Faculty Bibliography

This paper reports the concentrations of valine, leucine, isoleucine, phenylalanine, and tyrosine as determined in 53 discrete brain areas of 3- and 29-month-old male Fischer 344 rats microdissected by the punch technique. The levels of other amino acids in the same areas are reported in other papers of this series. The essential amino acids reported in this paper showed great regional heterogeneity, with concentrations in areas of the highest content being 9 to 12 times higher than levels in areas of the lowest content. The relative distributions of these amino acids were fairly similar in that in a number of areas the amino acids were all at very high levels and in some other areas they were all at low levels, with a few exceptions. With aging, levels of some amino acids increased and levels of some others did not change, but the predominant change was a significant decrease in levels with age. The results indicate high regional heterogeneity in amino acid levels and in the changes of these levels with age

This paper reports the distribution of methionine, histidine, lysine, arginine, and ornithine in 53 discrete brain areas of 3- and 29-month-old male Fischer 344 rats microdissected by the punch technique. Like that of the other amino acids were reported in previous papers of this series, the distribution of methionine and the basic amino acids was regionally highly heterogeneous. The ratios of levels in the areas of highest concentrations to levels in the areas of lowest concentration varied from 10 to 15 for these amino acids, except that it was 23 for arginine. This heterogeneity is also illustrated by the finding that in some areas arginine was more than 5% of the total amino acid content and in others was less than 0.5%. The distribution of methionine differed from that of the basic amino acids, which were high in hypothalamic areas and low in the limbic system. With aging, methionine and basic amino acids, like the other amino acids studied in this series, mainly decreased in level, although in a few cases increases could be seen. Significant decreases were noted more than five times as often as increases

In previous studies, we found a significantly higher (100% or more) content of cathepsin D in the aging brain. In the present study, we determined activity of Ca2(+)-activated neutral protease requiring millimolar Ca2+ (calpain II, CANP II) and amount of its endogenous inhibitor, calpastatin, in extracts of various brain regions of 3-month-old and 24-month-old male Fischer-344 rats. Calpain II was separated from calpastatin in a single step (chromatography) and its activity was tested using as substrates [methyl-14C]alpha-casein, the cytoskeletal proteins desmin and actin, and a mixture of neurofilament triplet proteins and glial fibrillary acidic proteins (GFAP). We found no changes in calpain II activity in pons-medulla and spinal cord, but significant increases were detected in cortex (72%) and striatum (63%) of the 24-month-old rats using [methyl-14C]alpha-casein as substrate. The profile of desmin and actin breakdown showed regional variations somewhat different from those of [methyl-14C]alpha-casein. With desmin, the greatest increases with age were in the striatum (82%) and hypothalamus (46%), but there were no alterations in cortex, cerebellum, and pons-medulla. With actin, slightly enhanced activity in cortex and cerebellum was noticeable. Calpastatin content in brain regions was also increased, with the regional pattern of increase fairly similar to the pattern of enzyme activity increase. The causes and the physiological consequences of increased calpain and calpastatin content in the aged brain are being investigated. That changes with age are somewhat different with the various brain protein substrates indicates that some of the properties of the enzyme also undergo alteration with age.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of D-tartrate containing media for measuring uptake of catecholamines into brain synaptic vesicles alters the properties of transport. Absolute concentrations of inhibitors determined in competition studies should be viewed with caution

Adult male C57BL/6By and BALB/cBy mice were housed either in large groups (20 per cage) or individually, and levels of plasma testosterone were measured in samples taken in the morning (9 to 10 A.M.) and in the evening (9 to 10 P.M.). No significant strain differences were found in testosterone levels, but the mean testis weight was significantly higher in the BALB/cBy strain. Two-way analysis of variances of pooled plasma testosterone data showed that social isolation of males results in a significant increase in A.M. (but not P.M.) testosterone concentrations and increased testis weight in both strains. Our results suggest that differential housing of a social species can affect testicular function. Since testicular function can also be influenced by the time of day, the question is raised whether the expression of circadian variation in plasma testosterone level is dependent on population density

Various substituents were condensed on the amino terminus of glycine, L-leucine, and L-phenylalanine either in a single step under anhydrous conditions in tetrahydrofuran (THF) or in an aqueous alkaline (Schotten-Baumann) multiple step reaction. Yields were comparable in the two procedures. In some instances, a product could be obtained by only one method. None of the samples at a concentration of 50 uM was inhibitory against a rat brain membrane-bound dipeptidyl aminopeptidase-V (DAP-V). Except for 2-bromo-2,2-diphenylacetyl-L-phenylalanine (BDAP),2-chloro-2,2-diphenylacetyl-L-phenylalanine (CDAP), and L-phenylalanyl methyl ketone (PMK), a similar lack of inhibition was found with a rat brain cytosolic puromycin-sensitive aminopeptidase (PSA-SII). The most potent compound showing competitive inhibition with Met-enkephalin as substrate, BDAP, had a K(i) of 4.2 uM. N-Trifluoroacetyl-L-phenylalanine (TFAP), BDAP, and CDAP had no significant effect on rat brain cathepsin D or bovine lung calpain 1. None of the compounds had any effect on 3-mercaptopropionic acid (MPA)-induced convulsions in mice. $$:

Aspartame (APM) at 500 mg/kg per day in drinking water was administered to rats throughout gestation and lactation. In the weanling rats at 20-22 days of age, aminergic neurotransmitter systems were examined. In cerebral cortex, the kinetics of [H-3] clonidine binding to adrenergic alpha2 receptors and of [H-3] ketanserin to serotonergic 5-HT2 receptors were not altered by perinatal exposure to APM. Dopaminergic systems in striatum, studied with [H-3] SCH-23390 and [H-3] spiperone at D1 and D2 receptors respectively, also were not affected. Levels of related amines and their major metabolites in cerebrum and striatum were the same in control weanlings and in weanlings of mothers treated with APM. No influence of APM on body weight changes, litter size, or weanling weights was observed. APM administered in drinking water more closely resembles human ingestion of large amounts of this sweetener in foods and beverages. These studies suggest that consumption of APM during pregnancy and lactation does not affect amine neurotransmitter systems in offspring. $$: