Long-term consequence of early iron-deficiency on dopaminergic neurotransmission in rats

Chronic marginal iron intakes during early development in mice result in persistent changes in dopamine metabolism and myelin composition

Marginal iron (Fe) deficiency is prevalent in children worldwide, yet the behavioral and biochemical effects of chronic marginal Fe intakes during early development are not well characterized. Using a murine model, previous work in our laboratory demonstrated persistent behavioral disturbances as a consequence of marginal Fe intakes during early development. In the present study, Swiss-Webster mice fed a control Fe diet (75 microgram Fe/g diet, n = 13 litters) or marginal Fe diet (14 microgram Fe/g diet, n = 16 litters) during gestation and through postnatal day (PND) 75 were killed on PND 75 for assessment of tissue mineral concentrations, dopamine metabolism, myelin fatty acid composition, and c- and m-aconitase activities. In addition, these outcomes were assessed in a group of offspring (n = 13 litters) fed a marginal Fe diet during gestation and lactation and then fed a control diet from PND 21-75. Marginal Fe mice demonstrated significant differences in brain iron concentrations, dopamine metabolism and myelin fatty acid composition relative to control mice; however, no difference in c- or m-aconitase activity was demonstrated in the brain. The postnatal consumption of Fe-adequate diets among marginal Fe offspring did not fully reverse all of the observed biochemical disturbances. This study demonstrates that chronic marginal Fe intakes during early development can result in significant changes in brain biochemistry. The persistence of some of these biochemical changes after postnatal Fe supplementation suggests that they are an irreversible consequence of developmental Fe restriction.

Effects of dietary supplementation with aluminum and citrate on iron metabolism in the rat

The metabolism of iron (Fe) has been shown to interact with that of aluminum (Al) in relation to intestinal absorption, transport in the blood plasma, and the induction of lipid peroxidation and cellular damage. Also, dietary supplementation with citrate has been shown to increase the absorption of both metals and, in the presence of high intakes of Fe and Al, leads to excessive accumulation of both metals in the body. In this study, the likely interaction between Al and internal Fe metabolism was investigated using rats fed diets that were either deficient, sufficient, or loaded with Fe, with or without the addition of Al and sodium citrate. These diets commenced when the rats were 4 wk old and were continued for 9-11 wk. At that time, Fe metabolism as assessed by measurement of organ uptake of 59Fe and 125I-transferrin, after iv injection of transferrin labeled with both isotopes, plus measurement of tissue concentrations of nonheme Fe and Al. The Fe-deficient diet and Fe-loaded diet led to states of Fe deficiency and Fe overload in the rats, and supplementation of the diet with Al increased Al levels in the kidneys, liver, and femurs, but, generally, only when the diet also contained citrate. Neither Al nor citrate supplementation of the diet had any effect on nonheme Fe concentrations in the liver, kidney, or brain, or on the uptake of 59Fe or 125I-transferrin by liver, kidney, brain, or spleen. Only with the femurs was a significant effect observed: increased 59Fe uptake in association with increased Al intake. Therefore, using this animal model, there was little evidence for interaction between Fe and Al metabolism, and no support was obtained for the hypothesis that dietary supplementation with Fe and citrate can lead to excessive Fe absorption and deposition in the tissues.

Oxidative damage in the central nervous system: protection by melatonin

Melatonin was recently reported to be an effective free radical scavenger and antioxidant. Melatonin is believed to scavenge the highly toxic hydroxyl radical, the peroxynitrite anion, and possibly the peroxyl radical. Also, secondarily, it reportedly scavenges the superoxide anion radical and it quenches singlet oxygen. Additionally, it stimulates mRNA levels for superoxide dismutase and the activities of glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase (all of which are antioxidative enzymes), thereby increasing its antioxidative capacity. Also, melatonin, at least at some sites, inhibits nitric oxide synthase, a pro-oxidative enzyme. In both in vivo and in vitro experiments melatonin has been shown to reduce lipid peroxidation and oxidative damage to nuclear DNA. While these effects have been observed primarily using pharmacological doses of melatonin, in a small number of experiments melatonin has been found to be physiologically relevant as an antioxidant as well. The efficacy of melatonin in inhibiting oxidative damage has been tested in a variety of neurological disease models where free radicals have been implicated as being in part causative of the condition. Thus, melatonin has been shown prophylactically to reduce amyloid beta protein toxicity of Alzheimer's disease, to reduce oxidative damage in several models of Parkinson's disease (dopamine auto-oxidation, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 6-hydroxydopamine), to protect against glutamate excitotoxicity, to reduce ischemia-reperfusion injury, to lower neural damage due to gamma-aminolevulinic acid (phorphyria), hyperbaric hyperoxia and a variety of neural toxins. Since endogenous melatonin levels fal 1 markedly in advanced age, the implication of these findings is that the loss of this antioxidant may contribute to the incidence or severity of some age-associated neurodegenerative diseases.

In vivo dopamine metabolism is altered in iron-deficient anemic rats

Previous studies of dopamine metabolism in iron-deficient rats demonstrated an elevation in extraneuronal levels of dopamine and a depression in the number of dopamine D2 receptors; however, the importance of anemia per se and the reversibility of these observations are not completely resolved. The purpose of this study was to determine if in vivo reuptake of caudate dopamine is altered by iron deficiency anemia, if it is reversible with iron therapy, and if anemia per se produced the same effects on dopamine metabolism. Male Sprague-Dawley rats (21-d old) were fed an iron-deficient diet (4 mg Fe/kg diet) and then iron repleted (5 mg iron dextran), or were fed an iron adequate diet (35 mg Fe/kg diet) and then given phenylhydrazine to induce hemolytic anemia. In vivo microdialysis was performed in steady-state conditions both before and after iron or no therapy and was followed by an intraperitoneal injection of a dopamine reuptake blocker (cocaine-HCl 30 mg/kg). Thirty percent higher extracellular dopamine levels in the caudate-putamen were observed in iron-deficient rats compared with control rats, but no differences were observed in tissue levels. Hemolytic anemic and iron-repleted rats had normal extracellular dopamine levels. The response to dopamine reuptake blockade was significantly attenuated in iron-deficient rats compared with control, iron-repleted, or hemolytic anemic rats. These experiments provide evidence that iron deficiency blunts the dopamine reuptake mechanism, that this is a reversible process in postweaning rats, and that anemia per se does not cause the increased extracellular dopamine levels.

Regional brain iron, ferritin and transferrin concentrations during iron deficiency and iron repletion in developing rats

Iron deficiency in young rats leads to a decrease in brain iron and ferritin concentrations, an increase in transferrin (Tf) concentration, and an increased rate of uptake of iron from the plasma pool. We conducted two experiments to determine whether brain iron, Tf and ferritin respond quickly to iron repletion and to determine whether brain regions respond heterogeneously. Weanling male Sprague-Dawley rats were fed an iron-deficient diet (<5 mg/kg Fe) for 2 wk followed by an iron-adequate diet (REPL group, 35 mg/kg Fe in Experiment 1 and 15 mg/kg Fe in Experiment 2) for 2 or 4 wks, respectively. Age-matched iron-deficient (ID) and control rats composed the other two groups. Fourteen days of repletion with 35 mg/kg Fe dietary treatment were adequate to normalize hematology, brain microsomal and cytosolic Fe and brain ferritin (Experiment 1). Brain transferrin concentrations in REPL rats, however, were significantly above the levels of controls. Regional brain iron decreased heterogeneously due to dietary iron deficiency (Experiment 2), with some regions having a propensity to keep iron (e.g., substantia nigra, pons, and thalamus) and others losing significant amounts of iron (cortex and hippocampus). Ferritin and Tf concentrations also varied significantly across brain regions in ID and control rats. The hippocampus had the most dramatic Tf response to iron deficiency with elevations of approximately 100%, whereas other regions, except striatum, were unaffected. The brain of developing rats thus distributes iron and iron regulatory proteins differently from the brain of adult rats and is quite avid in its reacquisition of iron during iron therapy.

Iron-deficiency anemia and infant development: effects of extended oral iron therapy

OBJECTIVE

To determine whether extended oral iron therapy corrects lower developmental test scores in infants with iron-deficiency anemia.

STUDY DESIGN

Double-blind, controlled trial in Costa Rica involving 32 12- to 23-month-old infants with iron-deficiency anemia and 54 nonanemic control subjects. Anemic infants were treated with orally administered iron for 6 months; half the nonanemic children were treated with iron and half with placebo. Developmental test scores and hematologic status were evaluated before treatment, after 3 months, and after 6 months.

RESULTS

Iron-deficient anemic infants received lower mental test scores than nonanemic infants at all three time points (p < 0.05 pretreatment and at 3 months, p = 0.07 at 6 months). There were no significant differences in motor test scores. More of the anemic infants were rated as unusually tearful and unhappy. Anemic infants came from families with lower maternal education and less support for child development and were less likely to be breast fed, were weaned earlier, and consumed more cow milk.

CONCLUSIONS

Lower mental test scores persisted in infants with iron-deficiency anemia despite extended oral iron therapy and an excellent hematologic response. Iron-deficiency anemia may serve as a marker for a variety of nutritional and family disadvantages that may adversely affect infant development.

Chlorpromazine stimulatory effect on iron uptake by rat brain synaptosomes

Clinical long-term neuroleptic administration induces extrapyramidal motor side-effects, of which tardive dyskinesia is the most important. Experimentally, dopamine D2 supersensitivity is observed after phenothiazine and butyrophenone treatment. Neuroleptic-induced tardive dyskinesia and D2 modulation have been linked to impaired iron homeostasis in the central nervous system. Increased nonheme iron levels found in the basal ganglia of patients with extrapyramidal symptomology support the connection between iron and neuronal dopaminergic modulation. We now report the effect of chlorpromazine on iron uptake by synaptosomes of rat brain from two different iron donors: [55Fe]citrate and [55Fe]transferrin. Iron uptake from both donors by cortical synaptosomes was stimulated by Ca2+ and enhanced by chlorpromazine in a saturable fashion. Synaptosomes from the striatum also showed increased (60%) iron uptake from [55Fe]citrate in the presence of chlorpromazine. Chlorpromazine stimulated iron uptake by cortical synaptosomes more efficiently than Ca2+, at physiological levels, from both [55Fe]transferrin (50%) and [55Fe]citrate (68%). Calcium potentiated the effect of chloropromazine upon cortical synaptosomal iron uptake from [55Fe]citrate, but had no apparent effect on the uptake from [55Fe]transferrin. Chlorpromazine-stimulated iron uptake from the latter was observed without addition of Ca2+. Moreover, fluorescence measurement of Ca2+ uptake by cortical synaptosomes showed intensified uptake in the presence of 50 microM chlorpromazine (42%). Visible spectral studies of chlorpromazine in the presence of Fe(3+)-citrate and diferric-transferrin did not reveal iron displacement by chlorpromazine from either of the two donors. These data suggest that chlorpromazine may increase iron uptake by neurons, and may be involved in the development of tardive dyskinesia and other extrapyramidal disorders.

Neurobehavioral dysfunctions associated with dietary iron overload

Excessive dietary Fe is known to be toxic, but the extent of neurobiological involvement is not clear. In the present study male weanling rats were fed diets containing Fe at 35 (control), 350, 3500, or 20000 ppm for 12 wk. An Fe-deficient group (4 ppm) was included for comparison. Rats were tested for behavioral and body weight changes at various times after initiation of diets, and liver and brain nonheme Fe were measured at term. Excess dietary Fe, primarily at 20000 ppm, significantly decreased activity, habituation, reflex startle, and conditioned avoidance response performance, and enhanced prepulse modulation of startle. Body weights were also markedly decreased. Fe-deficient animals showed similar behavioral effects but more moderate body weight changes. Liver nonheme Fe varied directly with dietary levels. Whole-brain nonheme Fe was significantly reduced in Fe-deficient animals but increased only at the 20000-ppm level. Homeostatic mechanisms appear to regulate whole-brain Fe more effectively under conditions of dietary Fe overload than under conditions of Fe deficiency. The behavioral changes associated with dietary Fe overload may represent secondary consequences of systemic toxicity.

Effects of diet and development upon the uptake and distribution of cerebral iron

In order to determine whether iron sequestered by the rat brain during the third week of postnatal life could be mobilized by subsequent dietary iron deficiency (ID), iron-59 (59Fe) was administered to rats at 2 weeks of age. The animals were placed on an ID or a control diet from age 4 through 8 weeks and killed by perfusion. Brain radioactivity was identical for both groups, and autoradiography revealed no differences in the distribution of radioactivity. Thus, neither the sequestration of cerebral iron acquired at age 2 weeks nor its subsequent redistribution was affected by ID. Since ID beginning after age 3 weeks reportedly produces a cerebral iron deficit that is in part reversible, an attempt was made to determine whether 59Fe administered after ID was preferentially delivered to any brain region. Rats were placed on an ID or a control diet from age 3 through 7 weeks and then injected with 59Fe, placed on a normal diet, and killed 2 weeks later. Thre was no difference between groups in amount or distribution of brain 59Fe, except in the choroid plexus, which was more radioactive in the ID rats than in the controls. This finding may represent a mechanism by which the choroid plexus buffers the brain against rapid rises in plasma iron content.

Serum prolactin levels and behavior in infants

This study examined the relationship between serum prolactin levels and behavior in infants and toddlers who experienced two potentially stressful experiences (developmental testing and venipuncture). Serum prolactin levels showed considerable consistency over a 3-month period (r = 0.64 between study entry and three months, p < 0.001, n = 50). There was also stability in having either a normal or a high value (> or = 25 ng/ml). Among children who had a normal value on initial testing, 97% also has a normal value after 3 months; 55% of those with initial high values continued to have high values (chi 2 = 19.26, p < 0.001). Children with high serum prolactin levels were more likely to be rated as unusually hesitant and unhappy during developmental testing. Overall, 53% of the children with serum prolactin levels > or = 25 ng/ml were considered abnormal in affect, compared to 20% of those with lower serum prolactin values (total n = 138, chi 2 = 13.56, p < 0.001). These results suggest that, even in early life, serum prolactin levels may reflect characteristic individual behavioral and neuroendocrine responses to stress.

Typical and atypical neuroleptics induce alteration in blood-brain barrier and brain 59FeCl3 uptake

Long-term neuroleptic medication of schizophrenic patients induces extrapyramidal motor side effects, of which tardive dyskinesia (TD) is the most severe. The etiology of TD is still obscure. Recently, it was suggested that abnormal iron metabolism may play a crucial role in neuroleptic-induced dopamine D2 receptor super-sensitivity. The apparent relationship between neuroleptics and iron is further supported by the increase of iron in the basal ganglia of patients with TD. We now report on the ability of neuroleptic to alter the blood-brain barrier in the rat and to potentiate the normally limited iron transport into the brain. Thus, chronic treatment of rats with chlorpromazine and haloperidol facilitated 59Fe3+ uptake into brain cells. In contrast, clozapine, an atypical antipsychotic neuroleptic with little extrapyramidal motor side effects, caused iron sedimentation in brain blood vessels with no sign of detectable iron in the cells. Moreover, chronic treatment with chlorpromazine and haloperidol caused a 43% and 24% reduction, respectively, in liver nonheme iron, whereas clozapine induced an 81% increase. The apparent different potentials of chlorpromazine, haloperidol, and clozapine to increase iron transport into the brain from its peripheral stores may be linked to the severity of extrapyramidal motor side effects they induce and to the pathophysiology of TD.

Basal ganglia iron in tardive dyskinesia: an MRI study

Alterations in brain iron could play an important role in the development of tardive dyskinesia in patients receiving neuroleptic medication. To test this hypothesis, magnetic resonance imaging scans of the brain were performed on 21 chronic schizophrenic patients. Ten patients met research diagnostic criteria for persistent tardive dyskinesia, and 11 were free of tardive dyskinesia. All patients had received long-term neuroleptic treatment and were on a stable neuroleptic dose for at least 3 months before scanning. The signal intensity of basal ganglia structures was obtained as a quantitative estimate of brain iron content. No difference was found in the signal intensity ratios between the two groups. This suggests that iron deposition in the basal ganglia, at least as assessed by this measure, does not play a role in the pathophysiology of tardive dyskinesia.

Iron in the brain

The location and function of iron in the central nervous system are reviewed with particular emphasis on human biology. Iron is distributed to different cell types in the brain in a heterogeneous fashion through the action of transferrin, transferrin receptors, and the metabolic needs of those cells. The function of this iron and its storage is documented in states of growth and development as well as during pathological states associated with aging. The information relating this biology to current observations of attention deficits in iron-deficient humans is also reviewed.

The possible role of iron in the etiopathology of Parkinson's disease

The identification of 6-hydroxydopamine (6-OHDA) and N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as dopaminergic neurotoxins that can induce parkinsonism in humans and animals has contributed to a better understanding of Parkinson's disease (PD). Although the involvement of similar neurotoxins has been implicated in PD, the etiology of the disease remains obscure. However, the recently described pathology of PD supports the view for a state of oxidative stress in the substantia nigra (SN), resulting as a consequence of the selective accumulation of iron in SN zona compacta and within the melanized dopamine neurons. Whether iron is directly involved cannot be ascertained. Nevertheless, the biochemical changes due to oxidative stress resulting from tissue iron overload (siderosis) are similar to those now being identified in parkinsonian SN. These include the reduction of mitochondrial electron transport, complex I and III activities, glutathione peroxidase activity, glutathione (GSH) ascorbate, calcium-binding protein, and superoxide dismutase and increase of basal lipid peroxidation and deposition of iron. The participation of iron-induced oxygen free radicals in the process of nigrostriatal dopamine neuron degeneration is strengthened by recent studies in which the neurotoxicity of 6-OHDA has been linked to the release of iron from its binding sites in ferritin. This is further supported by experiments with the prototype iron chelator, desferrioxamine (Desferal), a free-radical inhibitor, which protects against 6-OHDA-induced lesions in the rat. Indeed, intranigral iron injection in rats produces a selective lesioning of dopamine neurons, resulting in a behavioral and biochemical parkinsonism.

Intranigral iron injection induces behavioral and biochemical "parkinsonism" in rats

Elevated iron concentrations in the substantia nigra (SN) pars compacta have been implicated in the development of idiopathic Parkinson's disease. Because, as a transitional metal, iron promotes free radical formation, the role of iron in the degeneration of the nigrostriatal dopamine neurons in Parkinson's disease has received much attention. This study further investigates the cytotoxic effects of iron in the SN. Various concentrations of FeCl3 (1, 5, and 50 micrograms of Fe3+ in 5 microliters) were unilaterally injected into the SN of adult rats. The two lower doses of iron had no effect on striatal dopamine levels or on the behavioral responses of the rats. However, injection of 50 micrograms of Fe3+ resulted in a substantial selective decrease of striatal dopamine (95%), 3,4-dihydroxyphenylacetic acid (82%), and homovanillic acid (45%), without any change in norepinephrine concentration. Dopamine-related behavioral responses, such as spontaneous movements in a novel space and rearing, were significantly impaired, whereas amphetamine administration induced ipsilateral rotation in the iron-treated rats. The present study indicates that the nigrostriatal dopamine neurons are susceptible to the presence of ionic iron and thus supports the assumption that iron initiates dopaminergic neurodegeneration in Parkinson's disease.

Transferrin and iron uptake by the brain: effects of altered iron status

Transferrin (Tf) and iron uptake by the brain were measured in rats using 59Fe-125I-Tf and 131I-albumin (to correct for the plasma content of 59Fe and 125I-Tf in the organs). The rats were aged from 15 to 63 days and were fed (a) a low-iron diet (iron-deficient) or, as control, the same diet supplemented with iron, or (b) a chow diet with added carbonyl iron (iron overload), the chow diet alone acting as its control. Iron deficiency was associated with a significant decrease and iron overload with a significant increase in brain nonheme iron concentration relative to the controls. In each dietary treatment group, the uptake of Tf and iron by the brain decreased as the rats aged from 15 to 63 days. Both Tf and iron uptake were significantly greater in the iron-deficient rats than in their controls and lower in the iron-loaded rats than in the corresponding controls. Overall, iron deficiency produced about a doubling and iron overload a halving of the uptake values compared with the controls. In contrast to that in the brain, iron uptake by the femurs did not decrease with age and there was relatively little difference between the different dietary groups. 125I-Tf uptake by the brains of the iron-deficient rats increased very rapidly after injection of the labelled proteins, within 15 min reaching a plateau level which was maintained for at least 6 h. The uptake of 59Fe, however, increased rapidly for 1 h and then more slowly, and in terms of percentage of injected dose reached much higher values than did 125I-Tf uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of neuroleptic-induced dopamine D2 receptor supersensitivity by chronic iron salt treatment

The ability of neuroleptics to induce dopamine D2 receptor supersensitivity has been linked to the onset of tardive dyskinesia, the major side-effect of these drugs. Brain iron metabolism has been shown to be involved in the regulation of dopamine D2 receptors. We now examined the effect of chronic treatment with FeCl2 on chlorpromazine-induced D2 receptor supersensitivity. The results show that FeCl2 (5 mg/kg per day for 21 days) given to rats treated with chlorpromazine (10 mg/kg per day, for 21 days) prevented the onset of supersensitive biochemical and behavioral (apomorphine) expressions of DA D2 receptor. Inclusion of iron did not affect the chlorpromazine-induced sedation or hypothermia. Moreover, the combined chronic iron-chlorpromazine treatment produced the same net effects as chronic chlorpromazine on striatal amounts of dopamine, DOPAC (dihydroxyphenylacetic acid) and HVA (homovanillic acid). Chlorpromazine medication caused a decrease in liver non-haem iron levels (40%) but not in brain iron. The effect of the neuroleptic drug on iron stores and the involvement of iron in the neuroleptic-induced dopamine supersensitivity suggest that mobilization of iron from the periphery into the brain may play an important role in the mechanism of action of the neuroleptics.

The effects of iron deficiency and electric shock on learning in rats

It is hypothesized that electric shock can compensate for the learning deficit caused by iron deficiency in the experimental rat population, and that this effect will be sustained over a 3-week "rehabilitation" period. Forty-seven female Sprague-Dawley rats served as the experimental subjects. The learning capacity of the rats was assessed using a water Y-maze. The dependent variables were assessed twice, once after half had been made iron deficient, and again after the iron deficiency had been corrected. A 2 x 2 x 2 analysis of variance with repeated measures was employed, along with post-hoc tests, to assess the effects of the experimental manipulations on the rats' performance. The experimental results replicated previous findings regarding the damaging effects of iron deficiency on learning capacity in rats and confirmed that shock improves the performance of rats in the water Y-maze. Furthermore, it was found that shock and iron deficiency interact, such that the performance of iron-deficient rats subjected to electric shock is superior to that of rats not made iron deficient. This trend persists even after the hematological effects of iron deficiency are corrected, although to a less dramatic degree. A possible explanation for these findings is advanced.

Brain iron and ferritin in Parkinson's and Alzheimer's diseases

Semiquantitative histological evaluation of brain iron and ferritin in Parkinson's (PD) and Alzheimer's disease (DAT) have been performed in paraffin sections of brain regions which included frontal cortex, hippocampus, basal ganglia and brain stem. The results indicate a significant selective increase of Fe3+ and ferritin in substantia nigra zona compacta but not in zona reticulata of Parkinsonian brains, confirming the biochemical estimation of iron. No such changes were observed in the same regions of DAT brains. The increase of iron is evident in astrocytes, macrophages, reactive microglia and non-pigmented neurons, and in damaged areas devoid of pigmented neurons. In substantia nigra of PD and PD/DAT, strong ferritin reactivity was also associated with proliferated microglia. A faint iron staining was seen occasionally in peripheral halo of Lewy bodies. By contrast, in DAT and PD/DAT, strong ferritin immunoreactivity was observed in and around senile plaques and neurofibrillary tangles. The interrelationship between selective increase of iron and ferritin in PD requires further investigation, because both changes could participate in the induction of oxidative stress and neuronal death, due to their ability to promote formation of oxygen radicals.

An autoradiographic study of the uptake and distribution of iron by the brain of the young rat

Rats aged 15, 28, or 42 days were injected intraperitoneally with iron-59 and were sacrificed at varying intervals. Total acquisition of iron-59 by the brain, when compared to levels of iron-59 in blood sampled 48 h after injection, diminished with increasing age at injection. Cerebral levels of iron-59 in animals injected at age 15 days did not change with postinjection interval despite rapidly decreasing serum levels of iron-59. Thus, iron acquired by the brain early in postnatal development becomes sequestered in that organ. However, autoradiography of the brains of animals injected at age 15 days showed definite changes over time in the anatomic distribution of the isotope. This suggests that mechanisms may exist for the translocation of iron from one area of the brain to another.

Neuroleptic-induced supersensitivity and brain iron: I. Iron deficiency and neuroleptic-induced dopamine D2 receptor supersensitivity

Previous studies have shown that nutritional iron deficiency in rats reduces brain iron content, resulting in dopamine D2 receptor subsensitivity, as indicated by a decrease in [3H]spiperone binding in caudate nucleus and in behavioral responses to apomorphine. Both phenomena can be reversed by iron supplementation. The possibility that neuroleptic-induced dopamine D2 receptor supersensitivity involves an alteration in brain iron content was investigated in nutritionally iron-deficient and control rats chronically treated with haloperidol (5 mg/kg daily for 14 or 21 days). Neuroleptic treatment was initiated either (a) concurrently with iron deficiency or (b) 2 weeks after the start of iron deficiency. The results show that dopamine D2 receptor subsensitivity, a feature of iron deficiency, is absent in haloperidol-treated, iron-deficient groups. On the contrary, these animals demonstrated biochemical and behavioral dopamine D2 receptor supersensitivity that is relatively greater than that observed with control, haloperidol-treated animals. Haloperidol (5 mg/kg daily for 21 days) as well as chlorpromazine (10 mg/kg daily for 21 days) caused a significant reduction (20-25%) in liver nonheme iron stores as compared with values in control rats. However, in iron-deficient rats, in which liver iron stores were almost totally depleted, haloperidol had no effect. The ability of chronic haloperidol treatment to prevent the reduction of dopamine D2 receptor number during iron deficiency may be associated with alteration of body iron status. Thus, less iron may result in an increase in free haloperidol available to the dopamine D2 receptor.

Iron deficiency: does it matter?

Iron deficiency causes different abnormalities in the three major population groups that are at risk. In pregnant women, epidemiological studies suggest that anaemia, presumably due mainly to iron deficiency, is associated with an increased risk of low birth weight, prematurity, and perinatal mortality. In iron-deficient infants and children, there is convincing evidence of impaired psychomotor development and cognitive performance. Finally, iron-deficient women during the childbearing years (and iron-deficient men) have a decreased work capacity and less efficient response to exercise. These symptoms provide ample justification for preventing and treating a common and easily correctable nutritional disorder.

Increased iron (III) and total iron content in post mortem substantia nigra of parkinsonian brain

Significant differences in the content of iron (III) and total iron were found in post mortem substantia nigra of Parkinson's disease. There was an increase of 176% in the levels of total iron and 225% of iron (III) in the substantia nigra of the parkinsonian patients compared to age matched controls. In the cortex (Brodmann area 21), hippocampus, putamen, and globus pallidus there was no significant difference in the levels of iron (III) and total iron. Thus the changes in total iron, iron (III) and the iron (II)/iron (III) ratio in the parkinsonian substantia nigra are likely to be involved in the pathophysiology and treatment of this disorder.

Selective alteration in blood-brain barrier and insulin transport in iron-deficient rats

Nutritional iron deficiency induced in rats causes a significant reduction in level of brain nonheme iron and is accompanied by selective reduction of dopamine D2 receptor Bmax. Our previous studies have clearly demonstrated that these alterations can be restored to normal by supplementation with ferrous sulfate; however, neither brain nonheme iron level nor dopamine D2 receptor Bmax can be increased beyond control values even after long-term iron therapy. The possibility that iron deficiency can induce the breakdown of the blood-brain barrier (BBB) was examined. A 70 and 100% increase in brain uptake index (BUI) for L-glucose and insulin, respectively, were noted in iron-deficient rats. However, the BUI for valine was decreased by 40%, and those for L-norepinephrine and glycine were unchanged. In addition, it was demonstrated that in normal rats insulin is transported into the brain. The data show that iron deficiency selectively affects the integrity of the BBB for insulin, glucose, and valine transport. Whether the effect of iron deficiency on the BBB is at the level of the capillary endothelial cell tight junction is not yet known. However, this study has shown that an important nutritional disorder (iron-deficiency anemia) has a profound effect on the BBB and brain function.

A classification of sociomedical health indicators: perspectives for health administrators and health planners

The conceptualization and operationalization of measures of health status are considered. Health indicators are conceived as a subset of social indicators, and therefore, as any social indicator, they are viewed as derivative from social issues. The interrelationships of different frames of reference for defining and measuring health that have accompained three distinct health problem patterns in the United States are viewed from a developmental perspective. Mortality and morbidity rates, the traditional health indicators, by themselves no longer serve to assess health status in developed nations. Their deficiencies as indicators serve as background for a classification schema for sociomedical health status indicators that relates health definition frames of reference, measures of health status, and health problems. The role of a group of health indicators-sociomedical heath indicators-in the current formulation of health status measures is assessed.