Wheat Germ Supplementation Reduces Inflammation and Gut Epithelial Barrier Dysfunction in Female Interleukin-10 Knockout Mice Fed a Pro-Atherogenic Diet.

BACKGROUND: Mice lacking IL-10 are prone to gut inflammation. Additionally, decreased production of short-chain fatty acids (SCFAs) plays a significant role in the high-fat (HF) diet-induced loss of gut epithelial integrity. We have previously shown that wheat germ (WG) supplementation increased ileal expression of IL-22, an important cytokine in maintaining gut epithelial homeostasis. OBJECTIVES: This study investigated the effects of WG supplementation on gut inflammation and epithelial integrity in IL-10 knockout mice fed a pro-atherogenic diet. METHODS: Eight-week-old female C57BL/6 wild type mice were fed a control diet (10% fat kcal), and age-matched knockout mice were randomly assigned to 1 of 3 diets (n = 10/group): control, high-fat high-cholesterol (HFHC) [(43.4% fat kcal (∼49% saturated fat, 1% cholesterol)], or HFHC + 10% WG (HFWG) for 12 wk. Fecal SCFAs and total indole, ileal, and serum proinflammatory cytokines, gene or protein expression of tight junctions, and immunomodulatory transcription factors were assessed. Data were analyzed by 1-way ANOVA, and P < 0.05 was considered statistically significant. RESULTS: Fecal acetate, total SCFAs, and indole increased (P < 0.05) by at least 20% in HFWG compared with the other groups. WG increased (P < 0.0001, 2-fold) ileal Il22 (interleukin 22) to Il22ra2 (interleukin 22 receptor, alpha 2) mRNA ratio and prevented the HFHC diet-mediated increase in ileal protein expression of indoleamine 2,3 dioxygenase and pSTAT3 (phosphorylated signal transducer and activator of transcription 3). WG also prevented the HFHC diet-mediated reduction (P < 0.05) in ileal protein expression of the aryl hydrocarbon receptor and the tight junction protein, zonula occludens-1. Serum and ileal concentrations of the proinflammatory cytokine, IL-17, were lower (P < 0.05) by at least 30% in the HFWG group than in the HFHC group. CONCLUSIONS: Our findings demonstrate that the anti-inflammatory potential of WG in IL-10 KO mice consuming an atherogenic diet is partly attributable to its effects on the IL-22 signaling and pSTAT3-mediated production of T helper 17 proinflammatory cytokines.

Vitamin D binding protein gene polymorphisms are associated with lower plasma 25-hydroxy-cholecalciferol concentrations in Ethiopian lactating women.

Ethiopian women have been reported to have low plasma 25-hydroxy-cholecalciferol (25(OH)D) concentrations despite an abundance of sunshine. Low dietary vitamin D intake, limited skin exposure to sun, and genetics are among factors suggested to affect vitamin D status in this population. In this study (Clinical Trial NCT02210884), we hypothesized that polymorphisms in the vitamin D binding protein (VDBP) gene (rs7041, rs4588) are associated with reduced plasma 25(OH)D concentrations in Ethiopian women. Lactating Ethiopian women (n = 110) were randomly assigned to weekly administration of vitamin D3 (15,000 IU) or a placebo. Plasma 25(OH)D was measured at baseline (within 2 weeks of delivery, before supplementation) and at 3, 6, and 12 months after delivery. Associations between VDBP polymorphism status for rs7041 and rs4588 and plasma 25(OH)D were determined by analysis of variance and multiple linear and logistic regressions. Multiple linear regression with maternal age as a covariate revealed that rs7041 is associated with reduced plasma 25(OH)D (P = .021) and more risk alleles at rs7041 and rs4588 are associated with reduced plasma 25(OH)D (P = .017). Logistic regression models for vitamin D insufficiency showed that additional risk alleles for rs7041 and rs4588 are associated with increased odds ratios (OR = 1.66; 95% CI, 1.10-2.62; P = .019) for plasma 25(OH)D below 40 nmol/L. Supplementation increased plasma 25(OH)D at 3 months in women with fewer risk alleles and across all genotypes at 6 and 12 months. VDBP polymorphisms may contribute to vitamin D insufficiency in Ethiopian lactating women. Furthermore, VDBP polymorphisms may blunt short-term responses to vitamin D supplementation and require longer periods of intervention.

Pyrroloquinoline-Quinone Is More Than an Antioxidant: A Vitamin-like Accessory Factor Important in Health and Disease Prevention.

Pyrroloquinoline quinone (PQQ) is associated with biological processes such as mitochondriogenesis, reproduction, growth, and aging. In addition, PQQ attenuates clinically relevant dysfunctions (e.g., those associated with ischemia, inflammation and lipotoxicity). PQQ is novel among biofactors that are not currently accepted as vitamins or conditional vitamins. For example, the absence of PQQ in diets produces a response like a vitamin-related deficiency with recovery upon PQQ repletion in a dose-dependent manner. Moreover, potential health benefits, such as improved metabolic flexibility and immuno-and neuroprotection, are associated with PQQ supplementation. Here, we address PQQ's role as an enzymatic cofactor or accessory factor and highlight mechanisms underlying PQQ's actions. We review both large scale and targeted datasets demonstrating that a neonatal or perinatal PQQ deficiency reduces mitochondria content and mitochondrial-related gene expression. Data are reviewed that suggest PQQ's modulation of lactate acid and perhaps other dehydrogenases enhance NAD+-dependent sirtuin activity, along with the sirtuin targets, such as PGC-1α, NRF-1, NRF-2 and TFAM; thus, mediating mitochondrial functions. Taken together, current observations suggest vitamin-like PQQ has strong potential as a potent therapeutic nutraceutical.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs.

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Deficiency of ß-carotene oxygenase 2 induces mitochondrial fragmentation and activates the STING-IRF3 pathway in the mouse hypothalamus.

Hypothalamic inflammation has been linked to various aspects of central metabolic dysfunction and diseases in humans, including hyperphagia, altered energy expenditure, and obesity. We previously reported that loss of ß-carotene oxygenase 2 (BCO2), a mitochondrial inner membrane protein, causes the alteration of the hypothalamic metabolome, low-grade inflammation, and an increase in food intake in mice at an early age, e.g., 3-6 weeks. Here, we determined the extent to which the deficiency of BCO2 induces hypothalamic inflammation in BCO2 knockout mice. Mitochondrial proteomics, electron microscopy, and immunoblotting were used to assess the changes in hypothalamic mitochondrial dynamics and mitochondrial DNA sensing and signaling. The results showed that deficiency of BCO2 altered hypothalamic mitochondrial proteome and respiratory supercomplex assembly by enhancing the expression of NADH:ubiquinone oxidoreductase subunit A11 protein and improved cardiolipin synthesis. BCO2 deficiency potentiated mitochondrial fission but suppressed mitophagy and mitochondrial biogenesis. Furthermore, deficiency of BCO2 resulted in inactivation of mitochondrial MnSOD enzyme, excessive production of reactive oxygen species, and elevation of protein levels of stimulator of interferon genes (STING) and interferon regulatory factor 3 (IRF3) in the hypothalamus. The data suggest that BCO2 is essential for hypothalamic mitochondrial dynamics. BCO2 deficiency induces mitochondrial fragmentation and mitochondrial oxidative stress, which may lead to mitochondrial DNA release into the cytosol and subsequently sensing by activation of the STING-IRF3 signaling pathway in the mouse hypothalamus.

Pinto beans modulate the gut microbiome, augment MHC II protein, and antimicrobial peptide gene expression in mice fed a normal or western-style diet.

The onset of type 2 diabetes in obesity is associated with gut dysbiosis and a failure to confine commensal bacteria and toxins to the gut lumen while prebiotics may prevent these effects. This study evaluated the effects of pinto beans (PB) supplementation on cecal bacteria, short-chain fatty acids (SCFAs), distal ileal antigen presentation marker (major histocompatibility complex [MHC] II) and antimicrobial peptide genes during short-term high-fat, high sucrose (HFS) feeding. Six-week-old, male C57BL/6J mice were randomly assigned to four groups (n=12/group), and fed a control (C) or HFS diet with or without cooked PB (10%, wt/wt) for 30 days. Supplemental PB in both the C and HFS diets decreased the abundance of Tenericutes and the sulfate-reducing bacteria Bilophila. In contrast, PB raised the abundance of taxa within the SCFAs-producing family, Lachnospiraceae, compared to groups without PB. Consequently, fecal butyric acid was significantly higher in PB-supplemented groups compared to C and HFS groups. PB reversed the HFS-induced ablation of the distal ileal STAT3 phosphorylation, and up-regulated antimicrobial peptide genes (Reg3γ and Reg3ß). Furthermore, the expression of MHC II protein was elevated in the PB supplemented groups compared to C and HFS. Tenericutes and Bilophilia negatively correlated with activated STAT3 and MHC II proteins. Finally, supplemental PB improved fasting blood glucose, glucose tolerance and suppressed TNFα and inducible nitric oxide synthase mRNA in the visceral adipose tissue. Put together, the beneficial impact of PB supplementation on the gut may be central to its potential to protect against diet-induced inflammation and impaired glucose tolerance.

Astaxanthin-Shifted Gut Microbiota Is Associated with Inflammation and Metabolic Homeostasis in Mice.

BACKGROUND: Astaxanthin is a red lipophilic carotenoid that is often undetectable in human plasma due to the limited supply in typical Western diets. Despite its presence at lower than detectable concentrations, previous clinical feeding studies have reported that astaxanthin exhibits potent antioxidant properties. OBJECTIVE: We examined astaxanthin accumulation and its effects on gut microbiota, inflammation, and whole-body metabolic homeostasis in wild-type C57BL/6 J (WT) and ß-carotene oxygenase 2 (BCO2) knockout (KO) mice. METHODS: Six-wk-old male and female BCO2 KO and WT mice were provided with either nonpurified AIN93M (e.g., control diet) or the control diet supplemented with 0.04% astaxanthin (wt/wt) ad libitum for 8 wk. Whole-body energy expenditure was measured by indirect calorimetry. Feces were collected from individual mice for short-chain fatty acid assessment. Hepatic astaxanthin concentrations and liver metabolic markers, cecal gut microbiota profiling, inflammation markers in colonic lamina propria, and plasma samples were assessed. Data were analyzed by 3-way ANOVA followed by Tukey's post hoc analysis. RESULTS: BCO2 KO but not WT mice fed astaxanthin had ∼10-fold more of this compound in liver than controls (P < 0.05). In terms of the microbiota composition, deletion of BCO2 was associated with a significantly increased abundance of Mucispirillum schaedleri in mice regardless of gender. In addition to more liver astaxanthin in male KO compared with WT mice fed astaxanthin, the abundance of gut Akkermansia muciniphila was 385% greater, plasma glucagon-like peptide 1 was 27% greater, plasma glucagon and IL-1ß were 53% and 30% lower, respectively, and colon NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome activation was 23% lower (all P < 0.05) in male KO mice than the WT mice. CONCLUSIONS: Astaxanthin affects the gut microbiota composition in both genders, but the association with reductions in local and systemic inflammation, oxidative stress, and improvement of metabolic homeostasis only occurs in male mice.

Wheat Germ Supplementation Increases Lactobacillaceae and Promotes an Anti-inflammatory Gut Milieu in C57BL/6 Mice Fed a High-Fat, High-Sucrose Diet.

BACKGROUND: A link between high-fat diet consumption and obesity-related diseases is the disruption of the gut bacterial population, which promotes local and systemic inflammation. Wheat germ (WG) is rich in bioactive components with antioxidant and anti-inflammatory properties. OBJECTIVE: The aim of this study was to investigate the effects of WG supplementation in modulating the gut bacterial population and local and systemic inflammatory markers of mice fed a high-fat, high-sucrose (HFS) diet. METHODS: Six-week-old male C57BL/6 mice were randomly assigned to 4 groups (n = 12/group) and fed a control (C; 10% kcal fat, 10% kcal sucrose) or HFS (60% kcal fat, 20% kcal sucrose) diet with or without 10% WG (wt:wt) for 12 wk. Cecal bacteria was assessed via 16S rDNA sequencing, fecal short-chain fatty acids by GC, small intestinal CD4+ lymphocytes using flow cytometry, and gut antimicrobial peptide genes and inflammatory markers by quantitative polymerase chain reaction. Statistical analyses included Kruskal-Wallis/Dunn's test and 2-factor ANOVA using HFS and WG as factors. RESULTS: There was a 4-fold increase (P = 0.007) in the beneficial bacterial family, Lactobacillaceae, in the HFS + WG compared with the HFS group. Fecal propionic and n-butyric acids were elevated at least 2-fold in C + WG compared with the other groups (P < 0.0001). WG tended to increase (≥7%; P-trend = 0.12) small intestinal regulatory T cell:Th17 ratio, indicating a potential to induce an anti-inflammatory gut environment. WG elevated (≥35%) ileal gene expression of the anti-inflammatory cytokine Il10 compared to the unsupplemented groups (P = 0.038). Ileal gene expression of the antimicrobial peptides Reg3b and Reg3g was upregulated (≥95%) in the HFS + WG compared with other groups (P ≤ 0.040). WG reduced serum concentrations of the pro-inflammatory cytokines, interleukin (IL)-1B, IL-6, interferon-γ, and tumor necrosis factor-α (≥17%; P ≤ 0.012). CONCLUSIONS: WG selectively increased gut Lactobacillaceae, upregulated ileal antimicrobial peptides, and attenuated circulating pro-inflammatory cytokines of C57BL/6 mice fed a HFS diet. These changes may be vital in preventing HFS diet-induced comorbidities.

Ablation of ß,ß-carotene-9',10'-oxygenase 2 remodels the hypothalamic metabolome leading to metabolic disorders in mice.

ß,ß-Carotene-9',10'-oxygenase 2 (BCO2) is a protein localized to the inner membrane of mitochondria. It was initially discovered as an enzyme that catalyzes the asymmetric cleavage of carotenoids. Systemic depletion of BCO2 causes increased food intake and impaired hepatic lipid metabolism in mice. The aim of this current study was to determine the extent to which BCO2 exerts its role in hypothalamic nutrient metabolism and feeding behavior through remodeling the hypothalamic metabolome in mice. Male BCO2 knockout (KO) and the isogenic wild-type 129S6 (WT) mice at 6 weeks of age were used for metabolic and cytokine and hypothalamic metabolomics and biochemical analysis. Compared to the WT, BCO2 KO mice exhibited widespread disruptions in metabolism and metabolite homeostasis, an increase in fasting blood glucose, a decrease in circulating glucagon and leptin, an elevation of plasma interleukin 1 beta and tumor necrosis factor alpha, and impaired AMP-activated protein kinase signaling. The global hypothalamic metabolomic results revealed that depletion of BCO2 resulted in striking metabolic changes, including suppression of long-chain fatty acids transport into mitochondria, inhibition of the metabolism of dipeptides and sulfur-containing amino acids, and stimulation of local oxidative stress and inflammation in the hypothalamus of BCO2 KO mice. These findings suggest that BCO2 regulates hypothalamic mitochondrial function, nutrient metabolism, and local oxidative stress and inflammation. Complex interplay between the hormone signaling and impaired lipid and glucose metabolism could account for initiation of oxidative stress, inflammation and eventual metabolic disorders in BCO2 KO mice.

Dietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects.

Pyrroloquinoline quinone (PQQ) influences energy-related metabolism and neurologic functions in animals. The mechanism of action involves interactions with cell signaling pathways and mitochondrial function. However, little is known about the response to PQQ in humans. Using a crossover study design, 10 subjects (5 females, 5 males) ingested PQQ added to a fruit-flavored drink in two separate studies. In study 1, PQQ was given in a single dose (0.2 mg PQQ/kg). Multiple measurements of plasma and urine PQQ levels and changes in antioxidant potential [based on total peroxyl radical-trapping potential and thiobarbituric acid reactive product (TBAR) assays] were made throughout the period of 48 h. In study 2, PQQ was administered as a daily dose (0.3 mg PQQ/kg). After 76 h, measurements included indices of inflammation [plasma C-reactive protein, interleukin (IL)-6 levels], standard clinical indices (e.g., cholesterol, glucose, high-density lipoprotein, low-density lipoprotein, triglycerides, etc.) and (1)H-nuclear magnetic resonance estimates of urinary metabolites related in part to oxidative metabolism. The standard clinical indices were normal and not altered by PQQ supplementation. However, dietary PQQ exposure (Study 1) resulted in apparent changes in antioxidant potential based on malonaldehyde-related TBAR assessments. In Study 2, PQQ supplementation resulted in significant decreases in the levels of plasma C-reactive protein, IL-6 and urinary methylated amines such as trimethylamine N-oxide, and changes in urinary metabolites consistent with enhanced mitochondria-related functions. The data are among the first to link systemic effects of PQQ in animals to corresponding effects in humans.

A zinc transporter gene required for development of the nervous system.

The essentiality of zinc for normal brain development is well established. It has been suggested that primary and secondary zinc deficiencies can contribute to the occurrence of numerous human birth defects, including many involving the central nervous system. In a recent study, we searched for zinc transporter genes that were critical for neurodevelopment. We confirmed that ZIP12 is a zinc transporter encoded by the gene slc39a12 that is highly expressed in the central nervous systems of human, mouse, and frog (Xenopus tropicalis).Using loss-of-function methods, we determined that ZIP12 is required for neuronal differentiation and neurite outgrowth and necessary for neurulation and embryonic viability. These results highlight an essential need for zinc regulation during embryogenesis and nervous system development. We suggest that slc39a12 is a candidate gene for inherited neurodevelopmental defects in humans.

Altering pyrroloquinoline quinone nutritional status modulates mitochondrial, lipid, and energy metabolism in rats.

We have reported that pyrroloquinoline quinone (PQQ) improves reproduction, neonatal development, and mitochondrial function in animals by mechanisms that involve mitochondrial related cell signaling pathways. To extend these observations, the influence of PQQ on energy and lipid relationships and apparent protection against ischemia reperfusion injury are described herein. Sprague-Dawley rats were fed a nutritionally complete diet with PQQ added at either 0 (PQQ-) or 2 mg PQQ/Kg diet (PQQ+). Measurements included: 1) serum glucose and insulin, 2) total energy expenditure per metabolic body size (Wt(3/4)), 3) respiratory quotients (in the fed and fasted states), 4) changes in plasma lipids, 5) the relative mitochondrial amount in liver and heart, and 6) indices related to cardiac ischemia. For the latter, rats (PQQ- or PQQ+) were subjected to left anterior descending occlusions followed by 2 h of reperfusion to determine PQQ's influence on infarct size and myocardial tissue levels of malondialdehyde, an indicator of lipid peroxidation. Although no striking differences in serum glucose, insulin, and free fatty acid levels were observed, energy expenditure was lower in PQQ- vs. PQQ+ rats and energy expenditure (fed state) was correlated with the hepatic mitochondrial content. Elevations in plasma di- and triacylglyceride and ß-hydroxybutryic acid concentrations were also observed in PQQ- rats vs. PQQ+ rats. Moreover, PQQ administration (i.p. at 4.5 mg/kg BW for 3 days) resulted in a greater than 2-fold decrease in plasma triglycerides during a 6-hour fast than saline administration in a rat model of type 2 diabetes. Cardiac injury resulting from ischemia/reperfusion was more pronounced in PQQ- rats than in PQQ+ rats. Collectively, these data demonstrate that PQQ deficiency impacts a number of parameters related to normal mitochondrial function.

Identification of transcriptional networks responding to pyrroloquinoline quinone dietary supplementation and their influence on thioredoxin expression, and the JAK/STAT and MAPK pathways.

PQQ (pyrroloquinoline quinone) improves energy utilization and reproductive performance when added to rodent diets devoid of PQQ. In the present paper we describe changes in gene expression patterns and transcriptional networks that respond to dietary PQQ restriction or pharmacological administration. Rats were fed diets either deficient in PQQ (PQQ-) or supplemented with PQQ (approx. 6 nmol of PQQ/g of food; PQQ+). In addition, groups of rats were either repleted by administering PQQ to PQQ- rats (1.5 mg of PQQ intraperitoneal/kg of body weight at 12 h intervals for 36 h; PQQ-/+) or partially depleted by feeding the PQQ- diet to PQQ+ rats for 48 h (PQQ+/-). RNA extracted from liver and a Codelink(R) UniSet Rat I Bioarray system were used to assess gene transcript expression. Of the approx. 10000 rat sequences and control probes analysed, 238 were altered at the P<0.01 level by feeding on the PQQ- diet for 10 weeks. Short-term PQQ depletion resulted in changes in 438 transcripts (P<0.01). PQQ repletion reversed the changes in transcript expression caused by PQQ deficiency and resulted in an alteration of 847 of the total transcripts examined (P<0.01). Genes important for cellular stress (e.g. thioredoxin), mitochondriogenesis, cell signalling [JAK (Janus kinase)/STAT (signal transducer and activator of transcription) and MAPK (mitogen-activated protein kinase) pathways] and transport were most affected. qRT-PCR (quantitative real-time PCR) and functional assays aided in validating such processes as principal targets. Collectively, the results provide a mechanistic basis for previous functional observations associated with PQQ deficiency or PQQ administered in pharmacological amounts.

Potential physiological importance of pyrroloquinoline quinone.

Pyrroloquinoline quinone (PQQ) is a novel biofactor for which a proposition can be made for physiological importance. PQQ was first recognized as an enzyme cofactor in bacteria. It has recently been tentatively identified as a component of interstellar dust. Thus, PQQ may have been present throughout early biological conception and evolution. PQQ is also a potent plant growth factor. Consequently, for animals and humans, there has been constant exposure to PQQ. In animals, PQQ is reported to participate in a range of biological functions with apparent survival benefits (e.g., improved neonatal growth and reproductive performance). There are also benefits from PQQ supplementation related to cognitive, immune, and antioxidant functions, as well as protection from cardiac and neurological ischemic events. Although PQQ is not currently viewed as a vitamin, its involvement in cell signaling pathways, particularly those important to mitochondriogenesis in experimental animal models, may eventually provide a rationale for defining PQQ as vital to life. For humans, such evidence suggests there may be similar parallels or benefits from improving PQQ status.

Identification of a mutation in SLC30A2 (ZnT-2) in women with low milk zinc concentration that results in transient neonatal zinc deficiency.

Breast milk normally contains adequate zinc to meet infant requirements up to six months of age; however, transient neonatal zinc deficiency has been documented in exclusively breastfed infants of women with low milk zinc concentration. This condition is not corrected by maternal zinc supplementation, supporting the speculation that it results from an inherited genetic condition. We identified a family in which two exclusively breast-fed infants developed zinc deficiency that was associated with low milk zinc concentration in both women. Sequencing of genomic DNA detected a mis-sense mutation (Ade-->Gua) that substitutes a conserved histidine at amino acid 54 with arginine (H54R) in SLC30A2 (ZnT-2) that is present in both affected subjects and several other siblings. Gene knockdown of SLC30A2 in mammary epithelial cells reduced zinc secretion, illustrating the role of ZnT-2 in zinc secretion from this cell type. Expression of the H54R mutant in human embryonic kidney-293 cells resulted in reduced zinc secretion as a consequence of perinuclear, aggresomal accumulation, whereas co-expression of the H54R mutant and wild-type ZnT-2 did not abrogate increased zinc secretion in cells overexpressing wild-type ZnT-2 alone. Together, these data provide evidence that low milk zinc concentration in some women is a consequence of a genetic disorder resulting from a mutation in SLC30A2 and can result in neonatal zinc deficiency if unrecognized. Further studies are needed to evaluate the incidence and penetrance of this mutation in the human population.

Effect of high dietary manganese intake of neonatal rats on tissue mineral accumulation, striatal dopamine levels, and neurodevelopmental status.

Mn is an essential element, but may become neurotoxic at high levels. Recent reports of high Mn levels in hair of children with neurodevelopmental deficits suggest that these deficits could be due to Mn-induced neurotoxic effects on brain dopamine (DA) systems, although the mechanism is not well understood. Infant formulas contain considerably higher concentrations of Mn than human milk. Thus, formula-fed infants are exposed to high levels of Mn at a time when Mn homeostasis is incompletely developed. We studied the effects of dietary Mn supplementation of rat pups on tissue Mn accumulation, brain dopamine levels, infant neurodevelopmental status, and behavior at maturity. Newborn rats were supplemented daily with 0, 50, 250, or 500 microg Mn given orally from day 1 to day 20. Mineral analysis of small intestine and brain at day 14 showed a significant increase of tissue Mn in supplemented rats. Neurodevelopmental tests conducted at various ages showed significant delays as a function of Mn supplementation. At day 32, there was a significant positive relationship between passive avoidance errors and Mn supplementation levels. Brains of animals killed on day 40 showed a significant inverse relationship between Mn supplementation level and striatal dopamine concentration. These observations suggest that dietary exposure to high levels of Mn during infancy can be neurotoxic to rat pups and result in developmental deficits.

Effects of neonatal dietary manganese exposure on brain dopamine levels and neurocognitive functions.

Neonatal exposure to high levels of manganese (Mn) has been indirectly implicated as a causal agent in attention deficit hyperactivity disorder (ADHD), since Mn toxicity and ADHD both involve dysfunction in brain dopamine (DA) systems. This study was undertaken to examine this putative relationship in an animal model by determining if levels of neonatal dietary Mn exposure were related to brain DA levels and/or behavioral tests of executive function (EF) when the animals reached maturity. We used 32 newborn male Sprague-Dawley rats and randomly assigned them to one of the four dietary Mn supplementation conditions: 0, 50, 250 and 500 microg per day, administered daily in water from postnatal days 1-21. During days 50-64, the animals were given a burrowing detour test and a passive avoidance test. At day 65, the animals were killed and brains were assayed for DA. There was a statistically significant relationship (P = 0.003) between dietary Mn exposure and striatal DA. On the burrowing detour and passive avoidance, greater deficits were observed for animals subjected to higher Mn exposure, but these differences did not reach statistical significance. However, tests for heterogeneity of variance between groups were statistically significant for all measures, with positive relationship between Mn exposure and degree of within-group behavioral variability. Kendall's nonparametric test of the relationship between the three behavioral measures and striatal DA levels was also statistically significant (P = 0.02). These results lend support to the hypothesis that neonatal Mn exposure is related to brain DA levels and neurocognitive deficit in the rodent.