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PubMed1997

The effect of stepwise cerebral hypoperfusion on energy metabolism and amyloid precursor protein (APP) in cerebral cortex and hippocampus in the adult rat.

To study the relationship between cerebral blood flow, energy metabolism, and the formation of amyloid precursor protein (APP), an in vivo animal model was established in which stepwise long-term cerebral hypoperfusion states were induced. Adult rats underwent a stepwise chronic cerebral hypoperfusion by crosswise occlusion of the carotid and vertebral arteries with different periods and severity of hypoperfusion until the final steady-state experiment. Investigations of metabolic compounds were done in hippocampus and parietotemporal cerebral cortex. The analysis of energy-rich phosphates and adenosine was examined by HPLC analysis. Substrate concentrations of pyruvate and lactate were measured spectrophotometrically. The APP holoprotein was investigated by immunblot technique. Long-term cerebral hypoperfusion induced a decrease of energy-rich phosphates in the brain areas studied, whereas the concentration of adenosine and the ATP turnover were increased. Pyruvate decreased, and lactate was increased, pointing to a shift in the cytoplasmatic redox state. More severe changes were found in parietotemporal cerebral cortex in comparison to the hippocampus. After 2-vessel occlusion, the concentration of APP decreased, whereas the APP concentration was significantly increased in rat brain after 4-vessel occlusion. It has been demonstrated for the first time in vivo that the reduction in cerebral energy metabolism alters the formation of APP due to cerebral hypoperfusion.

Amyloid beta-Protein Precursor↗
PubMed1995

Distribution of tangles and threads in the cerebral cortex in progressive supranuclear palsy.

Recent studies have described silver- and tau-positive glia and threads in the degenerating lesions of progressive supranuclear palsy. In this study, Gallyas-Braak silver impregnation and several immunohistochemical techniques were employed to examine the distribution of tangles, abnormal glia and threads in the cerebral cortex of nine cases of progressive supranuclear palsy. In addition to neurofibrillary tangles, argentophilic glia and threads were impregnated exclusively by Gallyas-Braak technique. This technique demonstrated two types of glia profiles: tightly coiled intra-cytoplasmic profiles surrounding nuclei (coiled profiles) and thorn-like profiles with radial ramifications (thorn-like profiles). Thorn-like profiles are possibly in astrocytes and were detected in the cerebral cortex, while coiled profiles are possibly in oligodendroglia and were detected both in the cerebral cortex and subcortical white matter. Topographically, many neurofibrillary tangles were constantly seen in the frontal cortex and in the pre-central gyrus. Numerous neurofibrillary tangles were detected in the entorhinal cortex of the two brains. Argentophilic glia and threads were also frequent both in the frontal cortex and the precentral gyrus; however, they were more frequent in the pre-central gyrus that in the frontal cortex in four of the eight cases examined. In two brains, argentophilic threads were distributed widely in the cerebral cortex and white matter except for the temporal cortex. In immunohistochemical studies, argentophilic glia and threads were mostly positive for Tau 2, and a small number of them were weakly positive for ubiquitin and paired helical filament protein. The immunoproperties of these abnormal glia and threads seemed to be virtually identical to those of neurofibrillary tangles.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Postnatal ontogeny of uridine kinase in the cerebellum, hypothalamus, and cerebral cortex of the rat.

Postnatal developmental patterns of uridine kinase were determined in crude subcellular fractions of the rat cerebellum, hypothalamus and cerebral cortex at ages 3 through 60 days. The highest specific activity and predominant distribution of enzyme was in the 105,000 g supernatant of the 3 brain regions. Enzyme activity in hypothalamus and cerebral cortex was maximum at 3 days and decreased with age; in cerebellum it increased through 13 days and decreased thereafter. Thus, the pattern of activity in hypothalamus and cerebral cortex paralleled changes in DNA and RNA synthesis through age 60 days; in cerebellum, it more closely approximated changes in DNA synthesis during early development. Changes in Km with aging suggest that the brain regions contain more than one form of enzyme. The highest particulate activity was in the microsomal fraction of the cerebellum and hypothalamus at all ages and in the cortex at 35 and 60 days. Relative specific activity for microsomal fractions of the brain regions at 60 days indicate a concentration of the enzyme which may be relevant in the maintenance of RNA activity in adult brain.

Age Factors↗
PubMed2003

Role of lipids in the assembly of endoplasmic reticulum and dictyosomes in neuronal cells from the cerebral cortex of Yakutian ground squirrel (Citellus undulatus) during hibernation.

Phospholipids and cholesterol were assayed in homogenates and microsomal fractions from the cerebral cortex of summer-active, winter-torpid, and winter-active Yakutian ground squirrels (Citellus undulatus). Ultrastructural analysis of both microsomal fraction and intact neurons was performed by serial ultramicrotomy. The levels of sphingomyelin (SM), phosphatidylserine (PS), and phosphatidylethanolamine (PEA) were decreased in homogenates from the cerebral cortex of winter ground squirrels compared with the summer-active animals, while the levels of phosphatidylcholine (PC) and cardiolipin (CL) were increased. The level of cholesterol was decreased in the cerebral cortex of winter-torpid animals compared with both winter-active and summer-active animals, and the level of total phospholipids was decreased in comparison to the summer-active animals. Three-dimensional reconstruction of serial membrane profiles displayed the microsomal fraction to be an interconnected system of cisterns and vesicles, which corresponds to endoplasmic reticulum and dictyosomes (Golgi stacks) of intact neurons. In winter the content of PC was increased in the microsomal fraction, while the contents of lysophosphatidylcholine (LPC), PS, phosphatidylinositol (PI), and SM were decreased. In winter-torpid animals compared with the winter-active ones the contents of total phospholipids, PEA, LPC, and cholesterol were decreased. As for the winter-active ground squirrels, their lipid contents did not differ from those in the summer-active animals, but LPC content was decreased. The changes in microsomal lipid contents in intact pyramidal neurons throughout the hibernation were accompanied by disassembly of dictyosomes and endoplasmic reticulum (ER), including the decomposition of polyribosomes to monosomes. The ultrastructural analysis of nucleoli, ER, and dictyosomes of both winter-active and torpid ground squirrels showed a direct correlation between the increasing contents of both cholesterol and total phospholipids (mainly PEA and LPC) in microsomes and the structural recovery of endoplasmic reticulum, Golgi stacks, and nucleoli in intact pyramidal neurons. A role of seasonal variations in lipid contents of brain cells in their adaptation to low temperature is discussed. We also propose an involvement of cholesterol in the activation of protein-synthesizing function of endoplasmic reticulum and Golgi stacks in intact neurons.

Animals↗
PubMed1997

Differential distribution of the glutamate transporters GLT1 and rEAAC1 in rat cerebral cortex and thalamus: an in situ hybridization analysis.

The distributions in rat cerebral cortex and thalamus of the mRNAs encoding the glutamate transporters GLT1 and rEAAC1 (a rat homologue of rabbit EAAC1) were investigated by nonautoradiographic in situ hybridization using digoxigenin-labelled riboprobes. The probe recognizing rEAAC1 mRNA labelled exclusively neurons while GLT1 mRNA was found in glia as well as in select neuronal populations. The neurons containing the GLT1 transcript exhibited a distribution that was different from, and at some sites complementary to, the distribution of neurons containing rEAAC1 mRNA. In the subiculum, neurons positive for GLT1 and rEAAC1 were found in the deep and superficial part of the cell layer, respectively, while in the parietal neocortex GLT1 predominated in layer VI and rEAAC1 in layer V. Very few neuronal populations, most notably cells in hippocampal subfields CA3 and CA4, and in layer II in the entorhinal cortex, appeared to be equipped with both transcripts. In the thalamus the GLT1 labelling predominated in the midline and intralaminar nuclei while rEAAC1 labelling was found throughout this structure. It was concluded that the cerebral cortex and thalamus show cellular, laminar, as well as regional heterogeneities in the expression of the two glutamate transporters.

Amino Acid Transport System X-AG↗
PubMed1975

Effects of 6-hydroxydopamine and reserpine on amphetamine-induced release of norepinephrine in rat cerebral cortex.

Amphetamine released 3-H-norepinephrine from rat cerebral cortex tissue which had previously accumulated the 3-H-amine. Destruction of noradrenergic nerve endings by pretreatment of the rats with 6-hydroxydopamine inhibited the accumulation of 3-H-norepinephrine by the tissue and reduced the proportion of the 3-H-amine which was released by amphetamine. Inhibition of storage of 3-H-norepinephrine within nerve endings by pretreatment of the animals with reserpine also reduced accumulation of 3-H-norepinephrine but did not reduce the proportion of the accumulated 3-H-amine which was released by amphetamine. The addition of desipramine (an inhibitor of neuronal uptake) further reduced the accumulation of 3-H-norepinephrine in animals pretreated with reserpine but had no further effect in animals pretreated with 6-hydroxydopamine. A greater proportion of the 3-H-norepinephrine was converted to 3-H-deaminated metabolites in tissues of reserpine-treated animals than in the tissues of control or 6-hydroxydopamine-treated rats. Amphetamine-induced release of 3-H-norepinephrine was partially calcium dependent in tissues from control animals. After reserpine treatment, amphetamine-induced release of norepinephrine was independent of calcium, whereas potassium-mediated release was still markedly calcium dependent. These experiments indicate that amphetamine releases 3-H-norepinephrine primarily from storage sites within central adrenergic nerve endings. An analysis of the time course of release from tissues of rats treated with reserpine suggests that amphetamine is equally capable of releasing 3-H-norepinephrine from granular sites which are susceptible to reserpine and from reserpine-insensitive sites.

Amphetamine↗
PubMed2000

Repeated intracerebroventricular administration of beta-amyloid(25-35) to rats decreases muscarinic receptors in cerebral cortex.

The effects of repeated in vivo administration to rats of beta-amyloid(25-35) (betaA(25-35)) on several cholinergic markers have been studied and compared with those of a peptide with a scrambled sequence. Rats received intracerebroventricular injections of betaA(25-35) (5 or 20 microg/day) for 7 days and they were sacrificed at 2 or 3 weeks survival. The density of total muscarinic receptors labeled with [3H]N-methyl-scopolamine was dose-dependently decreased by betaA(25-35) in the cerebral cortex at 3 weeks survival. No changes were observed at 2 weeks survival in cerebral cortex or in the hippocampus, at any time. BetaA(25-35) administration did not modify choline acetyltranferase activity in cerebral cortex. However, in betaA(25-35)-treated rats hypertrophic/hyperactive positive acetylcholinesterase nucleus basalis cholinergic neurons were observed at 2 weeks survival, while the density of acetylcholinesterase-positive fibers of cerebral cortex was increased along with the number of cortical positive neurons at 3 weeks survival. These results suggest that increased cholinergic function may be responsible of muscarinic receptor down-regulation. Given the involvement of cholinergic systems in memory and learning, repeated administration of betaA(25-35) may represent a good approach to explore the role of betaA in Alzheimer's disease and to develop therapeutic strategies relevant to it.

Acetylcholinesterase↗
PubMed1997

Specific [3H]glutamate binding in the cerebral cortex and hippocampus of rats during development: effect of homocysteine-induced seizures.

Specific [3H]glutamate binding to synaptic membranes from the cerebral cortex and hippocampus of 7-, 12- and 18-day-old rats was examined, both in control animals and during seizures induced by homocysteine. In the cerebral cortex a transient peak of glutamate binding was observed in 7-day-old group, whereas in the hippocampus it occurred in 12-day-old animals. Total specific [3H]glutamate binding was not influenced by preceding seizure activity in either of the age groups and both the studied regions. NMDA- and QA-sensitive glutamate bindings represent the highest portion of the total binding. Moreover, NMDA-sensitive binding in the cerebral cortex of 7-day-old rats is significantly higher as compared to the two more mature groups. The proportion of individual receptor subtypes on total binding in each age group was not influenced by preceding seizure activity. However, NMDA-sensitive binding in the hippocampus of 12-day-old rats, sacrificed during homocysteine-induced seizures, was significantly increased as compared to corresponding controls. In contrast to the effect of NMDA, AMPA, kainate and quisqualate which displaced to a different extent [3H]glutamate binding, homocysteine had no effect when added to membrane preparations. Similarly, [3H]CPP and [3H]AMPA bindings were not affected in the presence of homocysteine. It thus seems unlikely that homocysteine is an effective agonist for conventional ionotropic glutamate receptors. Its potential activity at some of the modulatory sites at the NMDA receptor channel complex or at metabotropic receptors has to be clarified in further experiments.

Aging↗
PubMed2002

Stimulation of N-methyl-D-aspartate (NMDA) receptors inhibits neuronal migration in embryonic cerebral cortex: a tissue culture study.

We performed a tissue culture study using embryonic rat brain to investigate the effect of excessive stimulation of NMDA receptors on neuronal migration in the cerebral cortex. After progenitor cells in the ventricular zone of E16 cerebral cortex explants were labeled with [(3)H]thymidine, the explants were cultured for 48 h, and distributions of labelled cells were evaluated autoradiographically. Stimulation of NMDA receptors by NMDA and ibotenate, NMDA receptor agonists added to the culture medium in separate studies, caused percentages of labeled cells to decrease significantly in the intermediate zone and increase in the ventricular zone. The results suggest that in rat cerebral cortex, agonist stimulation of NMDA receptors inhibits neuronal migration.

Animals↗
PubMed1993

The calcium-binding protein calretinin is localized in a subset of interneurons in the rat cerebral cortex: a light and electron immunohistochemical study.

The distribution of the calcium binding protein, calretinin (CR) has been investigated immunohistochemically in the cerebral cortex of albino rats by light- and electron microscopy. At the light microscopical level the pattern of CR-immunoreactivity (ir) appeared very similar in all regions of the rat cerebral cortex. CR-immunoreactive cells were found sparsely in layer I to layer VI, and frequently also in the white matter of the corpus callosum. All CR-ir neurons revealed morphological characteristics of local interneurons. The calretinin positive interneurons could be grouped according to their laminar occurrence, dendritic arborization and the soma size into 5 cell type classes. Quantitative measurements were performed only in the visual cortex. CR-ir neurons were more frequent in the superficial layers II and III. In all other layers, CR-ir cells are sparsely distributed with no preferential laminar localization. At the electron microscopical level, CR-ir axonal boutons formed frequently symmetrical axo-dendritic contacts. In all animals we observed CR-ir axons forming also synaptses of asymmetrical type. In summary calretinin labelled an interneuronal subpopulation of the rat cerebral cortex, which seemed not to overlap in its distribution and labelled structures to those, containing the related calcium binding proteins parvalbumin and calbindin D-28k.

Animals↗
PubMed2003

Developmental changes in nitric oxide synthase protein expression in the rat striatum and cerebral cortex.

We examined the expression of brain nitric oxide synthase (bNOS) in two developing rat brain structures, the striatum and the cerebral cortex. For this purpose, we quantified the relative protein concentration level using the Western blotting method and densitometric scanning. 32 Wistar rats, divided according to survival period (PO-P120-postnatal days) were used in this study. Our results demonstrate that bNOS expression rises in these structures during the first week of postnatal life, reaching a maximum in the striatum on the 10th day and in the cerebral cortex on the 7th day of postnatal life. After the period of increase the expression declines and after the 14th day a stabilisation of bone protein concentration is observed, both in the striatum and the cerebral cortex. These changes in bone protein expression might be related to the important role of nitric oxide in the developing rat brain, especially in synaptogenesis, apoptosis and neurotransmission.

Aging↗
PubMed1989

Distribution of monoaminergic, cholinergic, and GABAergic markers in the human cerebral cortex.

Mapping of a number of biochemical markers for noradrenergic, dopaminergic, serotoninergic, cholinergic and GABAergic systems was undertaken in 93 samples removed from the human cerebral cortex. The right hemisphere of brains from two subjects with no known history of neurological and psychiatric diseases was examined. Neurotransmitter markers were present in all cortical samples analysed, suggesting a widespread distribution of the corresponding neurons throughout the cerebral cortex. Each marker distributed heterogeneously in a distinct pattern. Noradrenaline concentrations were highest in the frontoparietal region and lowest in prefrontal and occipital areas. Markers for dopaminergic neurons (dopamine levels, dopamine/noradrenaline ratio and homovanillic acid levels) seemed denser in the prefrontal and temporal regions. 5-Hydroxyindolacetic acid levels were particularly high in the occipital area and decreased along the caudorostral axis. Choline acetyltransferase activity was highest in temporal and frontal lobes, at variance with muscarinic receptor distribution, which was highest in occipital cortex. Glutamate decarboxylase activity, an index of GABAergic innervation, did not vary markedly among the different areas of the cerebral cortex. The different biochemical markers investigated were detected in all cerebral cortical regions; their distribution was not homogeneous. A mismatch was observed between the distribution of cholinergic neuronal systems and receptors.

Aged↗
PubMed2000

Pivagabine-induced increases in the abundance of CRF mRNA in the cerebral cortex and hypothalamus of rats.

The effect of treatment of rats with pivagabine (4-[(2,2-dimethyl-1-oxopropyl) amino] butanoic acid) for 4 days on the abundance of corticotropin-releasing factor (CRF) mRNA in the brain was investigated. Such treatment resulted in dose-dependent (100-300 mg/kg, i.p.) increases in the amount of CRF mRNA in both the hypothalamus and cerebral cortex. The maximal increases were thus apparent with the dose of 300 mg/kg in the hypothalamus (+108%) and cerebral cortex (+49%) 30 or 60 min, respectively, after the last drug injection. Foot-shock stress administered 30 min after the final drug injection had no effect on the pivagabine-induced increases in the abundance of CRF mRNA in the hypothalamus or cerebral cortex. Such stress also had no effect on the amounts of CRF mRNA in these brain regions of vehicle-treated rats. These results demonstrate that pivagabine increases the amount of CRF mRNA in both the hypothalamus and cerebral cortex of rats, effects that might be relevant to the action of this drug in preventing the stress-induced changes in CRF hypothalamic concentration.

Animals↗
PubMed2001

Expression of estrogen receptor (ER) -alpha and -beta transcripts in the neonatal and adult rat cerebral cortex, cerebellum, and olfactory bulb.

In the present study expression of estrogen receptor subtype -alpha (ERalpha) and -beta (ERbeta) in the cerebral cortex, cerebellum, and olfactory bulb was investigated and compared between neonatal (1 to approximately 3-days-old) and adult (250 to approximately 350 g) rats, using reverse transcription-polymerase chain reaction (RT-PCR). No ERalpha transcripts were detectable in the adult cerebellum and olfactory bulb, whereas very weak expression of ERalpha was present in the adult cerebral cortex. No significant difference in ERbeta transcripts was detectable between the neonatal and adult rats. While transcripts for both ER subtypes were co-expressed in these brain areas of neonatal rats, although ERalpha expression was significantly weaker than ERbeta. Even in the cerebral cortex known to contain both ER subtypes in adult rats, ERalpha transcripts in neonatal rats were much higher than in adult. These observations provide evidence for the existence of different expression patterns of ERalpha/ERbeta transcripts in these three brain areas between the neonatal and adult rats, suggesting that each ER subtype may play a distinct role in the regulation of differentiation, development, and functions of the brain by estrogen.

Animals↗
PubMed1979

Specific distribution of metabolic alterations in cerebral cortex following apomorphine administration.

The topographic distribution of dopaminergic receptors in the cerebral cortex closely parallels that of the dopaminergic innervation. In the rat, dopaminergic axons which originate in the mesencephalon are confined to a few discrete regions of the neocortex--anterior cingulate cortex, entorhinal cortex, frontal cortex (particularly anteromedial and supragenual areas) and the transitional zone between the neocortex and the pyriform cortex. Moreover, biochemical examinations of processes generally considered to be indicative of dopaminergic neuro-transmission--neuronal uptake of labelled dopamine or dopamine-activation of adenylate cyclase activity--have confirmed a highly restricted locus of action of dopaminergic systems in the cerebral cortex. We describe here data obtained using the 2-deoxyglucose technique in conjunction with conventional neuropharmacological techniques, suggesting that the influence of dopaminergic systems on cortical function extends beyond the known confines of the mesocortical dopaminergic system.

Animals↗
PubMed1999

Peripheral benzodiazepine receptors in cerebral cortex, but not in internal organs, are increased following inescapable stress and subsequent avoidance/escape shuttle-box testing.

Stress-induced alterations in peripheral benzodiazepine receptor (PBR) density have been reported in humans and in rats. However, the PBR response is highly specific, and its function remains largely unexplained. The aim of the present study was to investigate the relationship between behavior in the two-way active avoidance paradigm (2WAA) and post-test PBR densities in adrenal, testis, kidney, and cerebral cortex. Adult male Wistar rats were tested in the 2WAA either in the naive state (AA) or 24 h following shock preexposure (PE), known to interfere with avoidance/escape response acquisition, and decapitated immediately after testing. Control subjects were decapitated without experimental experience. The stressful characteristic of the experiment was validated by significantly increased post-test corticosterone levels in AA and PE subjects compared with controls, with a trend towards higher corticosterone levels in PE relative to AA rats. Similarly, PE compared with AA subjects tended to show retarded acquisition of the escape/avoidance response. PBR densities in adrenal, kidney, and testis and central benzodiazepine receptors (CBR) in the cerebral cortex remained unaffected by avoidance testing. Cerebral cortex PBR density was significantly increased in PE subjects. These findings suggest that avoidance testing, although stressful to the animals, led to changes confined to cerebral cortex PBR, indicating that the hypothalamic-pituitary-adrenal (HPA) response occurs independently of the PBR response in peripheral organs, and also suggest that the opportunity for coping alters the impact of the stressor on the subject and prevents the expression of PBR response in peripheral organs.

Adrenal Glands↗