Application of glial fibrillary acidic protein immunohistochemistry in the quantification of astrocytes in the rat brain.

Immunohistochemical staining for glial fibrillary acidic protein (GFAP) was employed as a tool for quantification of astrocytes in the rat brain. One-micron-methacrylate sections were prepared from 70-micron slices stained for GFAP by using a preembedding staining procedure. Numbers/unit area of astrocytes and nonastrocytes were determined for cortex, corpus callosum, and hippocampal neuropil. In each, counts from GFAP-stained, toluidine-blue-counterstained sections were compared with counts obtained from sections stained with toluidine blue alone. Numbers of nonastrocytes and total glia in all three regions were comparable in both groups of sections. Astrocyte counts in the cortex and hippocampus also showed no significant differences between the two groups. In contrast, the number of astrocytes in the corpus callosum was significantly lower in GFAP-stained, toluidine-blue-counterstained sections than in sections stained with toluidine blue alone. GFAP immunohistochemistry is a useful tool for the quantification of astrocytes in semi-thin plastic sections of rat brain.

The relationship between callosal variation and lateralization in mice is genotype-dependent.

The relation between morphological variation of the corpus callosum and variation in the degree of paw preference was investigated in 129/J and BALB/cCF mice. A positive relationship explaining 24% of the variance of paw preference was found in 129/J mice; no such relationship exists in BALB/cCF mice. It is suggested that, since the genetic dissimilarity between these two inbred strains is comparable in magnitude with the genetic dissimilarity between unrelated human subjects, genetic variation may have been an uncontrolled source of heterogeneity in previous human neuropsychological studies.

Studies on cholecystokinin-containing neuronal pathways in rat cerebral cortex and striatum.

Lesion experiments were performed to investigate the origin of CCK-containing afferents of the striatum. All the subdivisions of the striatum that were investigated seem to receive CCK afferents from dorsolateral and lateral neocortical areas. However, destruction of these cortical areas alone did not reduce CCK-IRC in the striatum. Only after an additional parasagittal severance of the corpus callosum were significant decreases in CCK-IRC of all striatal subdivisions observed. Thus, CCK neurons in ipsilateral midline areas (such as the cingulate cortex) or, more likely, in contralateral cortical areas, seem to project to the striatum of one side. The CCK fibers seem to enter the striatum via the capsula externa, since a lesion of this structure has been shown to diminish the CCK-IRC in the striatum. In addition, the dorsomedial part of the head of the striatum may receive a projection of CCK fibers from the anterior cingulate area. A series of lesions which severed the afferents of structures caudal to the striatum, that is, the amygdaloid complex and the ventral tegmental area plus substantia nigra, did not reduce CCK-IRC in the striatum. Some of these lesions even significantly enhanced CCK-IRC in several subdivisions of the ipsilateral and contralateral striatum. Further studies will be necessary to cast some light on these caudal CCK afferents to the striatum, which are obviously extremely complex.

Regional differences in extracellular ascorbic acid levels in the rat brain determined by high speed cyclic voltammetry.

High speed cyclic voltammetry was used in combination with pressure ejection of ascorbate oxidase for the determination of extracellular ascorbic acid within the brain of the anaesthetized rat. Large variations in absolute levels of ascorbate were found between animals although distribution patterns showed a good degree of reproducibility. Ascorbate levels in the white matter of the corpus callosum were found to be higher than in adjacent areas of grey matter (striatum and cortex).

Composition of axolemma-enriched fractions isolated from bovine CNS myelinated axons.

Axolemma-enriched fractions were isolated from the white matter of bovine corpus callosum via a purified preparation of myelinated axons which were osmotically shocked and fractionated on a discontinuous density gradient. Two membrane fractions of differing density were obtained: both were somewhat enriched over white matter whole homogenate in specific activity of acetylcholinesterase and 5'-nucleotidase and maximal binding capacity for saxitoxin. Both membrane fractions contained appreciable amounts of 2', 3'-cyclic nucleotide 3'-phosphohydrolase; the specific activity of antimycin-sensitive NAPH-cytochrome c reductase and cytochrome c oxidase indicated low levels of contamination by microsomal and mitochondrial membrane. The myelin which is concomitantly isolated with the axolemma-enriched fractions has a lipid and protein composition comparable to that of myelin isolated by other procedures. Both axolemma-enriched fractions contain about one half of their dry weight as lipid comprised of approximately 25% cholesterol, 25% galactolipid (cerebrosides and sulfatides in a molar ratio of about 4:1) and 50% phospholipid, mostly choline phosphatides and ethanolamine phospholes in an equimolar ratio. The axolemma fractions are also enriched in ganglioside content relative to the myelin fraction. The polypeptides of the axolemma-enriched fractions range from 20,000 to over 200,000 in molecular weight; the predominant proteins are in the range from 50,000 to 69,000. The most dense axolemma-enriched fraction is over fourfold enriched in glycoprotein content compared with myelin, with at least 10 different molecular-weight classes of glycoproteins as identified by Schiff stain of polyacrylamide gel protein profiles. The differences and similarities in the molecular composition of axolemma-enriched preparations which have been characterized to date are discussed.

Immunohistochemistry of brain 5-hydroxytryptamine.

An immunohistochemical assay for 5-hydroxytryptamine (5HT) has been developed, validated by parallel radioimmunoassay and a series of tests with monoamines or related molecules, and applied to the detection of 5HT in rat brain sections. The procedure seems to be more sensitive and specific than the classical Falck-Hillarp technique. Among amines and related compounds tested, only 5-methoxytryptamine has been found to cross-react. 5HT-immunoreactive neurons and/or fibres have been observed in the spinal cord, brain stem, hypothalamic nuclei, epiphysis and subcommissural organ, thalamus, striatum, corpus callosum, amygdala, hippocampus, olfactory tubercle, and cerebral cortex.

[Association of brain glycoprotein (NSA 3) with neuronal membranes and with the nodes of Ranvier]. / Association de la glycoprotéine cérébrale (ANS 3) à la membrane du neurone et aux étranglements de Ranvier.

The localisation of brain glycoprotein NSA 3 was studied by means of indirect immunofluorescence on alcohol fixed, paraffin embedded sections of Rat brain. These techniques allowed the localisation of NSA 3 to the membrane of some (about 10%) of the neurons. In the white matter, the patterns were in agreement with the localisation of the Ranvier nodes. The nodes of Ranvier were also stained in peripheral nerves.

Jimpy mouse myelin revisited with freeze-fracture.

Corpus callosum, cerebellum, and spinal cord from Jimpy mice, and control littermates, 15 and 21 days old, were prepared for freeze-fracture in a "cryofract" apparatus. The few myelinated axons in the Jimpy exhibited a striking paucity of particles in myelin P faces, though tight junctions were present. In addition, small maculae of particles were found on these P faces. Peripheral myelin appeared normal, both for the quantity and disposition of particles on their P faces.

alpha-Albumin (glial fibrillary acidic protein) in normal and pathological human brain and cerebrospinal fluid.

alpha-Albumin, a specific brain protein observed after agar gel electrophoresis and shown to be identical to the later described GFA, has been determined in normal and pathological human central nervous system and cerebrospinal fluid. The outcome of this study underlines the value of the detection of specific proteins of the brain in biological fluids.

The 13C/12C ratio in black pulmonary pigment: a mass spectrometric study.

Ratios of the two stable isotopes of carbon, 13C and 12C, were measured in black pulmonary pigment and in several endogenous tissues removed during 20 autopsies on Long Island, New York. The mass spectrometer used for carbon isotope ratio analyses has a precision of +/- 1 13C atom per million carbon atoms. The 13C/12C ratio was found to be distinctly lower in black pulmonary pigment than in endogenous tissues, the mean difference amounting to 65 13C atoms per million carbon atoms. The results demonstrate that the elemental carbon fraction of black pulmonary pigment is exogenous and constitutes roughly 30 per cent of the weight of the pigmented material. It was also observed that 13C/12C ratios in endogenous tissues from individual autopsy cases were not quite identical, tending to be slightly greater in corpus callosum than in liver or peripheral lung.

Ultrastructural localization study of two Wolfgram proteins in rat brain tissue.

The ultrastructural immunohistochemical localization of Wolfgram proteins W1 and W2 is described in young rat brain tissue. The labelling by the antiserum to W1 is restricted to oligodendroglial cells and myelin sheaths. The plasma membrane of the cells as well as the polysomes are positively stained whereas the mitochondria and the nuclei are always free of labelling. Glial cell processes with definite organelles, which are involved in the myelination of neighbouring axons, are also positive to the antiserum. In the myelin sheaths, the positive staining occurs predominantly at the dense period line of the innermost and outermost lamellae. The present results add further evidence for a specific local synthesis of these Wolfgram proteins in oligodendroglial cells during myelination.

Immunohistochemical studies of Wolfgram proteins in central nervous system of neurological mutant mice.

Immunohistochemical localization of Wolfgram proteins has been studied by the indirect immunoperoxidase technique with Wolfgram protein W1 antibodies in the nervous system of myelin deficient mutant mice: Jimpy, MSD and Quaking. In all these mutants, the myelinated fibers and the oligodendroglial cells (few in number) in the corpus callosum and the white matter of the cerebellum folium show a positive reaction to protein W1. These observations are in accordance with the immunological studies showing that the two major Wolfgram proteins, W1 and W2, of mutant mice have immunological similarities with that of the controls.

Correlative assay of computerized cranial tomography CCT, water content and specific gravity in normal and pathological postmortem brain.

An assay of water content and specific gravity in normal and pathological autopsy brain has been correlated with CCT attenuation values obtained just prior to brain cutting. Formalin fixation does not alter normal values so that fixed brain appears to be suitable for this type of study. Low attenuation values in CCT correlate better with changes in specific gravity, rather than water in infarcts, but they have a close relationship to water content in edema. The high water content in infarcts of the white matter reveals a striking disparity in fluid control between cortex and white matter, which has not been emphasized in experimental studies. Water movement within and around blood clots has been discussed.

Localization of cholinergic muscarinic receptors in rat brain by light microscopic radioautography.

Injection of a potent, cholinergic muscarinic antagonist, [3H]3-quinuclidinyl benzilate ([3H]QNB), results in a localization of the drug to muscarinic receptors in rat brain. The distribution of these drug receptors was examined in various brain regions previously thought to contain cholinergic neurons. They were localized to dendritic regions in the hippocampus, corpus striatum, nucleus accumbens and cerebral cortex. Particularly in the hippocampus, the receptor distribution may correspond to that for cholinergic nerve terminals.