Faculty Bibliography

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. $$:

Spontaneously occurring and drug-induced high voltage spike-and-wave electroencephalogram patterns were examined in inbred rats of the Fischer 344 and Buffalo strains and of the random-bred Sprague-Dawley strain at different ages. In addition, tyrosine hydroxylase activity and dopamine D2 receptor density were determined in the substantia nigra, corpus striatum, olfactory tubercle and ponsmedulla areas of Fisher 344 and Buffalo animals. High voltage spike-and-wave episodes were present in 87.5% of the 3-month-old and in 100% of the older Fischer 344 rats. High voltage spike-and-wave episodes were completely absent in 3-month-old Buffalo and Sprague-Dawley animals but could be induced by systemic injection of pentylenetetrazol and at an older age they appeared in 58.3% (12-month) and 71.4% (greater than 26-month) of the subjects of these strains. The incidence and duration of high voltage spike-and-wave episodes were significantly higher/longer in Fischer 344 rats than in the age-matched Buffalo and Sprague-Dawley animals. The dopamine blocker acepromazine induced a several-fold increase of the incidence and duration of high voltage spike-and-wave episodes in 3-month-old Fischer 344 rats, but failed to induce high voltage spike-and-wave episodes in Buffalo animals at this age. However, acepromazine also triggered high voltage spike-and-wave episodes in Buffalo rats when they were pretreated with subthreshold doses of pentylenetetrazol. Tyrosine hydroxylase activity was significantly higher in the substantia nigra, corpus striatum and olfactory tubercle of the Fischer 344 strain than in Buffalo rats. The higher tyrosine hydroxylase activity was paralleled with significantly higher D2 binding values in the corpus striatum and olfactory tubercle of Fischer 344 rats. These findings suggest that the neocortical high voltage spike-and-wave phenotype is genetically mediated and that the inbred Fischer 344 and Buffalo rats with defined bilineal origin will facilitate future works aimed at the identification of genetic elements involved in the generation of neocortical high voltage spike-and-wave episodes. The significant genotype x age interaction supports the suggestion, however, that high voltage spike-and-wave episodes are likely to be influenced by more than one gene; some of them are probably related to the regulation of brain aminergic systems

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