[Immunoelectrophoretic quantitation of the brain specific S-100 protein (author's transl)]

Decreased levels of S-100 protein in non-ulcer interstitial cystitis

Interstitial cystitis (IC) is a chronic debilitating condition which mainly affects women. Accumulated evidence indicates that IC is a heterogeneous syndrome. As compared to classic IC, the non-ulcer type of IC appears to be different concerning symptomatic, endoscopical and histological findings, as well as in response to various forms of treatment. S-100 is a neural protein considered to be located primarily in the axons. To explore further the neurogenic nature of the disease, we compared bladder wall S-100 content in controls and in patients with classic and non-ulcer IC. We noticed a decrease in S-100 content in non-ulcer IC as compared to controls. This may be an expression of altered peripheral innervation in non-ulcer IC, which, in turn, may be an indication of primary neurogenic etiology. The difference in S-100 content between classic and non-ulcer IC supports the hypothesis that they represent separate entities, which may explain differences in response to various treatments.

A simple quantitative dot-immunobinding assay for glial and neuronal marker proteins in SDS-solubilized brain tissue extracts

Immunoassays for quantitative determinations of the S-100 protein, the glial fibrillary acidic protein, the neuron specific enolase and the neurofilament proteins with molecular weight of 68 and 200 kDa in hot SDS sonicated rat brain extracts have been developed and characterized. The assays utilize a dot immunobinding technique, poly- or monoclonal antibodies and 125I-protein A. The SDS-sonication procedure was not found to affect the radioactivity recovery in the assay of the soluble S-100 protein or the neuron specific enolase. All 5 antigens can be measured with a within-assay variance below 10%. Even at a coefficient of variation less than or equal to 5%, the working ranges are approximately 30-100-fold with regard to the different antigens. It was found that gelatin-coated nitrocellulose membranes considerably increase the recovered radioactivity in the assay of the purified bovine S-100 protein, possibly by protein-protein interaction. This effect was not observed when SDS-sonicated rat brain extracts were assayed. The assay appears to be reproducible, convenient and rapid, and provides a high degree of precision in the determination of large number of samples.

Long term neurotoxicity of styrene. A quantitative study of glial fibrillary acidic protein (GFA) and S-100

Little information exists about the possible neurotoxicity of styrene. The present study was designed to explore whether long term inhalation exposure (three months) to styrene (90 and 320 ppm) could induce long lasting astroglial alterations in Sprague Dawley rats, traceable four months after exposure ceased. Styrene exposure at 320 ppm induced such alterations as shown by raised concentrations of the glial cell marker, glial fibrillary acidic protein (GFA) in the sensory motor cortex and in the hippocampus. GFA is the structural protein of the astroglial filaments and formation of these filaments has been shown after damage to the central nervous system from any cause. It is concluded that exposure to styrene at moderate exposure levels induces regional, long lasting astroglial reactions that serve as an indicator of solvent induced brain damage.

Parvalbumin increases in the caudate putamen of rats with vitamin D hypervitaminosis

The influence of chronic vitamin D3 application on the concentration of the four calcium-binding proteins parvalbumin, the 28-kDa calbindin-D, calmodulin, and S-100 was studied in various brain regions and in the kidney. Young rats were administered daily 20,000 international units of vitamin D3 per kg (body weight) over a period of 4 months. This chronic treatment resulted in a clinically mild hypervitaminosis that did not affect the content of calmodulin, the 28-kDa calbindin-D, and S-100. Also the concentration of parvalbumin in the cerebral cortex, hippocampus, and kidney remained unchanged. On the other hand, parvalbumin was increased about 50% in the caudate putamen of hypervitaminotic animals as compared to controls. Our results indicate that the metabolism of parvalbumin in the caudate putamen can be influenced by variations of the blood level of this steroid hormone.

Detection limits of different approaches in behavioral teratology, and correlation of effects with neurochemical parameters

Five laboratories collaborated in the evaluation of detection limits of different testing concepts in behavioral teratology. In one laboratory, rat dams were treated by gavage with five doses of methylmercury (0.0, 0.25, 0.05, 0.5, and 5.0 mg/kg/day). The treatment period was restricted to days 6 to 9 of gestation. The usual reproduction parameters were assessed in the dams. The offspring (88-99 per group) were subjected to a routine developmental and behavioral testing battery. After completion of these tests, random samples of the animals were further investigated in four other laboratories using the following techniques: auditory startle habituation, visual discrimination and figure-8 activity monitor; wheel-shaped activity monitor and spatial alternation operant conditioning; two-compartment locomotor activity, passive avoidance and male ultrasonic vocalization during sexual behavior; assays of the weight of different brain areas, their glial fibrillary acidic (GFA) protein and S-100 protein concentration. The following dose-dependent effects were noted in ascending dose sensitivity order: delayed vaginal opening; increased and more variable passiveness in spatial alternation; impaired swimming behavior, increased GFA protein concentration in the cerebellar vermis; increased auditory startle amplitude, decreased intertrial interval pokes in the visual discrimination test, increased percentage of visits in passive area of figure-8 activity monitor, increased path iteration frequencies and decreased local activity in the wheel-shaped activity monitor, decreased locomotor activity in the two-compartment monitor, increased cerebellar vermis weight, and decreased S-100 protein in the hippocampus. Therefore, this study showed comparable sensitivities for the behavioral testing battery, for some automated multiparametric test systems and for the neurochemical assays.

Irreversible effects of dichloromethane on the brain after long term exposure: a quantitative study of DNA and the glial cell marker proteins S-100 and GFA

Two astroglial proteins S-100 and GFA, as well as DNA, were quantitatively determined in different regions of the gerbil brain after continuous long term exposure to moderate concentrations of dichloromethane. The intention of the experiment was to expose three groups of animals at three different solvent concentrations (210, 350, or 700 ppm) for three months. Because of the high mortality rate, however, the 700 ppm experiment was terminated after seven weeks. In the 350 ppm experiment half the exposed animals died and the exposure period was terminated after ten weeks. After the exposure period, the surviving gerbils in the 350 ppm exposure group and those from the 210 ppm group were allowed a postexposure solvent free period of four months. After exposure to 350 ppm, increased concentrations of the two astroglial proteins were found in the frontal and sensory motor cerebral cortex, compatible with astrogliosis in these regions. Exposure to 350 ppm and 210 ppm decreased the concentrations of DNA in the hippocampus. Moreover, after exposure at 350 ppm, DNA concentrations were also decreased in the cerebellar hemispheres. These results indicate a decreased cell density in these brain regions, probably due to cell loss. The neurotoxic effects were not found to correlate with the endogenous formation of carbon monoxide.

Long lasting changes in gerbil brain after chronic ethanol exposure: a quantitative study of the glial cell marker S-100 and DNA

Glial S-100 protein, soluble protein, and DNA were quantitatively studied in brains of gerbils chronically exposed to ethanol in a nutritionally complete fluid diet. Eight different brain areas were studied. After exposure to ethanol for 3 months followed by a 4-month post-treatment ethanol-free period, increased amounts of S-100 protein per wet weight were found in the frontal cerebral cortex, the sensory-motor cerebral cortex, the posterior cerebellar vermis, and the brainstem. The increase of S-100 in the posterior cerebellar vermis was paralleled by an increase in DNA per wet weight, which was also increased in the anterior cerebellar vermis. However, a decreased content of DNA was observed in the frontal cerebral cortex, despite the increase of S-100 protein, suggesting a cell loss affecting cells other than astroglial in this area. In the cerebellar vermis, elevated concentrations of soluble proteins per wet weight were found, whereas a decreased amount was found in the anterior cerebellar hemispheres. It is suggested that the S-100 protein acts as a marker for astroglial cell volume and that a concomitant increase of S-100 protein and DNA might indicate an increase in the number of astroglial cells. Thus, our results obtained after ethanol exposure and subsequent ethanol abstinence are compatible with changes consisting of astroglial hypertrophy in the cortex areas and brainstem, as well as astroglial hypertrophy and/or proliferation in the posterior cerebellar vermis, a clear sign of the preceding noxae.

The effect of S-100a and S-100b proteins and Zn2+ on the assembly of brain microtubule proteins in vitro

The homologous proteins S-100a and S-100b affect the microtubule system in a distinctly different way in the presence of low molar ratios of Zn2+. Assembly of brain microtubule proteins can be almost completely inhibited and rapid disassembly can be induced by low molar amounts of S-100b in the presence of low molar ratios [2-4] of Zn2+. Higher molar ratios per S-100b (greater than 4) potentiate the general Zn2+ effect, promoting the formation of sheets of microtubules. However, the effect of S-100a is quite different, no inhibition of assembly can be observed and the presence of S-100a seems to protect the microtubule proteins against the effect of Zn2+ by chelating the Zn2+ and decreasing the free metal-ion concentration. S-100a or S-100b cannot bind to the microtubule polymer-form, either in the absence or in the presence of Zn2+.

Chemistry and biology of the S-100 protein

The S-100 protein is specific for the nervous system and, being present in all vertebrates, shows a high degree of stability of structure during evolution. In adult animals it is primarily localized to glial elements, although there is some evidence that a small proportion may be present in neuronal nuclei or their plasma membranes. During development it is synthesized rapidly at a relatively late period of differentiation of the nervous system. In glioma cell cultures there is a control mechanism that seems to involve some kind of signal at the external surface of the plasma membrane, possibly specific cell-cell contact, to stimulate S-100 synthesis. All of these biological properties of S-100 suggest that it is connected with some specific essential function that is common to the nervous system of all vertebrates. Several chemical properties of S-100 provide clues to this function. It is an unusually acidic and soluble protein and, in the absence of Ca2+, has no detectable hydrophobic regions accessible to solvent. It is capable of specifically binding Ca2+, a process that causes S-100 to undergo a conformational change that exposes a hydrophobic region to the solvent and stimulates binding of S-100 to membranes. The conformational change and the membrane-binding properties are reversible when Ca2+ is removed and are antagonized by monovalent cations such as K+ and Na+. These chemical properties suggest that S-100 may, as part of its function in the nervous system, be bound to some hydrophobic site, possibly a membrane, and that the extent of this binding is regulated by concentrations of Ca2+, K+ and Na+. If this is true, then it is important, as the next step in working out its function, to discover the exact site where S-100 binds in the nervous system.

Brain primary culture - a characterization

Primary cultures from rat or mouse brain hemispheres contain predominantly glial cells. These cells accumulated [3H]GABA and showed a specific fluorescence with FITC-labeled anti-S-100 antiserum. Round or elongated cells which reacted positively with antimacrophage antiserum and exhibited phagocytotic activity, were considered mesodermal macrophages. Big flat cells, unreactive to S-100 antiserum or to any other antiserum tested, showed a morphology similar to mesenchymal cells of a low differentiation grade. These cells formed a monolayer upon which other cell types grew. Positive reaction for alkaline phosphatases was used as a criterion to identify endothelial cells, the number of which increased with increasing age of the cultures. Anti-14-3-2 antiserum gave no specific reaction, indicating the presence of very few or no differentiated neurons in the cultures.

Effects of trichloroethylene inhalation on proteins of the gerbil brain

Inhalation exposure of adult Mongolian gerbils to 320 ppm of trichloroethylene (TCE) during 8 weeks causes a decrease of soluble proteins per wet weight in frontal cerebral cortex, cerebellar anterior part of the hemispheres and in the posterior part of vermis, as well as in hippocampus, although the levels of S 100, a glial cytoplasmic protein, showed an overgoing increase back to control levels, or a significant increase. In the sensory-motor cortex, an overgoing increase of soluble proteins, as well as of the S 100, were observed during the exposure period. One of the major soluble polypeptides (m.w. 50,000--52,000) of cerebral cortex, the cerebellar hemispheres and the brain stem, decreased at the end of the exposure period. Possible candidates for such a polypeptide are among others the subunit of microtubular protein or a subunit of (Na+K+)-ATPase. The results show that inhalation of TCE effect various brain areas differently. The observed biochemical changes could be interpreted as an adaptation and in some brain areas neuronal cells seem to be more sensitive than glial cells to TCE.

Distribution of S-100 and 14-3-2 proteins on neuronal cell membranes

The distribution of nervous tissue specific S-100 and 14.3.2 proteins was studied over the total surface of isolated, intact nerve cells by immunofluorescence microscopy. The distribution of the antigens was different on the front and back of the cells, indicating complicated S-100 and 14.3.2 patterns. A partly overlapping in membrane pattern of S-100 and 14.3.2 proteins was observed, although S-100 protein dominated with respect to membrane areas covered. At higher resolution the specific fluorescence appeared as conglomerates and islets. The neuronal membrane patterns of S-100 and 14.3.2 antigens, including synapses suggest that nerve cell membranes are functionally differentiated, thus greatly increasing the capacity for identification of incoming stimuli.

14-3-2 protein in rat brain

The distribution of the 14-3-2 protein in rat brain was investigated by immuno-electron microscopy using antiserum to the protein conjugated with peroxidase. 14-3-2 was demonstrated in the nuclear membrane, the endoplasmic reticular membranes and in the plasma membrane of nerve cells. The protein was also localized to the presynaptic densities and to the pre- and postsynaptic membranes. It could not be demonstrated in the membranes of the Golgi complex, inner membrane of mitochondria or in the nucleoplasm of neurons. No 14-3-2 protein was found in astrocytes, oligodendrocytes or in non-neuroectodermal tissue elements.

Glial cell characteristics in bulk-prepared cell fractions from human brain tumours

The heterogeneity of brain tumours, especially in the glioblastoma group, makes biochemical characterization of pieces of the tumours hazardous even with extensive histological controls. This study employs a technique by which separate cell populations are subsequently isolated from the tumours by means of density gradient centrifugation. Cells isolated from glial brain tumours with low density sedimentation rates show the highest levels of glial cell characteristics, i.e. S-100 content and active uptake of the neurotransmitter GABA.

S-100 in the central nervous system of rat, rabbit and guinea pig during postnatal development

The accumulation of the brain-specific S-100 protein has been studied during postnatal development of rat, rabbit and guinea pig quantitatively, using immunoelectrophoresis, and qualitatively, by immunoelectron microscopy. Newborn guinea pigs show high levels of S-100. The distribution was similar to that of adult animals with an enrichment of S-100 to the postsynaptic membranes and to the astrocytic filaments. The neuronal plasma membranes as well as the neuronal nuclear membranes, astrocytic and oligodendroglial plasma membranes, also showed a specific activity for S-100. The amount of S-100 increased linearly from birth until the 3rd and 4th postnatal week of rabbit and rat, respectively. During the 2nd and 3rd week rabbit and rat nervous systems showed an accumulation of S-100, especially in the postsynaptic membranes and in the astrocytic filaments. In this study we present evidence that the S-100 protein quantitatively and ultrastructurally appears according to a pattern which parallels the muturation of brain, showing adult characteristics already at birth in early developing brains (guinea pig) and a change towards adult pattern after birth in late developing brains (rat and rabbit). In the latter two species change towards an adult S-100 distribution pattern proceeds during the postnatal period concomitant with the enzymatic and electrophysiogical maturation of the brain.

Amino acid incorporation into total protein and levels of S-100 protein in discrete rat brain areas after prolonged protein or amino acid restriction

Young adult rats were fed an isocaloric diet for 28 days. The diet consisted of either 22% casein, or protein-restricted food consisting of a 5% mixture of soy and whey protein, or a synthetic amino acid mixed diet devoid of the essential amino acids tryptophan, valine, lysine, and threonine. The level of the nervous tissue-specific S-100 protein was quantified immunoelectrophoretically in 9 different brain areas. A marked decrease of S-100 was observed in hippocampus and posterior part of the cerebellar vermis per g wet weight in protein-restricted rats. An additional lowering was noticed in sensory motor cortex per mg soluble protein. This effect was potentiated with the amino acid-deficient diet. The in vitro incorporation of 3H-leucine into cerebellar proteins was slightly decreased in the low-protein-fed rats, and more markedly decreased in those receiving an amino acid-restricted diet.

The brain-specific S 100 protein in small cerebral stab wounds in the rat: a quantitative study

A quantitative study of the changes in water-soluble proteins and water-soluble S 100 was made in stab-wounded rat frontal cortex as compared to unoperated controls. No great changes occurred until 30 days after the injury. At that time there was no change in the amount of water-soluble S 100 protein/g wet weight, but a large decrease in the amount of water-soluble proteins/g wet weight and thus a proportionate increase in the amount of water-soluble S 100 protein/mg of water-soluble proteins. The significance of the results is discussed.

Cellular and subcellular distribution of the S-100 protein in rabbit and rat central nervous system

The cellular and subcellular distribution of the S-100 protein in rabbit and rat central nervous system was studied both quantitatively and qualitatively. Microcomplement fixation estimations on bulk-prepared neuronal and glial cells showed at least five to six times higher amounts of water-soluble S-100 in glial cell-enriched fractions as compared to fractions enriched in neuronal perikarya. Nerve cell fractions contained a higher percent of tissue-bound S-100 protein. High levels of S-100 protein were found in mitochondria and soluble protein fractions. Immunoelectron microscope investigations demonstrated S-100 protein in neuronal structures, such as the postsynaptic membrane and part of the plasma membrane. Among glial cells the astrocytic filaments contained high levels of S-100 protein. S-100 was also found in most subcellular membranes of astrocytes and oligodendrocytes.