Effect of zinc deficiency on the weight, cellularity and zinc concentration of different skeletal muscles in the post-weanling rat

Zinc at the crossroads of exercise and proteostasis

Zinc is an essential element for all forms of life, and one in every ten human proteins is a zinc protein. Zinc has catalytic, structural and signalling functions and its correct homeostasis affects many cellular processes. Zinc deficiency leads to detrimental consequences, especially in tissues with high demand such as skeletal muscle. Zinc cellular homeostasis is tightly regulated by different transport and buffer protein systems. Specifically, in skeletal muscle, zinc has been found to affect myogenesis and muscle regeneration due to its effects on muscle cell activation, proliferation and differentiation. In relation to skeletal muscle, exercise has been shown to modulate zinc serum and urinary levels and could directly affect cellular zinc transport. The oxidative stress induced by exercise may provide the basis for the mild zinc deficiency observed in athletes and could have severe consequences on health and sport performance. Proteostasis is induced during exercise and zinc plays an essential role in several of the associated pathways.

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Zinc deficiency could be a crucial issue in sport performance for athletes.

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Exercise could modulate zinc serum and cellular homeostasis.

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Zinc is part of proteostatic systems critical during exercise.

Role of Zinc in the Development/Progression of Alcoholic Liver Disease

OPINION STATEMENT

Many variables, aside from the amount and duration of alcohol consumption, play a role in the development and progression of alcoholic liver disease (ALD). One critical factor that can be modified is diet/nutrition. We have made major recent advances in our understanding of the interactions of nutrition and ALD. In this article, we review advances made in zinc metabolism/therapy for ALD. There is major zinc dyshomeostasis with ALD which is mediated, in part, by poor intake and absorption, increased excretion, and altered zinc transporters, especially ZIP14. Zinc deficiency plays an etiologic role in multiple mechanisms of ALD, ranging from intestinal barrier dysfunction to hepatocyte apoptosis. Zinc supplementation is highly effective at correcting these ALD mechanisms and preventing/treating experimental ALD. There is no Food and Drug Administration (FDA) approved therapy for any stage of ALD. Because animal and human data suggest that zinc deficiency occurs early in the course of ALD, we treat most ALD patients with daily oral zinc supplementation (220 mg zinc sulfate which contains 50 mg elemental zinc).

Apparent zinc absorption and zinc status of weanling rats fed moderately zinc-deficient diets enriched with beef tallow or sunflower oil

The aim of the study was to compare apparent Zn absorption and Zn status of weanling rats fed diets that differed in Zn level, fat level and fat source. Semi-synthetic diets, which were about isoenergetic and contained 3% soyabean oil, were supplemented with 7 or 100 mg Zn/kg to create a mild Zn deficiency (LZ) or a high Zn supply (HZ) and with 0 (LF), 22% beef tallow (BT) or 22% sunflower oil (SF) according to a 2 × 3 factorial design of treatments. They were fed ad libitum to 6 × 8 rats for 28 days. Energy intake and growth rates were comparable among the HZ groups. Weight gains in the LZ-LF, LZ-BT and LZ-SF groups averaged 5.54, 4.95 and 4.15 g/day, and apparent Zn absorption averaged 79.4, 60.3 and 48.0 μg Zn/day, respectively, whereas faecal Zn excretion was comparable among these groups. Apparent Zn absorption, and plasma and femur Zn concentrations were lower in the high-fat groups than in the LF group, possibly due to the high cellulose content of the BT and SF diets. Plasma Zn concentrations were higher in the animals fed the BT-based than in the SF-based diets, whereas femur and soft tissue Zn concentrations were comparable among these groups. The differences between the LZ-BT and LZ-SF groups in growth rate, Zn absorption rate and Zn status were confirmed in a second experiment. The results indicate that moderately Zn-deficient diets enriched with SF in relation to BT affect Zn metabolism of weanling rats by a yet unknown mechanism.

Consumption of a moderately Zn-deficient and Zn-supplemented diet affects soluble protein expression in rat soleus muscle

Zinc deficiency negatively affects muscle function, but there are limited biochemical data identifying the cause of this reduction in function. The objective of the present study was to identify soluble proteins in rat soleus muscle that were responsive to different levels of dietary zinc. Rats (n=21) were fed diets containing three concentrations of zinc: 5, 30 and 200 ppm for 42 days. There was no difference in body weights of the rats consuming the 5-ppm zinc diet compared to the rats consuming the 30- or 200-ppm zinc diets; however, bone zinc levels were significantly decreased in the 5-ppm dietary zinc group. Individual soluble protein fractions were isolated from these muscles and the samples were prepared for two-dimensional polyacrylamide gel electrophoresis. The expression levels of four proteins were significantly depressed by dietary Zn depletion and supplementation, S-glutathiolated carbonic anhydrase, myosin light polypeptide 3, heat shock protein 20 and heart fatty acid binding protein. This is the first report that indicates that both Zn depletion and supplementation result in protein expression profiles that may negatively affect skeletal muscle function. These results indicate that there are specific signaling pathways that require proper Zn nutriture for maintaining optimal muscle function and suggest that the consumption of pharmacologic doses of Zn may be detrimental to muscle function.

Metallothionein in mice reduces intestinal zinc loss during acute endotoxin inflammation, but not during starvation or dietary zinc restriction

Normal metallothionein [(MT)+/+] and MT-null (MT-/-) mice were used to examine the influence of MT on Zn retention and the metabolic consequences of 2 d food deprivation, with and without inflammation induced by intraperitoneal injection of bacterial endotoxin lipopolysaccharide (LPS). LPS reduced fecal Zn concentration in MT+/+ mice from 5.9 +/- 0.2 micromol/g on d 1 to 2.2 +/- 0.2 micromol/g on d 2, but not in MT-/- mice, 5.9 +/- 0.2 and 5.7 +/- 0. 5 micromol/g, respectively. MT+/+ mice fed an 8 mg Zn/kg diet and injected with LPS excreted 40% less Zn over 2 d than their MT-/- counterparts. Starvation for 2 d did not lower fecal Zn concentration in either genotype, although in MT+/+ mice, urinary Zn excretion was reduced from 12.7 +/- 1.3 nmol on d 1 to 5.9 +/- 1.8 nmol on d 2 and plasma Zn concentration was lowered to 9.8 +/- 0.4 micromol/L. Zn was not reduced in urine or plasma of MT-/- mice, with respective values of 10.8 +/- 2.0 nmol on d 1, 9.3 +/- 2.9 nmol on d 2 and 13.0 +/- 1.0 micromol/L. LPS injection resulted in much higher total liver Zn (677 +/- 27 nmol) and MT (106 +/- 2 nmol Cd bound/g) than starvation (Zn = 405 +/- 21, MT = 9 +/- 3) in MT+/+ mice after 2 d, but did not further reduce urinary Zn. LPS-injected MT-/- mice had no rise in liver Zn or fall in plasma and urine Zn. MT-/- mice fed a Zn-deficient (0.8 mg Zn/kg) diet lost 10% of body weight over 25 d compared with no loss in MT+/+ mice. Despite this, MT-/- mice excreted no more Zn via the gut than did MT+/+ mice. In summary, MT inhibits intestinal Zn loss when highly expressed. When uninduced, typically during Zn deficiency, MT appears to conserve Zn and body mass by reducing only urinary and other nonintestinal Zn losses.

Effects of magnesium and zinc deficiencies on growth and protein synthesis in skeletal muscle and the heart

The effects of magnesium or zinc deficiency on growth, tissue contents of Mg or Zn and protein synthesis have been compared in 4-13-week-old rats. When maintained on Mg-deficient fodder (1.6 mmol/kg) or Zn-deficient fodder (27 mumol/kg) rats showed a reduced weight gain, whereas repletion caused increased growth rates. Pair-feeding experiments showed that this could not be attributed to reduced energy intake only. In rats maintained on Mg-deficient fodder for 14 d [3H] leucine incorporation into skeletal muscle and the heart was reduced by 24-38% compared with pair-fed controls (P less than 0.001-0.002). The incorporation of [3H]phenylalanine was reduced by 19-31%. Tissue Mg contents, however, were only reduced by 6-7% (not significant). The pair-fed rats showed no reduction in the [3H]leucine incorporation compared with ad lib.-fed animals. In rats maintained on Zn-deficient fodder for 15 d [3H]leucine incorporation into skeletal and heart muscle was reduced by 57-64% compared with pair-fed controls. The pair-fed rats showed no reduction in the [3H]leucine incorporation compared with ad lib. fed animals. In the Zn-deficient animals the content of Zn was not reduced in the skeletal muscles, whereas there was a small (15%) but significant loss of Zn in the heart. In another experiment, Zn depletion for 17 d caused a reduction in [3H]leucine incorporation of 35-41%. After 5 d of Zn repletion this defect was restored, and the [3H]leucine incorporation was above control level in the skeletal muscles. It is concluded that the intact organism is very sensitive to dietary Mg or Zn deficiency, and that the reduced growth and protein synthesis cannot easily be attributed to the reduction of tissue Mg or Zn content per se. This points to the existence of other control mechanisms mediating down-regulation of growth and protein synthesis in response to reduced dietary supplies and the ensuing drop in the plasma concentrations of Mg and Zn.

Role of insulin-like growth factor-1 and growth hormone in growth inhibition induced by magnesium and zinc deficiencies

Nutritional deficiencies of magnesium or zinc lead to a progressive and often marked growth retardation. We have evaluated the effect of Mg and Zn deficiency on growth, serum insulin-like growth factor-1 (s-IGF-1), growth hormone (s-GH) and insulin (s-insulin) in young rats. In 3-week-old rats maintained on Mg-deficient fodder for 12 d the weight gain was reduced by about 34%, compared with pair-fed controls. This was accompanied by a 44% reduction in s-IGF-1, while s-insulin showed no decrease. After 3 weeks on Mg-deficient fodder, growth had ceased while serum Mg (s-Mg) and s-IGF-1 were reduced by 76 and 60% respectively. Following repletion with Mg, s-Mg was completely normalized in 1 week, and s-IGF-1 reached control level after 2 weeks. Growth rate increased, but the rats had failed to catch up fully in weight after 3.5 weeks. Absolute and relative pair-feeding were compared during a Mg repletion experiment. Absolute pair-fed animals were given the same absolute amount of fodder as the Mg-deficient rats had consumed the day before. Relative pair-fed animals were given the same amount of fodder, on a body-weight basis, consumed in the Mg-deficient group the day before. In a repletion experiment the two methods did not differ significantly from each other with respect to body-weight, muscle weight, tibia length and s-IGF-1, although there was a tendency towards higher levels in the relative pair-fed group. The peak in s-GH after growth hormone-releasing factor 40 (GRF 40) was 336 (SE 63) micrograms/l in 5-week-old rats that had been Mg depleted for 14 d, whereas age-matched control animals showed a peak of 363 (SE 54) micrograms/l (not significant). In 3-week-old rats maintained on Zn-deficient fodder for 14 d weight gain was reduced by 83% compared with pair-fed controls. Serum Zn (s-Zn) and s-IGF-1 were reduced by 80 and 69% respectively, while s-insulin was reduced by 66%. The Zn-deficient animals showed a more pronounced growth inhibition than that seen during Mg deficiency and after 17 d on Zn-deficient fodder s-IGF-1 was reduced by 83%. Following repletion with Zn, s-Zn was normalized and s-IGF-1 had increased by 194% (P less than 0.05) after 3 d. s-IGF-1, however, was not normalized until after 2.5 weeks of repletion.(ABSTRACT TRUNCATED AT 400 WORDS)

Plasma zinc concentrations during the first 2 years after diagnosis of insulin-dependent diabetes mellitus: a prospective study

Studies of zinc status in insulin-dependent diabetes mellitus (IDDM) have shown contradictory results. Zinc is essential for many enzymes involved in the human metabolism and may play a role in the biosynthesis and storage of insulin in the B-cell. We therefore prospectively followed 26 patients (14 males and 12 females) with newly diagnosed IDDM in order to determine the plasma zinc variation at the time of diagnosis and after 1, 3, 6, 12 and 24 months. Seventy-two healthy persons (36 males and 36 females) served as controls. Only minor differences in plasma zinc were demonstrated during the first 2 years of IDDM. A sex difference was found in healthy controls but only after 24 months in the diabetics. Quantitative changes of the B-cell function, development of insulin antibodies, age, body weight and serum albumin did not correlate with the course of plasma zinc.

Role of zinc in regulating the testicular function. Part 1. Effect of dietary zinc deficiency on serum levels of gonadotropins, prolactin and testosterone in male albino rats

Hypogonadism is a major manifestation of zinc deficiency in both humans and animals. In this study, we try to elucidate the main role of zinc in regulating the testicular function. Ninety male weanling albino rats were divided into three groups: control, zinc-deficient (ZD), and zinc-supplemented (ZS) groups. Six rats from each group were sacrificed every two weeks over a total period of ten weeks. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone (T) were estimated by radioimmunoassay technique. Serum zinc concentrations were also determined. Data revealed that serum zinc concentrations were significantly low in ZD group compared to both control and ZS groups. Normal FSH and LH but low PRL and T levels were demonstrated in sera of ZD group compared to both control and ZS groups. We came to the following conclusions: zinc deficiency has no effect on the pituitary gonadotropin output. Zinc deficiency affects the testicular function either directly through its effect on the testicular steroidogenesis and/or indirectly through its effect on the pituitary synthesis and/or secretion of PRL.

Altered tissue content of trace metals in diabetic hyperinsulinaemic sand rats (Psammomys obesus)

The concentrations of zinc, copper, and chromium in liver, kidney, muscle, bone and serum from control normoinsulinaemic and hyperinsulinaemic sand rats (Psammomys obesus) and from untreated spontaneously hyperinsulinaemic-hyperglycaemic sand rats were compared. A chronic hyperinsulinaemic-hyperglycaemic state was associated with a significant reduction (p less than 0.01) of zinc concentration in the liver, kidney and muscle but an elevation of zinc content in bone and of chromium in the liver. A hyperinsulinaemic-nor-moglycaemic state was not associated with similar changes in zinc concentration in the liver, kidney, muscle and bone. We conclude that in hyperinsulinaemic-hyperglycaemic sand rats there is a tendency to zinc depletion in several tissues. This depletion is not solely the result of a hyperinsulinaemic state but may be related to accompanying hyperglycaemia.

The effects of severe zinc deficiency on protein turnover in muscle and thymus

Measurements have been made of protein turnover, RNA and DNA in thymus and skeletal muscle from rats fed on a zinc-deficient diet (ZD) for 10 and 17 d, in pair-fed controls (CI) and in muscle from rats fed on the ZD diet for 24 d and then fed on restricted amounts of the deficient diet with (RIZS) or without (RIZD) Zn supplementation, for 8 d. In thymus the ZD diet induced a loss of DNA and protein which was not observed with the CI rats. Accumulation of RNA was less affected but protein synthesis was reduced. In muscle the accumulation of DNA and protein was slowed by the ZD diet, particularly in glycolytic muscles compared with oxidative muscles, and Zn supplementation increased DNA and protein. Protein synthesis and RNA concentrations were reduced in the ZD rats compared with the CI rats, but Zn supplementation at constant restricted food intake did not increase protein synthesis. Muscle protein synthesis per unit RNA varied markedly in the ZD rats after 10 d when the characteristic cycling of the food intakes and body-weight was most pronounced, the highest values being observed in the anabolic phase of the cycle although these were less than values for well-fed controls. The variability was inversely correlated with the plasma Zn levels. The extent of the variability was much less after 17 d and was not apparent in the food-restricted ZD animals. Protein degradation in muscle, assessed as the difference between overall and net protein synthesis, was faster in the ZD rats compared with the CI rats and fluctuated considerably, partly accounting for the cyclic changes in muscle after 10 d, and was entirely responsible after 17 d. The concentration of muscle-free 3-methylhistidine and its urinary excretion rate indicated inconsistent results which could not be satisfactorily interpreted. Plasma insulin was reduced in the ZD rats compared with the CI rats and was insensitive to food intake in contrast to urinary corticosterone excretion which was inversely correlated with the cyclic changes in body-weight and food intake. Furthermore, adrenalectomized rats exhibited increased mortality and reduced cycling of body-weight and food intake. Thus Zn deficiency impairs growth by a combination of reduced food intake, a reduced anabolic response to food due to a reduced capacity for protein synthesis and reduced activation of protein synthesis, possibly reflecting impaired insulin secretion, and an increased catabolic response to the reduced intake in which corticosterone may play a role.

Changes in zinc metabolism following exercise in human subjects

Changes in zinc (Zn) availability in muscle tissue that influence muscle performance in vitro have been observed. The effect of exercise of plasma Zn levels and urinary excretion of Zn was observed in sever untrained volunteers following brief intensive exercise and in seven trained volunteers after more prolonged road-running exercise. With brief exercise, plasma Zn decreased predominantly in the more loosely bound albumin fraction. Prolonged exercise resulted in a greater plasma Zn decrease of 30%. Urinary Zn excretion increased transiently with minimal effect on daily losses. However, weight loss by sweating was significant, and sweat Zn losses were greater than those in the urine. Exercise resulted in changes in Zn metabolism that may influence performance.

Growth and zinc homeostasis in the severely Zn-deficient rat

Male weanling rats were fed on diets either adequate (55 mg/kg), or severely deficient (0.4 mg/kg) in zinc, either ad lib. or in restricted amounts in four experiments. Measurements were made of growth rates and Zn contents of muscle and several individual tissues. Zn-deficient rats exhibited the expected symptoms of deficiency including growth retardation, cyclic changes in food intake and body-weight. Zn deficiency specifically reduced whole body and muscle growth rates as indicated by the fact that (a) growth rates were lower in ad lib.-fed Zn-deficient rats compared with rats pair-fed on the control diet in two experiments, (b) Zn supplementation increased body-weights of Zn-deficient rats given a restricted amount of diet at a level at which they maintained weight if unsupplemented, (c) Zn supplementation maintained body-weights of Zn-deficient rats fed a restricted amount of diet at a level at which they lost weight if unsupplemented (d) since the ratio, muscle mass: body-weight was lower in the Zn-deficient rats than in the pair-fed control groups, the reduction in muscle mass was greater than the reduction in body-weight. Zn concentrations were maintained in muscle, spleen and thymus, reduced in comparison to some but not all control groups in liver, kidney, testis and intestine, and markedly reduced in plasma and bone. In plasma, Zn concentrations varied inversely with the rate of change of body-weight during the cyclic changes in body-weight. Calculation of the total Zn in the tissues examined showed a marked increase in muscle Zn with a similar loss from bone, indicating that Zn can be redistributed from bone to allow the growth of other tissues. The magnitude of the increase in muscle Zn in the severely Zn-deficient rat, together with the magnitude of the total losses of muscle tissue during the catabolic phases of the cycling, indicate that in the Zn-deficient rat Zn may be highly conserved in catabolic states.

Changes in plasma zinc content after exercise in men fed a low-zinc diet

For 30 days five healthy men aged 23-57 yr consumed a diet adequate in zinc (8.6 mg/day); they ate a low-zinc diet (3.6 mg/day) for the next 120 days and then received a zinc-supplemented (33.6 mg/day) diet for 30 days. Copper intake was constant at 1.8 mg/day. Aerobic capacity was determined periodically during each diet period. Relative zinc balance (% of control) declined during depletion (r = -0.28, P less than 0.009). Pre- and postexercise zinc concentrations decreased when dietary zinc was restricted (r = -0.61, P less than 0.0001 and r = -0.78, P less than 0.0001) and increased with supplementation (r = 0.61, P less than 0.008 and r = 0.76, P less than 0.0003, respectively). Both plasma zinc and hematocrit increased (P less than 0.01) after maximal exercise. To minimize the effect of hemoconcentration during exercise, the van Beaumont quotient (J. Appl. Physiol. 34: 102-106, 1973) was calculated using pre- and postexercise hematocrit and plasma zinc. The initial quotient of 1.8 +/- 1.8% (mean +/- SE) declined (P less than 0.05) to -7.4 +/- 2.3% during depletion. With zinc repletion, the quotient increased to 6.9 +/- 3.6%, which was greater (P less than 0.05) than the quotient in depletion but similar to the initial quotient. The quotient was a strong predictor (r = 0.71, P less than 0.0005) of the change in relative zinc balance during zinc depletion. In contrast, no changes were found in plasma copper content. These data suggest that zinc mobilization from tissues is impaired during zinc depletion, and they validate the use of the van Beaumont quotient as an index of change in body zinc stores.

Zinc metabolism in normal and zinc-deficient rat brain

Zinc uptake and turnover was measured in nine brain regions, choroid plexus, arachnoid, and cerebrospinal fluid during a 28-day period following a single dose of 65Zn in rats fed Zn-adequate diets. Zinc entry into brain was slow with maximal 65Zn uptake (0.5% of administered dose) occurring between 5 and 14 days in contrast to its rapid metabolism in plasma and nonneural tissues. The brain stem, at the level of the caudal IV ventricle, had the highest rate of initial 65Zn uptake of any brain region. In general, turnover was most rapid in periventricular regions and least in the hippocampus. Relative to plasma, the choroid plexus concentrated 65Zn whereas 65Zn was undetectable in the cerebrospinal fluid after day 1. To determine if specific brain regions were particularly sensitive to changes in Zn status, 65Zn metabolism was measured in Zn-deficient rats and compared with ad libitum- and pair-fed controls. Zinc deficiency was associated with increased 65Zn retention by all brain regions; however, the effect was greatest in optic nerve and choroid plexus. The results of this study suggest that a formidable barrier to Zn entry into brain exists but is under homeostatic control, increasing net Zn uptake during dietary deficiency. Moreover, the choroid plexus may participate in cerebral Zn homeostasis, possibly by transporting Zn out of the cerebrospinal fluid compartment.

Zinc deficiency and anorexia in rats: normal feeding patterns and stress induced feeding

We report the effects of zinc deficiency on normal feeding behavior in rats and the effects of zinc deficiency on stress-induced eating in rats. Zinc deficient (ZD) rats weighed significantly less than their pair-fed and ad lib controls. Zinc repletion allowed improved growth, but ZD rats never displayed catch-up growth compared to their ad lib controls. ZD rats rapidly developed a depressed food efficiency ratio which normalized with zinc supplementation. Food consumption in ZD rats was approximately one-third that of ad lib controls and water intake was also significantly reduced. Mild tail pinch was able to induce feeding in these normally anorexic ZD rats. We conclude that zinc deficiency represents an interesting model of anorexia which may enhance our understanding of appetite regulation.

Zinc deficiency and anorexia in rats: the effect of central administration of norepinephrine, muscimol and bromerogocryptine

Anorexia is a major manifestation of zinc deficiency, but the mechanism(s) for this anorexia are not well defined. In this study we investigated the effects of three modulators of feeding response on the food consumption of zinc deficient rats. Zinc deficient rats showed partial resistance to norepinephrine, eating significantly less at the 20 micrograms dose than the zinc sufficient ad lib controls, and food ingestion could not be induced at the 10 micrograms dose. Similarly, higher doses of the GABA agonist, muscimol, were required to induce feeding in the zinc deficient animals compared to the zinc sufficient controls. The dopamine agonist, bromergocryptine, failed to induce feeding in the zinc deficient animals. These findings are compatible with the concept that zinc deficiency produces a generalized decrease in receptor responsibility, possibly secondary to alterations in membrane fluidity.

The role of the endogenous opiates in zinc deficiency anorexia

Anorexia is a major symptom of zinc deficiency, but the mechanism(s) for this anorexia are poorly defined. Recent studies have suggested an integral role for endogenous opiate peptides in appetite regulation. Dynorphin, a leucine-enkephalin containing opiate peptide, is a potent inducer of spontaneous feeding. In this study we showed that zinc deficient animals were relatively resistant to dynorphin-induced feeding. Measurement of dynorphin levels using a highly sensitive radioimmunoassay showed that zinc deficient animals had lower levels of dynorphin in the hypothalamus than did ad lib fed animals, with weight restricted animals having intermediate values. [3H]-naloxone binding was significantly increased to isolated brain membranes from zinc deficient animals using 1 nM unlabeled naloxone when compared to ad lib fed controls with the weight restricted animals again having intermediate values. These data suggest that abnormalities in endogenous opiate regulation of appetite may well play a role in the anorexia of zinc deficiency. The effects of zinc deficiency on endogenous opiate action appear to include alterations in receptor affinity, a post-receptor defect and alterations in the synthesis and/or release of dynorphin.

Leukocyte zinc in the assessment of zinc status

The problems of assessment of human zinc status are reviewed, with particular emphasis on the limitations to each of the current available measurements. The advantages and limitations of leukocytes are then described. Methods of preparation and potential problems in the assay for zinc are described in detail. The data so-far produced by this method are reviewed.

Effect of zinc deficiency on muscle fibre type frequencies in the post-weanling rat

Male weanling rats were maintained on diets either deficient or adequate in zinc for a period of 4 weeks. The rats on the deficient diet showed a reduction in food intakes and growth. After 4 weeks both soleus muscles and the lateral portion of the diaphragm were studied histochemically to examine the relative frequencies of the fibre types. The soleus muscles of the deficient animals showed a significant change in the proportion of slow and fast fibres. The diaphragm muscles of the deficient animals had a significant increase in the proportion of fast-twitch oxidative glycolytic fibres and a significant decrease in fast-twitch glycolytic fibres compared with the controls. Stainable lipid increased in the diaphragm muscle of the deficient animals with respect to their pair-fed controls.

Trace metal abnormalities in adults during hyperalimentation

Trace metal deficiencies are now a well-documented complication of total parenteral nutrition (TPN). Zinc deficiency may present in a variety of ways including acrodermatitis skin lesions, impaired immunity, poor growth or impaired wound healing, and mental disturbances. Copper deficiency presents a more uniform picture of hematologic abnormalities, usually anemia with leukopenia and neutropenia. Chromium and selenium deficiencies occur much less frequently, but well-documented cases have been reported. We currently recommended regular monitoring and supplementation of these four trace metals during TPN administration. This article describes the clinical abnormalities that may develop when deficiencies of trace metals occur during TPN administration, and we present recommendations for trace metal supplementation during TPN administration.

Ileal Paneth cells and IgA system in rats with severe zinc deficiency: an immunohistochemical and morphological study

Morphological abnormalities in Paneth cells occur in patients with acrodermatitis enteropathica, a hereditary disease associated with zinc deficiency; furthermore, rat Paneth cells contain large amounts of zinc. This study was conducted to assess the effect of severe zinc deficiency in Sprague-Dawley rats on various parameters of Paneth cells. Morphology at both the light microscopical and ultrastructural levels, Paneth cell numbers per crypt and the intracellular distribution of lysozyme were not altered by zinc deficiency. A weak correlation (r = +0.38, P = 0.05) was noted between ileal zinc concentration and numbers of IgA-containing Paneth cells per crypt. These findings indicate that the morphological abnormalities noted in human Paneth cells in patients with acrodermatitis enteropathica cannot be reproduced by experimental severe zinc deficiency in rats. Furthermore, these generally negative findings suggest that the severe diarrhoea often associated with zinc deficiency is not attributable to abnormalities induced in Paneth cells by zinc deficiency.