Gennaro Giordano

University of Washington Seattle, Seattle, Washington, United States

Are you Gennaro Giordano?

Claim your profile

Publications (55)150.76 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants. Exposure to these chemicals has been associated with developmental neurotoxicity, endocrine dysfunction, and reproductive disorders. Humans and wildlife are generally exposed to a mixture of these environmental pollutants, highlighting the need to evaluate the potential effects of combined exposures. In this study, we investigated the cytotoxic effects of the combined exposure to two PBDEs and two PCBs in a human neuronal cell line. 2,2',4,4'-Tetrabromodiphenyl ether, 2,2',4,4',5-pentabromodiphenyl ether, PCB-126 (3,3',4,4',5-pentachlorobiphenyl; a dioxin-like PCB), and PCB-153 (2,2',4,4',5,5'-hexachlorobiphenyl; a non-dioxin-like PCB) were chosen, because their concentrations are among the highest in human tissues and the environment. The results suggest that the nature of interactions is related to the PCB structure. Mixtures of PCB-153 and both PBDEs had a prevalently synergistic effect. In contrast, mixtures of each PBDE congener with PCB-126 showed additive effects at threshold concentrations, and synergistic effects at higher concentrations. These results emphasize the concept that the toxicity of xenobiotics may be affected by possible interactions, which may be of significance given the common coexposures to multiple contaminants. © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012.
    No preview · Article · Apr 2014 · Environmental Toxicology
  • Lucio G. Costa · Gennaro Giordano · Marina Guizzetti

    No preview · Article · Nov 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Quercetin is a common flavonoid polyphenol which has been shown to exert neuroprotective actions in vitro and in vivo. Though quercetin has antioxidant properties, it has been suggested that neuroprotection may be ascribed to its ability of inducing the cell's own defense mechanisms. The present study investigated whether quercetin could increase the levels of paraoxonase 2 (PON2), a mitochondrial enzyme expressed in brain cells, which has been shown to have potent antioxidant properties. PON2 protein, mRNA, and lactonase activity were highest in mouse striatal astrocytes. Quercetin increased PON2 levels, possibly by activating the JNK/AP-1 pathway. The increased PON2 levels induced by quercetin resulted in decreased oxidative stress and ensuing toxicity induced by two oxidants. The neuroprotective effect of quercetin was significantly diminished in cells from PON2 knockout mice. These findings suggest that induction of PON2 by quercetin represents an important mechanism by which this polyphenol may exert its neuroprotective action.
    Full-text · Article · Jun 2013 · Neurochemical Research
  • G Giordano · L Tait · C E Furlong · T B Cole · T J Kavanagh · L G Costa
    [Show abstract] [Hide abstract]
    ABSTRACT: Paraoxonase 2 (PON2), a member of a gene family that also includes PON1 and PON3, is expressed in most tissues, including the brain. In mouse brain, PON2 levels are highest in dopaminergic areas (e.g. striatum), and are higher in astrocytes than in neurons. PON2 is primarily located in mitochondria and exerts a potent antioxidant effect, protecting mouse CNS cells against oxidative stress. The aim of this study was to characterize PON2 expression and functions in the brains of male and female mice. Levels of PON2 (protein, mRNA, and lactonase activity) were higher in brain regions and cells of female mice. Astrocytes and neurons from male mice were significantly more sensitive (by 3-4-fold) to oxidative stress-induced toxicity than the same cells from female mice. Glutathione levels did not differ between genders. Importantly, no significant gender differences in susceptibility to the same oxidants were seen in cells from PON2(-/-) mice. Treatment with estradiol induced a time- and concentration-dependent increase in the levels of PON2 protein and mRNA in male (4.5-fold) and female (1.8-fold) astrocytes, which was dependent on activation of estrogen receptor alpha. In ovariectomized mice, PON2 protein and mRNA were decreased to male levels in brain regions and in liver. Estradiol protected astrocytes from wild-type mice against oxidative stress-induced neurotoxicity, but did not protect cells from PON2(-/-) mice. These results suggest that PON2 is a novel major intracellular factor that protects CNS cells against oxidative stress, and confers gender-dependent susceptibility to such stress. The lower expression of PON2 in males may have broad ramifications for susceptibility to diseases involving oxidative stress, including neurodegenerative diseases.
    No preview · Article · Jan 2013 · Free Radical Biology and Medicine
  • [Show abstract] [Hide abstract]
    ABSTRACT: Domoic acid (DomA) is a potent marine neurotoxin. By activating AMPA/kainate receptors, DomA induces oxidative stress-mediated apoptotic cell death in neurons. The effect of prolonged (10 day) exposure to a low, non-toxic concentration (5 nM) of DomA on acute (intermediate concentration) neurotoxicity of this toxin was investigated in cerebellar granule neurons (CGNs) from wild-type mice and mice lacking the glutamate cysteine ligase (GCL) modifier subunit (Gclm(-/-)). CGNs from Gclm(-/-) mice have very low glutathione (GSH) levels and are very sensitive to DomA toxicity. In CGNs from wild-type mice, prolonged exposure to 5 nM DomA did not cause any overt toxicity, but reduced oxidative stress-mediated apoptotic cell death induced by exposure to an intermediate concentration (100 nM for 24 h) of DomA. This protection was not observed in CGNs from Gclm(-/-) mice. Prolonged DomA exposure increased GSH levels in CGNs of wild-type, but not of Gclm(-/-) mice. Levels of GCLC (the catalytic subunit of GCL) protein and mRNA were increased in CGNs of both mouse strains, while levels of GCLM protein and mRNA, activity of GCL, and levels of GCL holoenzyme were only increased in CGNs of wild-type mice. Chronic DomA exposure also protected wild-type CGNs from acute toxicity of other oxidants. The results indicate that CGNs from Gclm(-/-) mice, which are already more sensitive to DomA toxicity, are unable to up-regulate their GSH levels. As Gclm(-/-) mice may represent a model for a common human polymorphism in GCLM, such individuals may be at particular risk for DomA-induced neurotoxicity.
    No preview · Article · Jan 2013 · Toxicological Sciences

  • No preview · Article · Jan 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Paraoxonase (PON1) is an A-esterase capable of hydrolyzing the active metabolites (oxons) of a number of organophosphorus (OP) insecticides such as parathion, diazinon and chlorpyrifos. PON1 activity is highest in liver and in plasma. Human PON1 displays two polymorphisms in the coding region (Q192R and L55M) and several polymorphisms in the promoter and the 3'-UTR regions. The Q192R polymorphism imparts differential catalytic activity toward some OP substrates, while the polymorphism at position -108 (C/T) is the major contributor of differences in the levels of PON1 expression. Both contribute to determining an individual's PON1 "status". Animal studies have shown that PON1 is an important determinant of OP toxicity. Administration of exogenous PON1 to rats or mice protects them from the toxicity of specific OPs. PON1 knockout mice display a high sensitivity to the toxicity of diazoxon and chlorpyrifos oxon, but not of paraoxon. In vitro catalytic efficiencies of purified PON(192) alloforms for hydrolysis of specific oxon substrates accurately predict the degree of in vivo protection afforded by each isoform. Evidence is slowly emerging that a low PON1 status may increase susceptibility to OP toxicity in humans. Low PON1 activity may also contribute to the developmental toxicity and neurotoxicity of OPs, as shown by animal and human studies.
    Full-text · Article · Jul 2012 · Toxicology
  • Source
    Gennaro Giordano · Lucio G Costa
    [Show abstract] [Hide abstract]
    ABSTRACT: The developing central nervous system is often more vulnerable to injury than the adult one. Of the almost 200 chemicals known to be neurotoxic, many are developmental neurotoxicants. Exposure to these compounds in utero or during childhood can contribute to a variety of neurodevelopmental and neurological disorders. Two established developmental neurotoxicants, methylmercury and lead, and two classes of chemicals, the polybrominated diphenyl ether flame retardants and the organophosphorus insecticides, which are emerging as potential developmental neurotoxicants, are discussed in this paper. Developmental neurotoxicants may also cause silent damage, which would manifest itself only as the individual ages, and may contribute to neurodegenerative diseases such as Parkinson's or Alzheimer's diseases. Guidelines for developmental neurotoxicity testing have been implemented, but there is still room for their improvement and for searching and validating alternative testing approaches.
    Preview · Article · Jun 2012
  • Gennaro Giordano · Lucio G Costa
    [Show abstract] [Hide abstract]
    ABSTRACT: Neurite outgrowth is a fundamental event in brain development, as well as in regeneration of damaged neurons. Astrocytes play a major role in neuritogenesis, by expressing and releasing factors that facilitate neurite outgrowth, such as extracellular matrix proteins, and factors that can inhibit neuritogenesis, such as the chondroitin sulfate proteoglycan neurocan. In this unit we describe a noncontact co-culture system of hippocampal neurons and cortical (or hippocampal) astrocytes for measurement of neurite outgrowth. Hippocampal pyramidal neurons are plated on glass coverslips, which are inverted onto an astrocyte feeder layer, allowing exposure of neurons to astrocyte-derived factors without direct contact between these two cell types. After co-culture, neurons are stained and photographed, and processes are assessed morphologically using Metamorph software. This method allows exposing astrocytes to various agents before co-culture in order to assess how these exposures may influence the ability of astrocytes to foster neurite outgrowth.
    No preview · Article · May 2012 · Current protocols in toxicology
  • L.G. Costa · M. Guizzetti · D. Pizzurro · G. Giordano
    [Show abstract] [Hide abstract]
    ABSTRACT: Neurite outgrowth in CNS neurons is primarily dependent on extracellular matrix proteins that are produced and released by glial cells. One of these proteins, fibronectin, together with laminin, plays a pivotal role in neuronal differentiation mediated by astrocytes. When co-cultured together, astrocytes interact with neurons and promote their differentiation; interference with this interaction can indirectly affect neuronal development. Cholinergic agonists, through activation of muscarinic M3 receptors in astrocytes increase their ability to promote neuritogenesis, largely by increasing the expression and release of fibronectin and laminin. This effect is mediated by activation of multiple signal transduction pathways in astrocytes. Ethanol, a known developmental neurotoxicant, inhibits muscarinic receptor signal transduction at the level of phosphor-lipase D, and antagonizes the astrocyte-mediated neuritogenic effect on hippocampal neurons. Similar effects of muscarinic agonists and of ethanol have been also seen in the in vitro hippocampal slice. Thyroid hormones (T3) can increase fibronectin expression in astrocytes, and hence increase neuritogenesis in cerebellar neurons. Conversely, astrocytes from hypothyroid animals, a condition know to cause profound developmental neurotoxicity, have decreased levels of fibronectin and decreased ability to promote neuritogenesis. The metal manganese, also increasingly recognized as a developmental neurotoxicant, accumulates in astrocytes, where it causes oxidative stress. Upon exposure to manganese, astrocytes have a decreased expression /release of fibronectin, and a decreased ability to foster neuritogenesis in hippocampal neurons. These effects are due to manganese-induced oxidative stress and are antagonized by antioxidants. Other oxidants, such as hydrogen peroxide or 2,3-dimethoxy-1,4-naphtoquinone, cause similar effects on astrocytic fibronectin and on neuritogenesis. Additionally, certain organophosphorus insecticides, such as diazinon and its oxygen analog diazoxon, which can also cause oxidative stress, are also capable of altering fibronectin expression and neuritogenesis. These studies indicate that interference with fibronectin expression/release in astrocytes greatly affects their ability to exert neuritogenic effects on developing neurons.
    No preview · Article · Jan 2012
  • Lucio G. Costa · Gennaro Giordano · Marina Guizzetti
    [Show abstract] [Hide abstract]
    ABSTRACT: This chapter discusses the in vitro approaches to developmental neurotoxicity. Neurotoxicity can be defined as any adverse effect on the chemistry, structure or function of the nervous system, induced by chemical or physical influences. A substance is defined as neurotoxic when it or its metabolites produce adverse effects as a result of direct interactions with the nervous system. The specific effects of the chemical on the nervous system can be detected in the course of standard toxicity testing such as developmental neurotoxicity (DNT) testing. The development of alternative in vitro models such as mammalian cells in culture or non-mammalian model systems could serve as tools for neurotoxicity and developmental neurotoxicity testing. Several issues need to be considered while choosing the mammalian cells in culture model for neurotoxicity testing such as limited lifespan, variability among different cultures, problems of purity and the need of particular attention during preparation and culturing etc. However, the in vitro systems are amenable and very useful for mechanistic studies at the cellular and molecular level and also provide a rapid, relatively inexpensive, and reliable way for screening chemicals for potential neurotoxicity and/or developmental neurotoxicity. A number of alternative non-mammalian models such as Zebrafish and C. elegans have been used to assess environmental toxicity. Finally, a battery of alternative testing models for neurotoxicity is not expected to fully replace current in vivo animal testing without efforts by regulatory agencies, institutions, foundations and private entities worldwide.
    No preview · Article · Dec 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In an in vitro co-culture system of astrocytes and neurons, stimulation of cholinergic muscarinic receptors in astrocytes had been shown to cause neuritogenesis in hippocampal neurons, and this effect was inhibited by ethanol. The present study sought to confirm these earlier findings in a more complex system, in vitro rat hippocampal slices in culture. Exposure of hippocampal slices to the cholinergic agonist carbachol (1mM for 24h) induced neurite outgrowth in hippocampal pyramidal neurons, which was mediated by activation of muscarinic M3 receptors. Specifically, carbachol induced a >4-fold increase in the length of the longest neurite, and a 4-fold increase in the length of minor neurites and in the number of branches. Co-incubation of carbachol with ethanol (50mM) resulted in significant inhibition of the effects induced by carbachol on all parameters measured. Neurite outgrowth in CNS neurons is dependent on various permissive factors that are produced and released by glial cells. In hippocampal slices carbachol increased the levels of two extracellular matrix protein, fibronectin and laminin-1, by 1.6-fold, as measured by Western blot. Co-incubation of carbachol with ethanol significantly inhibited these increases. Carbachol-induced increases in levels of extracellular matrix proteins were antagonized by a M3 muscarinic receptor antagonist. Furthermore, function-blocking fibronectin or laminin-1 antibodies antagonized the effect of carbachol on neurite outgrowth. These results indicate that in hippocampal slices stimulation of muscarinic M3 receptors induces neurite outgrowth, which is mediated by fibronectin and laminin-1, two extracellular matrix proteins released by astrocytes. By decreasing fibronectin and laminin levels ethanol prevents carbachol-induced neuritogenesis. These findings highlight the importance of glial-neuronal interactions as important targets in the developmental neurotoxicity of alcohol.
    Full-text · Article · Aug 2011 · Biochemical pharmacology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Glutathione (GSH) is a major player in cellular defense against oxidative stress. Deletion of the modifier subunit of glutamate cysteine ligase (GCLM), the first and the rate-limiting enzyme in the synthesis of GSH, leads to significantly lower GSH levels in all tissues including the brain. GCLM-knockout (Gclm(-/-)) mice may thus represent a model for compromised response to oxidative stress amenable to in vitro and in vivo investigations. In order to determine whether the diminished GSH content would by itself cause behavioral alterations, a series of behavioral tests were carried out comparing young adult Gclm(-/-) with wild-type mice. Tests included the rotarod, acoustic startle reflex and prepulse inhibition of the startle reflex, open field behavior, and the platform reversal variant of the Morris Water Maze. Results showed no differences between Gclm(-/-) and wild-type mice in any of the neurobehavioral tests. However, more subtle alterations, or changes which may appear as animals age, cannot be excluded.
    Full-text · Article · Apr 2011 · Journal of Toxicology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Astrocytes have been shown to release factors that affect various aspects of neuronal development. We have previously shown that the acetylcholine analog carbachol, by activating muscarinic M(3) receptors in rat astrocytes, increases their ability to promote neuritogenesis in hippocampal neurons. This effect was mediated by an increased expression and release by astrocytes of several permissive factors, a most relevant of which was fibronectin. In the present study we investigated the signal transduction pathways involved in these effects of carbachol in astrocytes. Results show that multiple pathways are involved in the effects of carbachol on astrocyte-mediated increases in fibronectin expression and neuritogenesis. These include the phospholipase D pathway, leading to sequential activation of protein kinase C (PKC) ζ, p70S6 kinase and nuclear factor-κB; the phosphoinositide-3 kinase pathway; and the PKC ε pathway leading to activation of mitogen activated protein kinase. These pathways were shown to mediate the effect of carbachol on neurite outgrowth as well as the increased expression of fibronectin, further substantiating the important role of the latter in astrocyte-mediated neuritogenesis. Interference with these signaling pathways would be expected to impair astrocyte-neurons communication leading to impaired neuronal development.
    Full-text · Article · Mar 2011 · European journal of pharmacology
  • Source
    Gennaro Giordano · Toby B Cole · Clement E Furlong · Lucio G Costa
    [Show abstract] [Hide abstract]
    ABSTRACT: The aims of this study were to characterize the expression of paraoxonase 2 (PON2) in mouse brain and to assess its antioxidant properties. PON2 levels were highest in the lung, intestine, heart and liver, and lower in the brain; in all tissues, PON2 expression was higher in female than in male mice. PON2 knockout [PON2(-/-)] mice did not express any PON2, as expected. In the brain, the highest levels of PON2 were found in the substantia nigra, the nucleus accumbens and the striatum, with lower levels in the cerebral cortex, hippocampus, cerebellum and brainstem. A similar regional distribution of PON2 activity (measured by dihydrocoumarin hydrolysis) was also found. PON3 was not detected in any brain area, while PON1 was expressed at very low levels, and did not show any regional difference. PON2 levels were higher in astrocytes than in neurons isolated from all brain regions, and were highest in cells from the striatum. PON2 activity and mRNA levels followed a similar pattern. Brain PON2 levels were highest around birth, and gradually declined. Subcellular distribution experiments indicated that PON2 is primarily expressed in microsomes and in mitochondria. The toxicity in neurons and astrocytes of agents known to cause oxidative stress (DMNQ and H(2)O(2)) was higher in cells from PON2(-/-) mice than in the same cells from wild-type mice, despite similar glutathione levels. These results indicate that PON2 is expressed in the brain, and that higher levels are found in dopaminergic regions such as the striatum, suggesting that this enzyme may provide protection against oxidative stress-mediated neurotoxicity.
    Full-text · Article · Feb 2011 · Toxicology and Applied Pharmacology
  • Source
    Lucio G Costa · Gennaro Giordano · Clement E Furlong
    [Show abstract] [Hide abstract]
    ABSTRACT: Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated enzyme displaying esterase and lactonase activity. PON1 hydrolyzes several organophosphorus (OP) insecticides and nerve agents, a number of exogenous and endogenous lactones, and metabolizes toxic oxidized lipids of low density lipoproteins (LDL) and HDL. As such, PON1 plays a relevant role in determining susceptibility to OP toxicity, cardiovascular diseases and several other diseases. Serum PON1 activity in a given population can vary by at least 40-fold. Most of this variation can be accounted for by genetic polymorphisms in the coding region (Q192R, L55M) and in the promoter region (T-108C). However, exogenous factors may also modulate PON1 activity and/or level of expression. This paper examines various factors that have been found to positively modulate PON1. Certain drugs (e.g. hypolipemic and anti-diabetic compounds), dietary factors (antioxidants, polyphenols), and life-style factors (moderate alcohol consumption) appear to increase PON1 activity. Given the relevance of PON1 in protecting from certain environmental exposure and from cardiovascular and other diseases, there is a need for further mechanistic, animal, and clinical research in this area, and for consideration of possible alternative strategies for increasing the levels and activity of PON1.
    Preview · Article · Feb 2011 · Biochemical pharmacology
  • Source
    Lucio G Costa · Gennaro Giordano
    [Show abstract] [Hide abstract]
    ABSTRACT: Polybrominated diphenyl ether (PBDE) flame retardants have become ubiquitous environmental pollutants. The relatively higher body burden in toddlers and children has raised concern for their potential developmental neurotoxicity, which has been suggested by animal studies, in vitro experiments, and recent human epidemiological evidence. While lower brominated PBDEs have been banned in several countries, the fully brominated decaBDE (BDE-209) is still utilized, though manufacturers will discontinue production in the U.S.A. in 2013. The recent decision by the U.S. Environmental Protection Agency to base the reference dose (RfD) for BDE-209 on a developmental neurotoxicity study has generated some controversy. Because of its bulky configuration, BDE-209 is poorly absorbed and does not easily penetrate the cell wall. Its acute and chronic toxicities are relatively low, with the liver and the thyroid as the primary targets, though there is some evidence of carcinogenicity. A few animal studies have indicated that BDE-209 may cause developmental neurotoxicity, affecting motor and cognitive domains, as seen for other PBDEs. Limited in vivo and in vitro studies have also evidenced effects of BDE-209 on thyroid hormone homeostasis and direct effects on nervous cells, again similar to what found with other lower brominated PBDEs. In contrast, a recent developmental neurotoxicity study, carried out according to international guidelines, has provided no evidence of adverse effects on neurodevelopment, and this should be considered in a future re-evaluation of BDE-209. While estimated exposure to BDE-209 in children is believed to be several orders of magnitude below the most conservative RfD proposed by the USEPA, questions remain on the extent and relevance of BDE-209 metabolism to lower brominated PBDEs in the environment and in humans.
    Preview · Article · Jan 2011 · NeuroToxicology
  • L.G. Costa · G. Giordano · M. Guizzetti
    [Show abstract] [Hide abstract]
    ABSTRACT: Signal transduction is a key process to transmit information from the extracellular milieu, and to elicit changes in the biological activity of target cells. Several cell signaling pathways can be targeted by neurotoxicants and developmental neurotoxicants. This chapter focuses on the interactions of ethanol, a known human developmental neurotoxicant, with signal transduction pathways stimulated by acetylcholine through activation of muscarinic receptors. It shows how initial observations in vivo, upon developmental exposure to ethanol, have been followed-up by a series of studies in cell culture systems which have allowed the discoveries that ethanol, by interfering with muscarinic signaling in astroglial cells, inhibits their proliferation and their ability to foster neuronal differentiation. Such effects of alcohol may be related to microencephaly and abnormal neuronal development, two hallmarks of the fetal alcohol syndrome.
    No preview · Article · Jan 2011 · Neuromethods
  • Gennaro Giordano · Lucio G Costa
    [Show abstract] [Hide abstract]
    ABSTRACT: Apoptosis is a natural process occurring during the development of central nervous system resulting in the elimination of neurons that may have formed faulty synapses. Apoptosis can also be triggered by deprivation of growth factors or by exposure to a variety of endogenous or exogenous compounds. Several methods exist to assess apoptosis in neuronal cells. The choice of a particular method for apoptosis detection is dependent on the cell system, the nature of the toxin or toxicant, the type of information being sought, and, finally, on technical limitations. In this chapter, we describe techniques to evaluate apoptosis in primary neuronal cell cultures based on the evaluation of three criteria: cell morphology, biochemical changes, and DNA degradation. To draw correct conclusions regarding the mode of cell death, a combination of some of the methods mentioned above should be used.
    No preview · Article · Jan 2011 · Methods in molecular biology (Clifton, N.J.)
  • Lucio G Costa · Gennaro Giordano · Marina Guizzetti
    [Show abstract] [Hide abstract]
    ABSTRACT: This introductory Chapter provides a brief overview of the field of neurotoxicology and of the role played by in vitro approaches in investigations on mechanisms of neurotoxicity and of developmental neurotoxicity, and in providing suitable models for neurotoxicity screening.
    No preview · Article · Jan 2011 · Methods in molecular biology (Clifton, N.J.)

Publication Stats

2k Citations
150.76 Total Impact Points

Institutions

  • 2005-2014
    • University of Washington Seattle
      • Department of Environmental and Occupational Health Sciences
      Seattle, Washington, United States
    • Sapienza University of Rome
      • Department of Physiology and Pharmacology "Vittorio Erspamer"
      Roma, Latium, Italy
  • 2013
    • Environmental and Occupational Health Sciences Institute
      Edison, New Jersey, United States
  • 2011
    • Università degli studi di Parma
      • Department of Clinical and Experimental Medicine
      Parma, Emilia-Romagna, Italy