scholarly journals Regional enzyme development in rat brain. Enzymes associated with glucose utilization

1984 ◽  
Vol 218 (1) ◽  
pp. 131-138 ◽  
Author(s):  
S F Leong ◽  
J B Clark
Keyword(s):  
Enzyme Activity ◽  
Lactate Dehydrogenase ◽  
Rat Brain ◽  
Brain Regions ◽  
Glycolytic Enzyme ◽  
Glycolytic Potential ◽  
Key Enzyme ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Potential Enzyme Activity ◽  
The Brain

The development of key enzyme activities concerned with glucose metabolism was studied in six regions of the rat brain in animals from just before birth (-2 days) through the neonatal and suckling period until adulthood (60 days old). The brain regions studied were the cerebellum, medulla oblongata and pons, hypothalamus, striatum, mid-brain and cortex. The enzymes whose developmental patterns were investigated were hexokinase (EC 2.7.1.1), aldolase (EC 4.1.2.13), lactate dehydrogenase (EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49). Hexokinase, aldolase and lactate dehydrogenase activities develop as a single cluster in all the regions studied, although the timing of this development varies from region to region. Glucose-6-phosphate dehydrogenase activity, however, declines relative to glycolytic enzyme activity as the brain matures. When the different brain regions are compared, it is clear that the medulla develops its glycolytic potential, as indicated by its potential enzyme activity, considerably earlier than the other regions (hypothalamus, striatum and mid-brain), with the cortex and cerebellar activities developing even later. This enzyme developmental sequence correlates well with the neurophylogenetic development of the brain and adds support to the hypothesis that the development of the potential for glycolysis in the brain is a necessary prerequisite for the development of neurological competence.

Oestrogen-2/4-hydroxylase activity in the rat brain during lactation and throughout the oestrous cycle

1985 ◽  
Vol 107 (2) ◽  
pp. 191-196 ◽  
Author(s):  
C. G. Brown ◽  
N. White ◽  
S. L. Jeffcoate
Keyword(s):  
Enzyme Activity ◽  
Pituitary Gland ◽  
Rat Brain ◽  
Brain Regions ◽  
Oestrous Cycle ◽  
Serum Prolactin ◽  
Hydroxylase Activity ◽  
Whole Brain ◽  
Cycle Enzyme ◽  
The Brain

ABSTRACT Oestrogen-2/4-hydroxylase activity was measured in whole brain, thalamus, amygdala, hypothalamus and pituitary gland of lactating rats and in whole brain of rats on different days of the oestrous cycle. Enzyme activity was increased in whole brain and in each of the brain regions examined (with the exception of the amygdala) in lactating rats. This increase in enzyme activity was associated with an increase in serum prolactin levels. During the oestrous cycle, enzyme activity in whole brain was higher on metoestrus and dioestrus than on pro-oestrus and oestrus. The decrease in enzyme on pro-oestrus was associated with an increase in both serum oestradiol and prolactin levels. These results are consistent with the hypothesis that changes in oestrogen-2/4-hydroxylase activity are associated with changes in prolactin and oestradiol secretion and may play a regulatory role in reproduction. J. Endocr. (1985) 107, 191–196

Differential recovery of acetylcholinesterase in guinea pig muscle and brain regions after soman treatment

1998 ◽  
Vol 17 (3) ◽  
pp. 157-162 ◽  
Author(s):  
Maxine C Lintern ◽  
Janet R Wetherell ◽  
Margaret E Smith
Keyword(s):  
Enzyme Activity ◽  
Time Course ◽  
Brain Regions ◽  
Similar Rate ◽  
Molecular Forms ◽  
Similar Degree ◽  
Brain Areas ◽  
Pig Muscle ◽  
Rate Of Recovery ◽  
The Brain

1 In brain areas of untreated guinea-pigs the highest activity of acetylcholinesterase was seen in the striatum and cerebellum, followed by the midbrain, medulla-pons and cortex, and the lowest in the hippocampus. The activity in diaphragm was sevenfold lower than in the hippocampus. 2 At 1 h after soman (27 mg/kg) administration the activity of the enzyme was dramatically reduced in all tissues studied. In muscle the three major molecular forms (A12, G4 and G1) showed a similar degree of inhibition and a similar rate of recovery and the activity had returned to normal by 7 days. 3 In the brain soman inhibited the G4 form more than the G1 form. The hippocampus, cortex and midbrain showed the greatest reductions in enzyme activity. At 7 days the activity in the cortex, medulla pons and striatum had recovered but in the hippocampus, midbrain and cerebellum it was still inhibited. 4 Thus the effects of soman administration varied in severity and time course in the different tissues studied. However the enzyme activity was still reduced in all tissues at 24 h when the overt signs of poisoning had disappeared.

Subcellular Distribution of DNA Polymerase Activity in Newborn Rat Brain and Liver

1971 ◽  
Vol 49 (12) ◽  
pp. 1285-1291 ◽  
Author(s):  
M. R. V. Murthy ◽  
A. D. Bharucha
Keyword(s):  
Enzyme Activity ◽  
Rat Brain ◽  
Dna Polymerase ◽  
Subcellular Fraction ◽  
Polymerase Activity ◽  
Particulate Material ◽  
Newborn Rat ◽  
Newborn Brain ◽  
Rat Brain And Liver ◽  
The Brain

DNA polymerase activities were determined in the cytoplasmic soluble, the nuclear soluble, and the nuclear particulate fractions of newborn rat brain and liver. The results indicate that a majority of the brain nuclear enzyme may be bound to particulate material while a majority of the liver nuclear enzyme may be free or only loosely bound. Although the subcellular distributions of DNA polymerase activity are widely different in newborn brain and liver, the enzyme activity in any given subcellular fraction is higher in liver than in brain.

High-affinity choline uptake in regions of rat brain and the effect of antidepressants

1979 ◽  
Vol 57 (6) ◽  
pp. 595-599 ◽  
Author(s):  
P. D. Hrdina ◽  
K. Elson
Keyword(s):  
Rat Brain ◽  
Tricyclic Antidepressants ◽  
Brain Regions ◽  
Choline Uptake ◽  
Dependent Manner ◽  
Choline Transport ◽  
High Affinity ◽  
Michaelis Constants ◽  
Dose Dependent ◽  
The Brain

The effect of tricyclic antidepressants, chlorpromazine, and some monoamine oxidase inhibitors on the accumulation of [14C]choline by crude synaptosomal (P2) fraction from different regions of rat brain (cortex, striatum, and hippocampus) was investigated. Analysis of choline uptake kinetics resulted in high- and low-affinity components with different Michaelis constants. All tricyclic antidepressants tested inhibited in a dose-dependent manner the high-affinity choline uptake in the three regions, amitriptyline being the most potent. The IC50 values correlated significantly with the relative potencies of imipramine congeners in binding to muscarinic receptors in the brain. Neither tranylcypromine nor pargyline in concentrations up to 0.1 mM had any effect on choline transport. Concentrations of tricyclic antidepressants effective in inhibiting the uptake of choline failed to influence significantly the activity of choline acetyltransferase in brain regions examined. The results suggest that the effect of imipramine congeners on high-affinity choline uptake may be reflected in the anticholinergic properties of these compounds.

scholarly journals Activation of rat brain ornithine decarboxylase by GTP

1994 ◽  
Vol 300 (2) ◽  
pp. 577-582 ◽  
Author(s):  
P T Kilpeläinen ◽  
O A Hietala
Keyword(s):  
Rat Brain ◽  
Ornithine Decarboxylase ◽  
Crude Extract ◽  
Brain Region ◽  
Enzyme Assay ◽  
Brain Regions ◽  
Irreversible Inhibitor ◽  
Heat Stable ◽  
First Time ◽  
The Brain

The activity of ornithine decarboxylase (ODC) measured in different regions of rat brain was highest in the hippocampus and lowest in the cerebellum. The ODC activity of a crude extract of the cerebellum was increased by the addition of GTP to the enzyme assay. Following dissociation of the ODC-antizyme complex by Sephadex G-75 chromatography in buffer containing 0.25 M NaCl, the GTP-activatable ODC was found in every brain region analysed. This GTP-activatable brain ODC has greater affinity for antizyme than the non-GTP-activatable brain ODC or the kidney ODC. The irreversible inhibitor of ODC, alpha-difluoromethylornithine (DFMO), inhibited approx. 60% of the ODC activity of all brain regions, whereas kidney ODC was inhibited totally by DFMO. When extracts of brain and kidney were incubated at 55 degrees C, kidney ODC was rapidly inactivated, but brain ODC was more heat-stable. Brain ODC, but not kidney ODC, was activated by GTP and ATP, and also by their deoxy forms. The K1/2 for activation of the enzyme was 2 microM for GTP and 40 microM for ATP. Using partially purified brain ODC, the activation by GTP was irreversible. These results demonstrate for the first time that the GTP-activatable ODC exists in the brain and is associated with the antizyme. The possible mechanisms of activation by GTP, the significance of this finding for the regulation of brain ODC, and the similarities to and differences from the GTP-activatable ODC found in certain rodent and human tumours are all discussed.

scholarly journals Regional Cerebral l-[14C-Methyl]Methionine Incorporation into Proteins: Evidence for Methionine Recycling in the Rat Brain

1992 ◽  
Vol 12 (4) ◽  
pp. 603-612 ◽  
Author(s):  
Anna M. Planas ◽  
Christian Prenant ◽  
Bernard M. Mazoyer ◽  
Dominique Comar ◽  
Luigi Di Giamberardino
Keyword(s):  
Rat Brain ◽  
Specific Activity ◽  
Plasma Source ◽  
Brain Regions ◽  
Emission Tomography ◽  
Protein Breakdown ◽  
Isotopic Equilibrium ◽  
Positron Emission ◽  
Time Periods ◽  
The Brain

The specific activity (SA) of free methionine was measured in plasma and in different regions of the rat brain at 15, 30, or 60 min after intravenous infusion of l-[14C- methyl]methionine. Within these time periods, an apparent steady state of labeled free methionine in plasma and in brain was reached. However, the brain-to-plasma free methionine SA ratio was found to be ∼0.5, showing that an isotopic equilibrium between brain and plasma was not attained. This suggests the presence of an endogenous source of brain free methionine (likely originating from protein breakdown), in addition to the plasma source. The contribution of this endogenous source to the content of free methionine varies significantly among the different brain regions. Our results indicate that the regional rates of protein synthesis measured with l-[11C- methyl]methionine using positron emission tomography would be underestimated, since the local fraction of brain methionine derived from protein degradation would not be considered.

scholarly journals Enzyme activity and composition of myelin and subcellular fractions in the developing rat brain

1969 ◽  
Vol 115 (5) ◽  
pp. 1051-1062 ◽  
Author(s):  
N. L. Banik ◽  
A. N. Davison
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Rat Brain ◽  
Membrane Fraction ◽  
Subcellular Fractions ◽  
Aminopeptidase Activity ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Developing Rat ◽  
The Brain

1. Subcellular fractions and myelin were isolated from developing and adult rat brain. 2. Measurements of chemical composition and enzyme activities indicate the presence of a second myelin-like fraction mainly in the brain of developing rats. 3. This membrane fraction has a different lipid composition from myelin, but resembles myelin in its content of phosphohydrolase and aminopeptidase activity. 4. It is suggested that the second myelin-like fraction may be a submicrosomal contaminant or it may be derived from oligodendroglial plasma membrane during myelinogenesis.

Cholecystokinin receptors in the brain: characterization and distribution

Science ◽  
1980 ◽  
Vol 208 (4448) ◽  
pp. 1155-1156 ◽  
Author(s):  
A Saito ◽  
H Sankaran ◽  
ID Goldfine ◽  
JA Williams
Keyword(s):  
Biological Activity ◽  
Rat Brain ◽  
Dissociation Constant ◽  
Binding Sites ◽  
Brain Regions ◽  
High Affinity ◽  
Cholecystokinin Receptors ◽  
Iodine 125 ◽  
The Brain

Specific cholecystokinin binding sites in particulate fractions of rat brain were measured with iodine 125-labeled Bolton-Hunter cholecystokinin, a cholecystokinin analog that has full biological activity. Binding was detected in brain regions known to contain immunoreactive cholecystokinin. Binding was saturable, reversible, of high affinity (dissociation constant, 1.7 x 10(-9) M), and was inhibited by cholecystokinin analogs but not by unrelated hormones.

scholarly journals Effect of phenylalanine metabolites on the activities of enzymes of ketone-body utilization in brain of suckling rats

1976 ◽  
Vol 160 (2) ◽  
pp. 217-222 ◽  
Author(s):  
J Benavides ◽  
C Gimenez ◽  
F Valdivieso ◽  
F Mayor
Keyword(s):  
Enzyme Activity ◽  
Mental Retardation ◽  
Rat Brain ◽  
Ketone Body ◽  
Lipid Synthesis ◽  
Developing Brain ◽  
Transferase Activity ◽  
Suckling Rats ◽  
Coa Transferase ◽  
The Brain

1. The effects of phenylalanine and its metabolites (phenylacetate, phenethylamine, phenyl-lactate, o-hydroxyphenylacetate and phenylpyruvate) on the activity of 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) 3-oxo acid CoA-transferase (EC 2.8.3.5) and acetoacetyl-CoA thiolase (EC 2.3.1.9) in brain of suckling rats were investigated. 2. The 3-hydroxybutyrate dehydrogenase from the brain of suckling rats had a Km for 3-hydroxybutyrate of 1.2 mM. Phenylpyruvate, phenylacetate and o-hydroxyphenylacetate inhibited the enzyme activity with Ki values of 0.5, 1.3 and 4.7 mM respectively. 3. The suckling-rat brain 3-oxo acid CoA-transferase activity had a Km for acetoacetate of 0.665 mM and for succinyl (3-carboxypropionyl)-CoA of 0.038 mM. The enzyme was inhibited with respect to acetoacetate by phenylpyruvate (Ki equals 1.3 mM) and o-hydroxyphenylacetate (Ki equals 4.5 mM). The reaction in the direction of acetoacetate was also inhibited by phenylpyruvate (Ki equals 1.6 mM) and o-hydroxyphenylacetate (Ki equals 4.5 mM). 4. Phenylpyruvate inhibited with respect to acetoacetyl-CoA both the mitochondrial (Ki equals 3.2 mM) and cytoplasmic (Ki equals 5.2 mM) acetoacetyl-CoA thiolase activities. 5. The results suggest that inhibition of 3-hydroxybutyrate dehydrogenase and 3-oxo acid CoA-transferase activities may impair ketone-body utilization and hence lipid synthesis in the developing brain. This suggestion is discussed with reference to the pathogenesis of mental retardation in phenylketonuria.

scholarly journals Regional enzyme development in rat brain. Enzymes of energy metabolism

1984 ◽  
Vol 218 (1) ◽  
pp. 139-145 ◽  
Author(s):  
S F Leong ◽  
J B Clark
Keyword(s):  
Rat Brain ◽  
Medulla Oblongata ◽  
Pyruvate Dehydrogenase ◽  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Aerobic Glycolysis ◽  
Tricarboxylic Acid Cycle ◽  
Brain Regions ◽  
Glycolytic Enzyme ◽  
Adult Rat

The development of several key enzymes of pyruvate and 3-hydroxybutyrate metabolism and of the tricarboxylic acid cycle was studied in six regions (cerebellum, medulla oblongata and pons, hypothalamus, striatum, mid-brain and cortex) of the neonatal, suckling and adult rat brain (2 days before birth to 60 days after birth). The enzymes whose developmental patterns were studied were: pyruvate dehydrogenase (EC 1.2.4.1), 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30), citrate synthase (EC 4.1.3.7), NAD-linked isocitrate dehydrogenase (EC 1.1.1.41) and fumarase (EC 4.2.1.2). Citrate synthase, isocitrate dehydrogenase and pyruvate dehydrogenase develop as a cluster in each region, although the pyruvate dehydrogenase appears to lag slightly behind the others. As with the glycolytic-enzyme cluster [Leong & Clark (1984) Biochem. J. 218, 131-138] the timing of the development of the activity of this group of enzymes varies from region to region; 50% of the adult activity developed first in the medulla oblongata, followed by the hypothalamus, striatum and mid-brain, and then in the cortex and cerebellum respectively. The 3-hydroxybutyrate dehydrogenase activity also develops earlier in the medulla oblongata than in the other regions. The results are discussed with respect to the neurophylogenetic development of the brain regions studied and the importance of the development of the enzymes of aerobic glycolysis in relationship to the development of neurological maturation.

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