Na+ independent binding of [3H] muscimol to a membrane fraction of the brains of normal and dwarf mice

Although their body weights were decreased by about 77% and their brain weights by about 30%, high-affinity [3H] muscimol binding to a cerebral membrane fraction was not altered in hereditary pituitary dwarf mice. Marked changes in the level of pituitary growth-associated hormones do not appear to be associated with a change in cerebral GABA-receptors.     

Na*-independent binding of [3H] muscimol to a membrane fraction of the brains of normal and dwarf mice

Summary Although their body weights were decreased by about 77% and their brain weights by about 30%, high-affinity [³H] muscimol binding to a cerebral membrane fraction was not altered in hereditary pituitary dwarf mice. Marked changes in the level of pituitary growth-associated hormones do not appear to be associated with a change in cerebral GABA-receptors.Supported by a UNESCO/IBRO Fellowship. Permanent address: Semmelweis University Medical School, 1st Institute of Biochemistry, Budapest, Hungary.     

Distribution of glycerophosphorylcholine diesterase in rat brain.

The distribution of glycerylphosphorylcholine diesterase in the rat brain has been examined. The enzyme was evenly distributed throughout the brain but was localized in the synaptosome (nerve ending) fraction which was prepared by ultracentrifugation.     

Distribution of glycerophosphorylcholine diesterase in rat brain

Summary The distribution of glycerylphosphorylcholine diesterase in the rat brain has been examined. The enzyme was evenly distributed throughout the brain but was localized in the synaptosome (nerve ending) fraction which was prepared by ultracentrifugation.     

Effect of desipramine on the contents of some free amino acids of mouse brain

I.p. injections of desipramine-HCl (100 mg/kg) produced decreases in the contents of several amino acids of mouse brain after 1 h. Using a 10-100 mg/kg range of doses, these effects appeared to be dose-dependent for alpha-alanine and aspartate. These changes may be due, in part, to a decrease in cerebral oxidative metabolism (Krebs cycle activity) which occurs secondarily to desipramine-induced hypothermia.     

Combined effect of veratridine and sodium aspartate on the rabbit retinas in vitro

Summary Combined effect of veratridine and sodium aspartate on rabbit retinas in vitro was studied. Observations suggested that mode of action of veratridine on the PII and PIII components of ERGs was modified by the presence of sodium aspartate in perfusate.     

Regional and subcellular distribution of superoxide dismutase in brain.

Superoxide dismutase has been found to be widely distributed and of approximately the same specific activity in all regions of human brain examined. It is not reduced during degeneration of the basal ganglia in Huntington's Chorea. After subcellular fractionation of human and guinea-pig cerebral cortex, the highest specific activity of the enzyme was found in the soluble fraction.     

Adenosine-3,5-phosphate levels in brain structures of rats submitted to four different behavioral procedures

Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect.     

Quantitative Bestimmung von RNS-Fraktionen im Gehirn frisch geschlüpfter Bienen (Apis mellifica)

Summary In the brain of the honeybee (Apis mellifica), it was found that the rRNA content decreases rapidly during the first 2 days of adult life. An increase is observed from days 3 to 5, followed by another decrease to a level inferior to that of day 2 to 3. Except for a rise on the 5th day, 4s RNA remains constant. An unidentified RNA fraction of low molecular weight (D) sharply decreases on day 5. The possibility is discussed that these results reflect changes in RNA metabolism that can be related to the sequences of activity observed in the bees during the first 9 days after hatching.     

‘Binding’ of glutamate and aspartate to synaptosomal fractions of six regions of the feline brain

The order of potency of binding of both glutamate and aspartate to synaptosomal fractions of brain regions was: cerebellar cortex caudate nucleus cerebral cortex > medulla pons > corona radiata. Glutamate was bound to a greater extent than aspartate to particles of all regions studied, except for cerebral cortex.     

The plasma level of some amino acids and physical and mental fatigue

Tryptophan is converted to 5-hydroxytryptamine (5-HT) in the brain and evidence is presented that an increase in the concentration of 5-HT can result in physical and mental fatigue during prolonged exercise. The entry of tryptophan in the brain is influenced by the plasma level of free tryptophan (that not bound to albumin) and, from competition for entry into brain, by the plasma level of branched chain amino acids. Hence, oral administration of branched chain amino acids could, theoretically, prevent the increase in 5-HT level during exercise and therefore delay physical and mental fatigue. Evidence in support of this hypothesis is presented.     

High-affinity binding of beta-alanine to cerebral synaptosomes might involve glycine-receptors.

High-affinity, Na+-independent binding of beta-alanine to a synaptosomal fraction of rat brain was potently inhibited by glycine and by some other alpha-amino acids, but not by taurine or GABA. This binding mechanism, which was also sensitive to both bicuculline and strychnine, might involve synaptic receptors for both beta-alanine and glycine.     

Regional and subcellular distribution of superoxide dismutase in brain

Summary Superoxide dismutase has been found to be widely distributed and of approximately the same specific activity in all regions of human brain examined. It is not reduced during degeneration of the basal ganglia in Huntington's Chorea. After subcellular fractionation of human and guinea-pig cerebral cortex, the highest specific activity of the enzyme was found in the soluble fraction.Acknowledgments. We thank the Huntington's Chorea Foundation for financial support. Address reprint requests to the Neurochemistry Lab., V. A. Hospital, Seattle, Wash. 98108, USA.     

The effect of dietary administration of aspartic acid on thymus weight in C57 black mice

Summary D,L aspartic acid incorporated at a level of 0.5% w/w into the diets of C57B1/10 male mice for 2–8 weeks increased significantly the thymus weight. Similar effects were observed after a 10 days' treatment of the mice with K- and Mg-salts of D,L aspartate (1%) in drinking water.     

Proteoglycans in ovine brain

Summary Sulphated proteoglycans were isolated using a dissociative method of extraction. Cerebrum accounted for the major portion of proteochondroitin sulphate in brain, whereas the brain stem fraction contained over half the proteoheparan sulphate. Chemical characterization studies demonstrated that heparan sulphate from cerebellum contain more N-sulphate glucosamine residues.     

Adenosine-3,5-phosphate levels in brain structures of rats submitted to four different behavioral procedures

Summary Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect.With support from FAPERGS, CNPq, and PROPESP-UFRGS, Brasil. We are grateful to Miss Sonia Eisinger for her valuable technical assistance.     

Dipeptidyl aminopeptidase in neonatal rat brain regions

Summary Changes in the activity of dipeptidyl aminopeptidase in rat pituitary gland and various brain regions were examined at 3, 5 and 20 weeks of age. The enzyme activity per g tissue wet weight in pituitary gland was the highest of all tissues studied. Subcellular distribution of the activity was also studied. The highest enzyme activity was found in a crude mitochondrial fraction including synaptosomes.     

Lysosome-rich synaptosomal preparations from rat mesencephalus (author's transl)]

Subcellular fraction, enriched with synaptosomes, obtained from rat brain has been found contaminated by lysosomes, as evidenced by the high content of acid phosphatase, their biochemical marker.     

Developmental and ageing changes in aminopeptidase activities in selected tissues of the rat

Aminopeptidase activities, assayed as arylamidase activities, were investigated in selected tissues of 1, 6, 12 and 24-month-old rats. The enzyme activities were found to have a heterogeneous distribution and age-related changes were observed. The highest levels of soluble arginyl-aminopeptidase activity were detected in brain homogenate at all the studied ages, whereas membrane-bound activity presented the highest levels in brain and kidney in the four ages tested. Aspartyl-aminopeptidase activity was detected mainly in the particulate fraction of kidney at all four ages. In 1, 6 and 12-month-old animals, soluble aspartyl-aminopeptidase activity was also higher in the kidney than in the rest of the tissues, whereas in the group of 2-year-old rats, the highest levels were found in both kidney and liver. Age-related changes were observed in all the studied tissues and for all the assayed enzymatic activities. In general, the maximal levels were detected in both the youngest and the oldest animals, and the minimal ones in 6 and 12-month-old rats. However, in the adrenals, the soluble and membrane-bound arginyl-aminopeptidase activity was higher in 6-month and 2-year-old rats than in 1-month and 12-month-old rats. These changes may reflect the functional status of the susceptible endogenous substrates of aminopeptidases.     

Characterization and localization of the rat,mouse and human testicular phosphatidylethanolamine binding protein

A cytosolic 23kDa protein was initially puified from bovine brain and shown to bind phosphatidylethanolamine. Later, it was also characterized in rat and human brain, and it is now known to be widespread, having been found in numerous tisues in several species. Here, we report the high level of mRNA and phosphatidyl ethanolamine binding protein expression in rat testis and to a lesser extent mouse testis. In human testis, although it was not detectable by Northern blot analysis, the mRNA was shown be present when PCR amplificatin was performed. Immunohistochemical experiments revealed that the testicular phosphatidylethanolamine binding protein (tPBP) is principally expressed in the elongated spermatids of both rat and mouse testis. This finding, and the association of tPBP with cellular membranes, suggest its possible implication in membrane remodelling during spermatid maturation.