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PubMed1978

An association between mitochondria and microtubules in synaptosomes and axon terminals of cerebral cortex.

A substantial number of synaptosomes prepared from rat cerebral cortex were found by electron microscopy to contain a horseshoe-shaped mitochondrion flanked by an arc of three to ten microtubules opposite the synaptic membrane specializations. The microtubules were replaced by characteristic paracrystals following the incubation of synaptosomes with vinblastine sulfate. A similar spatial organization of microtubules and mitochondria was also observed in some axon terminals of the cerebral cortex in situ. The significance of this novel observation is discussed with regard to the role of microtubules in axonal transport at the synaptic terminal and previous reports on the identification of tubulin in synaptosomes and subsynaptic structures.

Animals↗

PubMed1992

Narine occlusion decreases basal levels of Fos protein in the cerebral cortex of the lizard Podarcis hispanica.

Immunocytochemical study of cerebral cortex of the lizard Podarcis hispanica using an antibody directed to the M peptide of the rat c-Fos protein showed a distinct pattern of Fos distribution. Abundant Fos-immunoreactive neuronal nuclei were detected in the cell layers of the medial, the dorsal and the lateral cortices, whereas only a few nuclei were found in the cell layer of the dorsomedial cortex. The Fos immunoreactivity was characterized by Western blot analysis of nuclear extracts from lizard brain and showed a distinct band with an apparent molecular weight of 30,000. In band-shift assays, nuclear extracts from lizard brain were shown to contain AP-1 complexes. The basal expression of Fos immunoreactivity is related to sensory olfactory input in the cerebral cortex of the lizard since experiments with olfactory-deprived animals resulted in a complete absence of Fos immunoreactivity in the cortical areas.

Animals↗

PubMed1982

Influence of the state of ribosome association on the phosphorylation of ribosomal proteins in isolated ribosome--protein kinase systems from rat cerebral cortex.

Ribosomal protein phosphorylation was investigated in isolated ribosomal subunits and polyribosomes from rat cerebral cortex in the presence of [gamma-32P]ATP and purified catalytic subunit of cyclic AMP-dependent protein kinase from the same tissue. Ribosomal proteins that were most readily phosphorylated in isolated cerebral ribosomal subunits included proteins S2, S3a, S6 and S10 of the 40 S subunit and proteins L6, L13, L14, L19 and L29 of the 60 S subunit. These proteins were also phosphorylated in cellular preparations of rat cerebral cortex in situ or in vitro [Roberts & Ashby (1978) J. Biol. Chem. 253, 288-296; Roberts & Morelos (1979) Biochem. J. 184, 233-244]. However, several additional ribosomal proteins were phosphorylated when isolated 40 S or 60 S subunits were separately incubated in the reconstituted system. Analogous results were obtained with an equimolar mixture of cerebral 40 S and 60 S subunits under comparable conditions. In contrast, extensive exposure of purified cerebral polyribosomes to the catalytic subunit resulted in phosphorylation of only those ribosomal proteins of the 40 S subunit that were most highly labelled after the administration of [32P]Pi in vivo: proteins S2, S6 and S10. Ribosomal proteins of 60 S subunits that were readily phosphorylated in isolated cerebral polyribosomes included proteins L6, L13 and L29. These results indicate that polyribosome formation markedly decreases the number of ribosomal protein sites available for phosphorylation by the catalytic subunit of cyclic AMP-dependent protein kinase. Moreover, the findings suggest that, of the ribosomal protein phosphorylations observed in rat cerebral cortex in vivo, proteins S2, S6, S10, L6, L13 and L29 can be phosphorylated in polyribosomes, whereas proteins S3a, S5, L14 and L19 may become phosphorylated only in free ribosomal subunits.

Animals↗

PubMed1984

Stabilization of ascorbic acid and norepinephrine in vitro by the subcellular fractions of rat cerebral cortex.

The effect of various subcellular fractions of rat cerebral cortex on the autoxidation of ascorbic acid and norepinephrine in a physiological salt solution, pH 7.4, was investigated. The rate of the two reactions was determined spectrophotometrically at 265 and 480 nm, respectively. The cytoplasmic, microsomal, crude mitochondrial fractions and a soluble phase of mixed subcellular origin (100,000 g supernatant) were tested in an assay system in which the final dilution of the cellular components was in the 10(3) to 10(6) range. The samples were heat-treated (30 min at 100 degrees C) and dialyzed (50,000 mol.wt. cut-off) prior to analysis. The preparations produced approximately 80% inhibition at 10(3)-fold dilution and marginal inhibition at 10(5)-fold dilution, except the microsomal preparation, which was a considerably weaker inhibitor in the norepinephrine autoxidation test. The study shows that all three major subcellular compartments of the rat cerebral cortex have macromolecules with a high level of heat-stable autoxidation-inhibiting activity.

Animals↗

PubMed1994

Effect of NIK-247 on basal concentrations of extracellular acetylcholine in the cerebral cortex of conscious, freely moving rats.

We studied the effect of orally administered NIK-247 (9-amino-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]quinoline monohydrochloride monohydrate) on basal extracellular acetylcholine (ACh) concentrations in the rat cerebral cortex using microdialysis without the addition of cholinesterase inhibitor to the perfusion fluid and radioimmunoassay for ACh. In addition, the effect of oral administration of NIK-247 on acetylcholinesterase (AChE) activity in rat cerebral cortex was determined. The mean basal ACh content in the perfusate from the cerebral cortex of freely moving rats was 123.2 +/- 21.8 fmol/30 min (n = 7). NIK-247 (2.5-10.0 mg/kg, p.o.) increased the ACh content of the perfusate in a dose-dependent manner. NIK-247 at 10 mg/kg significantly increased the ACh content in the perfusate from 0.5 to 2.5 hr after administration, and the maximum increase was attained at 1 hr after administration. 9-Amino-1,2,3,4-tetrahydroacridine (5 mg/kg, p.o.) and physostigmine (0.5 mg/kg, i.p.) significantly increased the ACh content in the perfusate from 1 to 2 hr and from 0.5 to 1.5 hr after administration, respectively. AChE activities in the cerebral cortex were about 32% and 12% below the control value at 1 hr and 3 hr after administration of NIK-247 at 10 mg/kg, respectively. These findings demonstrate that NIK-247 increases extracellular ACh concentration and inhibits AChE activity in the cerebral cortex after oral administration, and they suggest that NIK-247 facilitates central cholinergic transmission.

Acetylcholine↗

PubMed1991

Serotoninergic innervation of the ferret cerebral cortex. I. Adult pattern.

We have investigated the serotoninergic innervation of the adult ferret cerebral cortex with immunohistochemical techniques. Distribution pattern of serotoninergic fibers in the ferret neocortex is characterized by a decrease in the density of fibers as one moves from the pial surface towards the white matter. Throughout the entire cerebral cortex, the serotoninergic fibers are very dense within the supragranular layers, especially within layer 1. In contrast, granular and infragranular layers exhibit only a sparse innervation. Although this general pattern of innervation is roughly the same in all cortical areas, significant variations in the fiber density are apparent in different regions. Areas 17, 1, 6, and 8 (primary visual cortex, presumptive somatosensory cortex, presumptive motor cortex, and prefrontal cortex, respectively) are described in more detail to illustrate the diversity of the serotoninergic innervation patterns. The density of innervation is highest in areas 1 and 6, intermediate in area 8, and lowest in area 17. It is noteworthy that while areas 1, 6, and 8 show a marked decrease in fiber density at the boundary between layer 3 and 4, the less strongly innervated area 17 shows a change in density in the transition from layer 2 to layer 3. The types of fibers found within the ferret cortex are similar to those described in other mammalian species. The bulk of the innervation is made by very fine fusiform axons with small ovoid varicosities. In addition to this fiber type, axons with thick round varicosities and some smooth nonvaricose axons were found. The latter types occur in very small numbers within the supragranular layers and mostly in more anterior cortical regions. While the general innervation pattern and the fiber types are similar to those described in the cat cerebral cortex, the pericellular baskets found in the cat cortex (Mulligan and Törk, J Comp Neurol 270:86-110, 1988) are not seen in the ferret.

Animals↗

PubMed1995

Effect of thyroid hormones on vasoactive intestinal polypeptide gene expression in the rat cerebral cortex and anterior pituitary.

We report here data on the expression of the various sequences derived from the prepro-vasoactive intestinal polypeptide (VIP) precursor and VIP mRNA in the anterior pituitary gland and cerebral cortex of hypothyroid and hyperthyroid rats. Using specific antisera to each of the prepro-VIP sequences we demonstrated an increase of all prepro-VIP derived sequences, and accordingly, found that the number of cells expressing each of these sequences were markedly augmented in the anterior pituitary of the hypothyroid rats. This was accompanied by a marked increase in VIP mRNA. In the cerebral cortex of the hypothyroid rats no changes were observed. In the pituitary of hyperthyroid animals a significant decrease was seen for prepro-VIP 22-79, VIP and prepro-VIP 156-170, whereas in the cerebral cortex a significant increase was observed for prepro-VIP 22-79, PHI and VIP. We were not able to demonstrate any changes in VIP mRNA in the cerebral cortex or pituitary of the hyperthyroid rats. Gel permeation chromatography and reverse-phase HPLC of extracts from cerebral cortex showed elution profiles identical to the synthetic counterparts. The reported data provide further evidence of a tissue-specific expression and regulation of the VIP gene products.

Animals↗

PubMed1995

The specification of neuronal fate: a common precursor for neurotransmitter subtypes in the rat cerebral cortex in vitro.

Neurotransmitter choice is a crucial step in neural development. In the cerebral cortex, pyramidal neurons use the excitatory neurotransmitter glutamate, whereas non-pyramidal cells use the inhibitory neurotransmitter GABA. We are interested in how these two neuronal types are generated. We labelled precursor cells from embryonic rat cerebral cortex with a retroviral vector in dissociated cell cultures, and examined the neurotransmitter phenotype of their progeny immunohistochemically after 2 weeks in vitro. We discovered, first, that precursor cells in culture generate glutamatergic and GABAergic neurons in proportions similar to those in vivo. Second, we found that neuronal precursor cells gave rise to both GABAergic and glutamatergic neurons. These results suggest that neuronal precursor cells in the cerebral cortex have the potential to generate both neuronal subtypes. Moreover, these data are consistent with a stochastic model of neurotransmitter specification.

Animals↗

PubMed1979

Ultrastructural demonstration of dehydrogenases in rat cerebral cortex.

Techniques for the ultrastructural demonstration of dehydrogenases in cerebral cortex are described. The best fixation for good fine structural preservation and retention of LDH and NADH-diphorase was obtained by perfusion with a misture of formaldehyde and glutaraldehyde and for SDH by perfusion with formaldehyde. Comparison of incubation conditions showed that consistent results were obtained using enzyme markers NBT and DS-NBT for LDH and NADH-diaphorase: DS-NBT was more satisfactory than NBT and BSPT for SDH. Penetration of incubation media was improved by Triton X-100: DMSO and ultrasonic treatment were less effective. The techniques enabled the first electron cytochemical demonstration of dehydrogenases in different elements of prefixed cerebral cortex. Ultrastructural sites of enzyme activities were localized within cristae and inter-membrane spaces of mitochondria in nerve cell cytoplasm and its processes, oligodendrocytes and astrocytes. Authenticity of the ultrastructural sites was confirmed by four different control experiments.

Animals↗

PubMed1989

Ontogeny of somatostatin in cerebral cortex of macaque monkey: an immunohistochemical study.

Distribution of somatostatin-immunoreactive cells in the cerebral cortex of macaque monkeys at embryonic day 120 (E120), E140, newborn, postnatal day 60 (P60) and adult stages were studied by the avidin-biotin-peroxidase immunohistochemical method. At all stages, there existed 3 types of cells in the gray matter: bipolar, multipolar and small-sized cells which stained only in perikaryon. Somatostatin-immunoreactive cells were observed from E120. The cell number increased between E120 and E140 and decreased until P60. At the newborn stage, a high density of cells was distributed in layer II of the prefrontal and parietal cortices (areas FD and PE). In layer I of the postcentral, parietal, temporal and preoccipital cortices (areas FA, PC, PE, TA, TE and OA), small numbers of horizontal cells were detected only at the embryonic and newborn stages. In adulthood, the number of somatostatin cells was much smaller than at the early stages (E140 and newborn). Compared to other cortical areas, in occipital cortex (area OC), there was little change in cell number during development. In occipito-temporal cortices, there were increases in cell number from posterior to anterior portion at all the stages. The large number of somatostatin cells in all layers of the cerebral cortex during the early stages indicates that somatostatin plays a role in the development of the monkey cerebral cortex.

Aging↗

PubMed2002

Stimulatory effects of pituitary adenylate cyclase-activating polypeptide on inositol phosphates accumulation in avian cerebral cortex and hypothalamus.

This study has demonstrated that the short and long form of the pituitary adenylate cyclase-activating polypeptide (PACAP), i.e. PACAP(27) and PACAP(38), moderately but significantly, and in a concentration (0.5-5 microM)-dependent manner, stimulated inositol phosphates (IPs) accumulation in myo-[(3)H]inositol-prelabeled cerebral cortical and hypothalamal slices of chick and duck, and in slices of rat cerebral cortex; both peptides had no effect on IPs formation in rat hypothalamus. Vasoactive intestinal peptide (VIP; 0.5-5 microM) weakly enhanced IPs accumulation in chick hypothalamus, had no significant action in chick cerebral cortex (in fact there was a tendency to attenuate the IPs response in this tissue), and slightly, but significantly, inhibited the IPs accumulation in rat cerebral cortex. VIP showed no activity in rat hypothalamus. It is concluded that the stimulatory action of PACAP on phosphoinositide metabolism in avian cerebral cortex, similar to rat cerebral cortex, is mediated via phospholipase C-linked PAC(1) type receptors. In chick hypothalamus, however, there may be a component of VPAC type receptors stimulating IPs formation.

Animals↗

PubMed1984

[A comparative study of free amino acid levels in serum and cerebral cortex in uremic rat].

The etiology of uremic encephalopathy remains largely unknown. In order to elucidate the role of amino acid changes in uremic encephalopathy, the free amino acids in serum and cerebral cortex were measured in the experimental uremic models. The rats weighing 200 g underwent bilateral ureteral ligation for 48 hours (acute uremia), while the other animals were kept for 4 months after unilateral nephrectomy followed by partial 2/3 nephrectomy of the remaining kidney (chronic uremia). They were confirmed to develop chemical changes compatible with uremia showing markedly elevated serum levels of BUN, creatinine and K+, and were compared with the sham-operated controls. The amino acid patterns, obtained from serum and cerebral cortex, were essentially identical in both acute and chronic uremia. In serum, aspartic acid, glycine and 3-methylhistidine were significantly elevated, and in addition citrulline, alpha-aminoadipic acid, cystine and gamma-aminobutyric acid specifically appeared in uremia. On the contrary, glutamic acid, leucine, lysine, tryptophan, tyrosine and valine were significantly reduced. Tyrosine/phenylalanine ratio, valine/glycine ratio, essential amino acids/non essential amino acids ratio were also apparently reduced in uremia. In cerebral cortex, aspartic acid, glutamine, glycine, histidine, ornithine, phenylalanine, phosphoethanolamine and taurine were significantly elevated, whereas 1-methylhistidine and 3-methylhistidine were specifically detected. Carnocine, glutamic acid and ornithine disclosed a significant reduction in uremia. The above complicated changes in cerebral cortex could not be explained simply by the enhanced permeability of the blood-brain barrier, or by the accelerated ammonia fixation. Therefore, it was suggested that the amino acid levels in cerebral cortex vary under the control of the sophisticated mechanism.

Amino Acids↗

PubMed1990

Somatosensory evoked potentials in rat cerebral cortex before and after middle cerebral artery occlusion.

We recorded somatosensory evoked potentials in pentobarbital-anesthetized rats before and after middle cerebral artery occlusion. Trigeminal (vibrissae), median (forelimb), and sciatic (hind limb) nerve stimuli produced consistent, robust, and sharply localized responses in the trigeminal, forelimb, and hind limb regions of the somatosensory cortex of 18 rats. These regions are situated at sequentially greater distances from the center of infarcts produced by middle cerebral artery occlusion. In eight rats, occlusion 1-2 mm below the rhinal fissure abolished somatosensory evoked potentials in all three cortical region within minutes. Positive wavelets preceding the primary cortical response were also diminished by the occlusion, suggesting that ischemia affected the thalamocortical white matter. Four of these eight rats did not show histologically apparent ischemic involvement of the hind limb cortical region at 3 hours after occlusion; sciatic nerve evoked potentials recovered substantially in all four rats, and the amplitudes exceeded baseline (129 +/- 30% at 1 hour, 173 +/- 33% at 3 hours) in three of the four rats. Three of the eight rats did not have gross ischemic involvement of the forelimb cortical region; median nerve evoked potentials recovered fully in all eight rats, but the amplitudes did not exceed baseline. All eight rats had evidence of ischemic damage in the trigeminal cortex; no rat showed full recovery in this region, and all but one had trigeminal evoked potentials that were less than 20% of baseline amplitudes by 3 hours after occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1963

Cerebral cortex: a sensorimotor amalgam in the marsupiala.

In the cerebral cortex of the opossum and the wallaby there Is a complete and coincident overlap of the sensory and the motor representations of the body. Within this sensorimotor area It is not possible to draw the line which in other mammals separates a primarily sensory area from a primarily motor area.

Animals↗

PubMed2005

Metabotropic glutamate receptor/phospholipase C pathway: a vulnerable target to Creutzfeldt-Jakob disease in the cerebral cortex.

Glutamate is the main excitatory neurotransmitter in the cerebral cortex. Altered glutamatergic transmission has been suggested as having a central role in many neurodegenerative diseases. Metabotropic glutamate receptors (mGluRs) are coupled to intracellular signal transduction via G proteins, and they mediate slower responses than ionotropic glutamate receptors. Group I mGluRs are positively coupled to phospholipase C beta1 (PLCbeta1). Creutzfeldt-Jakob disease (CJD) is a human transmissible spongiform encephalopathy associated with a dysfunction in the membrane glycoprotein PrP which is converted into an abnormal isoform, with a predominant beta-sheet structure, that is pathogenic and partially resistant to protease digestion. Proteins associated with the signal transduction of group I mGluRs were examined in the frontal cortex (area 8) of 12 cases with sCJD and four age-matched controls, by means of gel electrophoresis and Western blotting of total homogenates. Densitometric analysis of the bands demonstrated decreased expression levels of PLCbeta1 and PLCgamma, a non-related phospholipase which is a substrate of tyrosine kinase, in CJD cases when compared with controls. Novel protein kinase C delta (nPKCdelta) has also been found to be significantly decreased in CJD cases. However, no modifications in mGluR1 cPKCalpha expression levels are found in CJD when compared with controls. No modifications in PLCbeta1 solubility in PBS-, deoxycholate- and sodium dodecylsulphate-soluble fractions have been observed in CJD when compared with controls. Finally, no interactions between PLCbeta1 and PrP, as revealed by immunoprecipitation assays, have been found in CJD and controls. The present results show, for the first time, reduced expression levels of phospholipases, particularly PLCbeta1, which may interfere with group I mGluR signaling in the cerebral cortex in CJD. These abnormalities are not the result of abnormal PLC solubility or interactions with PrP. Selective involvement of group I mGluRs may have functional effects on glutamatergic transmission modulation and processing in CJD.

Adult↗

PubMed2004

[Ultrastructural changes in cerebral cortex and cerebellar cortex of rats under simulated weightlessness].

OBJECTIVE: To study the ultrastructural changes in the cerebral cortex and cerebellar cortex of rats under simulated weightlessness and the possible mechanism. METHOD: The tail-suspended rats model (-30 degrees head down tilt) was adopted to simulate weightlessness in the experiment. The rats were suspended for 7 d, 14 d, 21 d, and 28 d, and then were perfused through the hearts. The specimens were drawn from the rats' cerebral cortex and cerebellar cortex for electron microscopy. RESULT: The results showed that under simulated weightlessness, the main changes in the neuron can be described as follows: swelling of mitochondria, endoplasmic reticulum and Golgi complex, even formation of big empty vesicles; reduction of number of synaptic vesicles in IV layer; increase corrugation of capillary lumen and thickening of basement membrane. Degranulation of rough endoplasmic reticulum in Purkinje's cells of the cerebellar cortex occurred obviously. On the 14th and the 21st day of suspension, the changes were most significant and tended to return to normal on the 28th day. CONCLUSION: The experimental results demonstrated that simulated weightlessness led to ultrastructural changes in the cerebral cortex and cerebella cortex of rats. The ultrastructure changed with the course of simulated weightlessness and tended to return to normal. It showed an adaption to the simulated weightlessness.

Adaptation, Physiological↗

PubMed1998

Calbindin-D28k- and astroglial protein-immunoreactivities, and ultrastructural differentiation in the prenatal rat cerebral cortex and hippocampus are affected by maternal adrenalectomy.

Maternal adrenal steroid hormones have been proven to be crucial for lung and adrenal prenatal maturation. These hormones mediate the effects of prenatal stress crossing the placenta and influencing the development of the hypothalamus-pituitary-adrenal axis of fetuses. In the present study, we have compared the prenatal development of fetuses from adrenalectomized mothers (ADX group) and from sham-operated mothers. We have used immunohistochemistry for calcium binding-protein Calbindin-D28k, astroglial proteins vimentin and glial fibrillary acidic protein (GFAP), and the ultrastructural differentiation of the cerebral cortex and hippocampus to measure putative differences. The ontogeny of the Calbindin-D28k immunoreactivity was delayed, as transient Calbindin-positive neuronal populations in the ADX group disappeared later during development as compared to that of control animals both in cerebral cortex and hippocampus; cell counts revealed that ADX animals had a significantly higher number of Calbindin-positive cells than controls in the cerebral cortex, while that number was lower in ADX fetuses' hippocampus. Cerebral cortex of ADX animals also had a scattered distribution of stained cells compared with controls, while the hippocampi of the ADX animals had an impaired migration of marginal zone interneurons. No GFAP immunoreactivity was found in the studied prenatal stages. Instead, vimentin-immunoreactivity appeared more profusely distributed throughout the cerebral cortex, in the ADX group than in control animals. At the ultrastructural level, no remarkable differences were found before E20, when a higher undifferentiation in the ADX group, in both cerebral cortex and hippocampus, was evident. The results show for the first time the vulnerability of the prenatal rat brain to maternal adrenalectomy and the necessity of maternal glucocorticoids for encephalic development.

Adrenalectomy↗

PubMed1985

Anticholinergic potency of psychoactive drugs in human and rat cerebral cortex and striatum.

The affinity of selected antipsychotic and antidepressant drugs for the muscarinic receptor was studied in membranes from both human and rat striatum and cerebral cortex. While there are regional differences in the anticholinergic potency of the drugs, there is good agreement between the obtained inhibition constants from the corresponding human and rat striatum (r: 0.98) and from human and rat cerebral cortex (r: 0.96). There is also good agreement between the obtained Ki values within one species: human cerebral cortex versus human striatum (r: 0.99) and for rat cerebral cortex and rat striatum (r: 0.87). Thus, the previously published quantitative estimates of the antimuscarinic activity of psychoactive drugs which were derived from studies on membranes from rat brain give an accurate estimate of the antimuscarinic activity in human brain. The drugs tested in this study include chlorpromazine acetophenazine, haloperidol, sulpiride, remoxipride (FLA-731 (-), a substituted benzamide), amitriptyline and two serotonin uptake blockers: norzimelidine and alaproclate.

Aged↗