical production was different in these mouse lines; this may be one of the reasons for the differential resistance of neurons to hyperexcitation.

Nestin-Expressing Cells in the Human Hippocampus

Nestin, a protein of the intermediate filament family, is typical of undifferentiated neural stem and progenitor cells. The present report describes studies of nestin expression in the hippocampus of patients with epilepsy and identifies five types of nestin-immunopositive cells differing in terms of their morphological phenotype and immunological characteristics. These were cells with the phenotype of radial glial cells, bipolar cells, small dendritic cells, cells of the subependymal zone, and astrocyte-like cells. Two types of cell - radial gliocytes of the dentate fascia and NG2-immunopositive bipolar cells - can be regarded as neural precursors of different levels of commitment.

[Neuronal damage in the hippocampus of inbred mouse strains in the models of epilepsy induced by kainic acid and pilocarpine]

Elucidation of the mechanisms of neuronal damage is an important task of modem neuroscience and is of paramount importance for medicine. Present work compares two models of excitotoxic neuronal damage induced by kainic acid and pilocarpine, in which inbred C57BL/6J (C57BL) and FVB/NJ (FVB) mice were used. Both models produced higher neuronal damage in FVB although mortality was higher in C57BL. No significant differences between two strains of mice were found in seizures severity. Kainic acid demonstrated greater tropism to hippocampus in comparison with pilocarpine. Hsp-70 and Egr-1 expression was not significantly different in C57BL and FVB. Analysis of the isolated mitochondrial fraction has shown different degree of free radical production in the strains studied, that could be one of the reasons for unequal susceptibility of their neurons to excitotoxic cell death.

[Nestin-expressing cells in the human hippocampus]

Nestin is a protein that belongs to a family of intermediate filament proteins which are typical for undifferentiated neural stem and progenitor cells. In this work nestin expression was studied in the hippocampus obtained from patients with epilepsy. Immunohistochemical investigation demonstrated five types of nestin-positive cells, differing in morphological and immunological phenotype. These included cell with a radial glia phenotype, bipolar cells, small dendritic cells, subependymal and astrocyte-like cells. Two types of these cells: radial glia of dentate gyrus and bipolar NG2+ cells can be considered as neural progenitor cells possessing different degrees of commitment.

Short-term plasticity of cyclic adenosine 3',5'-monophosphate signaling in anterior pituitary corticotrope cells: the role of adenylyl cyclase isotypes

Anterior pituitary corticotropes show a wide repertory of responses to hypothalamic neuropeptides and adrenal corticosteroids. The hypothesis that plasticity of the cAMP signaling system underlies this adaptive versatility was investigated. In dispersed rat anterior pituitary cells, depletion of intracellular Ca2+ stores with thapsigargin combined with ryanodine or caffeine enhanced the corticotropin releasing-factor (CRF)-evoked cAMP response by 4-fold, whereas reduction of Ca2+ entry alone had no effect. CRF-induced cAMP was amplified 15-fold by arginine-vasopressin (AVP) or phorbol-dibutyrate ester. In the presence of inhibitors of cyclic nucleotide phosphodiesterases and phorbol-dibutyrate ester, the depletion of Ca2+ stores had no further effect on CRF-induced cAMP accumulation. Adenohypophysial expression of mRNAs for the Ca2+-inhibited adenylyl cyclases (ACs) VI and IX, and the protein kinase C-stimulated ACs II and VII was demonstrated. ACIX was detected in corticotropes by immunocytochemistry, whereas ACII and ACVI were not present. The data show negative feedback regulation of CRF-induced cAMP levels by Ca2+ derived from ryanodine receptor-operated intracellular stores. Stimulation of protein kinase C by AVP enhances Ca2+-independent cAMP synthesis, thus changing the characteristics of intracellular Ca2+ feedback. It is proposed that the modulation of intracellular Ca2+ feedback in corticotropes by AVP is an important element of physiological control.

Mouse strain differences in kainic acid sensitivity, seizure behavior, mortality, and hippocampal pathology

Genetic influences contribute to susceptibility to seizures and to excitotoxic injury, but it is unclear if/how these susceptibilities are linked. This study assessed the impact of genetic background on mouse strain seizure susceptibility, seizure phenotype, mortality, and hippocampal histopathology. A subcutaneous (s.c.) kainic acid multiple injection protocol was developed. Five mouse strains were tested: a and b) C57BL/6J and 129/SvJ, strains commonly used in gene targeting experiments; c) C3HeB/FeJ, a strain with reported sensitivity to the convulsant effects of kainic acid (KA); d) 129/SvEms, a strain reportedly susceptible to hippocampal excitotoxic cell death; and e) a mixed genetic background strain (129/SvJXC57BL/6J) from which targeted gene deletion experiments have been carried out. Histopathological features were examined at early (7-10 day), delayed (2-4 month), and late (6-13 month) time points.Mouse background strains can be genetically segregated based on excitotoxin sensitivity, seizure phenotype, mortality, and hippocampal histopathology. When injected with KA, C3HeB/FeJ and C57BL/6J strains were resistant to cell death and synaptic reorganization despite severe behavioral seizures, while 129/SvEms mice developed marked pyramidal cell loss and mossy fiber sprouting despite limited seizure activity. The mixed background 129/SvJXC57BL/6J group exhibited features of both parental strains. In the mouse strains tested, the duration or severity of seizure activity was not predictive of subsequent hippocampal pyramidal cell death and/or synaptic reorganization. Unlike rats, mice exhibiting prolonged high-grade KA-induced seizure activity did not develop subsequent spontaneous behavioral seizures.

[Neurogenesis in the adult mammalian brain]

The concept of the CNS cell composition stability has recently undergone significant changes. It was earlier believed that neurogenesis in the mammalian CNS took place only during embryonic and early postnatal development. New approaches make it possible to obtain new results overriding the dogma that neurogenesis is impossible in the adult brain. The present review summarizes the information about the neural stem cell. It has been demonstrated that new neurons are constantly formed in adult mammals, including man. In two brain zones, subventricular zone and denate gyrus, neurogenesis appears proceed throughout the entire life of mammals, including man. The newly arising neurons are essential for some important processes, such as memory and learning. Stem cells were found in the subependymal and/or ependymal layer. They express nestin, and have a low mitotic activity. During embryogenesis, the stem cell divides asymmetrically: one daughter cell resides as the stem cell in the ependymal layer and another migrates to the subventricular zone. There it gives rise very fast to a pool of dividing precursors, from which neural and glial cells differentiate and migrate to the sites of final localization. The epidermal and fibroblast growth factors act as mitogens for the neural stem cell. The neural stem cell gives rise to the cells of all germ layers in vitro and has a wide potential for differentiation in the adult organism. Hence, it can be used as a source of various cell types of the nervous tissue necessary for cellular transplantation therapy.

[Neural stem cells in the brain]

Stem cells in the central nervous system were usually considered as relevant for evaluation only in embryonic time. Recent advances in molecular cloning and immunological identification of the different cell types prove the presence of neurogenesis of the new neurons in adult mammals brains. New neurons are born in two areas of the mammal and human brain--sybventricular zone and subgranular zone of dentate gyrus. New born granular neurons of dentate gyrus have a great importance for memory and learning. New neurons originate from precursors which in culture and in situ could also transform into astrocytes and oligodendrocytes, thus fulfill criteria of neural stem cells. In culture, mitotic activity of these stem sells depends on fibroblast growth factor 2 and epidermal growth factor. Depletion of cultural medium of these factors and addition of serum, other growth factors (Platelet-derived growth factor and ciliary neurotrophic factor) leads to generation of neurons and astrocytes. Isolation and clonal analysis of stem cells is based on immunological markers such as nestin, beta-tubulin III, some types of membrane glicoproteids. Identification and visualization of stem cells in brain revealed two populations of cells which have properties of stem cells. In embryonic time, radial glia cells could give origin to neurons, in mature brain cells expressing glial fibrillar acidic protein typical marker of astrocytes fulfill criteria for stem cells. Neural stem cells could transform not only into mature neurons and glial cells but also into blood cells, thus revealing broad spectrum of progenitors from different embryonic tissues. Further progress in this field of neurobiology could give prosperity in the cell therapy of many brain diseases.

Expression of adenylyl cyclase type IX and calcineurin in synapses of the central nervous system

Distribution of type IX adenylyl cyclase and protein phosphatase calcineurin in the brain and in cultured hippocampal neurons from albino rat was immunohistochemically studied. Both enzymes were detected simultaneously in all synaptic structures of most cerebral neurons except for presynaptic sites, where calcium-inhibited type IX adenylyl cyclase was absent.

Characterisation of human adenylyl cyclase IX reveals inhibition by Ca(2+)/Calcineurin and differential mRNA plyadenylation

The functional diversity of adenylyl cyclases provides for different modes of cyclic AMP signalling in mammals. This study reports the cloning and functional characterisation of a cDNA encoding human adenylyl cyclase IX (ACIX). The data show that human ACIX is a Ca(2+)/calcineurin-inhibited adenylyl cyclase prominently expressed in vital organs, including brain, heart, and pancreas. ACIX mRNA was detected in several brain regions, including neocortex, hippocampus, striatum, and cerebellum. By in situ hybridisation, ACIX mRNA was localised to pyramidal and granule cells of the hippocampus, indicating that it is expressed predominantly in nerve cells. Further analysis of ACIX mRNA expression revealed two major forms of ACIX mRNA that arose through tissue-specific differential mRNA polyadenylation. Taken together, the data show that (a) human ACIX is under inhibitory control by Ca(2+) through calcineurin, (b) ACIX may be involved in higher brain functions, and (c) post-transcriptional regulation of ACIX gene expression is a species-specific control mechanism that may enhance the versatility of cyclic AMP signalling in humans.

[Nitric oxide synthase in neuroepithelial brain tumors]

Immunohistochemical investigation of NO-synthase in brain astrocytic tumors revealed intense reaction in many tumor cells as well as direct correlation in the intensity of reaction and the degree of tumor anaplasia. Grade I astrocytomas did not show immunoreactivity in contrast to high anaplastic tumors where many cells had positive reaction with a different degree of intensity. Positive immunoreaction was shown in many giant cells. Small cell glioblastomas and oligodendrogliomas were immunonegative. There was a direct correlation between NO-synthase expression and glial fibrillar acidic protein.

Neuropeptide Y-immunoreactive intracardiac neurones, granule-containing cells and nerves associated with ganglia and blood vessels in rat and guinea-pig heart

Intrinsic neuropeptide Y-containing neurones in rat and guinea-pig hearts were studied at the ultrastructural level by the pre-embedding peroxidase-antiperoxidase immunocytochemical technique. Intracardiac neuronal cell bodies were often weakly or moderately immunostained, and the labelling was usually pronounced in the Golgi complex, multivesicular bodies, some cisterns of granular endoplasmic reticulum and large granular vesicles. Neuropeptide Y-immunoreactive nerve fibres were also observed in association with intracardiac neurones. A subpopulation of neuropeptide Y-immunoreactive granule-containing cells in the rat heart are described for the first time and were very heavily labelled; other granule-containing cells were non-immunoreactive, but were contacted by neuropeptide Y-containing nerves. Preterminal regions of nerve fibres that were located in nerve bundles were only weakly neuropeptide Y-immunoreactive, in contrast to the heavy labelling observed in varicosities that contained many synaptic vesicles. Many neuropeptide Y-immunoreactive nerve fibres were associated with the coronary vasculature and were particularly prominent in the walls of small arteries and arterioles where labelled nerve varicosities were present close to the smooth muscle cells. Immunoreactive nerves were also seen in the myocardium, usually near to capillaries. In axonal varicosities, the central core of large granular vesicles was immunolabelled, and electron-dense immunoreactive material outlined the membranes of small and large clear vesicles. The significance of neuropeptide Y-immunoreactive intracardiac neurones and granule-containing cells and the origin of associated labelled nerve fibres in the heart are discussed.

[Age-related changes in the autonomic ganglia]

Ultrastructure of vegetative ganglions (neck-thoracic, intracardial and intestinal) of Wistar and SHR rats, 26-28 months of age was studied electron-microscopically. The most pronounced changes were found in the neck-thoracic ganglions where, apart from lipofuscin deposits, lamellar bodies were frequently found. Redistribution of neuromediators in the neuron body and an increase of the neuroactive substances release into the intercellular space of the ganglion occur with age. The data on possible postsynaptic influence on the presynapse by means of neuromediators are presented. Nissl bodies hypertrophy was observed in the neck-thoracic and intracardial ganglions of old SHR rats.

[Ultrastructure of the sympathetic ganglia in hypoxia]

Short-term hypoxia produces ultrastructural alterations in ganglions of rats in the form of dilatation of some membrane neuron compartments and sinuous plasmatic membrane. More long-term hypoxia produces structural changes of membrane cell components. An increase of lysosome number and lipofuscin granules alternations in chronic hypoxia (1 year) are similar to the age changes and are characterized by intensive accumulation of lipofuscin and Nissl bodies hypertrophy.

[Interneuronal interrelationships in autonomic ganglia (the ultrastructural aspects)]

Ultrastructural and immunocytochemical results of studies on interneuronal relationship in vegetative ganglia were represented. Age-related changes of synapses (appearance of synaptic type vesicles and smooth endoplasmic reticulum cisterns in postsynaptic terminals), peculiarities of interneuronal links in neurons containing neuropeptide Y and NO-synthase and structural manifestations of non-synaptic interneuronal links were shown. Modern views on interneuronal communications were discussed.

Nitric oxide synthase-containing neurones and nerve fibres within cardiac ganglia of rat and guinea-pig: an electron-microscopic immunocytochemical study

The nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity of intracardiac neurones in the rat and guinea-pig was studied at the ultrastructural level. While some nitric oxide synthase-containing intracardiac neurones were very heavily labelled, with electron-dense immunoprecipitate distributed throughout the neuronal cell bodies and their processes, most of the labelled neurones exhibited a lighter and more patchy distribution of nitric oxide synthase-immunoreactive material. Synapses made by nitric oxide synthase-negative nerve fibres with labelled intracardiac neurones were seen. Conversely, many nitric oxide synthase-containing nerve fibres that made synaptic contacts with unlabelled intracardiac neurones were also observed. Some small granule-containing cells were nitric oxide synthase-immunoreactive and were associated with unlabelled nerve terminals, while non-immunoreactive small granule-containing cells that were innervated by nitric oxide synthase-immunoreactive nerves were also seen. Small patches of osmiophilic electron-dense material were observed in the cytoplasm of NADPH-diaphorase-positive intracardiac neurones. This is the first description of the ultrastructural distribution of nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in a subpopulation of intracardiac neurones of rat and guinea-pig heart and provides further evidence in support of a role for nitric oxide in the local control of the heart by intrinsic neurones.

[The structure of the stellate sympathetic ganglia under long-term hypoxia]

Changes of mitochondrial ultrastructure indicating not only degenerative processes but also the presence of organelle adaptive reactions were demonstrated in sympathetic neurons. Appearance of osmiophilic inclusions in mitochondrial matrix relates to most typical organelle alterations in ageing. Number of smooth endoplasmic reticulum vesicles equal in size to synaptic vesicles of nerve cells processes grows higher. Such vesicles are usually located near postsynaptic active zones and areas with neuronal plasmolemma free from glia. Their outward resemblance does not allow to claim that neuromediators and neuromodulators may turn up in these vesicles, although dendrites contain and may release certain biologically active substances. Basic difference between 24 and 30-months old rats lies in earlier degenerations of nerve cells in old animals. Forming of dark granules may be also associated with conditions of fixation. Small granular (SG) cells lacked typical lipofuscine granules, while their ultrastructure changed insignificantly. SG cells capacity to divide mitotically in functional maturity is likely to be one of the possible explanations of such difference.

Ultrastructural investigation of nitric oxide synthase-immunoreactive nerves associated with coronary blood vessels of rat and guinea-pig

Ultrastructural investigation of nitric oxide synthase-immunoreactive nerves closely associated with blood vessels in rat and guinea-pig hearts revealed many labelled nerve fibres in the walls of the main branches of the coronary arteries, and in arterioles, capillaries and post-capillary venules. The number of nitric oxide synthase-containing nerve fibres associated with different vessels, even those of the same calibre, varied. Terminal regions of nitric oxide synthase-immunoreactive fibres were observed in the endocardium and myocardium. Nitric oxide synthase-labelled fibres displayed electron-dense immunoproduct in both varicose and intervaricose regions. Immunoreactive axonal varicosities contained both small and large synaptic vesicles. The characteristics of the nitric oxide synthase-immunoreactive nerve fibres observed in the heart and the possibility that these fibres represent the processes of intracardiac neurones and/or sensory neurones of extrinsic origin are discussed.

Inclusions similar to Hirano bodies in urinary bladder neurons of dogs

Unusual intracytoplasmatic inclusions were found in urinary bladder neurons in dogs. The plate-like inclusions were composed of thin filaments, and when viewed en face, appeared as oval or angular bodies with regular lattice work array. When viewed in a transverse section, they were of rod-like shape and were composed of longitudinal filaments and transverse bars. The inclusions were observed in all ganglia of the urinary bladders studied. Three-dimensional reconstruction of the inclusions was made, using a tilting device. By means of this reconstruction, it could be demonstrated that their ultrastructure is similar to that of Hirano bodies which occur in human neurons of the central nervous system in cases of neurodegenerative diseases. The authors suggest that unusual intraneuronal inclusions represent a peculiarity in cytoskeletal protein assembly typical of canine urinary bladder neurons.

Intracellular penetration of ruthenium red in embryonic nervous tissue

Electron microscopic investigations, using ruthenium red revealed that dye is usually observed in immature neuronal cells in autonomic ganglia of rat embryos and fetuses. Ruthenium red does not penetrate undamaged neurons in mature ganglia. Ruthenium red positive material covers neuronal cell plasmalemma even in early primordial phases of autonomic ganglia. Plasmalemma of growth zones does not react with ruthenium red. Intracellular penetration of immature neurons by ruthenium red, according to expectation, depends on damage to cell membrane due to the fixation procedure, especially in the growth zones.

[Ultrastructure of neurons of the human sympathetic ganglia after sudden death (morphometric study)]

Six cases of urgent autopsies after a sudden cardiac death (SCD) of persons at the age 40-60 years and 5 control cases have been investigated. Osmiophilic mitochondria with inclusions make 1% of the whole neuronal cytoplasm volume. If we take all mitochondria as 100%, volumetric density of mitochondria with osmiophilic inclusions makes 9.6%. Volumetric density of mitochondria at SCD in comparison with the control is significantly higher in connection with increase of their size. In other components of cytoplasm, in particular in lysosomes and lipofuscin, no changes are revealed.

[Staged quality of the transformation of the autonomic nervous system in ontogenesis]

As a result of neurohistochemical and electron microscopic investigations of the autonomic nervous system (ANS) in ontogenesis of the human being and mammalia the premediatory period of its development can be divided into the stage of the nervous crest cells migration into the place of the ganglia anlage and the stage of contact of preganglionic fibers with neural elements. These two stages occur heterochronically. The mediatory period of the ANS development is conditionally divided into five stages. The first is characterized with appearance of mediators in synapses and nervous plexuses in the internal organs. The second--consists in activation of gliocytogenesis and lasts up to 7 months of the human intrauterine life, when the third stage begins--the perinatal maturation of the ANS. In the nervous plexuses myelin fibers appear, perivascular plexuses and structure of the afferent endings become more complex. The fourth stage--completion of the ANS formation--takes place when the child is more than one year of age and it lasts up to sexual maturation. The nervous fibers myelinization is completed, amount of synapses in neurons increases. Then the fifth stage begins--stabilization of the VNS. The postmediatory period takes place not simultaneously in various ganglia of the VNS and has two stages. At first it becomes evident in the sympathetic part of the VNS. Certain morphofunctional manifestations start the stage of the initial exhausion of mediators. In neurons amount of lipofuscin granules grows large, some disturbances in mitochondria and osmiophilic lamellar bodies appear. This stage of the postmediatory period can start early, for example, in the human heart on the fourth decade of life and lasts in the organ up to 60-65 years, when the terminal stage takes place--involutive degeneration of the VNS plexuses.

[Morphofunctional study of the myocardium in alcoholic intoxication]

An experimental model of acute and chronic ethanol poisoning is described. Electrocardiographic and morphologic changes in the hearts of white rats, exposed to alcoholic intoxication, have been assessed. Typical ECG features as well as muscle-cell and neuron ultrastructure have been identified, so that they could be used for morphologic and functional assessment of alcoholic poisoning.

Electron microscopic study of cardiac ganglia in human fetuses

The early events in the development of the heart ganglia and nerves in human fetuses ranging from 5 to 12 weeks of gestation age were studied by transmission electron microscopy. The first neuroblasts in the atrial mesenchyme differ from surrounding cells in the presence of short cisternae of rough endoplasmic reticulum and in the absence of glycogen particles. The most valuable criterion for identification of neuroblasts is the presence of contacts with preganglionic nerve terminals. Only ganglia composed of compact aggregations of neuronal cells and nerve terminals have a complete glial sheath. The first signs of synapse formation were seen in 5-week-old fetuses; well developed synapses with many synaptic vesicles were found from the 8th week of gestation onwards. These were predominantly axodendritic synapses. It is proposed that synaptogenesis begins with the appearance of osmiophilic zones at the sites of interneuronal contacts, then synaptic vesicles move by axonal transport to reach the preformed specialized junctions and stop in axonal presynaptic varicosities.