Abstract: 1. The concentration of taurine in the diets, plasma, urine and breast milk were measured in vegans and age- and sex-matched omnivore controls. Plasma and urinary amino acid concentrations were also determined. 2. Taurine was absent from the vegan diet and occurred in variable amounts in the diets of the omnivores. Urinary taurine levels were less than half those of the omnivores but plasma and breast-milk levels were only slightly lower. 3. Dietary energy intakes were similar in the vegans and omnivores, but protein intakes tended to be lower in the vegans.

Abstract: Adult female cats were fed a defined purified diet (taurine-free) either alone or supplemented with 0.05% taurine for at least 6 mo prior to breeding. The reproductive performance by the taurine-depleted females was poor, whereas those receiving dietary taurine had normal pregnancies and deliveries. The taurine-depleted females suffered from severe retinal degeneration, including a large loss of photoreceptor outer segments, and degeneration of the tapetum lucidum, and greatly reduced concentrations of taurine in their body tissues and fluids. Surviving offspring from the taurine-depleted mothers exhibited a number of neurological abnormalities and substantially reduced concentrations of taurine in the body tissues and fluids. Except for greater concentrations of cystathionine in neural tissues, other free amino acids in tissues were unaffected. The specific activities of a number of enzymes involved in the biosynthesis of taurine were unchanged in liver and brain. The composition of maternal milk, total protein, protein amino acids and free amino acids was unchanged except for taurine content, suggesting that the abnormalities in the offspring resulted from the diminished dietary taurine.

Abstract: Free amino acids can be coupled to proteins by glutaraldehyde. Rabbits immunised with a bovine serum albumin-glutaraldehyde-amino acid conjugate form antibodies that recognise similar conjugates with brain proteins in glutaraldehyde-fixed tissue. Antisera raised against conjugated GABA (gamma-aminobutyrate), glutamate, aspartate, taurine, glutamine, or glycine were tested against a variety of small molecular compounds that had been fixed by glutaraldehyde to brain protein and immobilised on cellulose ester filters for processing together with the brain sections. This system permitted closely similar conditions for testing and immunocytochemistry. After removing antibodies against the carrier used for immunisation and against cross reacting amino acid conjugates the antisera showed a high specificity. The specific nature of the antisera was corroborated by solid phase adsorption to the homologous antigens and by inhibition experiments with free amino acids and amino acid-glutaraldehyde fixation complexes. After transection of the striatonigral pathway the ipsilateral substantia nigra was almost depleted of GABA-like immunoreactivity; this observation lends additional support to the selectivity of the GABA antiserum. A semiquantitative relation was established between the concentration of amino acid before fixation in a model system and the subsequent intensity of immunostaining. Similar model experiments suggested that the conjugation of an amino acid to brain protein with glutaraldehyde, and the immunoreactivity of the conjugates, may be significantly inhibited in the presence of high concentrations of other amino compounds.

Abstract: In this study the authors describe the use of dietary taurine to protect hamster lung epithelium from acute nitrogen dioxide (NO2) injury. The conclusions were based on histologic, ultrastructural, and freeze-fracture analyses. Hamsters were pretreated for 14 days with 0.5% taurine in their drinking water. They were then exposed to either 7 or 30 ppm NO2 for 24 hours. The lungs from animals of these experimental groups were compared with those from hamsters treated with only NO2, and those given only taurine and with untreated controls. After treatment, hamsters were anesthetized and perfusion-fixed through the right side of the heart with a solution containing 1% glutaraldehyde, 4% paraformaldehyde, and 0.2 M cacodylate. The trachea and lungs were removed en bloc and stored overnight in cacodylate buffer at 4 C. Terminal and respiratory bronchioles, including alveolar ducts and peribronchiolar alveoli, were dissected from each lobe and processed for embedding in Epon and freeze-fracture replication. Light and transmission electron microscopy revealed the typical inflammatory cell infiltrate in the bronchiolar and alveolar duct regions in the lungs of hamsters exposed to NO2. The bronchiolar epithelium appeared flattened because of loss and breakage of cilia on ciliated cells and apical protrusions of Clara cells. Clara-cell secretory granules were reduced or absent. Freeze-fracture replicas of tight junctions of bronchiolar epithelium analyzed by morphometric techniques demonstrated a reduction and fragmentation of fibrils. Only animals exposed to 30 ppm NO2 exhibited physiologic intercellular penetration of horseradish peroxidase. Hamsters pretreated with taurine and then exposed to NO2 showed none of these alterations. They exhibited the same morphologic features as the untreated controls and the hamsters treated only with taurine. On the basis of this evidence, it is suggested that prophylactic dietary taurine can prevent acute NO2-induced morphologic lung injury. Taurine may also be effective in preventing lung injury induced by other oxidant gases.

Abstract: Concentrations of taurine have been measured in 44 microdissected rat brain nuclei or areas Taurine is ubiquitously present and distributed unevenly in the rat brain: the ratio of the highest (pyriform cortex) to lowest (midbrain reticular formation) concentrations is 47:1 High taurine levels were found in cerebral cortical areas, caudate-puta-men, cerebellum, median eminence, and supraoptic nucleus Acute pain stress reduced taurine levels in the hypothalamus and the lower brainstem nuclei but not in cortical areas Increased locomotor and behavioral activities following a high dose of amphetamine elevated taurine concentrations significantly in the substantia nigra and locus ceruleus

Abstract: The taurine transport of flounder erythrocytes is associated with a cell volume regulation in anisosmotic media. An osmolality reduction leads to a cell volume increase, which is followed by a volume readajustment towards the original level. A 75 mosM reduction is accompanied by a 33 mumol g dry wt.-1 reduction in the cellular taurine content. The reduction in osmolality activates the taurine release mechanism by transiently increasing the rate coefficient for taurine efflux. The rate coefficient for taurine influx is similarly stimulated. This influx is mediated by a Na+-independent transport system. The concomitant activation of influx and efflux suggests a coupling between these two systems. Higher taurine efflux and influx rate coefficients which decayed more slowly with time were measured in cells suspended in Na+-free (choline replacement) media than in the presence of Na+. This suggests that Na+ may play a role in the taurine release mechanism. Noradrenaline induced a cellular swelling at normal osmolality (330 mosM), but had only a minor effect on the taurine efflux and influx and the cellular taurine content. Urea-induced cellular swelling at normal osmolality initiated a volume regulatory process and activated the taurine release mechanism, similarly to an osmolality reduction. These results show that osmolality reduction and cellular swelling are no prerequisites for the activation of the taurine release mechanism and the cell volume readajustment. It is suggested that the dimension of an intracellular solute compartment determines the activation level of this mechanism.

Abstract: An immunological approach to the detection of taurine resulted in antibodies specific enough to be used for immunocytochemical studies. The experimental conditions were similar to those previously described for raising antibodies against some small-sized neurotrans-mitter molecules: antisera were obtained from rabbits immunized with taurine conjugated to carrier proteins via glutaraldehyde and purified by adsorption on the glutar-aldehyde-treated protein carriers. Antibody affinity and specificity were determined in competition experiments between conjugated taurine and other conjugated amino acids or derivatives by enzyme-linked immunosorbent assay. The resulting cross-reactivity ratios, calculated at half-displacement, showed conjugated taurine to be the best recognized compound. Given the molecular structure of taurine and the method used to prepare the conjugate, it seemed necessary to perform an oxidation step. However, adsorption of antisera on reoxidized or non-reoxidized taurine conjugates suggested that reoxidation did not make a significant difference. Immunocytochemical application of the sera revealed populations of strongly immunopositive nerve cells in the cerebellum, striatum, and septum. The results confirmed that anti-taurine antibodies can be used as specific tools for a better understanding of the role of taurine in the central nervous system.

Abstract: Leukocyte and plasma concentrations of free glutathione, cysteine, methionine, and taurine, and total glutathione and cysteine concentrations were determined in healthy human subjects before and during a seven-day period of total energy deprivation. In leukocytes a progressive decline in total glutathione concentration was found during seven days of starvation due to a decrease in free glutathione content. An increased mixed protein-bound glutathione concentration was calculated, whereas the total cysteine level was unaltered. Fasting resulted in a decreased plasma concentration of free glutathione, whereas the total glutathione level remained unchanged. Free leukocyte concentrations of taurine and methionine were reduced, whereas plasma sulfur amino acid levels were essentially unaffected. These results probably reflect a limited availability of sulfur amino acids during fasting, when glutathione is used as cysteine reservoir for synthesis of other vital sulfur containing compounds. The potential use of leukocyte glutathione, methionine, and taurine concentrations as intracellular indicators of sulfur amino acid deficiency are stressed.

Abstract: The uptake-index method was used to study the transport of amino acids through the blood-retinal and blood-brain barriers in rats. The results indicate the existence of at least two different, similar carriers in both barriers, i.e., one each for neutral and basic amino acids. A third separate transport system for taurine was found in the blood-retinal barrier. All of the carrier systems studied transported amino acids from blood to nervous tissue.

Abstract: Studies of various parameters of amino acid and catecholamine metabolism in human cerebral cortex have provided a number of biochemical markers that appear to delineate areas of focal epileptic activity. These observations have been consolidated further by investigations of a number of experimental models of epilepsy in animals. In appraising this data, it is important to take into consideration whether the tissue samples were obtained during an actual seizure state or in an interictal period. It is also important when possible to assess the extent of astrogliosis and neuronal loss. Sites of spontaneously active epileptic spiking in the cerebral neocortex have a somewhat different amino acid profile when compared to gray matter obtained from surrounding nonspiking gyri several centimeters away. There is an elevation in glycine content, a relative diminution in taurine, and a trend towards lowered glutamic acid levels. However, the concentrations of the eight amino acids measured appear in both the foci and surround to still be within the general range for normal tissue. Measurements of key enzymes involved in the synthesis and regulation of neurotransmitters provide a complementary method of evaluating functional changes in epileptic brain as they are generally less labile than their substrates. There is a moderate increase in the activity of glutamic acid dehydrogenase, an enzyme that plays an important role in the synthesis of glutamic acid from glucose. In some patients a decrease in glutamic acid decarboxylase has also been reported: this enzyme forms gamma-aminobutyric acid (GABA) from glutamic acid and is thus important for inhibition in the central nervous system. Moreover, there is a striking increase in the activity of tyrosine hydroxylase, the rate-limiting enzyme responsible for catecholamine synthesis. The possibility of a focal abnormality in catecholamine metabolism is reinforced by the simultaneous finding of a relative decrease in the number of alpha-1 postsynaptic receptor sites. An important marker of energy metabolism in neural tissue, Na+,K+-ATPase activity, has also been found to be decreased in actively spiking human cerebral cortex. Data from experimental animal foci produced by topical application of convulsant agents show a consistent drop in glutamic acid tissue content. This can be matched to an efflux of glutamic acid from the cortical surface, which in turn is proportional to the electrographic activity of the spike focus. In addition, there is often also a decrease in taurine and GABA in such foci, as well as an increase in the levels of a number of neutral amino acids.(ABSTRACT TRUNCATED AT 400 WORDS)

Abstract: Levels of free amino acids were determined quantitatively in whole ocular tissues of the rat eye with aid of a sensitive amino acid analyzer. The tissues studied were the retina, vitreous, lens, iris-ciliary body, and cornea. The retina and lens contained a more concentrated free amino acid pool than other tissues. The neuroactive amino acids taurine, GABA, glutamic acid, aspartic acid, and glycine were clearly enriched in the retina. Taurine was the most abundant amino acid in all five tissue studied, and its high concentration in non-neural tissues, especially the lens, suggests that it must have other functions as well as neurotransmitter ones in the rat eye.

Abstract: The immunocytochemical method for demonstrating amino acids makes it possible to study accumulation and depletion of amino acids in individual tissue compartments resulting from experimental manipulations. We have incubated hippocampal slices in oxygenated Krebs solution, containing various additives, under basal conditions and during synaptic release of transmitters evoked by elevated K+ concentrations or by veratrine. Immunoreactivities for glutamate (Glu-LI), aspartate (Asp-LI), glutamine (Gln-LI), gamma-amino-butyrate (GABA-LI) and taurine (Tau-LI) have been demonstrated by specific antibodies after fixation of the slices in glutaraldehyde. Prolonged depolarisation depleted Glu-LI, Asp-LI and Gln-LI from nerve-ending-like structures. GABA-LI was less affected and Tau-LI not affected at all. The depletion of immunoreactivities could be prevented by metabolic precursors of transmitter amino acids, notably glutamine. This effect of glutamine was abolished by inhibiting glutaminase with diazooxonorleucine. Glu-LI, Asp-LI, GABA-LI and Gln-LI accumulated in astroglial cells during conditions of prolonged depolarization-induced release. The accumulation of GABA-LI in glia was strongly increased by inhibition of aminotransferases by aminooxyacetic acid. The described changes in Glu-LI were prevented by low Ca2+/high Mg2+, and promoted when the glial enzyme glutamine synthetase was inhibited by methionine sulfoximine. D-Aspartate, a metabolically inert competitive inhibitor/substrate for high affinity uptake of glutamate, inhibited the accumulation of Glu-LI in glia. The results confirm the biochemically derived theories on metabolic compartmentation in nervous tissue, and add knowledge on the dynamics of the cellular distribution of amino acids. They also indicate the possibilities offered by the present approach for studying metabolism and pharmacology at the cellular level.

Abstract: The amygdala is involved in temporal lobe seizures, in man as well as in animal models (refs. in Ben-Ari, 1981), and is among the brain structures from which epileptiform seizures can be most effectively elicited by repeated electrical stimulation (Racine, 1981) or by topical injections of neuroexcitants (Ben-Ari et al., 1980; Tremblay et al., 1983). A better understanding of how the amygdala participates in these epileptic phenomena requires, among other things, more insight into its transmitter mechanisms. The amino acid transmitters gamma-aminobutyrate (GABA), glutamate (Glu), and aspartate (Asp) are of particular interest in this respect since it is assumed that they play decisive roles in the pathogenesis and sequelae of epilepsy (Meldrum, 1984). It is now time for increased efforts to unravel the amino acid transmitter mechanisms in the amygdala. First, the efferent and afferent fiber systems of the various amygdaloid subdivisions have recently been mapped in considerable detail (refs. in Ben-Ari, 1981), facilitating the undertaking and interpretation of experiments aimed at tracing transmitter-specific pathways. Second, new methods have been introduced to supplement those based on autoradiography of in vitro high affinity uptake of radiolabeled amino acids or on immunocytochemistry of glutamic acid decarboxylase (GAD), which have hitherto been the predominant histological techniques in amino acid transmitter research (for references see 9ttersen and Storm-Mathisen, 1984a). Thus, evidence has accumulated that D-[3H]Asp and [3H]GABA, injected in vivo, are selectively transported in axons of Glu/Asp-ergic and GABA-ergic neurons, respectively, leading to labeling of the parent cell bodies (Streit, 1980). Further, we have developed immunocytochemical techniques for the demonstration of GABA, Glu, and Asp, using antisera raised against the amino acids conjugated to protein by glutaraldehyde (Storm-Mathisen et al., 1983, 1986; Ottersen and Storm-Mathisen, 1984a,b, 1985; Storm-Mathisen and Ottersen, 1986). Antisera have also been raised against conjugates of taurine (Tau; Madsen et al., 1985; Ottersen et al., 1985), which is a more equivocal transmitter candidate than GABA, Glu, and Asp. In the present paper we report data obtained with amino acid immunocytochemistry and autoradiography of amino acid uptake and transport. Some of the results have been published elsewhere (Fischer et al., 1982; Ottersen and Storm-Mathisen, 1984a; Storm-Mathisen and Ottersen, 1986).

Abstract: The effects of dietary taurine on fecal steroid excretion and bile acid pool size were investigated in Jcl: ICR strain mice. The mice were fed on semi-purified diets for five weeks: a cholesterol-free diet (Standard), a lithogenic diet containing 0.5% cholesterol and 0.25% sodium cholate (C-CA) and a lithogenic diet supplemented with 5% taurine (C-CA + 5% taurine). The changes in fecal steroid excretion were studied as a function of time and the bile acid pool size was estimated. Dietary taurine affected fecal bile acid excretion both quantitatively and qualitatively. No change in bile acid pool size was observed. The fecal excretion of bile acids increased in taurine-supplemented mice. The increase in the fecal neutral steroid excretion was less than that in C-CA fed mice. The proportion of chenodeoxycholic acid (CDCA) and the related bile acids to total bile acids increased both in the fecal bile acids and in the bile acid pool. Therefore, the protective effect of dietary taurine against cholesterol gallstone formation may be related to the stimulation of bile acid synthesis, especially of CDCA and related compounds.

Abstract: The response of plasma amino acids to two bovine protein formulas with different protein content (16 and 12 g/100 ml containing 60% whey proteins and 40% caseins) was measured in term infants These two groups of infants were compared with a group of infants that were breast-fed; all infants were fed ad libitum Concentrations of threonine, valine and total branched chain amino acids reflected the amount of protein provided Thus, the concentrations were higher in the higher protein formula infants from the second week of the study In the low protein formula infants these amino acids were lower but differed from the infants on breast milk at eight and twelve weeks Concentration of taurine was lower in the formula fed infants than they were in breast-fed infants at the end of the study The valine/glycine ratio in the low protein formula group was lower than in the breast-fed group for the first four weeks of the study After this time it was equal to that of the breast-fed group These differences in plasma amino acid concentrations give further evidence that formulas now in common use for term infants provide a protein intake in excess of protein requirements after the first months of life

Abstract: (1986). Taurine as a conditionally essential nutrient in man. Journal of the American College of Nutrition: Vol. 5, No. 2, pp. 121-5.

Abstract: The kinetics and specificity of taurine and β-alanine uptake were studied in primary cultures of rat astrocytes under identical experimental conditions. The uptake consisted of nonsaturable penetration and saturable high-affinity transport that was strictly sodium dependent. The cells accumulated taurine more effectively than β-alanine, both the affinity and uptake capacity being greater for taurine. Taurine uptake was competitively inhibited by β-alanine and GABA, the former being more potent. Also, hypotaurine and 2-guanidinoethanesulphonic acid strongly reduced taurine uptake, but L-2,4-diaminobutyric acid had no significant effect. β-Alanine uptake was also competitively inhibited by GABA, but the most potent inhibitors were hypotaurine and 2-guanidinoethanesulphonic acid.l-2,4-Diaminobutyric acid was moderately active. The uptake systems for taurine and β-alanine were thus in principle similar, and they exhibited certain characteristics typical for a neurotransmitter amino acid. The inhibition studies further suggest the existence of only one common transport system for taurine, β-alanine, and GABA in cultured primary astrocytes. The same uptake system may also be used for hypotaurine.

Abstract: This study examines the effect of a low sulfur amino acid diet (LTD) and a high taurine diet (HTD), compared with a normal diet, on the plasma, urine, muscle, brain and renal cortex levels of taurine in immature and adult rats. Milk taurine from lactating dams reflected the taurine content of the diet, being low in LTD-fed and high in HTD-fed animals. Nursing pups (7, 14 and 21 d old) often had plasma, urine and tissue--renal cortex, heart, skeletal muscle--levels of taurine related to dietary exposure, a situation also found in adult animals. These diets did not influence the urinary excretion of the sulfur-containing alpha-amino acids methionine and cystine but a sulfur aminoaciduria of immaturity was evident. By contrast, the content of taurine in brain was constant regardless of dietary intake of sulfur amino acids. An age-related decline in brain taurine content was found--as noted by others--but this too was influenced by diet. This dual finding of brain taurine constancy despite wide differences in sulfur amino acid intake and changes in the renal handling of taurine as influenced by diet suggest that the renal adaptive response serves to maintain the stability of brain taurine content.