RNA synthesis in different regions of rat brain at various time intervals after cerebellectomy

RNA synthesis was studied in cerebral cortex, thalamus and brain stem of rat, on the 3rd, 8th, 30th and 75th day after cerebellectomy. An increased RNA synthesis was detected in thalamus at the 30th day and in cerebral cortex and brain stem at the 75th day after cerebellectomy. Our findings suggest that motor compensation following the cerebellectomy could be supported by a spatio-temporal organization of macromolecular synthesis in different brain regions.     

Regional distribution of catecholamines in rat brain after L-3-O-methyldopa and L-dopa

The distribution of labelled dopamine (DA) and noradrenaline (NA) in the various brain regions of the rat was similar after administration of L-¹⁴C-3-0-methyldopa (OMD) or L-¹⁴C-dopa, DA showing the greatest accumulation in the striatum and NA in the hypothalamus. The concentration of catecholamines 2 hours after OMD amounted to 2–15 % of those found after L-dopa. In the whole brain, the cerebral catecholamines formed from dopa decreased more rapidly than those originating from OMD. In conclusion, OMD is a precursor of cerebral catecholamines; however, it is less effective than dopa.     

Increased acidic phospholipids in rat brain membranes after chronic ethanol administration

Two types of plasma membranes isolated from rat brain cortex were used to study the membrane-perturbing properties of ethanol. Rats administered ethanol in the form of a liquid diet showed an increase in levels of phosphatidylserines, phosphatidylinositols and phosphatidic acids as compared to controls. The results present evidence that chronic ethanol treatment results in an increase in the acidic phospholipids in brain membranes. This type of membrane modification may have important implications for the function of membrane transport enzymes such as (Na+, K+)-ATPase, which also increases in activity upon chronic ethanol administration.     

Determination of monoamines in rat brain regions after chronic administration of lithium

The effect of chronic administration of lithium on the concentration of biogenic amines and some of their metabolites in striatum, hippocampus, hypothalamus, pons-medulla and parietal cortex of rat were studied. Longterm lithium treatment modifies significantly the content of indoleamines in striatum and hypothalamus with minor changes in other structures. Catecholamine levels change after the treatment in striatum, hypothalamus, pons-medulla and parietal cortex. These results indicate that lithium treatment at therapeutic doses selectively modifies the catecholamine and indoleamine contents in discrete areas of the brain.     

Regional distribution of brain aminopeptidases in the rat]

Soluble and membrane-bound aminopeptidase activities in eleven regions of the rat brain were assayed using L-leucine-2-naphthylamide as a substrate. In addition, two metabolic enzymatic activities were compared: lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotransferase activities were significantly lower in cortical than in subcortical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did no differ between cortical areas and the rest of the zones studied. However, while no wide regional differences were found for the other enzymatic activities, membrane-bound aminopeptidase varied markedly across brain regions: a 5-fold difference was observed between zones. The differential distribution of this enzymatic activity is consistent with the hypothesis that it is responsible for the enzymatic inactivation of some neuroactive peptides.     

Tracking the changes in the HDL cholesterol levels at different time intervals after acute myocardial infraction

Low HDL cholesterol level in the blood increases the risk of unwanted coronary events in patients with verified CAD, which can be considerably decreased by appropriate and on-time application of pharmacologic and non-pharmacologic therapeutical measures. Numerous studies have shown that the level of the serum lipids, measured in the first 24 hours of the acute myocardial infarction, in fact is the basal lipid level, which is liable to changes immediately after the event, and gets back to its initial (basal) value within the next 6-12 weeks. In order to confirm if there are changes in the lipid profile and what they look like, particularly the HDL cholesterol in the blood, in 230 middle aged patients (59.87 +/- 13 years old), mostly males (66.5%) with ST-elevation acute myocardial infarction (STEMI), a follow-up of the HDL cholesterol level was performed, taken from the vein blood and determined by standard enzymatic methods at different time intervals after the actual event (24 hours, 3-7 days, 10-14 days, 30-60 days, 60-90-days) was performed. The results acquired showed that the patients with STEMI had a lower initial HDL cholesterol level, which showed a tendency to decrease three days after the actual event, and to be gradually "normalized" after 60-90 days, i.e. not only turning back the HDL cholesterol values to the initial level, but their overcoming too. It is interesting to mention, that the average value of HDL cholesterol level in the blood, checked after 60-90 days after the actual event, is overcoming that basal value in a positive sense, but it was further on higher than the desired aim of 40 mg/dl (1.03 mmol/l). From the results of our follow-ups, we can conclude that the optimal time for determining the HDL cholesterol level in the blood in patients with STEMI, are the first 24 hours of the actual event, since in the first 24 hours there is a relevant decrease of the HDL cholesterol level in the blood. The values of the lipid profile acquired at that period, should be considered as basal.     

Regional distribution of metorphamide in rat and guinea pig brain

A specific radioimmunoassay was developed for metorphamide, an endogenous, amidated opioid octapeptide, originally isolated from bovine brain and human pheochromocytoma tissues. The radioimmunoassay was used to determine the concentration of immunoreactive metorphamide in extracts from dissected regions of rat and guinea pig brain. Radioimmunoassay interfacing with Sephadex gel filtration and reverse phase high performance liquid chromatography confirmed that the immunoreactive substance measured corresponded to authentic metorphamide. Metorphamide was found to be widely distributed in brain regions from both species. However, the concentrations of immunoreactive metorphamide in regions from guinea pig brain were up to 5 times higher than the concentrations of immunoreactive metorphamide in rat brain regions. The results suggest that metorphamide is a specific processing product from proenkephalin in rodent brain.     

Changes in activities of some ammonia-metabolizing enzymes in the rat liver and the brain after chronic ethanol administration

The changes in the activities of ammonia-metabolizing enzymes in liver and brain after ethanol intoxication has been investigated in rats. After administration of ethanol 30% (w/v) 6g kg-1 for 4 weeks we found an increase in liver glutamate dehydrogenase and glutaminase activity. In brain tissue the glutaminase activity was significantly higher and glutamate dehydrogenase was significantly lower. Glutamine synthetase activity in liver and brain was practically unchanged. The reasons for these changes in the activities of some ammonia-metabolizing enzymes in liver and brain after ethanol ingestion have been discussed.     

Regional distribution, developmental changes, and cellular localization of CNTF-mRNA and protein in the rat brain

Ciliary neurotrophic factor (CNTF) is a potent survival molecule for a variety of embryonic neurons in culture. The developmental expression of CNTF occurs clearly after the time period of the physiological cell death of CNTF-responsive neurons. This, together with the sites of expression, excludes CNTF as a target-derived neuronal survival factor, at least in rodents. However, CNTF also participates in the induction of type 2 astrocyte differentiation in vitro. Here we demonstrate that the time course of the expression of CNTF-mRNA and protein in the rat optic nerve (as evaluated by quantitative Northern blot analysis and biological activity, respectively) is compatible with such a glial differentiation function of CNTF in vivo. We also show that the type 2 astrocyte-inducing activity previously demonstrated in optic nerve extract can be precipitated by an antiserum against CNTF. Immunohistochemical analysis of astrocytes in vitro and in vivo demonstrates that the expression of CNTF is confined to a subpopulation of type 1 astrocytes. The olfactory bulb of adult rats has comparably high levels of CNTF to the optic nerve, and here again, CNTF-immunoreactivity is localized in a subpopulation of astrocytes. However, the postnatal expression of CNTF in the olfactory bulb occurs later than in the optic nerve. In other brain regions both CNTF-mRNA and protein levels are much lower.     

Regional distribution and relative amounts of glutamate decarboxylase isoforms in rat and mouse brain.

The levels of the two isoforms of glutamate decarboxylase (GAD) were measured in 12 regions of adult rat brain and three regions of mouse brain by sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting with an antiserum that recognizes the identical C-terminal sequence in both isoforms from both species. In rat brain the amount of smaller isoform, GAD65, was greater than that of the larger isoform, GAD67, in all twelve regions. GAD65 ranged from 77-89% of total GAD in frontal cortex, hippocampus, hypothalamus, midbrain, olfactory bulb, periaqueductal gray matter, substantia nigra, striatum, thalamus and the ventral tegmental area. The proportion of GAD65 was lower in amygdala and cerebellum but still greater than half of the total. There was a strong correlation between total GAD protein and GAD activity. In the three mouse brain regions analysed (cerebellum, cerebral cortex and hippocampus) the proportion of GAD65 (35,47, and 51% of total GAD) was significantly lower than in the corresponding rat-brain regions. The amount of GAD67 was greater than the amount of GAD65 in mouse cerebellum and was approximately equal to the amount of GAD65 in mouse cerebral cortex and hippocampus.     

Regional distribution of colchicine-binding (microtubular) protein in the rat brain

The relative concentrations of microtubular protein (tubulin) in regions of rat brain were determined by taking advantage of its specific property of binding colchicine. In comparison with other tissues, all regions of the brain were rich in tubulin. The cerebral cortex, thalamus and hypothalamus had essentially the same concentration. The cerebellum and brain stem had a lower concentration (about 60 per cent of the cortical level). Although the functional significance of these differences is not clear, they may relate to two proposed functions of microtubules–cytoskeleton and cytoplasmic transport. The complex geometry of neurons and many glial cells with ramified processes must require extensive systems for maintaining shape and an active cytoplasmic transport.