Faculty Bibliography

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

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

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)

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

We developed monoclonal antibodies (mAbs) against two isozymes of a cytosolic puromycin-sensitive aminopeptidase (PSA-I and PSA-II) purified from chicken brain. The isozymes could be distinguished using Ouchterlony double-immunodiffusion and Western immunoblot. Their distribution in neuronal and glial cells as visualized by indirect immunofluorescence with these mAbs was found to differ: PSA-I was confined mostly to glial lysosomes; PSA-II showed fibrillar distribution in both types of nerve cells, but in disparate patterns. These results and our findings of peptide structural differences suggest that the two PSA isozymes are expressed differently in the nervous system

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

The behavioral and physiological effects of repeated nicotine administration are complex; sedation and hypothermia are present early but become attenuated while locomotor activity increases. Maximal blood levels and behavioral changes occur within 10 min of s.c. injection. We examined the effects of 10 nicotine injections (0.8 mg/kg) in 14 days on the levels of brain amines following challenge with either saline or nicotine on the 15th day. Dopamine, DOPAC, HVA, 3-methoxytyramine, norepinephrine, 5-hydroxytyramine, and 5-HIAA were measured in the frontal cortex, olfactory tubercle, nucleus accumbens, caudate-putamen, substantia nigra and ventral tegmental area. Ten minutes after nicotine was given to rats that had previously received only saline the levels of dopamine and its metabolite DOPAC indicated an increase in dopamine turnover in the nucleus accumbens. Of the areas examined the accumbens was the most sensitive to nicotine, with few significant amine changes in other regions. Twenty-four hours after the last nicotine injection the levels of dopamine and its metabolites indicated a sustained decrease in dopamine turnover in the accumbens induced by repeated administration. Following repeated nicotine a nicotine challenge still induced an acute increase in dopamine turnover in the accumbens, but the response was less than in animals not previously given nicotine. The results confirm earlier studies indicating that the accumbens is a major site of nicotine action

Structure-activity relationships were determined for cocaine congeners in counteracting the depolarization induced by the action of veratridine on voltage-dependent sodium channels of synaptoneurosomes from mouse brain cortex, and their potency was compared to those determined previously on Na+ uptake and batrachotoxinin binding. Cocaine, norcocaine, (+)-pseudococaine, (-)-pseudococaine, (+)-neopseudococaine, benzoyltropine, benzoylpseudotropine, ecgonine methylester, atropine, WIN-35,428, WIN-35,140, WIN-35,065-3, WIN-35,004, and procaine were tested for their potency in inhibiting depolarization as measured by the distribution of the lypophilic cation [3H]triphenylmethylphosphonium across the membrane. All of the tested compounds inhibited the veratridine-induced depolarization in a competitive manner. The structure-activity relationships were similar to those for inhibition of 22Na+ uptake in mouse brain homogenates, and the potency of these local anesthetics in inhibiting veratridine-induced uptake of [3H]triphenylmethylphosphonium correlated well with their potency in inhibiting [3H]batrachotoxinin A 20-alpha-benzoate binding in mouse brain synaptosomes

The rates of protein synthesis can be measured by a variety of methods including pulse labeling, massive precursor administration, Scornik method, continuous feeding of labeled precursor, infusion, and pellet implantation. Each technique has some advantages and disadvantages. Massive precursor administration and infusion are the most widely used. The advantage of massive precursor administration is its simplicity, however, the amino acid concentration used is much higher than physiological levels. Infusion, however, is much more complicated as a technique and requires complicated calculations. The synthesis rates can also be calculated from degradation curves. Some of the above techniques can be used both in vivo and in vitro, and also for different organs (Shahbazian et al. (1987), Int. J. Dev. Neurosci., 5: 39-42). The brain has rapid rates of protein synthesis both in vivo and in vitro, the latter being much lower for adults

The effect of nicotine on MPTP-induced changes in striatal dopamine receptors binding activity was investigated. Dopamine D1 and D2 receptors were labeled with [3H]SCH-23390 and [3H]spiperone respectively in BALB/cBy mice. With administration of only MPTP, which caused more than an 80% decrease in striatal dopamine level, binding of 0.15 nM [3H]spiperone was increased by 37%; whereas 0.3 nM [3H]SCH-23390 binding was unchanged. With chronic nicotine treatment (0.4 mg/kg twice daily for 7-9 days), [3H]SCH-23390 binding activity was increased by 27% and [3H]spiperone binding activity was unchanged. When nicotine was administered after MPTP, their separate effects could be seen in that both the D1 and D2 dopamine receptor ligand binding activities were increased and that nicotine elevated the ratio of D1/D2 receptor binding activities in MPTP-treated mice