Normal Human Cerebral Cortex Research Articles

ADENOSINE RECEPTORS IN POST‐MORTEM HUMAN CEREBRAL CORTEX AND THE EFFECT OF CARBAMAZEPINE

Representative A1 site- and A2 site-selective ligands for adenosine receptors were found to bind to a single class of non-co-operative sites in synaptic membranes prepared from pieces of normal human temporal lobe cerebral cortex obtained at autopsies performed within 24 h post-mortem. The known adenosine antagonists theophylline and 1-isobutyl-3-methylxanthine also bound to these sites and could completely displace either ligand. Computer analysis combining data from 21 separate experiments which used membranes prepared from seven different autopsy cases gave the following kinetic parameters for the site: equilibrium dissociation constants (KD) for L-PIA, 4.1 +/- 0.9 nmol/l; KD for NECA, 26 +/- 4 nmol/l; KD for theophylline, 28 +/- 5 mumol/l; receptor number (Bmax), 510 +/- 77 fmol/mg protein. Carbamazepine could also displace either radioligand from the sites, although solubility limits for this drug were reached at 50% receptor occupancy. The KD for carbamazepine was 138 +/- 18 mumol/l. Other anticonvulsants tested were generally ineffective at their therapeutic concentrations, although phenytoin showed a small amount of ligand binding inhibition. The results are in line with earlier studies in rodent tissue preparations, and suggest a possible purinergic component in the anticonvulsant activity of carbamazepine in a man.

Molecular forms of somatostatin, substance P and neurotensin in fresh human cerebral cortex

The molecular forms of somatostatin, substance P and neurotensin in fresh normal human cerebral cortex have been investigated using high performance liquid chromatography and radioimmunoassay. For each peptide most of the immunoreactivity measured corresponds to a single molecular form co-eluting with the authentic peptide. Small differences in the minor peaks of somatostatin and substance P immunoreactivity are seen when compared to the results of similar studies on post mortem human brain. A substantial difference in the molecular forms of neurotensin was seen which suggests that degradation of this peptide may occur post mortem.

Identification of major proteins in human cerebral cortex and brain tumors

Two-dimensional gel electrophoresis (2DE) is being increasingly employed for protein separation, and silver staining has greatly enhanced its sensitivity. However, the identity of most of the protein spots demonstrated by 2DE has yet to be established. Using immunoblotting and comigration techniques, this study describes the identification of 12 of the major spots seen on 2D gels of normal human cerebral cortex and of certain human brain tumors. These proteins include: actin, albumin, α-tubulin, β-tubulin, neuron-specific enolase (NSE), nonneuronal enolase, glutamate oxaloacetic transaminase, glial fibrillary acidic protein (GFAP), vimentin, a 66-kD intermediate filament protein, the 68-kD neurofilament protein, and the β subunit of the guanine nucleotide regulatory proteins(G-proteins). In addition, the application of this technique to the study of human brain tumors has been described. A large amount of GFAP is seen in astrocytomas; the meningioma gel is characterized by a prominent vimentin complex; and the presence of NSE in medulloblastomas is confirmed. The identification of the β subunit of the G-proteins introduces a valuable means of screening for this important messenger protein, which is only beginning to be studied. While being derived from normal and pathological CNS tissue, these data are widely applicable to the study of other biological materials.

I. Cytology and distribution in normal human cerebral cortex of neurons immunoreactive with antisera against neuropeptide Y

The frontal, parietal, and temporal cortices in normal human brains (Brodmann areas 10, 7a, 7b, and 21) are well endowed with numerous neurons, identifiable by immunoreactivity with antisera against the 36-amino acid brain peptide neuropeptide Y (NPY). These neurons with rare exception are small, intracortical, nonspiny neurons, 12-20 microns in somatic size, with long slender dendrites and exuberant axon plexuses exhibiting finely beaded varicosities. The cells are rarest in layers I and II, are found with frequency in the lower cortical layers (IV-VI) and in significant numbers in the subcortical white matter. Within the cortex the axonal plexuses of these peptide neurons rise straight up into the upper cortical layers or descend deep into the white matter. In layers I and II, numerous other lengthy axons, some possibly of extracortical afferent origin, run along the pial surface at right angles to the axial ones running perpendicular to the cortex. This endowment of peptide neurons and their processes forms a rich network in the cerebral cortex, relating with one another in complex fashion within palisades of terminals as well as with the other cortical neurons not labeled by these methods. It remains to be shown what functions these NPY neurons have individually and in their remarkable networks, and how they are altered in neurological disease.

Proteins in normal, irradiated, and postmortem human brain quantitatively compared by using two-dimensional gel electrophoresis.

Using a combination of two-dimensional gel electrophoresis (2DE), silver staining, and computerized densitometry, we studied protein patterns in human cerebral cortex: normal fresh-frozen, fresh-frozen but previously irradiated, and post-mortem. The relative molecular mass of the resolved proteins ranged from 14 400 to 100 000, the isoelectric points from 4.75 to 7.0. The pattern of proteins (six of them identified) was essentially the same for all three groups. However, computerized densitometry demonstrated significant alterations in the density of several spots in the irradiated and postmortem groups as compared with the normal controls. Irradiated cortex showed statistically significant changes in only six spots (three increased and three decreased in density); postmortem material showed 20 altered spots (16 diminished and four increased). Evidently normal human cerebral cortex has a consistent protein pattern on 2DE, which is quantitatively (but not qualitatively) altered in irradiated and postmortem material. These findings provide a point of reference against which proteins from abnormal brain material can be compared, both qualitatively and quantitatively.

A quantitative electron microscopic study of atypical structures in normal human cerebral cortex

Biopsy samples of the cerebral cortex from four normal human brains were examined in the electron microscope for the presence of abnormalities related to neurones and neuroglia. Atypical forms of axons, axon terminals and dendrites, many of them similar to those described in a variety of pathological and experimental material, were found to occur in small but appreciable numbers. Neuroglia exhibiting atypical inclusions occurred but were much less common. Physiologically altered neuronal perikarya were not encountered apart from one neuronal death. An area of 3.6 x 10(5) mu2 was scanned from each brain and atypical structures were categorised and counted. The possible implications of the presence of these structures in normal brain in discussed and the need for neuropathologists and neuroanatomists to be aware of the existence of atypical forms of neuronal processes in normal human and animal brains is emphasised.

Cyclic AMP formation in human brain: An [formula omitted] stimulation by neurotransmitters

Samples of normal human cerebellar and cerebral cortex have been tested in vitro with histamine, serotonin and norepinephrine and the formation of cyclic adenosine-3'5'-monophosphate (cAMP) has been measured. Only norepinephrine exerts a clearly stimulating effect on cAMP formation in both tissues. In this respect, human brain cyclase resembles more that of the rat than the monkey, which does not respond to norepinephrine.

The isolation of neurons from normal and abnormal human cerebral cortex.

AMONG the degenerative diseases of the nervous system of metabolic origin, there is a group of conditions in which substances accumulate to excess within neurons. In some of these processes, the nature of the stored material has been well characterized. In Tay-Sachs disease, the accumulation of a particular ganglioside is well-documented. Recently, there have been suggestions about the nature of the enzymatic defect; for example, the dysfunction of a catabolic enzyme, a lipid hexoseaminidase 1 (oral communication, with L. Svennerholm, MD, May 1968). In other diseases, the fact that there is storage of some material is well-documented, but the composition of the stored material and the nature of the metabolic defect is not known. An example of this type of disease is the late infantile form of neuronal storage disease. The study of the neuronal storage diseases is handicapped by the fact that not all cells show the storage