Brain Copper Research Articles

Copper exposure and the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss)

AbstractSublethal concentrations of copper in water cause the degeneration of olfactory receptors in rainbow trout (Oncorhynchus mykiss). Receptor cell loss has been correlated to the loss of olfaction in fish and may cause difficulties in olfactory mediated behaviors such as migration. This study investigated the effects of three levels of copper (100, 75 and 50 mg L−1) on the olfactory epithelium of rainbow trout. Twenty fish randomly allocated between three exposure groups and one control were exposed for 24 hours under static renewal conditions. Light and scanning electron microscopic observations of olfactory tissue were taken to determine the extent of degeneration of receptors. In addition, levels of copper and zinc in the brain tissues were analyzed to determine if the olfactory route was a significant route of copper exposure and transfer to fish brain tissue. Results indicate that degeneration of receptors is related to the concentration of copper. Levels of copper in brain were found to be belo...

Further characterization of the process of in vitro uptake of radiolabeled copper by the rat brain

We have previously demonstrated that hypothalmic slices obtained from adult male rats accumulate 67Cu by two ligand-dependent, saturable processes: a high and low affinity process. To further establish the generality of these uptake processes, we defined the ligand requirements and the saturation kinetics of 67Cu uptake by tissue slices obtained from the newborn hypothalamus (HT); adult male hypothalamus, hippocampus, cortex, median eminence, and caudate nucleus; hypothalamus and hippocampus of castrated (14 days) males and of pregnant (19 days) and ovariectomized (14 days) females. It was found that ionic 67Cu2+ was poorly taken up by newborn HT and adult caudate, complexation with His enhanced 67Cu uptake 3-4-fold, and complexation with albumin inhibited 67Cu uptake. These ligand requirements are identical to those we have previously shown for the adult HT. When 67Cu uptake was evaluated under conditions optimal for the high or the low affinity process, for each process the dose response curves generated from these various tissues were very similar. In addition, we assessed the uptake of both components of the CuHis2 complex by incubating tissues with 67Cu3 H-His2 and found that the tissue ratio of 67Cu:3H was a sigmoidal function of the concentration of the Cu complex such that at greater than 5 microM, the ratio was about 3-fold greater than the medium ratio; indicating preferential uptake of 67Cu relative to 3H-His. The changes in isotope ratios were observed in newborn HT and adult HT, as well as caudate. These similarities in the ligand requirements and saturation kinetics of 67Cu uptake establish the generality of these two processes of in vitro uptake of copper in the rat brain.

D-Penicillamine-induced copper deficiency in suckling mice: neurological abnormalities and brain mitochondrial enzyme activities

Brain mitochondrial enzyme activities were examined in 15-day-old suckling mice which were daily injected with d-penicillamine (DP), a chelating agent of copper. Newborn mice treated with DP (1 g/kg/day) showed retarded weight gain, hyperelasticity of skin, and a bizarre forelimb posture with subcutaneous edema on experimental day (ED) 7. Paraparesis or dragging of the hindlimbs was observed by ED 15. Brain copper contents of DP-treated mice decreased to 34% of the controls on ED 15. Cytochrome c oxidase activity (complex IV) in the brain showed 51% decrease of the controls, on the contrary, rotenone-sensitive NADH cytochrome c reductase (complex I + III) and succinate cytochrome c reductase (complex II + III) were normal. Histochemistry of cytochrome c oxidase in the cerebellum of DP-treated mice disclosed diffuse reduction of staining, especially in Purkinje cells. These data show that DP-induced copper deficiency in the brain subsequently disturbs mitochondrial electron transport system, selectively cytochrome c oxidase activity. This seems to be a useful animal model not only for Menkes' kinky hair disease but also for mitochondrial encephalomyopathy.

The effects of age and sex on seven elements in Sprague-Dawley rat organs

This study reports age-related changes in 7 element (iron, copper, zinc, manganese, mercury, cadmium and lead) concentrations in the liver, kidney and brain of male and female Sprague-Dawley rats from 1 to 364 days of age. Atomic absorption spectrometry was used for the measurements. Copper, mercury and cadmium in the male and female kidneys increased from weaning until 127 days of age, as did iron concentrations in the female liver and kidney. After 127 days, especially, the copper concentration in the female kidney and cadmium concentration in the male and female kidney increased further. Consistent and statistically significant (P less than 0.05) sex differences in element concentrations were found for three elements (iron, copper and zinc). Except for the zinc concentration in the liver from 50 to 72 days, iron (in liver and kidney), zinc (in kidney) and copper (in liver, kidney and brain) concentrations in female rats during the adult stage, were all higher than those of male rats. Isolated differences for other elements (manganese, mercury and cadmium) were also found. The data will be helpful when setting up long-term animal investigations of the biological effect of elements.

Vitamin C Treatment in Menkes’ Disease: Failure to Affect Biochemical and Clinical Parameters

Menkes’ disease (kinky hair disease, McKusick 30940) is an X-linked recessive disorder characterized by progressive neurological degeneration, hypothermia, seizures, growth retardation, abnormal hair and abnormalities of the major arteries, with death usually within the first 3 years of life (Menkes et al., 1962; Danks et al., 1972). There is an abnormal distribution of copper with low serum, cerebrospinal fluid (CSF), brain and hepatic copper levels but increased copper concentration in kidney, muscle and gut. Cultured fibroblasts show an abnormal accumulation of copper but reduced levels of lysyl oxidase, a copper-containing enzyme (Royce et al., 1980). Decreased activities of other copper-dependent enzymes, such as cytochrome c oxidase, tyrosinase and dopamine-β-hydroxylase, explain many of the clinical symptoms. An abnormal metallothionein gene regulation in response to copper has been found (Leone et al., 1985), but the basic defect has yet to be identified.

Effect of estrogen on serum and tissue levels of copper and zinc.

Estrogen along with progestogen is the most widely used form of contraceptive by women. Its use in any dose, form or route has been shown to increase serum copper and ceruloplasmin levels in humans and rats. However, its effect on plasma zinc levels is not established unequivocally. We demonstrated in female Long-Evans-Hooded rats that 4 weeks after implantation with 17 beta-estradiol their serum copper and ceruloplasmin and brain copper levels increased while hepatic copper levels decreased significantly. Kidney copper levels increased transitorily after 2 weeks but not after 4 weeks. Zinc levels were affected only in the liver of these animals. It may be concluded that estrogen therapy depletes hepatic stores of these elements with abnormal accumulation of copper in the brain. Health implications of these changes need further investigation.

Developmental changes of selected minerals in Zucker rats.

Effects of obesity and age on copper, iron, zinc, sodium, potassium, and protein were compared in liver, kidney, brain, and muscle of obese (fa/fa) and nonobese (non-fa/fa) male Zucker rats. Blood plasma cerulopasmin, copper, zinc, sodium, and potassium were also determined. Mean brain weight of fa/fa rats was less than that of non-fa/fa rats at 12 weeks of age; mean brain protein concentration was greater in fa/fa than in non-fa/fa at 5 and 12 weeks of age. At 18-19 days of age, mean sodium concentration (mg/g protein) in liver of fa/fa was less than that of non-fa/fa. At 5 weeks of age, mean copper concentration (microgram/g protein) in kidney was greater in fa/fa. Mean total copper, iron, zinc, sodium, and potassium in liver and kidney were greater in fa/fa than in non-fa/fa at 5 weeks because of the larger livers and kidneys of fa/fa. Mean concentrations of copper, zinc, sodium, and potassium per gram of brain protein were slightly (6-10%) less in fa/fa than in non-fa/fa at 5 weeks. By 12 weeks, mean concentrations of copper in liver, kidney, (tibialis) muscle, and blood plasma, ceruloplasmin in blood plasma, zinc in liver and muscle, iron in muscle, and sodium in liver were greater in fa/fa than in non-fa/fa. However, total amount of each mineral in muscle at 12 weeks was less in fa/fa than in non-fa/fa because of the smaller mean muscle weight of fa/fa. Mean concentrations of copper and zinc in brain and of iron in liver and brain were less in fa/fa than in non-fa/fa at 12 weeks. The major age-related changes in fa/fa that were not observed in non-fa/fa were large increases in liver and kidney copper between 5 and 12 weeks of age. It seems that the abnormal mineral metabolism is a consequence of the obesity, but the mechanisms are not identified.

Menkes症モデルマウス(Macular mouse)の銅代謝

The copper, zinc and metallothionein contents were measurded in various tissues of mutant (hemizygous and homozygous) macular, heterozygous macular and normal mice. The copper contents in the kidney and small intestine of 7-day-old mutants and heterozygotes were much higher than in normal mice, whereas the copper contents in the other tissues (liver, brain spleen and serum) were low. Renal copper contents of 1-day-old mutants were not different from contents of normal mice, whereas those of 7-, and 14-day-old mutants were significantly elevated. Hepatic and brain copper contents were extremely low at all stages compared to normals. Copper therapy was applide to 7-day-old mutant mice. One day after injection, hepatic copper contents in mutants increased slightly compared to the normal controls, whereas renal copper contents increasded greatly. Seven days after injection, hepatic copper contents in mutants decreased greatly compared to the normal control, whereas the increase in renal copper contents remained. One and 7 days after injectin, brain copper contents in mutants and normal mice increasde slightly compared to untreated mice. The renal MT-Cu contents in 7- and 8-day-old mutants and heterozygotes were significantly greater than that of normal mice. The marked elevation in renal MT-Cu contents was also observed in 8- and 9-week-old mutants and heterozygotes. In contrast to the kidney, hepatic MT-Cu contents in 7- and 8-day-old mutants and heterozygotes were much lower than in normal mice. In contrast to copper, no significant differences in zinc levels in any tissue were evident.

PLACENTAL COPPER TRANSPORT IN THE BRINDLED MOUSE

The X-linked mouse mutant brindled is a model for Menkes syndrome. In young hemizygotes, reduced liver and brain copper concentrations are associated with neurologic dysfunction. In fetuses copper concentrations in placenta and kidney are higher in brindled than controls while those in liver and carcass are lower. To treat the copper deficiency in brindled young, heterozygotes were injected at 16 or 18 days gestation with copper, 6 mcg/g/dose, as cupric chloride, 18 and 6 hours before sacrifice. Placental, carcass, and hepatic copper concentrations in brindled fetuses increased (p>0.006). Injection of methylprednisolone, 5 mcg/g, 20 hours before the copper, to increase fetal hepatic copper storage through metallothionein induction, resulted only in further increase in the carcass copper concentrations. These data suggest: placental copper transport in brindled fetuses is impaired; hepatic copper binding capacity of control and brindled fetuses is limited and cannot be augmented by pretreatment with methylprednisolone; extra-hepatic copper binding may be increased with methylprednisolone, which implicates induction of extra-hepatic metallothionein in both groups of animals.

Sex-related interactions of cadmium and lead in changing cardiovascular homeostasis and tissue metal levels of chronically exposed rats.

The mechanisms by which chronic exposure to lead (Pb), cadmium (Cd) or Pb plus Cd may affect cardiovascular homeostasis are still controversial (Iannaccone et al. 1981; Boscolo et al. 1981; Carmignani et al. 1983). Pb determined sympathetic hyperactivity, baroreflex hyposensitivity, vagal parasympathetic hypofunc-tion, and increased cardiovascular responsiveness to angiotensin II and catecholamines in male Sprague-Dawley rats that received 50 µg/ml of the metal (as acetate) in drinking water for 160–180 days (Iannaccone et al. 1981). Pb also reduced the urinary kallikrein and affected the plasma renin activities of Pb-exposed workers (Boscolo et al. 1978). The mechanisms underlying the cardiac and vascular modifications induced by chronic exposure of both humans and laboratory animals to Cd have been previously reviewed (Carmignani and Boscolo 1984, 1985; Boscolo and Carmignani 1986). Pb and Cd may have additive effects in inducing heart-related diseases or arterial hypertension (Carmignani and Boscolo 1984; Boscolo and Carmignani 1986). However, these additive effects of Pb and Cd were not confirmed in a study carried out on male Sprague-Dawley rats treated with 20 µg/ml of Cd (as acetate) and/or 50 µg/ml of Pb (as acetate) in drinking water for 180-210 days. In this study Cd seemed to act by predominantly peripheral effector mechanisms, while Pb showed central neurogenic actions; both metals altered specifically the levels of zinc (Zn) and copper (Cu) in kidney and brain (Carmignani et al. 1983).

Effects of copper on dopaminergic function in the rat corpus striatum

Copper-loading was produced in rats by administration of 0.125% CuSO 4 in the drinking water for a period of 11 months from weaning. At conclusion of the treatment the animals had significant increases in liver (552%) and brain (26%) copper content relative to age-matched controls. Whereas the concentration of dopamine was unaffected, the concentration of 3,4-dihydroxyphenylacetic acid in the corpus striatum was found to be lower (25% decrease) in the copper-treated group. Saturation studies of the striatal D-2 dopamine receptors using [ 3H]spiperone indicated that in copper-loaded animals the affinity was significantly increased threefold, whereas there was a trend for the number of receptors to decrease. When included in the radioligand binding assay, copper salts (Cu 2+) inhibited specific [ 3H]spiperone binding to untreated corpora striata. The inhibition produced by copper was competitive with a significant decrease in affinity, the 50% effective concentration of Cu 2+ was 21 to 24 μ M, and the potency of dopamine agonists was also decreased. These results are discussed in relation to the mechanism by which copper affects dopaminergic function and to the use of copper-loaded rats as a model of Wilson's disease.

Histochemical demonstration of copper in normal rat brain and spinal cord

The high sensitivity of the magnesium-dithizonate silver-dithizonate (MDSD) staining procedure makes this method very suitable for the histochemical localization of copper in different regions of the central nervous system of adult rats. In the telencephalon (bulbus olfactorius, nucleus caudatus-putamen, septum pellucidum and area dentata), diencephalon (nucleus habenulae medialis, nuclei of the hypothalamus in the vicinity of the third ventricle, and corpus mamillare), mesencephalon (substantia nigra), cerebellum (mainly in the nodulus), pons (locus coeruleus, nucleus vestibularis), medulla oblongata (nucleus tractus solitarii) and spinal cord, the glial cells exhibit specific copper staining. The glial cells of some circumventricular organs (e.g. the subfornical organ) are also stained using the MDSD method. The significant staining observed in white-matter glial cells (e.g. in the corpus callosum, cerebellum and spinal cord) further indicates the very high sensitivity of this method. In glial cells of the same regions, the presence of copper can likewise be demonstrated using the modified sulphide silver method. On the basis of the present histochemical results, it is suggested that copper may play an important role in the normal physiological functioning of glial cells and also, via glial-neuron interactions, in neuronal processes.

Effect of copper on the binding and electrophysiological actions of cyclohexyladenosine

Since copper ions irreversibly reduce the binding of cyclohexyladenosine (CHA) to rat brain membranes and copper levels are elevated in the brains of seizure-prone mice, the binding of CHA was compared in seizure-prone DBA/2 and control C57 mice. No strain difference was detected in the binding of CHA or the reduction of that binding by copper, although copper was more potent than in rats (IC 50 12 μM). In rat hippocampal slices copper did not diminish the inhibitory effects of adenosine or CHA. The results suggest that the seizure sensitivity of DBA/2 mice is not due to an effect of copper on purine receptors and that the copper binding domain of purine receptors is inaccessible to extracellular copper.

Effect of oral cadmium administration to female rats during pregnancy on zinc, copper, and iron content in placenta, foetal liver, kidney, intestine, and brain.

Cadmium chloride was administered in drinking water at a concentration of 50 ppm cadmium to female rats for 20 days of gestation. The foetuses were then removed from the uteri of the dams. Gestational exposure to oral cadmium resulted in decreased zinc, copper, iron, metallothionein, and thionein-bound zinc content in foetal liver as well as in reduced copper content in placenta and foetal intestine, brain and kidney. Subcellular fractionation of the foetal liver revealed decreased nuclear and cytoplasmic zinc content as well as decreased microsomal iron content. Pregnant rats exposed to oral cadmium revealed decreased serum zinc and iron concentration as well as reduced ceruloplasmin activity. The decreased zinc, copper, and iron content in foetal organs is suggested to be causally connected with the diminished availability of these metals in the maternal circulation.

Copper distribution in the normal human brain.

Copper concentration was determined in samples from 38 areas of 7 normal human brains. The grey matter contained higher concentrations of copper than the white matter. Identical areas of the grey and white matter of the cerebral cortex showed significant differences between individuals. In the caudate nucleus the highest concentrations of copper were found in the tail followed by the body and the head, respectively. A negative linear regression between age and brain copper levels was demonstrated.

Excessive intake of copper: Influence on longevity and cadmium accumulation in mice

Feeding copper gluconate in the drinking water to C57BL/6J male for a lifetime decreased the mean survival times by 14.4% when given at a concentration of 5 × 10 -3 M (317 ppm copper). The maximum life span was reduced by 12.8% (from 986 to 874 days). Survival data at lower copper concentrations are also reported. Serum, brain, heart and kidney copper concentrations were unaltered by feeding 5 × 10 -3 M copper gluconate. Only liver concentrations increased. Cadmium concentrations in liver and kidney of 168-, 406- and 664-day-old mice were essentially unchanged after feeding copper gluconate for 104 days. We conclude that chronic consumption of copper does not prevent or reduce the normal accumulation of cadmium found in aging mice.

IMPAIRED COPPER UTILIZATION IN THE COPPER-DEFICIENT BRINDLED MOUSE MUTANT

The Brindled mouse mutant is a model for the Kinky Hair syndrome. Male Brindled hemizygous suckling mice demonstrate poor growth and neurologic deterioration beginning during the first week of life and ending with death by the end of the second week. Newborn Brindled carriers are asymptomatic with normal brain copper concentration; liver copper concentration is low and the renal copper is high. Newborn carrier pups suckled by Brindled dams put on low copper diets on the day of parturition, however, show deficient weight gain by the age of 6 days and by 12 days weigh approximately one-half their normal litter-mates. Neurologic symptoms developed in the copper-deficient young carriers by age 12-14 days while their normal litter-mates remained asymptomatic. Tissue copper studies demonstrate that the liver and brain copper concentration in the carrier is no different from that of the normals, although the renal copper is greater than twice as high. On copper-deficient diets, the brain and liver concentrations of normal and heterozygous young decrease to comparable levels, but heterozygotes also develop systemic and neurologic symptoms. These observations are thought to implicate an abnormality in copper utilization in Brindled carriers brought out by marginal copper intake.

Repletion of Copper-Deficient Mice and Brindled Mice with Copper or Iron

Studies were conducted in suckling mice to investigate copper-dependent anemia. Brindled (Mobr/y) mice, which have a genetic defect that affects copper metabolism, were compared to their normal brothers (Mo+/y) as well as to anemic suckling mice that were copper-deficient (-Cu) because their dams were consuming a diet low in copper and to a fourth group of control suckling mice (+Cu) from copper-supplemented dams. Mice were given a subcutaneous injection of NaCl, FeCl2 or CuCl2 providing 50 µg of Na, Fe or Cu, respectively, when 7 days old and were killed 5 days later. Injection of FeCl2 into -Cu mice elevated liver iron 2.7-fold and raised hemoglobin levels to those observed in the +Cu and Mo+/y mice. Ceruloplasmin activity remained low at 5% of control levels. Injection of CuCl2 into -Cu mice resulted in significant increases in body and brain weight, elevations in serum copper and ceruloplasmin activities and hemoglobin levels. Liver copper rose and iron fell, both to levels observed in +Cu and Mo+/y mice. Brain copper and norepinephrine concentrations rose to control levels. Injection of CuCl2 into Mobr/y mice, although resulting in darker pigmentation and normal serum copper and ceruloplasmin levels, failed to stimulate growth or change brain weight. Furthermore, liver and brain copper levels did not rise to normal levels despite significant improvements. Similarly, brain norepinephrine levels rose, but were still below normal. Brindled mice do not respond to copper therapy to the same degree as do -Cu mice. Iron therapy was successful in reversing the anemia of -Cu mice but was without effect on growth or brain development.

Cardiovascular homeostasis in rats chronically exposed to mercuric chloride.

Two groups of male Sprague-Dawley rats received from weaning 50 micrograms/ml of mercury as mercuric chloride (HgCl2) in drinking water for 320 and 350 days. Hg exposure increased cardiac inotropism, without chronotropic changes, in both groups, and induced arterial hypertension in the rats exposed for 350 days. In the exposed rats, cardiovascular responses to the stimulation of peripheral alpha and beta adrenoceptors were decreased and increased, respectively, possibly through a reduced intracellular availability of calcium ions for contractile mechanisms. Hg exposure did not affect either vagal or sympathetic activity or cardiovascular reactivity to several physiological agonists. On the other hand, Hg exposure induced baroreflex hyposensitivity and produced a drastic alteration of the levels of copper and zinc in brain and kidney.

The effect of dietary methionine on the copper content of tissues and survival of young and old mice

We tested the possibility that methionine might improve the lifespan of male C57BL/6J mice, based upon the ability of methionine to chelate copper. Old mice given 0.05M methionine in their drinking water for 42 days had lower brain copper concentrations p < 0.05. The decrease in liver, kidney, and heart copper was not significant when compared to unsupplemented controls. The lifespan of old mice was unchanged by feeding 0.05M methionine. Young mice, however, experienced a 16.9% decrease in their average lifespan and a decreased maximum lifespan when given supplemental methionine. We conclude that dietary supplements of methionine may be useful for removing copper from the brain but they also can increase the rate of senescence in mice.