INCORPORATION OF 14C FROM [U-14C]GLUCOSE INTO FREE AMINO ACIDS IN MOUSE BRAIN REGIONS UNDER CYANIDE INTOXICATION

—During anoxia induced by the administration of potassium cyanide, [U-¹⁴C]glucose was injected intraperitoneally into adult mice and they were decapitated at 5, 15 and 30 min after the injection. After freeze-drying in vacuo, differences in the uptake of radioactive carbon from [U-¹⁴C]glucose into free amino acids (glutamate + glutamine, aspartate + asparagine, GABA, alanine and glycine) in mouse cerebral neocortex, cerebellar hemisphere, caudate nucleus, thalamus, hypothalamus and medulla oblongata were investigated (by macroautoradiography and GLC separation) and compared with those obtained under normal conditions. (1) During anoxia, autoradiographical densities in the thalamus and medulla oblongata were higher than that in the cerebral neocortex and caudate nucleus. (2) Among specific radioactivities (d.p.m./μmol) of free amino acids, alanine gave the highest value during anoxia, except in the cerebellar hemisphere and hypothalamus at 5 min and the medulla oblongata at 30 min. (3) During anoxia, the specific radioactivities of alanine and glycine in each brain region did not significantly decrease at 15 and 30 min compared with those under normal conditions. During anoxia, the specific radioactivity of glutamate + glutamine in the cerebellar hemisphere and hypothalamus did not significantly decrease compared with the normal conditions, while that of GABA, aspartate + asparagine and glutamate + glutamine in the cerebral neocortex, caudate nucleus, thalamus and medulla oblongata showed an increase. (4) The percentage decrease of glutamate + glutamine and aspartate + asparagine at 5 and 15 min was highly significant in the cerebral neocortex and caudate nucleus.     

Brain Amine Concentrations after Monoamine Oxidase Inhibitor Administration

The concentrations of 5-hydroxytryptamine (5HT), noradrenaline, and dopamine were estimated post mortem in brain stem, hypothalamus, and caudate nucleus in 33 patients who had been treated with isocarboxazid, clorgyline, or tranylcypromine and 11 controls. Similar and highly significant increases in 5HT and noradrenaline concentration occurred with all three drugs. The distribution was unimodal, but about a quarter of the patients showed only a small increase in brain amines. Tranylcypromine seemed to have a significantly greater effect on dopamine in caudate nucleus and hypothalamus compared with isocarboxazid and clorgyline. In the doses used chlorpromazine did not reduce the amine concentrations. Four patients with Parkinson''s syndrome had low concentrations of dopamine in caudate nucleus in spite of monoamine oxidase inhibitor administration.     

Iron Deficiency Alters Discrete Proteins in Rat Caudate Nucleus and Nucleus Accumbens

Young rats (21 days old) made nutritionally iron deficient, by feeding them a semisynthetic diet containing skimmed milk for 5 weeks, had significantly lowered hemoglobin levels (5.2 +/- 4 g/100 ml). The nonheme iron content in caudate nucleus was decreased by 47%. The behavioral response of iron-deficient rats to apomorphine (2 mg/kg) and the density of 3,4-dihydroxyphenylethylamine (dopamine) D2 receptors, as measured by [3H]spiperone binding in caudate nucleus, were significantly reduced by 70 and 53%, respectively. The possibility that nutritional iron deficiency may affect protein content in brain was investigated by measuring the apparent concentration of proteins in caudate nucleus and nucleus accumbens from iron-deficient and control animals using two-dimensional gel electrophoresis. The data indicate that iron deficiency can affect content in these two brain regions. Significant changes in the content of 10 proteins were noted in the caudate nucleus and nucleus accumbens in iron-deficient rats. The albumin level was significantly increased in both regions studied, whereas the neuron-specific enolase level was increased in the nucleus accumbens and the glial fibrillary acidic protein level was reduced in the caudate nucleus. The significance of these protein content changes, as well as a reduction in content of a 94-kilodalton protein (a molecular size similar to that of the D2 dopamine receptor), remains to be established.     

Biochemical characterization of alpha-adrenergic receptors in human brain and changes in Alzheimer-type dementia

Using ligand binding techniques, we studied alpha-adrenergic receptors in brains obtained at autopsy from seven histologically normal controls and seven patients with histopathologically verified Alzheimer-type dementia (ATD). Binding of the alpha-adrenergic antagonists [3H]prazosin and [3H]yohimbine to membranes of human brains exhibited characteristics compatible with alpha 1- and alpha 2-adrenergic receptors, respectively. Binding of both ligands was saturable and reversible, with dissociation constants of 0.15 nM for [3H]prazosin and 5.5 nM for [3H]yohimbine. [3H]Prazosin binding was highest in the hippocampus and frontal cortex and lowest in the caudate and putamen in the control brains. [3H]Yohimbine binding was highest in the nucleus basalis of Meynert (NbM) and frontal cortex and lowest in the caudate and cerebellar hemisphere in the control brains. Compared with values for the controls, [3H]prazosin binding sites were significantly reduced in number in the hippocampus and cerebellar hemisphere, and [3H]yohimbine binding sites were significantly reduced in number in the NbM in the ATD brains. These results suggest that alpha 1- and alpha 2-adrenergic receptors are present in the human brain and that there are significant changes in numbers of both receptors in selected regions in patients with ATD.     

Changes in β-Adrenergic Receptor Subtypes in Alzheimer-Type Dementia

Using ligand binding techniques, we studied beta-adrenergic receptor subtypes in brains obtained at autopsy from seven histologically normal controls and seven histopathologically verified cases with Alzheimer-type dementia (ATD). Inhibition of [3H]dihydroalprenolol [( 3H]DHA) binding by the selective beta 1 antagonist, metoprolol, results in nonlinear Hofstee plots, suggesting the presence of the two receptor subtypes in the human brain. The calculated ratios of beta 1/beta 2-adrenergic receptors in control brains are as follows: frontal cortex, 49:51; temporal cortex, 31:69; hippocampus, 66:34; thalamus, 23:77; putamen, 70:30; caudate, 48:52; nucleus basalis of Meynert (NbM), 43:57; cerebellar hemisphere, 25:75. Compared with the controls, total concentrations of beta-adrenergic receptors were significantly reduced only in the thalamus of the ATD brains. beta 1-Adrenergic receptor concentrations were significantly reduced in the hippocampus and increased in the NbM and cerebellar hemisphere, whereas beta 2-adrenergic receptor concentrations were significantly reduced in the thalamus, NbM, and cerebellar hemisphere and increased in the hippocampus and putamen of the ATD brains. These results suggest that beta 1- and beta 2-adrenergic receptors are present in the human brain and that there are significant changes in both receptor subtypes in selected brain regions in patients with ATD.     

Effect of Cerebellar Lesions on Monoamine Levels in Various Brain Areas of the Cat

Abstract: Modifications in the content of monoamines after different lesions of the cerebellar cortex were investigated in eight prosencephalic structures of cat's brain. Apart from other minor changes, lesions of the posterior vermis induced significant changes in the thalamus (decrease of DA and increase of 5-HT). Lesions of the cortex of a cerebellar hemisphere, on the other hand, produced an increase of 5-HT in the caudate nucleus and an increase of DA in the hippocampus in addition to a generalized increase of 5-HT in all the prosencephalic structures studied. These findings are discussed in relation to the anatomical connections of the lesioned areas and their expected role in the sleep-wakefulness cycle.     

Antagonism of presynaptic dopamine receptors by phenothiazine drug metabolites

Electrically evoked release of dopamine from the caudate nucleus is reduced by the dopamine receptor agonists, apomorphine and bromocriptine, and facilitated by neuroleptic drugs, which act as dopamine autoreceptor antagonists. The potencies of chlorpromazine, fluphenazine, levomepromazine and their hydroxy-metabolites in modulating electrically evoked release of dopamine were examined by superfusion of rabbit caudate nucleus slices pre-incubated with 3H-dopamine. O-Desmethyl levomepromazine, 3-hydroxy- and 7-hydroxy metabolites of chlorpromazine and levomepromazine facilitated electrically evoked release of 3H-dopamine, having potencies similar to that of the parent compounds. 7-Hydroxy fluphenazine was less active than fluphenazine in this system. These results indicate that phenolic metabolites of chlorpromazine and levomepromazine, but not of fluphenazine, may contribute to effects of the drugs mediated by presynaptic dopamine receptors.     

Effect of clozapine on the behavioral and electrographic indices of the arrest function of the caudate nucleus in cats

In unrestrained cats clozapine in increasing doses (1--5 mg/kg) caused a behavioural depression and suppression of amphetamine-induced stereotypy of behaviour against the background of marked vegetative shifts. Similarly to chlorpromazine clozapine intensified the behavioural arrest reaction) and electrographic (neocortical caudate spindle) indices of the arrest function of the caudate nucleus. Arrest reaction changed more distinctly in stimulation of the ventral parts of the head of the nucleus. Clozapine also eliminated the weakening of the caudate responses caused by the stereotypical doses of amphetamine.     

Effect of catecholaminergic substances on the proconvulsive properties of the caudate nucleus]

In the freely moving rats stimulants of catecholaminergic tramission (DOPA, apomorphine, d,1-amphetamine, and also their combination with disulfiram) reduced the proconvulsive properties of the caudate nucleus. Under the effect of these substances there occurred a shortening of the cortical electroencephalographic response to a single stimulation of the nucleus in the animals given subconvulsive doses of pentaxylenetetrazol and a reduction of the extent of the spike-wave rhythm induced by the repeated caudate stimuli. On the contrary, inhibitors of catecholaminergic transmission (chlorpromazine, haloperidol, alpha-methyltyrosine and disulfiram) intensified the proconvulsive effect of the caudate nucleus.     

Monoaminergic influences of the caudate nucleus on conditioned food-getting reactions in rats]

Influence of microinjections of monoamines and glutamic acid into the caudate nucleus head on conditioned food-procuring reaction was studied in experiments on rats. Dopamine, noradrenaline and glutamic acid prolong the latency of the reflex, while serotonin reduces it. However, all the drugs tested reduce the number of conditioned food-procuring movements. The effects of dopamine are achieved through neurone receptors of the caudate nucleus which are sensitive to haloperidol and chlorpromazine; effects of serotonin are mediated through the D-serotoninoreactive systems, and those of noradrenaline, through the alpha-adrenoreactive systems of the neostriatum neurones. The inhibitory effect of glutamic acid is not due to the action on the serotonino-, adreno-, or dopamine receptors of caudate units.     

The effect of electrostimulation of the caudate nucleus and somatosensory cortex on defensive instrumental reactions in dogs]

It has been shown that the effect of stimulation of the caudate nucleus head in the contralateral hemisphere differs at different stages of achievement of a defensive instrumental habit in dogs. Stimulation preceding the action of the conditioned signal or delivered simultaneously with the beginning of the latter did not change the criteria for the achievement of successive programs of the instrumental defensive reaction. Stimulation of the same areas in the last phase of the instrumental response, as a rule, lead to the cessation of instrumental movement. A conclusion has been drawn that in a defensive situation the inhibitory influence of the caudate nucleus on instrumental behaviour of intact dogs is not so sharply expressed as in experiments with alimentary reinforcement. In dogs with a preliminary ablation of the CI and CII cortical zones of the contralateral hemisphere, stimulation of the caudate nucleus head was attended with a sharp drop in every criterion of the instrumental defensive reactions.     

Biochemical Characterization of α-Adrenergic Receptors in Human Brain and Changes in Alzheimer-Type Dementia

Abstract Using ligand binding techniques, we studied α-adrenergic receptors in brains obtained at autopsy from seven histologically normal controls and seven patients with histopathologically verified Alzheimer-type dementia (ATD). Binding of the α-adrenergic antagonists [³H]prazosin and [³H]yohimbine to membranes of human brains exhibited characteristics compatible with α₁- and α₂-adrenergic receptors, respectively. Binding of both ligands was saturable and reversible, with dissociation constants of 0.15 nM for [³H]prazosin and 5.5 nM for [³H]yohimbine. [³H]Prazosin binding was highest in the hippocampus and frontal cortex and lowest in the caudate and putamen in the control brains. [³H]Yohimbine binding was highest in the nucleus basalis of Meynert (NbM) and frontal cortex and lowest in the caudate and cerebellar hemisphere in the control brains. Compared with values for the controls, [³H]prazosin binding sites were significantly reduced in number in the hippocampus and cerebellar hemisphere, and [³H]yohimbine binding sites were significantly reduced in number in the NbM in the ATD brains. These results suggest that α₁ and α₂-adrenergic receptors are present in the human brain and that there are significant changes in numbers of both receptors in selected regions in patients with ATD.     

An Investigation of Age-Related Iron Deposition Using Susceptibility Weighted Imaging

Aim

To quantify age-dependent iron deposition changes in healthy subjects using Susceptibility Weighted Imaging (SWI).

Materials and Methods

In total, 143 healthy volunteers were enrolled. All underwent conventional MR and SWI sequences. Subjects were divided into eight groups according to age. Using phase images to quantify iron deposition in the head of the caudate nucleus and the lenticular nucleus, the angle radian value was calculated and compared between groups. ANOVA/Pearson correlation coefficient linear regression analysis and polynomial fitting were performed to analyze the relationship between iron deposition in the head of the caudate nucleus and lenticular nucleus with age.

Results

Iron deposition in the lenticular nucleus increased in individuals aged up to 40 years, but did not change in those aged over 40 years once a peak had been reached. In the head of the caudate nucleus, iron deposition peaked at 60 years (p<0.05). The correlation coefficients for iron deposition in the L-head of the caudate nucleus, R-head of the caudate nucleus, L-lenticular nucleus and R-lenticular nucleus with age were 0.67691, 0.48585, 0.5228 and 0.5228 (p<0.001, respectively). Linear regression analyses showed a significant correlation between iron deposition levels in with age groups.

Conclusions

Iron deposition in the lenticular nucleus was found to increase with age, reaching a plateau at 40 years. Iron deposition in the head of the caudate nucleus also increased with age, reaching a plateau at 60 years.     

Effect of Iron Chelators on Dopamine D2 Receptors

Nutritional iron deficiency induced in rats causes a selective reduction of [3H]spiperone binding in caudate nucleus. This effect can be reversed by iron supplementation in vivo. The possibility that iron may be involved in the dopamine D2 receptor was investigated by examining the effect of various iron and noniron chelators on the binding of [3H]spiperone in rat caudate nucleus. Iron chelators 1,10-phenanthroline, 2,4,6-tripyridyl-s-triazine, alpha, alpha'-dipyridyl, and desferrioxamine mesylate inhibited the binding of [3H]spiperone. The inhibition by 1,10-phenanthroline was noncompetitive and reversible. In the presence of FeCl2 or FeCl3, the inhibitory effect of 1,10-phenanthroline was potentiated. Iron salts or chelators were without effect on the binding of [3H]dihydroalprenolol to beta-adrenoreceptors in caudate nucleus; thus the action of iron chelators on the dopamine D2 receptor tends to be selective. Incubation of caudate nucleus membrane prepared from iron-deficient rats with FeCl2 or FeCl3 did not reverse the diminished binding of [3H]spiperone. The present study indicates that if iron is involved in the physiological regulation of dopamine D2 agonist-antagonist binding sites, it is more complex than hitherto considered.     

Regional aspects of the delay of acquisition conditioned avoidance responding by chlorpromazine

Chlorpromazine injected into the amygdala, septum, or caudate delayed the acquisition of a one-way active avoidance response. Injections into nine other brain areas were inactive. Following a standard dose of chlorpromazine at its ED₅₀ for delaying avoidance acquisition, tissue levels of chlorpromazine from those animals displaying reduced acquisition were significantly higher in the caudate and amygdala than from animals not demonstrating a drug effect.     

The Effect of Mesencephalic Lesions on Tyramine and Dopamine in the Caudate Nucleus of the Rat

Abstract: The dopamine (DA)-containing nerve terminals in the caudate nucleus arise from cell bodies located in the substantia nigra (pars compacta), and it is possible that p-tyramine- and m-tyramine-containing neurons may also exist in this nucleus. We have studied the effects of unilateral electrolytic lesions of the pars compacta in rat on levels of DA, p-tyramine, m-tyramine, and homovanillic acid in the caudate nucleus after various survival times. At 12 and 24 h following lesioning the ipsilateral level of p-tyramine was significantly reduced compared with the contralateral side, whereas the concentrations of m-tyramine, DA, and homovanillic acid were significantly increased. Thus, in the short term, the lesion results in an increase in DA turnover, which is accompanied by an increase in m-tyramine levels and a decrease in p-tyramine levels. Similar changes occur following pharmacological treatments (chlorpromazine, d-amphetamine, l-DOPA) that increase DA turnover. At survival times of 2, 11, and 25 days, the ipsilateral concentrations of m-tyramine, DA, and homovanillic acid were reduced along with p-tyramine. These longer-term alterations in amine levels are most likely a consequence of degeneration of nigro-striatal axons. Placement of a lesion 1 mm dorsal to the usual position centering on the pars compacta produced different biochemical changes from those seen after the pars compacta lesion. One day following this lesion the concentration of p-tyramine was slightly reduced; DA was unaffected, but the concentration of m-tyramine was profoundly increased, even more so than after the pars compacta lesion. This could indicate the existence of specific m-tyramine-containing cell bodies located dorsal to the substantia nigra. The results suggest that p- and m-tyramine in the caudate nucleus originate from neurons in or close to the substantia nigra. The results in the short term following the lesion support the observation that there is an inverse relationship between p-tyramine concentration and DA turnover in the caudate nucleus.     

Correction of changes induced by toluene in the cortical and subcortical structures of albino rat brain

The number and weight of cells in the cortical and subcortical structures of the cerebral and cerebellar motor system in albino rats after a long-term exposure to toluene were determined. Toluene intoxication proved to kill projection neurons and interneurons in the sensorimotor cortex, ventrolateral thalamic nucleus, caudate nucleus, pallidum, red nucleus, and inferior olivary complex. The decreased number of cerebellar cells was mediated by atrophic changes as indicated by the decrease in the area and dry weight of Purkinje cells. The addition of plaferon LB to the diet attenuated the cytotoxic effect of toluene.     

Conditioned reflexes following unilateral damage to the premotor cortex and the dorsal portion of the head of the caudate nucleus in dogs

The study was carried out on dogs by the secretory-motor method with a two-side reinforcement. Simultaneous and unilateral lesion of the premotor cortex and of the dorsal part of the caudate nucleus head brought about prolonged disturbances of the vegetative components (pulse and respiratory rate) and in the choice of the side of food reinforcement. The change in the magnitude of conditioned salivation, latencies of secretion and motor reaction was temporary, and by the end of the third postoperative period their initial magnitudes were restored. The duration of the disturbances of higher nervous activity depended on the localization and extent of lesion of the caudate nucleus head. Tests were made with chlorpromazine and caffeine before and after the lesion of the brain structures. The tests in the postoperative period revealed latent disturbances in the dog higher nervous activity. It is assumed that the premotor cortex and the dorsal part of the caudate nucleus head are one of the sub-systems involved in the regulation of vegetative, somatic components of unconditioned behaviour and in the analysis of conditioned stimuli.     

Hemispheric asymmetry of the nigrostriatal system of the brain in rats genetically predisposed to catalepsy]

Hemispheric asymmetry of nigro-striate system in a strain of rats GC bred from Wistar for a predisposition to cataleptic reaction was studied by means of biochemical and morphological methods. Hemispheric asymmetry was found in GC and Wistar rats with respect to aminopeptidase activity in neurons of caudate nucleus, with a more pronounced left-side increase in GC rats, the asymmetry index being 13.7%. Acetylcholine esterase activity in subcellular particles of caudate nucleus showed an inversion of asymmetry with higher activity in the left hemisphere of Wistar and right hemisphere of GC rats, and asymmetry index of 15.5%. With respect to the number of astroglia cells in S. nigra, and astroglia and oligodendroglia in N. accumbens there was also an inversion of asymmetry in GC rats who had more cells in the structures of the left hemisphere, whereas Wistar rats had more in the right hemisphere. The asymmetry index was high and equal to 29.8% for astroglia in S. nigra, and 17% for astroglia and 21.4% for oligodendroglia in N. accumbens. However, in S. nigra the number of neurons and oligodendroglia cells was equally increased in the right hemisphere in GC and Wistar rats. The data suggest that the mechanism of hereditary pathology of brain nigro-striate system involves both enhancement and inversion of the hemispheric asymmetry.     

A SENSITIVE ENZYMATIC-RADIOISOTOPIC ASSAY FOR 3,4-DIHYDROXYPHENYLACETIC ACID

Abstract— An assay for 3,4-dihydroxyphenylacetic acid (DOPAC) capable of detecting as little as 1 pmole of DOPAC is described. The basis of the assay is the O -methylation of DOPAC utilizing S -[methyl-³H]adenosyl-l-methionine and a partially purified catechol- O -methyl transferase to form [methyl-³H]homovanillic acid. The [methyl-³H]homovanillic acid is purified with ion exchange resin and either solvent partitions or TLC. Utilizing this assay, the effect of either chlorpromazine or reserpine upon the content of DOPAC both in the caudate nucleus and in the substantia nigra was determined. Both of these drugs increase the level of DOPAC in the caudate nucleus but have minimal effects upon the level of DOPAC in the substantia nigra.